Showing posts with label schematics. Show all posts
Showing posts with label schematics. Show all posts

Schematics Water Level Indicator With 7-Segment Display PCB

Circuits available for indicating water level is usually consist of LEDs to indicate the liquid level. But this circuit uses a 7-segment LED display instead of normal LED's for numeric display of water level.Moreover, a buzzer is used to alert you of water overflowing from the tank. The circuit shows the water level by displaying L, H and F for low, half and full, respectively. You can use this circuit for water tank motor control or a stand alone circuit.

Circuit Diagram of Water Level Indicator With 7-Segment Display : Click  to enlarge

This circuit uses Five sensors to sense water levels in the tank. When the tank is empty, the input
pins of IC 7404 (NOT gate IC) are pulled high via a 1M ohm resistor. So it outputs a low voltage. As water starts filling the tank, a low voltage is available at the input pins of the gate and it outputs a high voltage.

When the water in the tank rises to touch the low level sensor, pin 5 of gate N3 gets a low voltage and results in high output at pin 6. Pin 6 of the gate is connected to pin 10 of gate N9, so pin 10 also goes high. Now as both pins 9 and 10 of gate N9 are high, its output pin 8 also goes high. As a result, positive supply is applied to DIS3 and it shows ‘L’ indicating low level of water in the tank.
Similarly all levels are displayed in the numeric display.

Assemble the circuit on a strip board and enclose within a non corrosive material. Use a 5V regulated supply for powering the circuit.
read more "Schematics Water Level Indicator With 7-Segment Display PCB"

Schematics Temperature Controller For PC PCB


Our computer may often heated up due to long use or the hot climate, temperature controllers are necessary.  You need to do a temperature measurement to ensure that the computer is work within the allowed range. To reduce pc temperature, here is circuit diagram of a simple temperature controller for your personal computer (PC) based on a temperature sensor LM35 and a comparator CA3140. The circuit turns off the PC when the temperature of the computer increases beyond a particular, optimum temperature value. This avoids overheating of some integrated chips (IC) that may not be able to dissipate heat fast enough.

Circuit Diagram of PC Temperature Controller  : Click  to enlarge


For this pc temperature controller , the cut off temperature is assumed to be 55 degree Celsius. The circuit contains a temperature sensor LM35 and comparator. ( The threshold value of 55 can be adjusted using VR1 potentiometer actually varies the comparator reference voltage). The R1,R2 and ZD1(9V,0.5W) used for stabilizing the output of the rectifier. In normal temperature, the comparator produces an error voltage which triggers the triac that give supply to PC (load). Whenever the PC temperature go beyond the threshold value, the comparator output become low, causes to shut down the triac hence the PC.

  • Assemble the circuit on any general-purpose PCB.
  • You can use this as a PC expansion card if properly assembled.
read more "Schematics Temperature Controller For PC PCB"

Schematics Battery Powered Soldering Iron PCB

As we know, traditional soldering irons uses mains ac supply to get heated but this will be annoying when we want to use it in the absence of mains supply. Here is a simple inexpensive circuit which we can call it as a inverter for normal soldering iron (25W, 30W, 35W). The circuit can drive the soldering iron in the absence of power supply from mains. This cold soldering iron circuit uses eight transistors and few resistors and capacitors. The battery should be a 12 Volt 7Ah.

Circuit Diagram of Battery Powered Soldering Iron : Click  to enlarge

Each BC547 transitors - T1 and T2 form an astable multivibrator that produces 50Hz signal. The output of it drives the pnp darlington driver stage transistors formed by transistors T3-T5 and T6 utilizing BC558 and BD140. Two 2N3055 power transistors will perform push-pull operation whose output drives the transformer X1 which drives the soldering iron.When you power the circuit using switch S1, transformer X1 produces 230V AC at its primary terminal. This voltage can be used to heat your soldering iron. The battery backup will depend upon the power rating of the iron.


