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Tester or
Instrumentation
Circuits, Page 1d
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Last Updated on:
Wednesday, November 29, 2017 05:38 AM |
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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
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- 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.
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- 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.
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- 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.
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Links to electronic circuits,
electronic schematics, designs for engineers, hobbyists, students & inventors:
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5 Watt 80 Meter QRP CW Transceiver - A great deal of interest has
been generated by my previous design articles, so I decided to go to work on
a full blown transceiver design. After several months of work, the ROSE-80
.... |
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50 MHz Frequency Counter - This project is nice and small
frequency counter that reads frequency from 1 Hz to 50 MHz that I have
modified from original designed by Weeder Technologies . I have designed new
PCB to fit with 16X1 LCD and change source code for compatible with new
small PCB Specifications, Auto-ranging with floating decimal point., Up to 7
digits displayed on 1X16 LCD., Auto-adjusting gate speed (0.1 sec to 1
sec)., Microcontroller-based circuitry provides for simplicity, ease of
assembly, and highly stable readout., Sensitivity approximately 100 mV RMS
(100 Hz to 2 MHz), 800 mV RMS @ 50 MHz., Input overload protected.
….(electronic schematic added 11/08) |
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50 MHz Frequency Counter Voltage Meter & SwR/PWR Indicator - This
is a successor of the PIC16C71 4-digit LED f-counter & V-meter. Some hard to
find parts used in the previous version, which are out of production for
some time, has been omitted. A rather early PIC16C71 has also been replaced
by 28-pin device PIC16F876....(electronic schematic / circuit added
03/03/03) |
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500W low cost 12V to 220V inverter - Using this circuit you can convert the
12V dc in to the 220V Ac. In this circuit 4047 is use to generate the square wave of
50hz and amplify the current and then amplify the voltage by using the step
transformer…..(Circuit design added 09/08) |
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555 Go/No Go Tester - This is a more advanced unit with a precise timed
testing procedure. R1 (2M2) is same as 2.2 MegOhm. The two timers
determine the allowable accuracy for the timer IC under test. Potentiometers P1 and P2
permit ready adjustment for the desired range…. [Tony van Roon's circuit] |
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555 Timer IC Tester - The 555-tester above is basically a led flasher
circuit but with the 555 removed. Imagen the output being a square-wave pulse with a
high and low pulse, and is so indicated by the two leds, one 'Hi' and the other one
'Lo'. When you have a good 555 under test…. [Tony van Roon's circuit] |
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5V/1A Power Supply - …. |
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