Showing posts with label power supply. Show all posts
Showing posts with label power supply. Show all posts

Circuit LED Bar Off Indicator Schematic Diagrams

Circuit LED Bar Off Indicator schematics Circuit Electronics,
The simple indicator presented in this article may be combined, in principle, with any circuit that contains an LED bar display driven by a Type LM3914 IC. It ensures that an LED will light when all LEDs driven by the LM3914 are out. This prevents one drawing the erroneous conclusion that, since all the LEDs are out, the circuit is switched off. The circuit then continues to draw current, which, especially if it is battery powered, costs unnecessary money, apart from other considerations. The LED in the monitor draws a current of only 1 mA. When the LEDs forming the bar, D1–D10 are all out, there is no potential difference across R3, so that T1 is off and T2 is on.

This results in T3, in conjunction with R5 and the internal reference voltage of IC1, to form a current source that causes a constant current to flow through D11 so that the diode lights. When on of diodes D1–D10 lights, a potential difference ensues across R3, which causes T1 to come on. This results in T2 being switched off so that there is no collector current through T3. Consequently, there is no feedback at the emitter of T3, so that the current through R2 rises appreciably. The current through R2 determines the current through the LEDs in the bar. Therefore, when T3 is enabled, the current through R2, and thus the total current in the circuit, is reduced considerably.

Schematics for LED Bar Off Indicator Circuit Electronics
read more "Circuit LED Bar Off Indicator Schematic Diagrams"

Circuit Low Battery Indicator II Schematic Diagrams

Circuit Low battery Indicator II schematics Circuit Electronics,
This circuit indicates the remaining battery life bAy varying the duty cycle and flash rate of an LED as the battery voltage decreases. In fact, the circuit actually indicates five battery conditions: (1) a steady glow assures indicates that the battery is healthy; (2) a 2Hz flicker (briefly off) indicates that the battery is starting to show age; (3) a 5Hz 50% duty-cycle flash is a warning that you should have a spare battery on hand; (4) a brief flicker on at a 2Hz rate indicates the battery's last gasp; and (5) when the LED is continuously off, it's time to replace the battery. IC1 is wired as an oscillator/comparator, with a nominal fixed voltage reference of about 1.5V on its pin 2 (inverting) input (actually, it varies between about 1.7V and 1.4V depending on the hysteresis provided via R6).

This reference voltage is derived from a voltage divider consisting of resistors R4 R5, which are connected across the 5V rail derived from regulator REG1, and feedback resistor R6. Similarly, IC1's pin 3 input (non-inverting) is connected to a voltage divider consisting of R1 R2 which are across the 9V battery. Using the component values shown, the circuit will switch LED1 from being continuously on to flash mode when the 9V battery drops to about 6.5V. Subsequently, LED1 is continuously off for battery voltages below 5.5V.

Naturally, you can tweak the resistor values in the divider network for different voltage thresholds as desired. In operation, the circuit oscillates only when the sampled battery voltage (ie, the voltage on pin 3) is between the upper and lower voltage thresholds set on pin 2. Capacitor C3 provides the timing. Above and below these limits, IC1 simply functions as a comparator and holds LED1 continuously on or off. Finally, to precisely set the "dead-battery" threshold, make R4 adjustable to offset the variations in regulator tolerance.

Schematics for Low battery Indicator II Circuit Electronics
read more "Circuit Low Battery Indicator II Schematic Diagrams"

Circuit Low Battery Indicator I Schematic Diagrams

Circuit Low battery Indicator I schematics Circuit Electronics,
Here is the circuit diagram of low battery indicator from silicon chip electronics. This simple circuit lights LED1 when the battery voltage drops below the setting set by trimpot VR1. In effect, VR1 and associated resistors bias Q1 on which holds Q2 and the LED off. When the voltage drops below the set value, Q1 turns off, allowing Q2 to turn on and light the LED. The circuit is suitable for nominal battery voltages up to 12V.

Schematics for Low battery Indicator I Circuit Electronics
read more "Circuit Low Battery Indicator I Schematic Diagrams"

Circuit Earth Fault Indicator Schematic Diagrams

Circuit Earth Fault Indicator schematics Circuit Electronics,
The security of many electrical devices depends today on the availability of an earthed mains outlet. We should remember that these are connected to the frame or to the metal housing of the equipment and so it routes to the protective earth (PE) connections. In this setup, mains voltage, however small, will cause the differential circuit breaker to trip. The circuit breaker is part of any modern electrical installation. This type of security device may however become defective due to common corrosion as we have seen many times on various older household devices, as well as on construction sites.

Actually, since these devices are frequently in wet conditions, the screw and/or lug used to connect the earth wire to the device frame corrodes gradually and ends up breaking or causing a faulty contact. The remedy is then worse than the problem because the user, thinking that he/she is protected by earth, does not take special precautions and risks his/her life. However, all that’s needed is an extremely simple system to automatically detect any break in the earth connection; so simple that we ask ourselves why it is not already included as part of all factory production for appliances that carry any such risk, as we have discussed above.

We propose it as a project for you to build using this schematic. The live wire (L) of the mains power supply is connected to diode D1 which ensures simple half-wave rectification which is sufficient for our use. The current which is available is limited to a very low value by resistor R2. If the appliance earth connection to which our circuit is installed is efficient, this current is directed to earth via resistor R1 and the rest of the circuit is inactive due to insufficient power. If the earth connection is disconnected, the current supplied by D1 and R2 charges up capacitor C1.

When the voltage at the terminals of the capacitor reaches about 60 volts, neon indicator light La1 is turned on and emits a flashing light which discharges capacitor C1 at the same time. This phenomenon is reproduced indefinitely as long as the earth connection has not been restored, and the neon light continues to flash to attract attention in case of danger. Building the project is not particularly difficult but, since it is a project aimed at human safety, we must take the maximum of precautions concerning the choice of components utilised. Therefore, C1 must have an operating voltage of at least 160 volts while R2 must be a 0.5-watt resistor, not for reasons of power dissipation, but in order to maintain the voltage.

