"ON" feature for the SV power switch


just a simple suggestion:
why not use a transistor, wired emitter+collector on both sides of the wires that lead to the pushbutton and exposing the base (with a 1K resistor for ex) as a pin for turning ON the switch?
today I’m using this setup (with an overkill BC337 NPN) to power the switch ON (see it as the transistor is wired in parallel with the pushbutton). OFF is as usual done with the dedicated PIN.
YOu may wonder why do this? the setup I’m using it for is a very common one: driving an ESC. A 10-15A ESC uses at least 40mA, some of them even as high as 100mA (Rocar Robbe: 80mA). Multiply that by two (a differential driven robot) and you get a pretty heavy power consumption for a robot that should idle with the least power draw as possible.
So today, I’m using two pololu switches to turn them OFF when the motors are not used. Turning them is accomplished by the setup described above.

Another example would be to use a solar cell for ex for turning on a robot: when it gets exposed to light, it wakes up.
I think that adding a 1K smd resistor, 1 NPN low power transistor and 1 male header extra won’t raise the price for the switch by more than 0.2 USD. The feature you win however is clearly a +.


The reason we didn’t do what you’re suggesting is that it assumes something else is already powered that can turn on the transistor, in which case that device could just directly turn a MOSFET on and off rather than dealing with our latching circuit and requiring separate I/O lines for on and off. Are you using both the transistor and a physical switch in parallel in your application?

- Jan


using another mosfet would be a solution, but why not use something existing already, instead of finding, buying and paying for the shipping of another MOSFET, knowing that logic level mosfets aren’t that cheap.

Yes, i’m using both in parallel mostly because sometimes you’re not sure if it’s not your code’s fault that the power switch doesn’t switch on, so a “manual” way of “checking” is a nice feature to have (instead of hooking a logic probe or multimeter or oscilloscope).