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Tester or
Instrumentation Circuits, Page 3
Testers:
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Last Updated on:
Friday, March 12, 2010 12:07 PM |
| Circuits
Designed by Dave Johnson, P.E. : |
- CAPACITANCE
TYPE LIQUID LEVEL MONITOR
This circuit was originally designed to monitor the level of liquid natural gas in a
tank but it can be used to also measure almost any liquid. Two custom insulated
metal tubes form a capacitor plate. The capacitance between the two tubes increases
as the level of the liquid rises. The circuit converts an increase of capacitance
into a positive voltage change. The circuit could be changed to handle almost any
scale factor needed.
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- Cheap
Electrostatic Discharge Tester
Anyone who has ever had a shocking experience on an
especially dry day is acutely aware of the kinds of high voltage that can be
generated from a simple walk across a carpeted floor. Those same finger to metal
sparks can destroy or disrupt sensitive electronic circuits. Good design practices
take great care to avoid such potential disasters by maintaining sufficient
insulation between metal or plastic enclosure parts and the electronics within or by
shielding any especially sensitive components....
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- Cheap Light
Power Meter
Some time ago I was experimenting with the use of some low leakage photovoltaic
solar cells, to harvest some energy from the diffuse lighting inside a room.
The plan was to use a small array of solar cells (the type often used on solar
powered calculators) to keep a super capacitor charged, drawing power from the light
within an inside room...
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Links to electronic circuits,
electronic schematics, designs for engineers, hobbyists, students & inventors:
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CDV700 Geiger Counter Probe Rebuilding - (electronic design added 6/07) |
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Cell Cycler Sorting Sires Superior Batteries - 06/23/94 EDN-Design Ideas: To
assemble superior NiCd batteries, you need to form and match individual cells
making up a battery. First, formation takes place in a NiCd cell only after numerous
charge-discharge cycles. Second, you must collect voltage data during se cycles to
match up cells having uniform characteristics.....(design idea added 3/03) |
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Cheap and easy inductance tester uses few components - 04/12/07 EDN-Design Ideas:
This circuit plus a frequency counter or oscilloscope measures unmarked
inductors.....(design idea added 05/06/07) |
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Cheap Electrostatic Discharge Tester - Anyone who has ever had a shocking
experience on an especially dry day is acutely aware of the kinds of high voltage that
can be generated from a simple walk across a carpeted floor. Those same finger to
metal sparks can destroy or disrupt sensitive electronic circuits. Good design
practices take great care to avoid such potential disasters by maintaining sufficient
insulation between metal or plastic enclosure parts and the electronics within or by
shielding any especially sensitive components.... ….(designed by David A. Johnson) |
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Cheap Light Power Meter - Some time ago I was experimenting with the use of some
low leakage photovoltaic solar cells, to harvest some energy from the diffuse lighting
inside a room. The plan was to use a small array of solar cells (the type often
used on solar powered calculators) to keep a super capacitor charged, drawing power
from the light within an inside room... ….(designed by David A. Johnson) |
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Cheap pushbutton replaces rotary switch - 10/26/00 EDN-Design Ideas: / PDF
contains multiple circuits, scroll to find this circuit The common JFET current-source
in Figure 1a has average output impedance and depends heavily on the JFET's V P and I
DSS variations. These manufacturi.....(design idea added 07/03) |
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