The neon light can be any type, possibly used, or it may be part of an indicator light to make it easier to attach to the protected appliance. In the second case, we must obviously get rid of its series resistor which would prevent proper operation here. During installation of the circuit in the appliance to be protected, we should also clearly mark Live (L) and Neutral (N) (for example, seek Live with a simple screwdriver) because inverting these two wires at this point will disable proper operation. The final point, which is self-evident considering the principle used here: the earth connection for our setup must be hooked up to the frame of the appliance to be protected at a different point than where the normal earth wire is connected.

Schematics for Earth Fault Indicator Circuit Electronics
read more "Circuit Earth Fault Indicator Schematic Diagrams"

Circuit Battery Indicator Circuit For The Car Schematic Diagrams

Circuit battery Indicator Circuit For The Car schematics Circuit Electronics,
This i-TRIXX circuit can prevent a whole lot of trouble for those of you who go on holiday in a caravan. It would be a significant damper on your holiday spirit when you are ready to leave the camping and discover that you have used your battery too much and that you are now unable to start the car. This annoyance can be avoided if you were warned early enough by an illuminated LED when the charge in the battery threatens to become too low.

A quiet, out of the way, in the countryside camping is what modern people look for to be able to unwind. However, we do not want to be completely deprived of all our creature comforts. We don’t cope very long without electric light or a TV! And in the absence of a mains power outlet the car battery has to function as energy source, with the risk that later on there will be too little left to start the engine. The little circuit presented here gives you an early warning when the battery voltage (and therefore its stored energy) threatens to become too low.

 The setting of T1 and T2 determines whether LED D2 will light up when the battery voltage drops below a certain level. Junction FET T3 is used as a current source in order to try to keep the current through the LED as constant as possible. In this way the indicator remains lit even when the battery is in a state of very deep discharge (< 4 volt). The LED is a good low-current type that is still very bright at a very small current (1 to 2 mA). Voltage divider R1 and R2 has been calculated such that T1 will start to conduct when the voltage of the battery is greater than 12 V.

If you think this threshold is too high (or: if you think that you can still start your car with a lower battery voltage), then you can reduce the value of R2 or replace it with a 50-k preset (connected as an adjustable resistor). When T1 conducts, the base current to T2 is interrupted and the collector of T2 will become high through R4. In this state T3 does not conduct and the LED is off. When the battery voltage drops below 12 V, T1 will block and T2 will start to conduct. R5 is now connected to ground via T2 which turns T3 into a current source of about 2 mA that drives the LED.

There is, of course, a transition region during which the current through the LED slowly increases; after all, T1 and T2 do not switch with in?nite gain! In our prototype the LED changed from fully off to fully on at a voltage variation from 12 to 11 V. As a bonus, a partially illuminated LED gives a rough indication as to how much the voltage actually is. Diode D1 prevents the circuit from inadvertently giving up the ghost if the circuit is connected incorrectly to the battery (reverse polarity). In practice, because of variations in the specifications of the transistors, the threshold and the current level through the LED can be different.

Test the circuit thoroughly before using it. If you want a brighter indicator, you can increase the current through the LED by replacing T3 with a BF245B or BF245C. When the LED is off, the current through the circuit is barely 30 µA at a battery voltage of 14.4 V. With the LED is on and at a battery voltage of about 10 V, the current consumption is about 2 mA. Even with an illuminated LED, the circuit is not likely to be the cause of a flat battery. Even a good quality battery will have a self discharge rate which is many times greater than the maximum current consumption of this circuit!

Schematics for battery Indicator Circuit For The Car Circuit Electronics
read more "Circuit Battery Indicator Circuit For The Car Schematic Diagrams"

Circuit Battery Voltage Indicator Schematic Diagrams

Circuit battery Voltage Indicator schematics Circuit Electronics,
Monitors battery voltage, Three-LED Display

Connecting this circuit to the battery of your vehicle, you will always know at a glance the approximate voltage available. An indication of battery voltage is useful to the motorist for monitoring the battery's capacity to deliver current, and as a check on the efficiency of the dynamo or alternator. Threshold voltages of the Leds are set by means of two Zener Diodes (D6 D10) plus two further Diodes wired in series (D4, D5 and D8, D9 respectively) adding a step of about 1.3V to the nominal Zener voltage.

Circuit diagram:

battery Voltage Indicator Circuit diagram


R1 = 1k
R2 = 100K
R3 = 1k
R4 = 3.3K
R5 = 3.3K
R6 = 1k
R7 = 3.3K
R8 = 3.3K
Q1 = BC547
Q2 = BC547
Q3 = BC557
D1 = Red Led
D2 = Amber Led
D3 = 1N4148
D4 = 1N4148
D5 = 1N4148
D6 = BZX79C10
D7 = Green Led
D8 = 1N4148
D9 = 1N4148
D10 = BZX79C12

  • Red LED D1 is on when battery voltage is 11.5V or less. This indicates a low battery charge.
  • Amber LED D2 is on when battery voltage is comprised in the 11.5 - 13.5V range. This indicates that the battery is good if the motor is off. When motor is running, this indicates no charge from dynamo or alternator.
  • Green LED D7 is on when battery voltage is 13.5V or more. This indicates a normal condition when motor is running and dynamo or alternator is charging.

Schematics for battery Voltage Indicator Circuit Electronics
read more "Circuit Battery Voltage Indicator Schematic Diagrams"

Circuit Remote Operated Home Appliances Circuit Schematic Diagrams

Circuit Remote Operated Home Appliances Circuit schematics Circuit Electronics,
Here is the circuit diagram of Remote Operated Home Appliances or Remote controlled Home appliances. Connect this circuit to any of your home appliances (lamp, fan, radio, etc) to make the appliance turn on/off from a TV, VCD, VCR, Air Conditioner or DVD remote control. The circuit can be activated from up to 10 meters. It is very easy to build and can be assembled on a veroboard or a general-purpose pcb.


