Raghunathan R wrote:
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"I have never seen a 1F capacitor in my life. Must be very BBBIIIGGG I suppose !"

No, not really :o) I have one here right in front of me that is about the same size as a Lithium cell (just a bit thicker; about 5mm).


"Dont forget the blocking diode."

Don't forget two blocking diodes! In this circuit, if you exchange the supercap for a battery, you must also put a diode in series with the battery, or the power supply will try to charge the battery, with potentially disastrous consequences.

If you're using SMD, a dual Schottky diode, like the BAT54 would be a good choice.


Rob.