Thank you for that explanation, apparently there are a lot of things related to electrical theory that I don't know. I had no idea the gate could just pick up enough voltage right out of the air to trigger it. I always thought voltage and current went hand in hand, that voltage was the speed that current travels at. I had no idea that voltage could exist with no current.
I'm still trying to wrap my head around this. I had always thought it was kind of like this analogy comparing to an automobile. Where the size of the vehicle is the current, and the speed it travels is the voltage. So like you could have a semi truck traveling slow, would be high current low voltage. Or a ferrari traveling fast, would be low current at high voltage. Or any combination of such. However if no vehicle were to exist (no current), than how can there be a measurement of how fast something that doesn't exist is moving?
And just to confirm, the pulldown resistor should be about 2k, and go from the gate of the SCR to the negative terminal of the battery that triggers the SCR?
Thanks.