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Tester or
Instrumentation Circuits, Page 2
Testers:
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M-O P
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Last Updated on:
Sunday, February 05, 2012 05:34 AM |
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Circuits Designed by Dave Johnson, P.E. : |
- 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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AC Current Controls Hour Meter - Many systems require routine maintenance
based on machine operation time. The circuit below is a simple way to turn on
a hour meter whenever AC power is supplied to the machine. An inexpensive
snap-on current transformer from Magnetics Inc, is used to detect the AC current.
The output of the transformer is fed to a voltage doubler circuit. When 0.5 AC
amps or more of current is flowing, the circuit generates sufficient voltage to turn
on the n-channel MOSFET. Once tuned on, the transistor routes voltage to the
hour meter. Some hour meters contain their own battery, so no external power
is needed. In those cases, the transistor switch alone will turn on the hour
meter.
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- AC
Power Line Hi/Lo Voltage Tester
If you wish to test a line-powered device under both a 15% high and a 15% low
voltage condition, you can use the circuit below. The circuit uses an 18v
transformer with a 3 amp rating. A double pole, double throw toggle switch
then switches in the transformer voltage in either a buck or a boost mode. In
the buck mode, the transformer voltage is subtracted from the line voltage. In
the boost mode, the transformer voltage is added to the line voltage. With an
18vac transformer the normal 120vac voltage is switched between 102vac and 138vac.
For 240vac power line tests, use a 36vac transformer rated at 2A.
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Battery Amp-hour Capacity Tester
I bought some lithium ion rechargeable batteries a while back. I was planning on
using them to modify some solar powered LED spot lights. What I like about these
new batteries is that they are the same size as a standard 1.5v alkaline AA cell.
With such a package, I can use a standard AA battery holder. The battery
manufacturer claims an amp-hour capacity of 2.2 amp-hours. Usually, these amp-hour
figures are made using rather small loads, conducted over a long period of time....
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Bidirectional DC
Current Indicator
This circuit is handy for battery powered systems. The circuit is self-powered
using a single 3v lithium coin cell. The current draw is so low that the
battery should last for years. The hobby circuit flashes a red LED when DC
current is drawn from the battery and flashes a green LED whenever current flows
into the battery. Two “probe” input wires connect across a section of cable,
which acts as a shunt resistor. A voltage of only 5mv in either direction will
trigger a LED indication.
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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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Links to electronic circuits,
electronic schematics, designs for engineers, hobbyists, students & inventors:
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A Low Cost Watt-Hour Energy Meter Based on the ADE7755 - AN-559 Analog
Devices Application Notes....[App Note] |
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A Low Cost Watt-Hour Energy Meter Based on the ADE7757 - AN-679 Analog
Devices Application Notes....[App Note] |
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A Precision Wideband Current Probe for LCD Backlight Measurement - DN101
Design Notes (Linear Technology) (app note added 1/06) |
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A simple Remote control Tester - .... |
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A Tamper-Resistant Watt-Hour Energy Meter - AN-563 Analog Devices
Application Notes....[App Note] Based on ADE7751 and Two Current Sensors
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A Tamper-Resistant Watt-Hour Energy Meter Based on the AD7751 - AN-574
Analog Devices Application Notes....[App Note] With a Current Transformer and a
Low Resistant Shunt |
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AC continuity tester finds single ended faults in cables - 21-Feb-08 Issue
of EDN A continuity tester injects an AC signal into the conductors of a cable
to find circuit faults.... [Design Idea by Kevin Bilke, Maxim Integrated Products,
Fleet, Hants, UK] |
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AC Current Controls Hour Meter - Many systems require routine maintenance
based on machine operation time. The circuit below is a simple way to turn on a
hour meter whenever AC power is supplied to the machine. An inexpensive snap-on
current transformer from Magnetics Inc, is used to detect the AC current. The output
of the transformer is fed to a voltage doubler circuit. When 0.5 AC amps or more
of current is flowing, the circuit generates sufficient voltage to turn on the
n-channel MOSFET. Once tuned on, the transistor routes voltage to the hour
meter. Some hour meters contain their own battery, so no external power is
needed. In those cases, the transistor switch alone will turn on the hour meter.
[Designed by David A. Johnson] |
AC Power
Line Hi/Lo Voltage Tester
If you wish to test a line-powered device under both a 15% high and a 15% low voltage
condition, you can use the circuit below. The circuit uses an 18v transformer
with a 3 amp rating. A double pole, double throw toggle switch then switches in
the transformer voltage in either a buck or a boost mode. In the buck mode, the
transformer voltage is subtracted from the line voltage. In the boost mode, the
transformer voltage is added to the line voltage. With an 18vac transformer the
normal 120vac voltage is switched between 102vac and 138vac. For 240vac power line
tests, use a 36vac transformer rated at 2A. [Designed by David A. Johnson] |
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