  • Assemble the circuit on a general PCB and enclose within a cabinet with battery.
  • Use suitable heat-sinks for transistors T5 through T8.
read more "Schematics Battery Powered Soldering Iron PCB"

Schematics Ultracapacitors Vs Batteries PCB

This post will explain the advantages and disadvantages of ordinary lead-acid battery and the new age Ultracapacitors.

Most of our vehicles are fitted with lead-acid battery to meet intermittent loads to driver such as horn, turn indicators, brake light etc. The battery life is about two years if maintained properly. After the it's life is over we have to replace it by the same one usually costly one. If not, the driver may have compromise the safty features.

Ultracapacitors, with their short charging time, are ideally suited for the intermittent loads and have a usable life exceeding (over 500,000 cycles) that of vehicle. By experiments conducted in motor cycles clearly indicates that the ultracapacitors meets the requirement of powering the extra loads of the vehicle such as horn and turn lights. Ultracapacitors store energy electrostatically, which can be done at very fast charging rate.

Advantages Of Utracapacitor

  • High expected lifetime, more than 10 years
  • Ultracapacitors have high power density
  • Short charge-discharge time
  • Maintenance free
  • Wide operating temperature
  • Less weight
  • Short circuit protection
  • No special charge control needed
  • More than 90% efficiency

Disadvantages of Ultracapacitors
  • Low energy density
  • Self discharge is high

Advantages of Batteries
  • High energy density
  • Low self discharge
  • Discharge curve is flat

Disadvantages of Batteries
  • Long charging time
  • Low life time is about 1-3 years
  • Charge-discharge life of 1000 cycles approx.
  • Charging control is necessary
  • Bulky and high weight
  • Over scaling needed for some applications

read more "Schematics Ultracapacitors Vs Batteries PCB"

Schematics Design And Simulate Circuits Using Proteus PCB

In this post I will tell you about a software that provides you the advanced circuit design and simulation core for your home use or in professional field. Yes, I am telling about the wonderful Proteus software. Proteus is a by product of  labcenter electronics which contains two sub software's in it.

1. ISIS Schematic Capture

This software is for design and simulation of mainly digital circuits. The normal schematic designing using computer can often be the most time consuming element of the exercise. The Proteus ISIS is created for professionals by the following advantages.

  • Runs ON windows Xp and 2K
  • Automatic wire routing and dot placement/removal
  • Easily select components
  • rearrange pin assignments
  • Bill of Materials option
  • One click simulation
  • Netlist outputs to suit all popular PCB layout tools

The Proteus design suite can also be used as a schematic drawing software for documentation also. Did you notice the circuits posted on CircuitSector? The circuits published here was actually designed using proteus. So it can be used as a web publisher for circuit diagrams.

By the way ISIS can be used for analog as well as digital simulation. It is well worked with almost all basic microcontrollers such as 8051 and microprocessors.

2. ARES PCB layout

By the name indicated, this is a powerful PCB layout software called Advanced Routing and Editing Software.This wonderful program offers netlist based PCB design complete with a suite of high performance design automation tools.


  • High speed performance using Hardware acceleration
  • True layer transparency
  • 32 bit high-precision database
  • Integration with ISIS
  • Automatic Back-Annotation of component renumbering, pin-swap and gate-swap changes
  • 2D-drawing with vast symbol library

For students, this software will help you in your studies,how? you can simulate your circuits on Proteus which you tried and failed on your actual electronic circuits lab in collage. So download a virtual electronics lab to your computer now.

read more "Schematics Design And Simulate Circuits Using Proteus PCB"

Schematics 20W Low cost Emergency Light PCB

Here is simple circuit of a simple emergency light that can be constructed without much pain. The components of this circuit are 2 transistors, a transformer, 20 Watt fluorescent tube, 6V battery and some resistors and pots. the transformer of this emergency lamp doing a job of stepping up the voltage induced at its primary coil. But we use a 12-0-12 center tapped transformer for this purpose and the usual primary is used as secondary.

