Tools and measuring electronic circuits

This circuit generates a good 1KHz sinewave using the inverted Wien bridge configuration. Features a variable output, low distortion and low output impedance... [read]

This 3 channel 15 LED spectrum analyzer is the perfect addition to any audio amp project.... [read]

This is one of the simplest circuit for a PC parallel port based DLA. The Circuit is mainly used to protect the port which is fabricated on the motherboard... [read]

The 555 Stepper Pulse Generator kit will help you with the pulse required to drive your favorite DC Servo Motor application.... [read]

Here is a handy gadget for test- ing of infrared (IR) based re- mote control transmitters used for TVs and VCRs etc. The IR signals from a remote control transmitter... [read]

Here is a handy gadget for test- ing of infrared (IR) based re- mote control transmitters used for TVs and VCRs etc.... [read]

This circuit uses the versatile MAX038 function generator. Although in this circuit some of the advanced characteristics of this IC are disabled, you can generate... [read]

This simple circuit uses an incandescent lamp to detect airflow.... [read]

A Beat Balance Metal Detector made from discrete components. Interesting design.... [read]

This circuit uses two 741s or equivalent op amp to form a beeper that is used to detect short circuits.... [read]

This circuit is basically an audio amplifier, but it is placed in this category because it may be used as signal tracer. It is built around simple National... [read]

you will have an instrument capable of measuring all but the largest capacitors used in radio circuits.... [read]

This circuit was designed to detect when a call is incoming in a cellular phone (even when the calling tone of the device is switched-off) by means of a flashing... [read]

One more kind of metal detectors.... [read]

Colour sensor is an interesting project for hobbyists. The cir- cuit can sense eight colours, i.e. blue, green and red (primary colours); magenta, yellow and... [read]

Simple connection tester built with famous 741 op-amp circuit. Very useful for every electronics workshop.... [read]

This is a CMOS IC (CD4033) based circuit which can be used to detect presence of mains AC voltage without any electrical contact with the conductor carrying... [read]

Several simple circuits were tried -- a lamp, battery and probes still demanded the attention of the eyes; replacing the lamp with a buzzer was more successful... [read]

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... [read]

The circuit below responds to sound pressure levels from about 60 to 70 dB. The sound is picked up by an 8 ohm speaker, amplified by a transistor stage and... [read]

It allows us to evaluate the speed of any object moving, especially cars and other vehicles... [read]

This circuit is a Digital Radar Speedometer. It allows us to evaluate the speed of any object moving, especially cars and other vehicles. The speed is calculated... [read]

This circuit measures the distance covered during a walk.... [read]

The ICL7107 is a 3 1/2 digit LED A/D convertor. It contains an internal voltage reference, high isolation analog switches, sequential control logic, and the... [read]

This circuit is sensitive to low frequency electromagnetic radiation and will detect for example hidden wiring or the field that encompasses a transformer.... [read]

This lovely circuit is a real gem! Easy to assemble and more sensitive than many commercial devices available.... [read]

Stethoscopes are not only useful for doctors, but home mechanics, exterminators, spying and any number of other uses. Standard stethoscopes provide no amplification... [read]

This is a very straightforward circuit. The first stage acts as a crystal receiver.... [read]

Built around a single 8038 waveform generator IC, this circuit produces sine, square or triangle waves from 20Hz to 200kHz in four switched ranges.... [read]

A circuit to extract and measure the modulated carrier of an Infra Red remote control... [read]

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... [read]

Here is a VLF receiver tuned to 300 kHz designed to detect the crackle of approaching lightning. A bright lamp flashes in sychrony with the lightning bolts... [read]

Most analogue multimeters are capable of measuring resistance over quite a wide range of values, but are rather inconvenient in use due to the reverse reading... [read]

This circuit is a Logic Probe. It indicates the logic state of the node of any TTL logic circuit. To do that, we have to supply the probe with the same power... [read]

The two circuits below illustrate generating low frequency sinewaves by shifting the phase of the signal through an RC network so that oscillation occurs where... [read]

Producing low-distortion sine waves, this oscillator operates over the range 16 to 22000 Hz.... [read]

Here is an interesting circuit for a magnetic proximity switch which can be used in various applications. The magnetic proximity switch circuit, in principle,... [read]

A single chip metal detecor with a range of a few inches. This is useful for decting nails or screws in walls and floors, or for locating buried mains cable.... [read]

This device should measure electromagnetic energy, but only the one which human body absorbs.... [read]

This is a variation on the astable multivibrator. Circuit was recently developed to test for N-mosfets(the power kind e.g irf830)... [read]

H ere is a circuit of an off-line telephone tester which does not require any telephone line for testing a telephone instrument. The circuit is so simple that... [read]

I call this the huntron circuit because a company by that name made a similar device. It is useful for trouble-shooting.... [read]

Here is a simple technique for measuring frequencies over quite a wide frequency range and with acceptable accuracy limits using a PC. It follows the basic... [read]

This circuit uses a CA3420 BiMOS op amp to form a picoammeter with 4 ranges. The exceptionally low input current (typically 0.2pA) makes the CA3420 highly... [read]

This simple device checks if their is water in a pot plant. You stick the two probes(paperclips)into the pot plant and if the LED lights, it means there is... [read]

This simple circuit generates narrow pulses at about 700-800Hz frequency. The pulses, containing harmonics up to the MHz region, can be injected into audio... [read]

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,... [read]

Sawtooth wave generators using opamp are very common. But the disadvantage is that it requires a bipolar power supply. A sawtooth wave generator can be built... [read]

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... [read]

This circuit is intended to provide good square waves converting a sine wave picked-up from an existing generator. Its major feature consists in the fact that... [read]

A simple test circuit to fault find audio and radio equipment. Can be used to inject a square wave signal, rich in harmonics, or used with headphones as an... [read]

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)... [read]

Here is a versatile circuit of IF signal generator which may be of interest to radio hobbyists and professionals alike.... [read]

Here's a simple lie detector that can be built in a few minutes, but can be incredibly useful when you want to know if someone is really telling you the truth.... [read]

Tester for servo devices.... [read]

This is a very simple circuit utilizing a 555 timer IC to generate square wave of frequency that can be adjusted by a potentiometer.... [read]

This oscillator produces sinusoidal wave. It's made around LF351 or TL071CN or TL081CN. A classic Wien Bridge oscillator... [read]

The 2 pushbuttons = S1: Start/Pause. S2: Stop/Reset. If you want to play your message, put S3 at Play. Then push S1 to start playing and again to pause. If... [read]

This device can detect negative ions in air. It has very few components: one FET, two resistors and battery. You also need multimeter to complete device. This... [read]

This simple circuit has helped me out on many occasions. It is able to check transistors, in the circuit, down to 40 ohms across the collector-base or base-emitter... [read]

Here is a simple triangle/squarewave generator using a common 1458 dual op-amp that can be used from very low frequencies to about 10 Khz.... [read]

When the input voltage is 0 the LED glows. The LED stops glowing when the voltage rises to the level determined by R2. Reverse + and - pins to reverse operating... [read]

Tool for XTall testing. This one is MUST HAVE when you work with radio devices, RC toys...... [read]

Here is a handy zener diode tester which tests zener diodes with breakdown voltages extending up to 120 volts. The main advantage of this circuit is that it... [read]