momentary switch help needed

[Dr_Evil]

This is for a potato gun upgrade. I've had it with the POS grill ignitors that you have to keep pressing. My plan is to have two screws come into the combustion area on opposite sides with about 1/4" gap between them. I found these which will work.

https://www.sparkfun.com/products/11218

I ordered one along with one of these since all I wanted to do was to run in momentarily since a normal small momentary switch might not handle 3 amps.

https://www.sparkfun.com/products/8903

During some testing before installation, I found out the PCB provides constant on power. Pressing the switch again does not power it off under a load. It worked fine when verifying power output using a DMM. That means I have to disconnect the battery to turn it off...

So now I'm looking for another method to run the spark gap igniter. I either need a momentary switch like the one below or something similar to the PCB above that is truly momentary.

https://www.sparkfun.com/products/9190

Any ideas?

 

[rhd]

This works:

Except instead of using the IC in the image, go with SSM3J328RLF(TCT-ND instead. It's 6A instead of 3A, but same package size, and pin-compatible (I think - double check).

 

[Dr_Evil]

Are there any PCBs for that circuit that you know of?

Any other ideas out there?

 

[rhd]

Are there any PCBs for that circuit that you know of?

Any other ideas out there?

Nope. But it's a really easy one to setup. SOT-23-3 is common, there's probably a part for it in Eagle somewhere without needing to make your own.

If you don't want to go PCB, there are lots of through-hole MOSFETs and resistors. No need to go surface mount. You can make that circuit the same way people make DIY linears.

 

[The Lightning Stalker]

That transistor will dissipate about 1/4W @ 3A. Keep that in mind when designing your PCB. Use nice
wide tracks to suck up the heat in case someone gets a little trigger happy.

 

[rhd]

That transistor will dissipate about 1/4W @ 3A. Keep that in mind when designing your PCB. Use nice
wide tracks to suck up the heat in case someone gets a little trigger happy.

If you want to really cut the heat, and are trying to avoid a PCB, you could just use something like this:
IPS075N03L G-ND

 

[Dr_Evil]

What about something like this?

APF3024H - PANASONIC EW APF3024H - POWER RELAY, 250VAC, 6A, SPST-NO, PCB | Newark element14 US

 

[Sigurthr]

You can also do it with a NPN mosfet but it interrupts the ground return line instead of the Vcc line. There you would use a 10k and 100k resistor to apply 90% Vcc voltage to the gate. Choice of mosfet depends on what voltage your Vcc is.