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This circuit was designed at the request of Carl Hanson at KNX-FM. He needed it for their automation system.. |
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If you don't like my hand-drawn schematic, then click on it !! |
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This circuit was submitted to and became the National First Prize Winner for Broadcast Management and Engineering Magazine's 'Great Idea Contest" for
1987.. |
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Here's How it works: When power is first applied to the circuit, the parallel combination of C1/R2 is charged to 1/2 VCC through the voltage divider
R1/R2.
When PB1 is closed, C1 discharges through the coil of RL1. This pulls in the relay , and the wiper is held in by the current through RL1 and R1.
Any charge remaining on C1 discharges through R2, so when PB1 is pressed again, C1
(representing a short this time) makes the relay drop out, returning the circuit to its original condition. |
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So, it provides a toggling 'Push-On / Push-Off' action using two resistors, a capacitor, and a relay. And because of the simplicity, it's virtually
foolproof... |
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