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Circuits designed by David Johnson, P.E.
Last Updated on:
Thursday, March 22, 2012 04:18 AM
Master Category List -
Dave's Circuits
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Fluid Level
Detectors / Monitors Circuits |
- 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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- 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.
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- Precision Low
Capacitance Meter
This circuit was originally designed to measure the volume of the fluid inside a
10cc syringe. It used two copper foil strips attached to the outside barrel of the
syringe. The fluid between the two copper strips increases the capacitance. As the
fluid volume decreased, the capacitance also decreased. With the circuit shown
below, it is possible to calibrate the circuit, so the voltage produced is proportional
to the fluid volume inside the syringe. With the values shown, the circuit
produces a 5v DC output,...
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Fluid Level
Detectors / Monitors Circuits
Master Category List - Dave's Circuits
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