Testers or Instruments electronic circuits, beginning with #'s

Tester or Instrumentation Circuits, Page 1a
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Last Updated on: Wednesday, November 29, 2017 05:38 AM

Circuits Designed by Dave Johnson, P.E. :

1 AMP CURRENT INJECTOR
When you need to measure resistance down to a few micro ohms, this circuit works great. It is powered from two "C" cell batteries and is designed to inject a well-regulated one amp of current into the unknown resistance. By measuring the voltage drop across the resistor with a digital voltmeter, the resistance value can be accurately measured. The circuit also is equipped with a low battery monitor. Published in Popular Electronics, November 1992

120vac Under Voltage Tester
Using a cheap 24vac transformer, this circuit can test a product under low 95vac conditions. With the components show, it has a rating of 250 watts max.

20MHz VCSEL 3mW LASER TEST CIRCUIT
This circuit takes advantage of some new vertical cavity surface emitting lasers (VCSEL) that don’t require light output control circuits. The circuit shows how to drive the device from a single high speed CMOS IC. The circuit can easily be modified to transmit signals from kilohertz to about 50MHz.

40KHZ LED TEST SIGNAL GENERATOR
This 40KHz crystal controlled oscillator circuit drives an infrared LED with powerful 40ma pulses. The circuit can be used to test optical communications circuits, designed to receive 40KHz modulated light signals.

Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

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1GHZ Frequency Meter - This is 1GHz frequency counter with 100KHz resolution. Meter is built in around PIC16F84A microcontroller and SAB6456 / U813BS prescaller....(electronic circuit added 07/07/07)

2 GHz Frequency Counter - This simple counter is useful for frequency measurements of various wireless equipments, especially transmitters, receivers and signal generators in VHF/UHF band…(circuit added 8/06)

20MHz High Speed Function Generator - The High Speed Function Generator was published in the professional electronics section of the Aug 1996 issue of Electronics Australia, and has proven to be extremely popular. The kit is no longer available from any of the kit suppliers. The project is capable of generating 20MHz or greater Sine, Square, Triangle, and TTL waveforms. ….(electronic schematic added 11/08)

20MHz VCSEL 3mW Laser Test Circuit - This circuit takes advantage of some new vertical cavity surface emitting lasers (VCSEL) that don’t require light output control circuits. The circuit shows how to drive the device from a single high speed CMOS IC. The circuit can easily be modified to transmit signals from kilohertz to about 50MHz.... [Designed by David A. Johnson]

220 Volt Live Wire in Wall Scanner - This little circuit will help you to scan line of a 220V live wire in wall. FET gate is connected to a capacitive metal sensor (which is usually a simple metal plate). When you hold sensor close to wall, LED will indicate current flow around where it detects wire. Works on 9VDC.... [Peter Jakab, Electrical Engineer, Engineer of Informatics]

220/230VAC Input 12VAC Output 100VA Max Halogen Converter - Fully Assembled and Tested demo board CD including datasheets, application notes and ballast design software Features: Short Circuit and Overload Protection, Fully dimmable with all dimmer types, Compensated Load Regulation, Over temperature shutdown, EMI Filter (added 3/05)

220V mains monitor - With this circuit you will be able to monitor the quality of the mains. There are 4 distinct sections, each supervising a parameter pertinent to the quality of the supply line. The noise section consists of a 50Hz filter and a speaker where you will hear the noise present on the line. The bicolor LED should be adjusted for the least light with the 5k pot and gives a visual indication....(added 9/07)

24-Bit ADC Measures from DC to Daylight - DN219 Design Notes (Linear Technology) (app note added 6/06)

250mW HF CW Transmitter - Electroinic circuit…. [from Harry Lythall's website]

25-kV generator tests insulation - 06/04/98 EDN-Design Ideas....To generate high voltages with proper insulation between the "hot node" and the rest of the circuitry, a car ignition coil can function in place of a high-voltage transformer. These coils have voltage ratings of approximately 20 kV, so you can use them to produce voltages.... [Design Idea by Lukasz S�liwczyn�ski and Przemyslaw Krehlik, University of Mining and Metallurgy, Krak�w, Poland]

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