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Tools and measuring circuit diagrams

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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]

Analog Milliamp Meter Used as Voltmeter
Analog Milliamp Meter Used as Voltmeter
December 28, 2010

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 current of the meter movement. So,... [more]

Digital Voltmeter
Digital Voltmeter
December 25, 2010

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 display drivers. [more]

Fuse Monitor / Alarm
Fuse Monitor / Alarm
December 25, 2010

A simple way to see if a fuse has blown without removing it from its holder. [more]

Precision Audio Millivoltmeter
Precision Audio Millivoltmeter
December 12, 2010

Measures 10mV to 50Volt RMS in eight ranges Simply connect to your Avo-meter set @ 50uA range [more]

Picoammeter circuit with 4 ranges
Picoammeter circuit with 4 ranges
December 8, 2010

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 suited for use in a picoammeter circuit. Input transient... [more]

PIC diode tester
PIC diode tester
December 2, 2010

This is a simple use of the PIC 16F84 about a diode tester. [more]

Logic Probe
Logic Probe
November 30, 2010

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 of the circuit... [more]

Self-powered Fast Battery-Tester
Self-powered Fast Battery-Tester
November 30, 2010

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... [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]



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