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Circuits designed by David Johnson, P.E.
Last Updated on: Thursday, April 07, 2016 02:04 PM

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Medical Electronic Circuits

Alarm sounds when Power Cord is Unplugged  -  Many medical devices, such a portable X-ray and ultrasound equipment, carry their own batteries. However, the frantic pace of some hospital emergency rooms might cause the device to be shoved off into a corner without being plugged back into an AC power source to recharge their batteries. So, I designed this circuit to emit an audible alarm whenever the device’s power cord was unplugged from the wall for a period of time . . . [Hobby Circuit designed by David Johnson P.E.,  07/08/00]


Circuit Monitors Power Loss  -  For some medical equipment it is important for an operator to know when power is lost to the machine. The beeper is powered from a 9v battery and requires the machine to have a power switch with a third set of contacts . . . [Hobby Circuit designed by David Johnson P.E.,  03/26/99]

Corona Monitor  -  The circuit is powered by +5v and has an on-board voltage regulator as a reference voltage.  The current from a reversed biased photodiode is converted into a voltage using an op Amp circuit.  That output voltage is fed to a voltage comparator circuit.  Included is an adjustment in the current to voltage converter, to calibrate the installed circuit . . . [Circuit by Dave Johnson P.E.,  02/01/10]


Power Loss Beeper  -  For some medical equipment it is important for an operator to know when power is lost to the machine. The beeper is powered from a 9v battery and requires the machine to have a power switch with a third set of contacts . . . [Circuit by Dave Johnson P.E.,  03/26/99]


Unplugged Power Cord Alarm  -  Many medical devices, such a portable X-ray and ultrasound equipment, carry their own batteries. However, the frantic pace of some hospital emergency rooms might cause the device to be shoved off into a corner without being plugged back into an AC power source to recharge their batteries. So, I designed this circuit to emit an audible alarm whenever the device’s power cord was unplugged from the wall for a period of time . . . [Circuit by David Johnson P.E.,  07/08/00]


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