EVER WISHED YOU COULD CONTROL THE TEMPERATURE OF YOUR DC SUPPLIED SOLDERING IRON?. Or the on / off duration of a flashing bulb,small motor stop and go operation,how about being able to maintain accurate temperature control of your jacket heating supply.Some of the few applications for this circuit ,I am sure you may have some other ideas for this versatile circuit.

Modified SCR control for DC application

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Modifications

The AC supply has been removed and the trigger pulses are now obtained from a 555 IC Timer from pin 3 through a diode to gate B of the CD4011 and the entire circuit is now independent of the SCR except for the trigger pulses to the SCR gate .A 9V battery is used to supply the circuit making it a very small and portable unit .

SCR Supply

Whitin the SCR specifications any independent DC supply and current can be used at the SCR input .

Battery voltage monitor

A battery voltage monitor can be added to the circuit as shown on page ten , If the zener circuit is used a 6.8V zener should be used and adjust for the LED to just come on at around 7.5V.