Pushbutton SV -- remote "on" in addition to "off"?

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1

I’d like to use the pushbutton with a “remote on” capability in addition to the "remote off."
I was thinking I could hook up an N-channel MOSFET (like my favorite BS170) instead of the switch, but the diagram doesn’t give enough information to tell whether this is possible or not.

  1. Which polarity does the switch have?
  2. Is one of the switch terminals tied to either “Vin” or “GND”?
  3. If this isn’t going to work out, what else can I use? An opto-isolator? If so, I still need to know switch polarity and desired on resistance.
2

Hello.

A MOSFET instead of the switch won’t work. I’m not sure what you mean by the “polarity” of the switch, but both sides need to be able to go high and low (neither side is just connected to Vin or GND). If you have something that can turn on your MOSFET, why do you need this pushbutton power switch at all? You can just turn on and off a P-channel MOSFET directly.

- Jan

3

The MOSFET needs a constant gate voltage. This button only needs a pulse. The output I have is a pulse that comes from an ignition key signal controller, and I want the power button to drive about 8A of load. I don’t want to wire something like a Schmidt trigger myself if I can just buy it ready-made.

Given that the contact is N.O. how come it need both sides to go high/low? What’s the actual controller or circuit used?
Really, this switch, but with an “on” signal to match the “off” signal, would serve as a very nice ready-made toggle relay. Something to consider :slight_smile:

4

I see. You could hook up your MOSFET from the button pin closer to the PCB edge to ground; turning on your MOSFET would turn on the switch and put it in the latched on state. You would not be able to use that MOSFET to turn off the circuit; you could still do that with the existing “off” pin. You can see more about the circuit in the patent.

We have had a few requests similar to yours, so I will consider making a product with the separate on and off inputs.

- Jan

5

Thanks for the suggestion! Yeah, if you build one that’s exactly what I want, that’d be pretty convenient :slight_smile:

Also, I think I can build my own latch (without the push-on, push-off function) with two N-channels and a power P-channel, but taking the time to make it a robust circuit is, well, time :slight_smile: