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DiscoverCircuits.com, has
26,000+ electronic circuits or schematics
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Current Monitors / Sensors / Detectors Alarms Circuits
Designed by David A. Johnson, P.E.
Last Updated on:
Monday, April 21, 2008 04:19 AM
Master Category List - Dave's Circuits
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- AC Current Monitor
The hobby circuit below shows how a small current transformer from Magnetek can be used to monitor AC current to a load. The AC voltage developed at the secondary of the transformer
can be scaled so it can be read by any digital multimeter. The transformer is rated at 30 amps.
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- ISOLATED AC CURRENT MONITOR
This circuit uses a small AC current transformer from Magnetek to produce an isolated voltage proportional to the AC current in the primary winding. The transformer contains a single
turn primary with a low 0.001-ohm resistance. It can easily handle 30 amps of AC current and provides at least 500vac of isolation. With the components shown, the output AC
voltage is scaled so 1 amp of current produces 100mv of AC voltage.
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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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- Pump Motor Monitor
This circuit can turn on a light or sound a beeper, whenever an AC line powered pump motor turns on. It is designed to detect the motor
current using a small inductor placed on the outside of the motor’s power cable. No direct wire contact is needed.
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More Current Monitors / Sensors / Detectors Circuits
Master Category List - Dave's Circuits
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