R1 = 220K
R2 = 330R
R3 = 1K
R4 = 330R
R5 = 47R
C1 = 100uF-16V
C2 = 100nF-63V
C3 = 470uF-16V
D1 = 1N4007
D2 = Red LED
D3 = Green LED
Q1 = BC558
Q2 = BC548
IR = TSOP1738
IC1 = CD4017
RL1 = Relay 5V DC

Circuit Operation:

The 38kHz infrared rays generated by the remote control are received by IR receiver module TSOP1738 of the circuit. Pin 1 of TSOP1738 is connected to ground, pin 2 is connected to the power supply through R5 and the output is taken from pin 3. The output signal is amplified by Q1. The amplified signal is fed to clock pin 14 of decade counter IC CD4017 (IC1). Pin 8 of IC1 is grounded, pin 16 is connected to vcc and pin 3 is connected to D2 (Red LED), which glows to indicate that the appliance is ‘off.’

The output of IC1 is taken from its pin 2. D3 connected to pin 2 is used to indicate the ‘on’ state of the appliance. Q2 connected to pin 2 of IC1 drives relay RL1. D1 acts as a freewheeling diode. The appliance to be controlled is connected between the pole of the relay and neutral terminal of mains. It gets connected to live terminal of AC mains via normally opened (N/O) contact when the relay energizes. If you want to operate a DC 12 volt relay then use a regulated DC 12 volt power supply for DC 12 volt Relay and remember that the circuit voltage not be exceeded more than DC 5 volts

Schematics for Remote Operated Home Appliances Circuit Circuit Electronics
read more "Circuit Remote Operated Home Appliances Circuit Schematic Diagrams"

Circuit Long-Range IR Transmitter Schematic Diagrams

Circuit Long-Range IR Transmitter schematics Circuit Electronics,
Most of the IR remotes work reliably within a range of 5 metres. The circuit complexity increases if you design the IR transmitter for reliable operation over a longer range, say, 10 metres. To double the range from 5 metres to 10 metres, you need to increase the transmitted power four times. If you wish to real i se a highly directional IR beam (very narrow beam), you can suitably use an IR laser pointer as the IR signal source.

The laser pointer is readily available in the market. However, with a very narrow beam from the laser pointer, you have to take extra care, lest a small jerk to the gadget may change the beam orientation and cause loss of contact. Here is a simple circuit that will give you a pretty long range. It uses three infrared transmitting LEDs (IR1 through IR3) in series to increase the radiated power.

Further, to increase the directivity and so also the power density, you may assemble the IR LEDs inside the reflector of a torch. For increasing the circuit efficiency, a MOSFET (BS170) has been used, which acts as a switch and thus reif a transistor were used. To avoid any dip during its ‘on’/‘off’ operations, a 100µF reservoir capacitor C2 is used across the battery supply. Its advantage will be more obvious when the IR transmitter is powered by ordinary batteries.

Capacitor C2 supplies extra charge during ‘switching on’ operations. As the MOSFET exhibits large capacitance across gate-source terminals, a special drive arrangement has been made using npn-pnp Darl ington pair of BC547 and BC557 (as emitter followers), to avoid distortion of the gate drive input. Data (CMOS-compatible) to be transmitted is used for modulating the 38 kHz frequency generated by CD4047 (IC1). However, in the circuit shown here, tactile switch S1 has been used for modulating and transmitting the IR signal.

Assemble the circuit on a general-purpose pcb. Use switch S2 for power ‘on’/‘off’ control. Commercially available IR receiver modules (e.g., TSOP1738) could be used for efficient reception of the transmitted IR signals.

Schematics for Long-Range IR Transmitter Circuit Electronics
read more "Circuit Long-Range IR Transmitter Schematic Diagrams"

Circuit IR Remote Control Receiver Schematic Diagrams

Circuit IR Remote control Receiver schematics Circuit Electronics,
With many audio systems consisting of separate units, you’ll often find that due to economic reasons only the amplifier has a remote control receiver module. The control signals are then sent to the other units using patch cables. The tuner and CD player, for example, won’t have a built-in receiver module. When the tuner from such a system is bought separately it can therefore not be used directly with a remote control, which is a big disadvantage in practice. The only way in which this can be accomplished is to connect an IR receiver to the input used by the patch cable. And that is exactly what this circuit is for. In practice it is not always clear which signal should be used and what its polarity should be.

IR Remote <a href='' title='Control Circuit' target='_blank'>control</a> Receiver Circuit <a href=''>diagram</a>
IR Remote control Receiver Circuit diagram

However, it will most likely be a demodulated signal. For these reasons we’ve combined a standard IR receiver module and two inverters. The first inverter also functions as a buffer, since the output of the module has a high impedance. The output of the receiver module is active low, so the first inverter outputs a non-inverting signal. The second inverter inverts this signal again. Jumper JP1 is used to select which of the signals is presented at the output. R2 protects the output from short circuits or possible over-loading of the electronics in the equipment it’s driving (for example when the input circuit uses 3 V logic).

R1/C1 suppress any possible supply spikes. Batteries are suitable for the power supply, because the circuit only takes about 1 mA. With a set of four rechargeable batteries with a capacity of 1800 mAh the circuit can function continuously for 2.5 months. Four NiMH cells and a charger are therefore perfect for the power supply. If you can be sure that the circuit will always be switched off when not in use, you could also use three ordinary alkaline batteries (AA cells). Because of their slightly larger capacity they will probably last for about half a year. When making your choice you should of course keep in mind that rechargeables are better for the environment.