Circuit Diagram of 20W Low cost Fluorescent Light : Click  to enlarge

The circuit as well as the working is very simple. The oscillations produced by the 2N 3055, SL 100 transistors are given to the primary of the transformer. The two transistors are connected as Darlington pairs. So that supply voltage is get through the R1 resistor via transformer. We can adjust the oscillating frequency thereby brightness of the flurescent tube by adjusting the 1K potentiometer.
read more "Schematics 20W Low cost Emergency Light PCB"

Schematics Water Tank Controller Circuit PCB

Here is an automatic water tank controller that controls the operation of a water pump through a 12V 10amp relay. When ever the water level of the tank short circuits the points A and B in the circuit diagram, the pump get turned off automatically. This home water pump controller circuit is comparably simple and low cost and can be assembled easily on a common PCB.

Circuit Diagram of Water Pump - Motor Controller : Click  to enlarge


The circuit schematic diagram of the tank controlller is given on the image. Whe the switch S1 in the circuit is pressed, a biasing will get to the transistor Q1 through resistor R1 and the relay will be turned on. So the pump connected on the relay will also switched on. We can place the terminals A and B in the upper side of the water tank. Whenever the water shortcircuits these points, the Q1 transistor will be on and the relay will cuttoff and the motor also turned off.

  • Make sure that all resistors used in the circuit is 1/2 W.
  • The relay power rating can be varied according to the motor ratings.

read more "Schematics Water Tank Controller Circuit PCB"

Schematics Small Surround Sound Decoder

Small Surround Sound Decoder  circuit diagram

This is surround sound decoder. With this circuit, you can divide the 2 channel (R and L channel) stereo output become 4 channel output that are R channel, L channel, Center out and Rear out. This circuit will enrich your audio sound system.

For full explanation about this circuit, please visit this PAGE
read more "Schematics Small Surround Sound Decoder"

Schematic Diagram PC IrDA interface

DIY IR interface

This circuit is also from
Since it is very hard for me to get the infrared interface (TFDU4100), I start to look in the old/damage handphones.
It looks something like this.

Now, you need to remove it using the hot air blower perhaps.

Connecting to motherboard

Please refer to
on how connect this irda module to your motherboard.


Infrared Transceiver Modules

Here are the pin layout and picture of the device.

Pin Description of TFDU4100

Pin Number Function Description I/O Active
1 IRED Anode
IRED anode, should be externally connected
to VCC2 through a current control
2 IRED Cathode
IRED cathode, internally connected to
driver transistor
3 Txd Transmit Data Input 1 High
4 Rxd
Received Data Output, open collector.
No external pull–up or pull–down resistor
is required (20 k. resistor internal to device).
Pin is inactive during transmission.
0 Low
5 NC Do not connect
6 VCC1/SD Supply Voltage / Shutdown
7 SC Sensitivity control 1 High
8 GND Ground
read more "Schematic Diagram PC IrDA interface"

Schematics Temperature Controlled Soldering Iron Circuit PCB

Every technician uses soldering iron in different power rates such as 10W, 20W, 25W, 30W etc. It is very difficult to change the soldering iron each time with specific uses. Here is a solution to this problem by assembling a simple temperature controlled soldering iron circuit which enables you to use your soldering iron in variable power rates from 10w to 35W.

Circuit Diagram of  Temperature Controlled Soldering Iron: Click  to enlarge

The above situation can be achieved by connecting a rotary switch. You should connect the phase line to the blue line represented in the circuit schematics. Also, connect the black wire to the power socket which the soldering iron has to be connected. Supply the neutral line of the soldering iron externally. Actually we adjust the the voltage to the gate terminal of the triac BT 136 so that the we get the output current according to this voltage. This controlls the temperature of the active soldering iron.
read more "Schematics Temperature Controlled Soldering Iron Circuit PCB"

Schematics Microcontroller project PCB




This work includes, GTP USB (not plus or lite) .

