Best method for remote control of a PSU

Yes. They are called latching relays. Just about any large electronics supplier sells these (see Newark Electronics, Digikey, Mouser Electronics, etc.)

BRW

To begin with, eliminate NTC1, NTC2 and SW2. You don't need a DPDT relay - single pole is fine. And yes, there are latching relays that are pulse operated and do not require holding current.

Ed

Use the pulse to energize the relay, but then get power to hold the relay in from whatever it is you're powering. You'd need a little circuitry to turn it off, say a gate where if power is on, then when a pulse comes in, it gets inverted and interrupts the power to the relay, turning it off.

Good Luck! Rich

Thanks all for your suggestions.

I think I may have found a suitable latching relay at Digikey (not much selection). I've noticed that they must be derated 75% for non-resistive loads. The largest current carrying capacity is two amps resistive load and 0.5A non-resistive.

I have a 14VAC 4.4VA Transformer coming next week hopefully Monday; I can take some measurements to see if 0.5A_rms is adequate for sure with safety margin. The LM317 is for 12V @ 0.125A.