Tester or Instrumentation
Circuits, Page 8
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Last Updated on:
Friday, March 12, 2010 12:07 PM |
| Circuits
Designed by Dave Johnson, P.E. : |
- LASER/LED
LIGHT OUTPUT INTENSITY METER
This circuit uses a large 1cm X 1cm silicon PIN photo diode and a transimpedance
amplifier to measure the light power output of infrared and visible LEDs and laser
diodes. It can be modified to produce almost any milliwatts to volts scale factor.
It can be connected to either a multi-meter or an oscilloscope.
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- LIGHT
RECEIVER WORKS FROM 1KHz TO OVER 70MHz
This circuit uses one tiny C-MOS inverter IC to form a modulated light receiver with
a very fast response. It is designed around a PIN photo diode that is packaged for
use with plastic optical fibers. It can be used as an optical fiber receiver. By
using the open end of the optical fiber it can "sniff" out any modulated light
signals.
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Low Value Capacitance Meter
This circuit was originally designed to measure the volume of fluid inside a medical
syringe. As designed, it produces a zero to 5 volt output, corresponding
to a capacitance change of about 10 picofarads. With a digital voltmeter, at
its output, it can resolve a capacitance change of 0.002 picofarads or 2
femtofarads. (added 12/04)
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Links to electronic circuits,
electronic schematics, designs for engineers, hobbyists, students & inventors:
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Laser/Led Light Output Intensity Meter - This circuit uses a large 1cm X 1cm
silicon PIN photo diode and a transimpedance amplifier to measure the light power
output of infrared and visible LEDs and laser diodes. It can be modified to
produce almost any milliwatts to volts scale factor. It can be connected to either
a multi-meter or an oscilloscope. ….(designed by David A. Johnson) |
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Latching Continuity Tester - A continuity tester is a must on every service
bench for testing cables, pcboards, switches, motors, plugs, jacks, relays, and
many other kinds of components. But there are times when a simple continuity test
(Tony van Roon's or your multi-meter) doesn't tell the whole story. For example,
vibration-induced problems in automobile wiring can be extremely difficult to ....
(Tony van Roon's electronic design added 2/06) |
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Latching Continuity Tester - 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 have solved many intermittend problem with this highly flexible
unit...;(electronic design added 5/09) |
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LB-25: Linear Brief 25 True RMS Detector - National Semiconductor Application
Note (app note added 2/06) |
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LB-48: Linear Brief 48 Simple Voltmeter Monitors TTL Supplies - National
Semiconductor Application Note (app note added 2/06) |
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LC- and Q-meters-Radiometer MM1f multimeter - Modification in particular to
achieve better reading between 20nH-2µH coil inductance. Note the series coil, it
is the secret why it is possible to measure inductance values down towards zero.
(Since it is a gif file it prints better than it seems on the screen). It is
usually no problem...(added 07/07/07) |
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LC Meter Based on the AVR Microcontroller - Calculates and displays L and C
from oscillation frequency using reference components. This instrument requires
two precision components: A precision capacitor and a precision inductor. You only
need to start with one precision component, either the reference capacitor or the
reference inductor, and using this meter, you can select or adjust the other
precision component. In my case, I used a pretty high accuracy BK Precision
inductance/capacitance meter and sorted through piles of inductors and capacitors
to find those that had the lowest error. I then used those parts, a 1 millihenry
inductor and a 0.01 microfarad capacitor, in this meter. The basis of this project
is several similar projects on the world wide web and some magazine articles
before the world wide web was a common means of information interchange.
Unfortunately, I am not able to determine the originator(s) of the concept, but I
suspect that it is as old as radio. Another project on my web site, LC
Determination by Resonant Frequency Measurement, measures the resonant frequency
of an L/C circuit, but the hardware stops at the frequency measurement. It does
not proceed to calculate the unknown inductance or capacitance. ….(circuit design
added 11/08) |
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LCD Frequency Counter PIC16F84 - (schematic added 8/03) |
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LED Ammeter - Measures current up to 10A with selected 100mA, 10mA and 1mA
resolutions. (circuit added 8/06) |
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LED Audio UV Monitor - The circuit is completely conventional, and is based on
the application notes from National Semiconductor. The circuit is shown in Figure
1 and as you can see it uses a single IC and a few discrete components. The extra
diode (D3) is included to ensure that the DC to the LEDs is almost unfiltered....
(added 5/02) |
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LED Battery Condition Indicator - (circuit / schematic added 6/05) |
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LED Decibel Meter - 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 can also use a dynamic
microphone but I found the speaker was more sensitive. The remaining 3 sections of
the LM324 quad op-amp are used as ....(electronic circuit added 10/05) |
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LED display digital Voltmeter - This digital voltmeter is ideal to use for
measuring the output voltage of your DC power supply. It includes a 3.5-digit LED
display with a negative voltage indicator. It measures DC voltages from 0 to 199.9V
with a resolution of 0.1V. The voltmeter is based on single ICL7107 chip and may be
fitted on a small 3cm x 7cm ...(electronic design added 6/07) |
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LED Oscilloscope - George Katz of Balgowlah Boys high in Sydney presented a solid
state oscilloscope. He says "probably the best advantage is its very small size and
the fact that it can run off the power supply of the circuit being tested. Although it
has a low frequency range, it can still be used for most circuits. Its poor resolution
will still allow for most waveforms to be visualized." ….(electronic schematic added
11/08) |
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LED Oscilloscope - Uses a matrix of 100 LED as a display (circuit added 8/06)
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LED power meter - Used for testing RF transmitters (electronic circuit added
05/07) |
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LED Voltmeter - Measures voltages up to 199.9V with 0.1V resolution.
(circuit added 8/06) |
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LED Voltmeter Expanded Scale (ideal for your car) - Its Useful to see the charge
voltage. This Helps in detecting a Bad Alternator before it creates a dead
battery....(electronic schematic added 12/08) |
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LED VU Meter - The circuit is completely conventional, and is based on the
application notes from National Semiconductor. The circuit is shown in Figure 1 and as
you can see it uses a single IC and a few discrete components. The extra diode (D3) is
included to ensure that the DC to the LEDs is almost unfiltered.....(schematic added
6/07) |
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