The schematic, photos and PCB have been developed by PICMASTERS based on

some valuable works done before.

This programmer supports pic10F, 12F, 16C, 16F, 18F,24Cxx Eeprom.

Unfortunately, it works with only Winpic800 v.355.

We have succesfully tried it with some pics; PIC18F252, 18F2455, 18F2550,

18F2520, 16F84, 16F628 and 24C32 eeprom.

The best and fastest method of pic programming.

All you need (hex file, winpic800, schematic, PCB board in ARES)

are included.

You must program pic18F2550 with hex file by a classical programmer.

circuit schematic. You can see the type and value of the companents.

Download original circuit picture...

The first PCB;double Layout...

second pcb or socket PCB;double layer..


thank's for coming^^

read more "Schematics Microcontroller project PCB"

Schematics Dark Activated Switch Using 741 and BC 109 PCB

Here is a simple but useful switch circuit that will activate a relay when light falls below a particular level. The sensitivity of the light level circuit can be adjusted by VR1 and the relay contacts that may used to drive an external light or buzzer.

The ORP12 photocell works as a light sensor in the circuit. The dark resistance of ORP12 will high as 1M and in light it will be as low as 80 ohm. The 1M preset will give you a selection capability of light sensitiveness to the dark activated switch. The op-amp senses the voltage difference between pins 2 and 3. The control VR1 is adjusted so that the relay is off, the output of the op-amp will be around 2 Volts. When light falls the resistance of the photo cell increases and the difference in input voltage is amplified by the opamp. This cause an increase in the base voltage of the transistor which results in activating the relay and switching action will takes place.

Click on the image to enlarge

You can assemble the circuit on a general purpose PCB and make sure that the relay contacts provide adequate isolation and have ample rating for the load.
read more "Schematics Dark Activated Switch Using 741 and BC 109 PCB"

Schematics Long Range IR Transmitter Circuit PCB

Most of the infrared remotes work on the range below 5 meters. The complexity of the circuit increases when we have to transmit the IR to longer ranges say 10 meters. So you need to multiply the transmitted power into usually four times. This IR transmitter circuit will give you pretty long range.

Circuit Diagram of  Long Range IR Transmitter: Click  to enlarge


 This simple infrared transmitter circuit uses 3 IR transmitter LEDs connected in series to increase the power. The mosfet BS170 which act as a switch, has been used to increase the circuit efficiency. Data (CMOS-compatible) tobe transmitted is used for modulating the 38kHz frequency generated by CD4047 (IC1).


  • Assemble the circuit on a general purpose PCB.
  • Use TSOP1738  IR receiving module for efficient reception.
  • Assemble the IR LEDs in a torch reflector to increase directivity.
read more "Schematics Long Range IR Transmitter Circuit PCB"

Schematics Strobe Light Circuit with Timing PCB

Here is a strobe light circuit which has an option to set the flashing rate. Unlike other circuits here we use a Flash tube that usually use in flash cameras. In ordinary cameras, the flash may be work only after ten or twenty seconds. But in this circuit we can adjust flashing time by adjusting the potentiometer provided in the circuit.

Circuit Diagram of Strobe Light  : Click  to enlarge


1N4007 diodes and the 22/350V capacitors do the job of converting the input AC voltage into DC. This gives the triggering voltage to triac. The potentiometer adjust the voltage through it and this result change in the charging and discharging time of 22/350V capacitors. The output of the triac is connected to the output transformer which enlarges the voltage to drive flash tube.
read more "Schematics Strobe Light Circuit with Timing PCB"

Schematics Simple FM Transmitter

This FM transmitter claimed to be a very good transmitter. This circuit is worked very well since this circuit is actually copied from available electronic kit.
Simple FM Transmitter circuit diagram

Component part:

R1 100K
R2 220K
R3 22R
R4 1K trimmer
R5 1K
R6 56K
R7 1M
R8 1K2
T1 BF244A or BF245A FET
T2 2N3819 FET
T3 BC307/8/9 or BC557/8/9 PNP

