field strength meter
Here is a very simple and useful project of a moisture level LED Meter circuit that can be used as a sensor or detector to measure humidity or moisture level in...
field strength meter fsm
Field strength meter circuit is a very useful device for measuring the RF output of any transmitter or experimenting different antennas with the transmitter. Th...
digital remote thermometer
This circuit is intended for precision centigrade temperature measurement, with a transmitter section converting to frequency the sensor`s output voltage, which...
electronic torricelli barometer
Although it does not have the same charm as real mercury barometers with long glass tubes on pieces of carved and polished wood, the Torricelli barometer discus...
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 tra...
decibel meter
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 one ...
signal tracer and injector
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 audi...
analog milliamp meter used as voltmeter
A milliamp meter can be used as a volt meter by adding a series resistance. The resistance needed is the full scale voltage reading divided by the full scale cu...
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 c...
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 c...
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`...
crystal tester
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 sign...
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...
field strength meter
You can`t expect great performance from such a simple detector-based meter. Sensitivity is just adequate enough to get a basic idea of the power that your trans...
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 app...
3 6 volt cell phone battery meter
This is a similar circuit to the above and provides a 4 LED bar graph indicating the voltage of a common 3.6 volt Lithium - Ion recharable cell phone battery. T...
digital step km counter
This circuit measures the distance covered during a walk. Hardware is located in a small box slipped in pants` pocket and the display is conceived in the follow...
digital step km counter circuit schematic
This circuit measures the distance covered during a walk. Hardware is located in a small box slipped in pants` pocket and the display is conceived in the follow...
vu meter 5 with uaa180
This circuit of measurement of level uses the UAA180 of SIEMENS and a circuit of rectification of precision, round the IC2B. The calibration has become in steps...
build at home an accurate low cost capacitance meter
...