Re: SSR question

On 9/12/2024 10:45 AM, john larkin wrote:

On Wed, 11 Sep 2024 21:55:57 -0700, John Robertson <jrr@flippers.com>
wrote:
 

On 2024-09-11 8:08 p.m., john larkin wrote:

>
Given a power supply that needs 120 volts AC input, I'd like to use a
small front-panel power switch at some low voltage, not run the AC
line up to the front panel.
>
Do people make SSRs that would do that, accept a low-voltage switch
closure to switch AC?
>

>
Sure, there are the TRAIC SSR bricks that take 4 to 32VDC to switch -
and can handle tens of amps.
>
https://www.digikey.ca/en/products/filter/solid-state-relays-ssr/183?s=N4IgTCBcDaIIIGEAEAXATgSwIYGMQF0BfIA
>
And also the opto-isolated TRAICs like the MOC302x family from Lite-On.
>
Of course you need some power to enable that stuff to run - perhaps a
capacitor/resistor driven supply that sucks a tiny amount of current
from the power line to enable the drive circuit?
>
John :-#)#

 Yes, I'd need another isolated ACline power supply to make the drive
voltage for the SSR.
 The alternative is to do what is common, have a giant power inlet
block on the back (IEC, emi, fuses, big switch) and run that into my
24 volt supply, and use the front-panel switch to enable the supply or
switch its output.
 

The mechanical solution used in a number of older HP test equipment pieces (and probably some other stuff) is put the switch set back on the main PCB and the front panel switch connects to a long plastic rod which pushes it indirectly.