D1 Varicap diode (eg. BB119)
D2 1N4148
C1 5pF ceramic
C2 6pF ceramic
C3 15pF ceramic
C4 trimmer cap
C5 15pF ceramic
C6 1nF ceramic
C7 100uF electrolytic
C8 4.7uF electrolytic
C9 100pF ceramic

Frequency range is 100-108 MHz. The circuit is only mono circuit, and accepts an audio input from either a microphone or other source. The input impedance is 1Mohm. The input sensitivity is 5mV and the max input signal is 10mV. The transmitted signal can be picked up on a FM radio. The circuit can be used for short-range transmission, eg. for wireless microphones.

The power supply to use is 9-14 V DC, one of the little rectangular 9V batteries is fine. Connect this to the + and - points on the PCB. The sound input goes to the points marked "MIKE". The antenna should be connected to the point marked "ANT". The emitter's output impedance is 50 ohms. You can make your own fancy antenna if you like.

read more "Schematics Simple FM Transmitter"

Schematics Video Amplifier Circuit for Camera PCB

There are occasions when you want to view your video clips taken in your digital camera on your TV. You can do so by interfacing the camera video output to video input of your TV. But this times you cant connect directly as it needs some amplification before the signal reaches from camera to television.

Circuit Diagram of Video Amplifier for camera : Click  to enlarge

The video amplifier schematic circuit shown in the figure is a simple PAL video amp, expected to have a 3db bandwidth of 5.5MHz. You can connect your camera to TV through this circuit. So this is a low level transistorized video amplifier stage that accepts 1V (p-p) and outputs 2V(p-p) signal.

  • The circuit requires a 5V dc power supply

read more "Schematics Video Amplifier Circuit for Camera PCB"

Schematics 35 Tips to Design a Reliable PCB PCB

Printed circuit boards are essential to professionally design any electronic system. It is often happens that a circuit which functions well over a breadboard may not work properly when implemented on a PCB. This leads to complexity over circuit and system engineers need to be spend at least 2-3 days to rectify the problems. 

The causes for this failures are numerous, PCB design and fabricating is one of them.If the pCB is not designed properly, it often need a high level of rework. PCB design tips listed here is intended to help you to improve the reliability of PCB design.

Checklist For PCB Design

1. First of all verify that the schematic you designed is compatible with your schematic circuit diagram.

2. Make sure that the flow of the signal is maintained over the designed layout.

3. Distribute the circuit components over the entire PCB and observe the weight distribution in all area.

4. Try to keep the components of same family in same direction which will reduce the errors and complexity  of the design

5. Mark PCB body outline or physical size of all the components and ensure that all components on the PCB can well placed and  avoid chances of overlapping.

6. Check that the components reference text are not placed direct under the components which will be head ache to service engineer.

7. Make sure that the connectors are well arranged and the person assembling the circuit can connect external peripherals without tightening each other.

8. The component references should be of readable font and size

9. Check the placement of fixed components with their respective origin of  placement

10. Label all the layer of PCB properly

11. Make sure that test points are there in the circuit

12. Avoid placements of components near the edge of the PCB as it may create problems during machine placement of components (SMD) or during wave/re flow soldering.

13. Design the components according to the component packages from different manufactures. The body size of the components may vary from manufacture to manufacture although the pitch of the components remains same.

14. Make sure that the position of mounting holes is as per the mechanical placement of the PCB and the  placement of PCB in the cabinet. Mounting holes are designed as non-electric unless that are connected to graoung or any other nets

15. Dont make too many holes near the edges of the PCB. This may lead to break the entire board.

16. Provide the sufficien number of mounting holes as long PCBs tnd to warp if not supported normally.

17. Check the ratio between pad size and drill size. There should be sufficient area for soldering the component leads properly. Generally the pad size must be 2-3 times larger than drill size.

