Hello,
I am wanting to build a circuit which when a 5 VDC input goes to zero volts (not necessarily ground) the circuit produces 9 VDC output of up to 100 ma of current from a small "transistor" battery. Does anyone have any ideas? I would like to also be able to adjust the output from 5 to 9 VDC.
This might seem a bit strange, why would I want to produce 5V when 5V goes to zero? I need to use this for when the radio signal on a PIC receiver goes to zero and the output D1 pin goes from 5 VDC to zero VDC. I want to alarm when the signal goes away and need to produce some voltage when the 5V disappears.