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Miscellaneous tools circuit diagrams

Decibel Meter
Decibel Meter
December 29, 2010

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 LM324 op-amp section. You... [more]

Simple Servo Tester
Simple Servo Tester
November 30, 2010

This is a simple servo tester which will comprehensively test the capabilities of almost any modern servo. It has two pushbuttons, CENTRE and SWEEP and a potentiometer which works as follows: - CENTRE Does exactly... [more]

Signal Tracer and Injector
Signal Tracer and Injector
November 16, 2010

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 audio tracer. [more]

Pulse-Generator & Signal-Tracer
Pulse-Generator & Signal-Tracer
November 15, 2010

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 or radio-frequency stages of amplifiers, receivers and the like for testing... [more]

Ultra-simple Voltage Probe
Ultra-simple Voltage Probe
October 12, 2010

This circuit is not a novelty, but it proved so useful, simple and cheap that it's worth building. [more]

Quick On-Board Junction Tester Circuit Diagram
Quick On-Board Junction Tester Circuit Diagram
September 26, 2010

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... [more]

Electronic Torricelli Barometer
Electronic Torricelli Barometer
September 26, 2010

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 discussed here is a functional equivalent and electronic replica... [more]


circuit from:http://www.extremecircuits.net/2010/05/electronic-torricelli-barometer.html

Latching Continuity Tester
Latching Continuity Tester
June 23, 2010

This Latching Continuity Tester can help you locate those difficult-to-find intermittent short and opens that other testers always seem to miss. It has been part of my workbench for many years and performs superb. I... [more]

Digital Frequency Meter 1HZ - 1MHZ
Digital Frequency Meter 1HZ - 1MHZ
April 23, 2010

This circuit is a frequency meter, low cost. [more]

Signal and Tone Activated Relay Switch
Signal and Tone Activated Relay Switch
April 23, 2010

Signal and Tone Activated Relay Switch [more]