18. Check the drill size specified in the design. MArk it is furnished or non furnished in case of multilayer PCB.

19. At least 0.2mm extra drill diameter to fill the component lead as well as solder properly to top layer in a plate through hole (PTH) PCB.

20. Define the global spacing such as track to track, pad to pad,track to pad etc to overcome manufactures limitations.

21. Ensure that the minimum number of drill tools in the PCB to reduce the machine cycle time.

22. Different nets or connections should have minimum and maximum trace width.

23. Avoid routing traces at the edge of the PCB

24. Avoid rout traces at 90 degree corner. You can route trace on 135 degree instead of 90

25. Placing via holes under metal components are not appreciated as it leads the solder to flow through vias and short circuit the components.

26. Check the trace width depending upon the current requirement of the circuit elements.

27. When designing SMD's dont forget to place fidcials. These should be placed over the tree edges of the PCB

28. Never place via hole adjacent to an SMD lan area in the case of an SMD design.

29. The components reference text should not be placed on a land or pad as it will not allow good soldering

30. For reference, don't forget to place the part number, company logo and revision code in the design.

31. Write PCB notes properly to give necessary information about copper thickness requirement,tolerance etc.

32. Make sure that the component spacing satisfies the requirement of the developing automatic equipment.

33. It is appreciable to add machine readable labels such as bar code in the design.

34. PCB's are often required to be stepped and repeated onto an array for assembly. So you must provide a correct assemble array data to assembler.

35. After all, make sure that your design is optimized for maximum material utilization.

These routine tips in PCB designing should help you to make better PCB and improving the reliability of the assembly.
read more "Schematics 35 Tips to Design a Reliable PCB PCB"

Schematics Automatic Low Cost Night Lamp PCB

The circuit of automatic night lamp published early is little bit costly. But this circuit of automatic  night lamp is perfect for hobbyists that it is uses very cheap components. It can be used as a bedroom light or a porch light. This night  lamp circuit can connect directly to 230 V ac and surprisingly it doesn't use any eliminators or transformers so the cost will be further reduced.

We all know that a bulb need phase and neutral at its terminals to glow properly. So here we connect anyone of it direct to lamp and the other one connected through a triac. So lamp glows only when pulses available at triac gate. The pulses required for triac is made available by a diac through a LDR. So triac get its trigger only in night.

Circuit Diagram of Automatic Low Cost Night Lamp : Click  to enlarge

You need to assemble the circuit in a common PCB or a strip board and enclose it within a plastic case. Fit the holder of a bub to the case and connect directly to the socket. Note that you should adjust the RV1 preset to adjust the gate voltage of triac
read more "Schematics Automatic Low Cost Night Lamp PCB"

Schematics Touch Control Switch Using 555 PCB

Here is the circuit diagram of an automatic touch plate controller using NE555 IC. The circuit turns on a relay when anyone touches the input metal plate for a short period of time. After then it switch off the relay or controlled device automatically. This circuit can be connected to calling bells, Buzzers, small toys etc.

     Circuit Diagram of  touch plate controller using NE555 : Click  to enlarge

We can connect toy motors to this circuit through a SL100 transistor, where we can avoid D1 and D2 Diodes.
read more "Schematics Touch Control Switch Using 555 PCB"

Schematics Battery Charge Level Indicator Circuit PCB

Battery charge indicators are essential for maintaining the battery at a constant charge level. The over charging and undercharging of battery will shorten its life. So here is a simple battery level indicator circuit using Two LED's.

 Click on the image to enlarge

 In this circuit the red LED glows if there is a low battery charge and the green one will glow if the battery become charged. The core if this circuit is two BC 107 transistors. The transistor Q1 is in saturation under fully charged battery voltage. So the green led glows by completting the circuit while the red LED will not glow. When the battery charge falls below a particular voltage, the Q1 become cutoff and now Q2 become saturated. so the red LED glows. So this indiacates the battery has to be charged
read more "Schematics Battery Charge Level Indicator Circuit PCB"