SSR question

[john larkin]

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?

[John Robertson]

Post by john larkin
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 :-#)#

[Jan Panteltje]

On a sunny day (Wed, 11 Sep 2024 21:55:57 -0700) it happened John Robertson

Post by John Robertson

Post by john larkin
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?

Opto-triac, powered from a photo-cell connected to a small coin type battery like for SRAM backup?
Of course impulse switch, nano amps CMOS D flip flop..

Have some Microchip PIC single button on/off stuff like that,

[Chris Jones]

Post by John Robertson

Post by john larkin
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.

You could use a little generator - the EnOcean wireless wall switches do
that to avoid using a battery. When you press it, the mechanical energy
from your finger powers a tiny generator and powers the transmitter
(either Bluetooth or another standard).

If someone would package just the button part that does the generating,
leaving off the radio, it might well make enough power to turn on a SSR
for a cycle or two, which could then power the thing up properly.

[john larkin]

On Fri, 13 Sep 2024 21:17:02 +1000, Chris Jones

Post by Chris Jones

Post by John Robertson

Post by john larkin
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.

You could use a little generator - the EnOcean wireless wall switches do
that to avoid using a battery. When you press it, the mechanical energy
from your finger powers a tiny generator and powers the transmitter
(either Bluetooth or another standard).
If someone would package just the button part that does the generating,
leaving off the radio, it might well make enough power to turn on a SSR
for a cycle or two, which could then power the thing up properly.

Reminds me of an old telephone ringer magneto that I had as a kid. It
packed a pretty good shock.

How about a stepper motor with a knob? They make good generators.

[john larkin]

Post by john larkin
On Fri, 13 Sep 2024 21:17:02 +1000, Chris Jones

Post by Chris Jones

Post by John Robertson

Post by john larkin
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.

You could use a little generator - the EnOcean wireless wall switches do
that to avoid using a battery. When you press it, the mechanical energy
from your finger powers a tiny generator and powers the transmitter
(either Bluetooth or another standard).
If someone would package just the button part that does the generating,
leaving off the radio, it might well make enough power to turn on a SSR
for a cycle or two, which could then power the thing up properly.

Reminds me of an old telephone ringer magneto that I had as a kid. It
packed a pretty good shock.
How about a stepper motor with a knob? They make good generators.

Two windings of a stepper could be combined to make a positive voltage
when spun clockwise and negative if spun CCW. That can drive a
single-coil latching relay.

[john larkin]

Post by John Robertson

Post by john larkin
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.

[bitrex]

Post by John Robertson

Post by john larkin
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.

[Jan Panteltje]

On a sunny day (Wed, 11 Sep 2024 20:08:36 -0700) it happened john larkin

Post by john larkin
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?

You mean triacs?
Opto-triacs?

[Pimpom]

Post by john larkin
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?

There should be several models to choose from. I used them in the early
90s in a limited production - a few hundred units - for the state power
agency here when they needed some automated sequence switching. They
work fine as long as the higher leakage compared to mechanical switches
doesn't matter. For low power, I've used the cute TO-66 style models.

Then there are the MOC30xx opto-coupled triac drivers. I used several of
those in a one-off product for the state racing association.

[piglet]

Post by john larkin
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?

I think Piotr Wyderski posted a cool looking circuit using a small hf pulse
transformer as isolation and coupling. Shorting the isolated LV side loaded
or stopped an oscillator or something.

The 1960s GE SCR manual showed ways to do that too but using 50/60Hz
transformers which are now not cost effective.

[john larkin]

On Thu, 12 Sep 2024 20:09:31 -0000 (UTC), piglet

Post by piglet

Post by john larkin
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?

I think Piotr Wyderski posted a cool looking circuit using a small hf pulse
transformer as isolation and coupling. Shorting the isolated LV side loaded
or stopped an oscillator or something.
The 1960s GE SCR manual showed ways to do that too but using 50/60Hz
transformers which are now not cost effective.

Some people sell a small potted PCB-mount brick that's an AC-line
powered power supply. But I'd have to design a PCB and run line
voltage into it.

Some biggish universal-input metal-box power supplies have a
contact-closure enable input. May as well use one of those, even
thought I only need a few watts.

The product is a high-voltage pulse generator, probably a detonator or
something. We don't know.

[Klaus Vestergaard Kragelund]

Post by john larkin
On Thu, 12 Sep 2024 20:09:31 -0000 (UTC), piglet

Post by piglet

Post by john larkin
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?

I think Piotr Wyderski posted a cool looking circuit using a small hf pulse
transformer as isolation and coupling. Shorting the isolated LV side loaded
or stopped an oscillator or something.
The 1960s GE SCR manual showed ways to do that too but using 50/60Hz
transformers which are now not cost effective.

Some people sell a small potted PCB-mount brick that's an AC-line
powered power supply. But I'd have to design a PCB and run line
voltage into it.
Some biggish universal-input metal-box power supplies have a
contact-closure enable input. May as well use one of those, even
thought I only need a few watts.
The product is a high-voltage pulse generator, probably a detonator or
something. We don't know.

One thing to look out for, is the robustness against spurious turn-on
(add snubber).

Also, if you draw more than just low power, look out for the zero
crossing distortion. That might result in failing to comply with
conducted emission tests.

I did a design on a 650W heater with several outputs, and in that one we
had to roll our own driver, to make sure the Triacs was kept on during
the zero crossing. One design implementation had back to back FETs.

[Joe Gwinn]

Post by john larkin
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?

There is a commercial module used by electricians to control a light
(AC Powered) by opening and closing a reed switch actuated by a magnet
installed in the top edge of a closet door. I have one in my house.

Joe Gwinn