- 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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- ACCEPTABLE VOLTAGE INDICTOR
I have used this circuit many times in custom test fixtures where a simple go-no go
indication was needed. The circuit can also be used to adjust a particular
voltage be within specific high or low limits. The three LEDs will indicate if
the voltage is high, low or OK. When connected to other converters, such as a
frequency to voltage converter, a current to voltage converter or a power to voltage
meter, it could provide a quick indication of a proper level.
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- BROAD BAND 2MHz OPTICAL
FIBER RECEIVER
If you need more sensitivity than the above circuit this circuit provides about ten
times more gain. It too is designed around an inexpensive plastic optical fiber
detector.
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- BROAD BAND 5MHz OPTICAL
FIBER RECEIVER
This circuit is a simple broad band light detector that uses a very inexpensive IC
and a PIN photodiode that is packaged for use with plastic optical fibers. It has a
bandwidth from 1KHz to over 5MHz. It is great for experimenting with various
modulated light sources.
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- BROAD BAND 50MHz OPTICAL
FIBER RECEIVER VERSION A
If the above circuit it still too slow, you can try this circuit. What it lacks in
sensitivity it makes up for in speed. The circuit attaches a plastic fiber optic PIN
photodiode assembly to a small box containing a small 3v battery and a standard BNC
plug. When the box is plugged into to the input of an oscilloscope with a 50-ohm
termination resistor, it can detect light pulse frequencies beyond 100MHz.
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Brownout Voltage Tester
I used this circuit years ago to test AC line powered devices under 95vac line
voltage conditions. It has a rating of 250 watts.
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