Now for latching relays ...


Andy G4JNT
 

Can anyone come up with a simpler configuration for driving LATCHING 28V relays from a 12V supply than this?   
 

Same basic concept as Ian's, except that there is no longer any need for a holding current;  the voltage doubled pulse from the capacitor does it all.   I couldn't find a way to recharge the capacitor through the relay coil, hence the 270 ohms resistor

It works with all my latching relays, with coil resistances from 160 to 500 ohms.

Drive to the FETs is assumed to be a pulse, otherwise power is dissipated unnecessarily in the 270R

Andy  G4JNT

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