Schematics for IR Remote control Receiver Circuit Electronics
read more "Circuit IR Remote Control Receiver Schematic Diagrams"

Circuit IR–S/PDIF Receiver Schematic Diagrams

Circuit IR–S/PDIF Receiver schematics Circuit Electronics,
This simple circuit proves to achieve surprisingly good results when used with the IR–S/PDIF transmitter described elsewhere in this site. The IR receiver consists of nothing more than a photodiode, a FET and three inverter gates used as amplifier. The FET is used as an input amplifier and filter, due to its low parasitic capacitance. This allows R1 to have a relatively high resistance, which increases the sensitivity of the receiver. The bandwidth is primarily determined by photo-diode D1, and with a value of 2k2 for R1, it is always greater than 20 MHz. The operating current of the FET is intentionally set rather high (around 10 mA) using R2, which also serves to ensure adequate bandwidth. The voltage across R2 is approximately 0.28–0.29 V.

The combination of L1 and R3 forms a high-pass filter that allows signals above 1 MHz to pass. L1 is a standard noise-suppression choke. From this filter, the signal is fed to two inverters configured as amplifiers. The third and final inverter (IC1c) generates a logic-level signal. This 74HCU04 provides so much gain that there is a large risk of oscillation, particularly when the final stage is loaded with a 75-Ω coaxial cable. In case of problems (which will depend heavily on the construction), it may be beneficial to add a separate, decoupled buffer stage for the output, which will also allow the proper output impedance (75 Ω) to be maintained in order to prevent any reflections.

When building the circuit, make sure that the currents from IC1 do not flow through the ground path for T1. If necessary, use two separate ground planes and local decoupling. Furthermore, the circuit must be regarded as a high-frequency design, so it’s a good idea to provide the best possible screening between the input and the output. With the component values shown in the schematic, the range is around 1.2 metres without anything extra, which is not especially large. However, the range can easily be extended by using a small positive lens (as is commonly done with standard IRDA modules). In our experiments, we used an inexpensive magnifying glass, and once we got the photodiode positioned at the focus after a bit of adjustment.

IR–S/PDIF Receiver Circuit <a href=''>diagram</a>
IR–S/PDIF Receiver Circuit diagram

We were able to achieve a range of 9 metres using the same transmitter (with a sampling frequency of 44.1 kHz). This does require the transmitter and receiver to be physically well aligned to each other. As you can see, a bit of experimenting certainly pays off here! It may also be possible to try other types of photodiode. The HDSL-5420 indicated in the schematic has a dome lens, but there is a similar model with a flat-top case (HDSL-5400). It has an acceptance angle of 110°, and with the same level of illumination, it generates nearly four times as much current.

The current consumption of the circuit is 43 mA with no signal and approximately 26 mA with a signal (fs = 44.1 kHz) That is rather high for battery operation, but it can handled quite readily using a pair of rechargeable NiMH cells. Incidentally, the circuit will also work at 4.5 V and even 3 V. If a logic-level output is needed, C3 at the output can be replaced by a jumper. Finally, there is one other thing worth mentioning. With the HSDL-5400 that we had to play with, the cathode marking (a dark-blue line on the side below one lead) was on the wrong side (!). So if you want to be sure that the diode is fitted properly, it’s a good idea to measure the DC voltage across R1, which should be practically zero.

Schematics for IR–S/PDIF Receiver Circuit Electronics
read more "Circuit IR–S/PDIF Receiver Schematic Diagrams"

Circuit IR–S/PDIF Transmitter Schematic Diagrams

Circuit IR–S/PDIF Transmitter schematics Circuit Electronics,
The best-known ways to transmit a digital audio signal (S/PDIF) are to use a standard 75Ω coaxial cable or Toslink optical modules with matching optical cable. Naturally, it can happen that for whatever reason, you cannot (or don’t wish to) run a cable between the equipment items in question. With a wireless solution, you have the choice of a wideband RF transmitter or an optical variant. Here we describe a simple optical transmitter. The matching IR-S/PDIF receiver is described else-where in this website. Although designing such an IR transmitter/receiver system does not have to be particularly difficult, in practice there are still several obstacles to be overcome. For one thing, the LEDs must have sufficient optical switching speed to properly pass the high frequencies of the S/PDIF signal, and they must also produce sufficient light intensity to deliver a noise-free signal at the receiver over a reasonable distance.

IR–S/PDIF Transmitter Circuit <a href=''>diagram</a>
IR–S/PDIF Transmitter Circuit diagram

At a sampling frequency of 48 kHz, it’s necessary to be able to transfer pulses only 163 ns wide! The LEDs selected here (Agilent HSDL-4230) have optical rise and fall times of 40 ns, which proved to be fast enough in practice. With a beam angle of only 17°, they can also provide high light intensity. The downside is that the combination of transmitter and receiver is highly directional, but the small beam angle also has its advantages. It means that fewer LEDs are necessary, and there is less risk of continuously looking into an intense infrared source. The circuit is essentially built according to a standard design. The S/PDIF signal received on K1 is amplified by IC1a to a level that is adequate for further use. JP1 allows you to use a Toslink module as the signal source if desired. JP1 is followed by a voltage divider, which biases IC1b at just below half of the supply voltage.

This causes the output level of the buffer stage driving switching transistor T1 to be low in the absence of a signal, which in turn causes IR LEDs D1 and D2 to remain off. The buffer stage is formed by the remaining gates of IC1. This has primarily been done with an eye to elevated capacitive loading, in the unlikely event that you decide to use more LEDs. A small DMOS transistor (BS170) is used for T1; it is highly suitable for fast switching applications. Its maximum switching time is only 10 ns (typically 4 ns). Getting D1 and D2 to conduct is not a problem. However, stopping D1 and D2 from conducting requires a small addition to what is otherwise a rather standard IR transmitter stage, due to the presence of parasitic capacitances.

