Vacuum Tubes Valves
Musical & effects
Yagi Uda Antennas
Metal Detector Circuits
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Human Sensing Circuits
RF & Radiation
Optical Sensing Circuits
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Data Bus Circuits
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RF Converter Circuits
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Video Wall circuits
TV Video Circuits
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8051 / 8052
PCB CAD Software
Car bike Circuits
555 Timer Circuits
Remote Control Toy
H Bridge Circuit
DIY HV Variable Cap
DIY PMA alternator
Interconnection & Timing
Digital Signal Integrity
Digital & Bipolars
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Regulated Power Supply
4 Band Resistor
5 Band resistor
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Meter Counter Circuits
Zener diode tester
This is a circuit to test zener diodes. It hooks up to a 120V AC line and boosts the output voltage to over 300V allowing you to test zener diodes of any voltage. The circuit also has a push button switch to triple the current, if needed. The output is attached to 2 pairs of alligator clips. One pair is to attach to the diode. The second pair is
salt tester circuit
This circuit was designed to detect the approximate percentage of salt contained in a liquid. After careful setting it can be useful to persons needing a quick, rough indication of the salt content in liquid foods for diet purposes etc. This circuit is using LM324 as main components. This is the figure of the circuit; IC1A op-amp is wired as a DC
how to test servo servo tester simple
If you have a servo and you wan`t to test it and you do not have a remote control to do that, or want a tester to test it you can try making the following schematic of servo tester. You can se is based on a 555 timer. The circuit is very simple and cheap to make and it will work just fine. I will post other schematics of servo testers. You can al
oxygen sensor tester circuit board
A 12V supply is connected to the 12V positive wire, the current flows through a protection diode and a capacitor, in order to filter the voltage into a smoother flow. The zener resistor (R5) limits the current flowing to the zener diode, which regulates the voltage down to 9. 1 volts. Current for the various inputs of the Integrated Circuit is then
servo speed tester
This is probably the simplest Circuit to test a Servo, This circuit tests the speed of servo. Here we use potentiometer to controll the speed of the servo. By applying very less voltage like 4. 5V and reducing the pot value, you can also adjust the position of the servo! Check this Circuit which uses push switches to run a servo in Clock-wise and a
lm3914 ic based on simple battery tester
This circuit employs the popular and easy to find LM3914 IC. This kind of IC is quite very simple to drive, requires no voltage regulators (it features a built in voltage regulator) and can be powered from almost every resource. Once the test switch is pushed, the Car battery voltage is supply into a high impedance voltage divider. His function is
circuit transistor tester
Circuit transistor tester is a fairly simple circuit tester. Transistor tester circuit shown below can be used to measure and know the pins and determine the condition of the transistor. In addition this circuit transistor tester can also find out what kind of transistors are measured. Transistor tester circuit is built with 2 transistor, an amper
simple multiple continuity tester
The continuity tester is a handy adjunct to an ohmmeter. The unit or component whose continuity is to be checked is connected between terminals E1 and E2 (which may be probes or croc clips). The test current then flowing through the unit/component on test causes a potential drop across resistor R2, which is applied to the non-inverting input of bu
pc based digital ic tester
Check the following IC`s7400, 7402, 7404, 7408, 7432, 7486. Visual Basic Program is used to show the results on the PC. The Microcontroller AT89S52 receives the IC number from the PC and check the Gates IC with the Truth table and sent back the result to the PC.
Crystal tester circuit
555 timer tester
simple but reliable car battery tester
This circuit uses the popular and easy to find LM3914 IC. This IC is very simple to drive, needs no voltage regulators (it has a built in voltage regulator) and can be powered from almost every source. This circuit is very easy to explain: When the test button is pressed, the Car battery voltage is feed into a high impedance voltage divider. His p
ir remote control tester
zener diode tester schematic
Using electronic scheme below can be designed a zener diode tester using few electronic parts. Using this zener tester and a multimeter can be measured and determined with a high precision threshold voltage of a zener diode. Zener voltage can be read with a DC voltmeter connected in parallel with zener diode. If contact S1 is closed, the resistance
40khz ir infrared tester
Built servo tester cicuit as shown - only action is for the servo to twitch when power switched on, cannot see any real reason why wont work - ideas anyone I haven`t built this circuit yet so I can`t comment on the circuits efficacy. I do have some experience of using servos in radio controlled models, both aircraft and cars. Whenever I have...
