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Tester or
Instrumentation
Circuits, Page 1c
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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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[_OLD-ads-dont_upload/OLD I-ADS from web/ad-djandassoc.htm] |
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40 Meter Direct Conversion Receiver - Using the circuit of
direct-conversion receiver described here, one can listen to amateur radio
QSO signals in CW as well as in SSB mode in the 40-metre band. The circuit
makes use…. |
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4000 series CMOS Logic Ics - There are many ICs in the 4000 series
and this page only covers a selection, concentrating on the most useful
gates, counters, decoders and display drivers. For each IC there is a
diagram showing the pin arrangement and brief notes explain the function of
the pins where necessary. The notes also explain if the IC's
properties....(circuit added 06/07/08) |
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40kHz IR Tester - Use this circuit to test if the light coming
from your 40khz IR emitter is really emitting the right frequency. The
schematic says to use a GP1U5X ir module, but probably any 40khz detector
module will work.… [Andy Wilson's site] |
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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.... [Designed by David A. Johnson] |
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40MHz 32 Channel Logic Analyser - This project was published in Electronics
Australia in Oct/Nov 96. It is a 32 Channel, 40Mhz, fully PC controlled TTL/CMOS logic
analyzer with internal/external triggering and trigger delay. Internal triggering is
fully maskable (High/Low/Don't Care) on all 32 channels. The whole things fits on one
single sided PCB with virtually no wiring! ….... |
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40MHz Frequency Counter Module - This circuit is ideal for adding a low cost
frequency display to a function generator or other design. I doubt if it is possible
to get a cheaper design using off the shelf components!. In fact, I challenge anyone
to make a cheaper design using garden variety components!. The upper frequency limit
is dependent upon the upper limit of the 74HC390 chips which is roughly 40MHz.
….(electronic schematic added 11/08) |
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4-20ma Current Loop Tester - Using just a few components, this circuit can
simulate signals from various instruments, which source a constant current.
[Designed by David A. Johnson] |
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4–20ma Current Loop Tester - This circuit injects an adjustable current
through a wire loop. Using a digital current meter, the current can be adjusted
from near zero to over 24 milliamps. (added 12/04) …. [Designed by David A.
Johnson] |
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4Channel Oscilloscope Adapter - will introduce the adapter to see the
wavefrom of four kinds of the signals at the same time with the oscilloscope on these
pages. At the classy oscilloscope, it is equipped with the function to see more than
one signal at the same time. The one which I am having can see only the one signal.
Therefore, I made the adapter to see four kinds of the signals at the same
time....(circuit / schematic design added 07/08/09) |
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