<a href=''  title='Power Supply Circuit' target='_blank'>power supply</a> IR–S/PDIF Transmitter Circuit <a href=''>diagram</a>This consists of R7 and R8, which are connected in parallel with the LEDs to quickly discharge the parasitic capacitors. The drawback of this addition is naturally that it somewhat increases the current consumption, but with the prototype this proved to be only around 10 percent. With no signal, the circuit consumes only 25 mA. With a signal, the output stage is responsible for nearly all of the current consumption, which rises to approximately 170 mA. In order to prevent possible interference at such high currents and avoid degrading the signal handling of the input stage, everything must be well decoupled. For instance, the combination of L2, C4 and C5 is used to decouple IC1.

The circuit around T1 must be kept as compact as possible and placed as close as possible to the voltage regulator, in order to prevent the generation of external interference or input interference. If necessary, place a noise-suppression choke (with a decoupling capacitor to ground) in series with R9. Note that this choke must be able to handle 0.3 A, and if you use additional stages, this rating must be increased proportionally. The circuit should preferably be fitted into a well-screened enclosure, and it is recommended to provide a mains filter for the 230-V input of the power supply. For the sake of completeness, we have included a standard power supply in the schematic diagram, but any other stabilised 5-V supply could be used as well. LED D3 serves as the obligatory mains power indicator.

Schematics for IR–S/PDIF Transmitter Circuit Electronics
read more "Circuit IR–S/PDIF Transmitter Schematic Diagrams"

Circuit 100W Inverter Circuit Schematic Schematic Diagrams

Circuit 100W Inverter Circuit Schematic schematics Circuit Electronics,
Here is a 100 Watt inverter circuit using minimum number of components. I think it is quite difficult to make a decent one like this with further less components.Here we use CD 4047 IC from Texas Instruments for generating the 100 Hz pulses and four 2N3055 transistors for driving the load. The IC1 Cd4047 wired as an astable multivibrator produces two 180 degree out of phase 100 Hz pulse trains.

These pulse trains are preamplified by the two TIP122 transistors.The out puts of the TIP 122 transistors are amplified by four 2N3055 transistors (two transistors for each half cycle) to drive the inverter transformer.The 220V AC will be available at the secondary of the transformer. Nothing complex just the elementary inverter principle and the circuit works great for small loads like a few bulbs or fans.If you need just a low cost inverter in the region of 100 W, then this is the best.


P1 = 250K
R1 = 4.7K
R2 = 4.7K
R3 = 0.1R-5W
R4 = 0.1R-5W
R5 = 0.1R-5W
R6 = 0.1R-5W
C1 = 0.022uF
C2 = 220uF-25V
D1 = BY127
D2 = 9.1V Zener
Q1 = TIP122
Q2 = TIP122
Q3 = 2N3055
Q4 = 2N3055
Q5 = 2N3055
Q6 = 2N3055
F1 = 10A Fuse
IC1 = CD4047
T1 = 12-0-12V
Transformr Connected in Reverse

  • A 12 V car battery can be used as the 12V source.
  • Use the POT R1 to set the output frequency to50Hz.
  • For the transformer get a 12-0-12 V , 10A step down transformer.But here the 12-
  • 0-12 V winding will be the primary and 220V winding will be the secondary.
  • If you could not get a 10A rated transformer , don’t worry a 5A one will be just
  • enough. But the allowed out put power will be reduced to 60W.
  • Use a 10 A fuse in series with the battery as shown in circuit.
  • Mount the IC on a IC holder.
  • Remember,this circuit is nothing when compared to advanced PWM
  • inverters.This is a low cost circuit meant for low scale applications.

Design tips:
  1. The maximum allowed output power of an inverter depends on two factors.The
  2. maximum current rating of the transformer primary and the current rating of the driving
  3. transistors.
  4. For example ,to get a 100 Watt output using 12 V car battery the primary current will be
  5. ~8A ,(100/12) because P=VxI.So the primary of transformer must be rated above 8A.
  6. Also here ,each final driver transistors must be rated above 4A. Here two will be
  7. conducting parallel in each half cycle, so I=8/2 = 4A .
  8. These are only rough calculations and enough for this circuit.

Schematics for 100W Inverter Circuit Schematic Circuit Electronics
read more "Circuit 100W Inverter Circuit Schematic Schematic Diagrams"

Circuit Cheap 12V to 220V Inverter Schematic Diagrams

Circuit Cheap 12V to 220V Inverter schematics Circuit Electronics,
Even though today’s electrical appliances are increasingly often self-powered, especially the portable ones you carry around when camping or holidaying in summer, you do still sometimes need a source of 230 V AC - and while we’re about it, why not at a frequency close to that of the mains? As long as the power required from such a source remains relatively low - here we’ve chosen 30 VA - it’s very easy to build an inverter with simple, cheap components that many electronics hobbyists may even already have.

Though it is possible to build a more powerful circuit, the complexity caused by the very heavy currents to be handled on the low-voltage side leads to circuits that would be out of place in this summer issue. Let’s not forget, for example, that just to get a meager 1 amp at 230 VAC, the battery primary side would have to handle more than 20 ADC!. The circuit diagram of our project is easy to follow. A classic 555 timer chip, identified as IC1, is configured as an astable multivibrator at a frequency close to 100 Hz, which can be adjusted accurately by means of potentiometer P1.
As the mark/space ratio (duty factor) of the 555 output is a long way from being 1:1 (50%), it is used to drive a D-type flip-flop produced using a CMOS type 4013 IC. This produces perfect complementary square-wave signals (i.e. in antiphase) on its Q and Q outputs suitable for driving the output power transistors. As the output current available from the CMOS 4013 is very small, Darlington power transistors are used to arrive at the necessary output current. We have chosen MJ3001s from the now defunct Motorola (only as a semi-conductor manufacturer, of course!) which are cheap and readily available, but any equivalent power Darlington could be used.

