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Tester or Instrumentation Circuits, Page
3 Testers: #'sA-BCDEF-GH-KLM-OPQ-RSTV-Z Last Updated on:
Friday, August 29, 2008 02:34 PM
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.
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.
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.
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.
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.
Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students
& inventors:
A 4 to 20 mA loop needs no external power source: 09/13/01 EDN Design Ideas / (added 11/05) The simple circuit in Figure 1 uses
a low-current-drain MAX407)3H amplifier to sense current flowing through a 4to 20-mA loop. The circuit senses current through a 1Ω resistor with a fixed gain of 100 and uses no
battery or dc power supply. The low current drain of amplifier (0.
AB-2: High Voltage
Testing: A description of high voltage test standards as y relate to Isoloop isolators. These standards include UL1950, UL1577, UL3101-1 and VDE0884. .
(added 6/06)
Accurate Digital LC Meter: Based on PIC16F84A microcontroller, 16x1 LCD and LM311 IC (circuit added 8/06)
Accurately measure resistance with less than perfect components: 11/11/04 EDN Design Ideas / (added 5/05) For transducers, such as
strain gauges or rmistors, you must accurately and inexpensively measure resistance using circuitry built with imperfect components and in which gain and offset errors can significantly limit
accuracy of ohmic measurements. The right circuit topology makes it possible to eliminate most error terms while measuring ohms, leaving accuracy to be determined by jus...
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