create hfe tester circuit diagram
simple crystal tester circuit
build yourself a simple continuity tester
Remote tester circuit also resembles the logic of a dark sensor (using BC557) . LDR has been replaced with IR sensor TSOP 1738. The circuit works as a remote tester. Pressing a remote control switch near the IR sensor, switches on the LED D2. I am Sagar Sapkota living in Espoo, Finland. I have done Master`s degree in Electronics and Communicatio
car and motorcycle battery tester
Going camping nowadays involves taking lots of electronic equipment whether for day to day running or for fun and entertainment. Most of the time a charged lead acid battery and a power inverter would be used to ensure a smoothly organized holiday where ideally the missus and the children cheerfully use their electric and electronic gear! With...
ir remote control tester
As I was developing my IR Extender Circuit, I needed to find a way of measuring the relative intensities of different Infra red light sources. This circuit is the result of my research. I have used a photodiode, SFH2030 as an infra red sensor. A MOSFET opamp, CA3140 is used in the differential mode to amplify the pulses of current from the photodi
battery tester circuit schematic
Is the battery empty, or is there something wrong with the device? That s always a difficult question when your walkman or some other battery-powered device appears to be dead when you switch it on. Before you take it to the shop for servicing, the first thing you should do is to test the battery or batteries. Of course, this means you need a...
This is a variation on the astable multivibrator. Circuit was recently developed to test for N-mosfets(the power kind e.g irf830)..
diode zener tester
Many times we have found itself in the necessity to use a Zener diode and cannot to know the voltage of operation. Many times we cannot read the characteristics or the type that is written on her..
This circuit enables you to test quartz resonators at the range values from 32kHz to 24MHz. Confirmation of good state of quartz resonator is done by diode signalling LED and acoustic signal..
components voltage tester circuit schematic
This simple circuit tests speakers, microphones, transformers and voltage. It`s basically a very low frequency oscillator that produces extremely short `fruity` pulses. The type of sound produced is very easy to hear and to determine the precise direction it is coming from, thus making it ideal for checking the phasing in multiple speaker...
invisible broken wire detector
Portable loads such as video cameras, halogen flood lights, electrical irons, hand drillers, grinders, and cutters are powered by connecting long 2- or 3-core cables to the mains plug. Due to prolonged usage, the power cord wires are subjected to mechanical strain and stress, which can lead to internal snapping of wires at any point. In such a...
self powered fast battery tester
This circuit runs a fast battery test without the need of power supply or expensive moving-coil voltmeters. It has two ranges: when SW1 is set as shown in the circuit diagram, the device can test 3V to 15V batteries. When SW1 is switched to the other position, only 1.5V cells can be tested..
quick on board junction tester circuit diagram
Short circuits or broken pcb tracks can be easily recognized by means of a Multimeter, but this tool can give wrong results when testing the efficiency of a transistor or diode, unless the device under test is unsoldered and removed from the pcb. A further shortcoming affecting such way of testing is the necessity to keep firmly the probes on...
555 tester circuit
A project of a 555 tester circuit, the circuit will start blinking LEDs when power is applied which will indicate that the IC is working correctly..
crystal tester circuit
A very useful project of a crystal tester circuit or xtal tester circuit built with only few components the circuit form an oscillator that will only oscillate if the under test crystal is in good working condition and the oscillator output voltage will be rectified by 1N914 diodes and filtered by 0. 1uF capacitor and reach
Frequency Meter Circuits
VU Meter Circuits
Ultrasonic distance finder circuit
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is measured. There are three main categories of distance measurement methods in use: a) By...
Simple Metal detector circuit with CD4030
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to find something potentially valuable, hidden a few centimeters below the soil. So many...
Fully automatic watering circuit for flower pots
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This circuit comes as a solution to this problem. Depending on humidity of the pot at...
Simple deep searching metal detector circuit
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the circuit of this metal detector, it is possible to detect a metal coin in depth of 90 to...
Sub-Harmonic Bass Converter for Electric Guitars
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound, such as filtering or distortion. Instead, a frequency division system produces outputs...
Echo Depth Sounding Sonar for Boats
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the calibration of the rope. This arrangement still exists in some yachts. The big...
100W HiFi Audio Amplifier Circuit
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power supply must be symmetrical so that no electrolytic capacitors are needed at the outlet....
Plant-Pot Water Level Indicator Circuit
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower. The circuit of the device is shown in Figure 2. The water detection is made from the bottom...
Analogue Sound Preasure dB-Meter Circuit
The best human ear can capture sounds from 20Hz to 20KHz. These limits are known to be the broadest that can exist. Normally the normal limits range from 100Hz to about 13KHz and depend on the age and health of the individual. We for our measurements and to have a good accuracy we will get the limits of 20Hz to 20KHz. A sound to be heard does...
DIY HV Variable Capacitor
DIY PMA Alternator Plans
Digital Signal Integrity