These drive a 230 V to 2 × 9 V center-tapped transformer used ‘backwards’ to produce the 230 V output. The presence of the 230 VAC voltage is indicated by a neon light, while a VDR (voltage dependent resistor) type S10K250 or S07K250 clips off the spikes and surges that may appear at the transistor switching points. The output signal this circuit produces is approximately a square wave; only approximately, since it is somewhat distorted by passing through the transformer. Fortunately, it is suitable for the majority of electrical devices it is capable of supplying, whether they be light bulbs, small motors, or power supplies for electronic devices.

R1 = 18k?
R2 = 3k3
R3 = 1k
R4,R5 = 1k?5
R6 = VDR S10K250 (or S07K250)
P1 = 100 k potentiometer
C1 = 330nF
C2 = 1000 µF 25V
T1,T2 = MJ3001
IC1 = 555
IC2 = 4013
LA1 = neon light 230 V
F1 = fuse, 5A
TR1 = mains transformer, 2x9V 40VA (see text)
4 solder pins

Note that, even though the circuit is intended and designed for powering by a car battery, i.e. from 12 V, the transformer is specified with a 9 V primary. But at full power you need to allow for a voltage drop of around 3 V between the collector and emitter of the power transistors. This relatively high saturation voltage is in fact a ‘shortcoming’ common to all devices in Darlington configuration, which actually consists of two transistors in one case. We’re suggesting a pcb design to make it easy to construct this project; as the component overlay shows, the pcb only carries the low-power, low-voltage components.

The Darlington transistors should be fitted onto a finned anodized aluminum heat-sink using the standard insulating accessories of mica washers and shouldered washers, as their collectors are connected to the metal cans and would otherwise be short-circuited. An output power of 30 VA implies a current consumption of the order of 3 A from the 12 V battery at the ‘primary side’. So the wires connecting the collectors of the MJ3001s [1] T1 and T2 to the transformer primary, the emitters of T1 and T2 to the battery negative terminal, and the battery positive terminal to the transformer primary will need to have a minimum cross-sectional area of 2 mm2 so as to minimize voltage drop.

The transformer can be any 230 V to 2 × 9 V type, with an E/I iron core or toroidal, rated at around 40 VA. Properly constructed on the board shown here, the circuit should work at once, the only adjustment being to set the output to a frequency of 50 Hz with P1. You should keep in minds that the frequency stability of the 555 is fairly poor by today’s standards, so you shouldn’t rely on it to drive your radio-alarm correctly – but is such a device very useful or indeed desirable to have on holiday anyway? Watch out too for the fact that the output voltage of this inverter is just as dangerous as the mains from your domestic power sockets.

So you need to apply just the same safety rules! Also, the project should be enclosed in a sturdy ABS or diecast so no parts can be touched while in operation. The circuit should not be too difficult to adapt to other mains voltages or frequencies, for example 110 V, 115 V or 127 V, 60 Hz. The AC voltage requires a transformer with a different primary voltage (which here becomes the secondary), and the frequency, some adjusting of P1 and possibly minor changes to the values of timing components R1 and C1 on the 555.

Schematics for Cheap 12V to 220V Inverter Circuit Electronics
read more "Circuit Cheap 12V to 220V Inverter Schematic Diagrams"

Circuit IC Controlled Emergency Light With Charger Circuit Schematic Diagrams

Circuit IC controlled Emergency Light With Charger Circuit schematics Circuit Electronics,
Here is the circuit diagram of IC controlled Emergancy Light With Charger or simply 12V to 220V AC inverter circuit. The circuit shown here is that of the IC controlled emergency light. Its main features are: automatic switching-on of the light on mains failure and battery charger with over-charge protection. When mains is absent, relay RL2 is in de-energized state, feeding battery supply to inverter section via its N/C contacts and switch S1.

The inverter section comprises IC2 (NE555) which is used in stable mode to produce sharp pulses at the rate of 50 Hz for driving the MOSFETs. The output of IC2 is fed to gate of MOSFET (Q4) directly while it is applied to MOSFET (Q3) gate after inversion by transistor Q2. Thus the power amplifier built around MOSFETs Q3 and Q4 functions in push-pull mode. The output across secondary of transformer T2 can easily drive a 230-volt, 20-watt fluorescent tube. In case light is not required to be on during mains failure, simply flip switch S1 to off position. battery overcharge preventer circuit is built around IC1 (LM308).

Its non-inverting pin is held at a reference voltage of approximately 6.9 volts which is obtained using diode D5 (1N4148) and 6.2-volt zener D6. The inverting pin of IC1 is connected to the positive terminal of battery. Thus when mains supply is present, IC1 comparator output is high, unless battery voltage exceeds 6.9 volts. So transistor Q1 is normally forward biased, which energises relay RL1. In this state the battery remains on charge via N/O contacts of relay RL1 and current limiting resistor R2. When battery voltage exceeds 6.9 volts (overcharged condition), IC1 output goes low and relay RL1 gets de-energised, and thus stops further charging of battery. MOSFETs Q and Q4 may be mounted on suitable heat sinks.


R1 = 1K
R2 = 10R-1W
R3 = 820R
R4 = 1K
R5 = 10K
R6 = 1K
R7 = 100R
R8 = 1K

C1 = 1000uF-25V
C2 = 10uF-16V
C3 = 0.01uF

D1 = 1N4007
D2 = 1N4007
D3 = 1N4007
D4 = 1N4007
D5 = 1N4148
D6 = 6.2V Zener
D7 = 1N4007
D8 = 1N4148

Q1 = SL100
Q2 = 2N2222
Q3 = IRF840
Q4 = IRF840

Integrated Circuits
IC1 = LM308
IC2 = NE555

S1 = SPST switch
B1 = 6V-4A battery
B2 = 6V-4A battery
TI = 220V AC Primary to 0V-6V 250mA Secondary Transformer
T2 = 4.5V-0V-4.5V 5A Primary To 230V AC Secondary Transformer

Schematics for IC controlled Emergency Light With Charger Circuit Circuit Electronics
read more "Circuit IC Controlled Emergency Light With Charger Circuit Schematic Diagrams"

Circuit Fully Automatic Emergency Light Schematic Diagrams

Circuit Fully Automatic Emergency Light schematics Circuit Electronics,
This simple automatic emergency light has the following advantages over conventional emergency lights:
  1. The charging circuit stops automatically when the battery is fully charged. So you can leave the emergency light connected to AC mains overnight without any fear.
  2. Emergency light automatically turns on when mains fails. So you don’t need a torch to locate it.
  3. When mains power is available, emergency light automatically turns off.
The circuit can be divided into inverter and charger sections. The inverter section is built around timer NE555, while the charger section is built around 3-terminal adjustable regulator LM317. In the inverter section, NE555 is wired as an astable multivibrator that produces a 15kHz squarewave. Output pin 3 of IC 555 is connected to the Darlington pair formed by transistors SL100 (T1) and 2N3055 (T2) via resistor R4.

The Darlington pair drives ferrite transformer X1 to light up the tubelight. For fabricating inverter transformer X1, use two EE ferrite cores (of 25×13×8mm size each) along with plastic former. Wind 10 turns of 22 SWG on primary and 500 turns of 34 SWG wire on secondary using some insulation between the primary and secondary. To connect the tube-light to ferrite transformer X1, first short both terminals of each side of the tube-light and then connect to the secondary of X1. (You can also use a Darlington pair of transistors BC547 and 2N6292 for a 6W tube-light with the same transformer.)
When mains power is available, reset pin 4 of IC 555 is grounded via transistor T4. Thus, IC1 (NE555) does not produce square-wave and emergency light turns off in the presence of mains supply. When mains fails, transistor T4 does not conduct and reset pin 4 gets positive supply though resistor R3. IC1(NE555) starts producing square wave and tube-light turns on via ferrite transformer X1. In the charger section, input AC mains is stepped down by transformer X2 to deliver 9V-0-9V AC at 500mA. Diodes D1 and D2 rectify the output of the transformer. Capacitors C3 and C4 act as filters to eliminate ripples.

The unregulated DC voltage is fed to IC LM317 (IC2). By adjusting preset VR1, the output voltage can be adjusted to deliver the charging voltage. When the battery gets charged above 6.8V, zener diode ZD1 conducts and regulator IC2 stops delivering the charging voltage. Assemble the circuit on a general-purpose pcb and enclose in a cabinet with enough space for the battery and switches. Connect a 230V AC power plug to feed charging voltage to the battery and make a 20W tube outlet in the cabinet to switch on the tube-light.

Schematics for Fully Automatic Emergency Light Circuit Electronics
read more "Circuit Fully Automatic Emergency Light Schematic Diagrams"

Circuit 12V Dimmer Schematic Diagrams

Circuit 12V Dimmer schematics Circuit Electronics,
A dimmer is quite unusual in a caravan or on a boat. Here we describe how you can make one. So if you would like to be able to adjust the mood when you’re entertaining friends and acquaintances, then this circuit enables you to do so. Designing a dimmer for 12 V is tricky business. The dimmers you find in your home are designed to operate from an AC voltage and use this AC voltage as a fundamental characteristic for their operation. Because we now have to start with 12 V DC, we have to generate the AC voltage ourselves.
We also have to keep in mind that we’re dealing with battery-powered equipment and have to be frugal with energy. The circuit that we finally arrived at can easily drive 6 lamps of 10 W each. Fewer are also possible, of course. In any case, the total current has to be smaller than 10 A. L1 and S1 can be adapted to suit a smaller current, if required. Note that the whole circuit will also work from 6 V.

Schematics for 12V Dimmer Circuit Electronics
read more "Circuit 12V Dimmer Schematic Diagrams"

Circuit Traffic Lights For Model Cars Or Model Railways Schematic Diagrams

Circuit Traffic Lights For Model Cars Or Model Railways schematics Circuit Electronics,
Kids these days seem to have most things you see in the toy shops, so if you have a son or grandson who has a collection of cars, here is something he will really appreciate. And it will be really special as you will be giving something made by you - a set of traffic lights for his cars. This traffic light circuit uses a 555 timer IC as the master timer. The 220kO timing resistor and 10µF capacitor control the timing pulses, giving a period of about three seconds. The 3-second output pulses are used to clock a 4017 decade counter whose outputs directly drive the green, orange and red LEDs. To obtain a longer time for the red and green lights compared with the orange light, two outputs are ORed using 1N4148 diodes for the red and green LEDs, while the orange is driven by one output only.

This gives about 6 seconds for the red and green LEDs and 3 seconds for the orange. When power is first applied, the RC network connected to pins 1 and 15 of IC2 resets the 4017 and the green LED cycle begins. The orange and red cycles follow and at the end of the red cycle, pin 1 will go high to reset the 4017 to start the green cycle all over again. You can experiment with the cycle times by adjusting the 220kO resistor or by combining more or less 4017 outputs to achieve different ON times for the three LEDs.

 The circuit is designed to be powered by a 9V battery and this is the maximum voltage that is recommended. This is because the LEDs are directly driven by the 4017 with no current limiting resistor being used. The 4017 naturally limits the current that it can supply to 15mA. An extension of this project would be to make a second set of lights for the cross traffic. Here you would use the same 555 as a master timer for both sets of lights (otherwise chaos would ensue) and a separate 4017 to drive the three extra LEDs. Of course, you would have to take care and ensure that green and orange outputs on each set of lights correspond with red on the other!

Schematics for Traffic Lights For Model Cars Or Model Railways Circuit Electronics
read more "Circuit Traffic Lights For Model Cars Or Model Railways Schematic Diagrams"

Circuit Stroboscope Uses White LEDs Schematic Diagrams

Circuit Stroboscope Uses White LEDs schematics Circuit Electronics,
This stroboscope circuit uses 16 high-brightness white LEDs in a torch housing and it provides a signal output to a frequency counter to provide a rev counter display. IC1 is 555 astable multivibrator and it provides a signal to IC2, a 4046 phase lock loop. IC2 and the two 4017 Johnson decade counters, IC3 IC4, make up a frequency multiplier with a factor of 60 (IC3 divides by 10 while IC4 divides by six). The multiplied frequency is taken from the VCO (voltage controlled oscillator) output of IC2 at pin 4 and this becomes the signal to drive the frequency counter. Its output reading is the speed of the shaft being measured in RPM. A narrow positive-going pulse train to turn on Q1 and the LEDs is obtained from pin 3 of IC4. This has the advantage of giving a much sharper marker line (on the shaft) illumination. The unit can be powered from a 12V 500mA plugpack or a suitable battery.

Editorial note:
At switching frequencies above 100Hz (6000 RPM) the persistence of the phosphor of the white LEDs will make the circuit ineffective. To run the circuit at much higher frequencies, substitute LEDs without phosphors; eg, red, green or yellow or a mixture of these).
Schematics for Stroboscope Uses White LEDs Circuit Electronics
read more "Circuit Stroboscope Uses White LEDs Schematic Diagrams"

Circuit Inductive LED Timing Light Schematic Diagrams

Circuit Inductive LED Timing Light schematics Circuit Electronics,
A useful timing strobe can be constructed using high-brightness LEDs and a few common components. Ignition pulses from the number 1 cylinder high-tension lead are used to trigger the circuit via a home-made inductive pickup. Transistors Q1 Q2 buffer and amplify the pulses from the pickup, which then drive the inputs of three Schmitt-trigger inverters (IC1a, IC1c IC1f). Each positive pulse at the inverter inputs causes a low pulse at their outputs, forward-biasing D2 and immediately discharging the 6.8nF capacitor. When the capacitor is discharged, the inputs of the second bank of three inverters (IC1b, IC1d IC1e) see a logic low level, so their outputs go high, driving Q3 into conduction and powering the LED array. After the pulse ends, the IC1a, IC1c IC1f inverter outputs return high, reverse biasing D2.


However, it takes some time for the 6.8nF capacitor to charge to the logic high threshold voltage of the inverters’ inputs, effectively stretching the initial pulse width and lighting the LEDs for the required amount of time. The pickup can be salvaged from an old Xenon timing light or made up from a "C" type ferrite or powered iron core large enough to fit around a HT lead. Some experimentation will be required to determine the number of turns required to achieve reliable triggering. About 100 turns of light-gauge wire proved sufficient on the prototype. A cleat is used to close the magnetic path around the lead and is held in place with a large battery clip. Miniature screened microphone cable can be used to connect the pickup to the circuit, to prevent interference from other sources.

Schematics for Inductive LED Timing Light Circuit Electronics
read more "Circuit Inductive LED Timing Light Schematic Diagrams"

Circuit Luxury Car Interior Light Schematic Diagrams

Circuit Luxury Car Interior Light schematics Circuit Electronics,
This circuit is much more modest, but certainly still worth the effort. It provides a high quality interior light delay. This is a feature that is included as standard with most modern cars, although the version with an automatic dimmer is generally only found in the more expensive models. With this circuit it is possible to upgrade second hand and mid-range models with an interior light delay that slowly dims after the door has been closed. The dimming of the light is implemented by means of pulse-width modulation. This requires a triangle wave oscillator and a comparator.

Two opamps are generally required to generate a good triangle wave, but because the waveform doesn’t have to be accurate, we can make do with a single opamp. This results in the circuit around IC1.A, a relaxation oscillator supplying a square wave output. The voltage at the inverting input has more of a triangular shape. This signal can be used as long as we do not put too much of a load on it. The high impedance input of IC1.B certainly won’t cause problems in this respect. This opamp is used as a comparator and compares the voltage of the triangular wave with that across the door switch. When the door is open, the switch closes and creates a short to the chassis of the car.

The output of the opamp will then be high, causing T1 to conduct and the interior light will turn on. When the door is closed the light will continue to burn at full strength until the voltage across C2 reaches the lower side of the triangle wave (about 5 V). The comparator will now switch its output at the same rate of the triangle wave (about 500 Hz), with a slowly reducing pulse width, which results in a slowly reducing brightness of the interior light. R8 and C3 protect the circuit from voltage spikes that may be induced by the fast switching of the light. The delay and dimming time can be adjusted with R6 and C2. Smaller values result in shorter times. You can vary the dimming time on its own by adjusting R1, as this changes the amplitude of the triangle wave across C1.

R7 limits the discharge current of C2; if this were too big,it would considerably reduce the lifespan of the capacitor. There is no need to worry about reducing the life of the car battery. The circuit consumes just 350 µA when the lamp is off and a TLC272 is used for the dual opamp. A TL082 will take about 1 mA. These values won’t discharge a normal car battery very quickly; the self-discharge is probably many times higher. It is also possible to use an LM358, TL072 or TL062 for IC1. R8 then needs to have a value between 47 Ω and 100 Ω. Since T1 is always either fully on or fully off, hardly any heat is generated.

At a current of 2 A the voltage drop across the transistor is about 100 mV, giving rise to a dissipation of 200 mW. This is such a small amount that no heatsink is required. The whole circuit can therefore remain very compact and should be easily fitted in the car, behind the fabric of the roof for example.

R1,R2,R6 = 120kΩ
R3,R4 = 100kΩ
R5 = 470Ω
R7 = 100Ω
R8 = 220Ω
C1 = 10nF
C2 = 100µF-25V
C3 = 10µF-25V
T1 = BUZ10
IC1 = TLC272CP

Schematics for Luxury Car Interior Light Circuit Electronics
read more "Circuit Luxury Car Interior Light Schematic Diagrams"