I'm getting close to finishing my brand spanking new gate control design. I sincerely appreciate all the help I've received out here.
My latest challenge is to extinguish an LED when a circuit is grounded. To do so, I require a simple transistor inverter. However, I could not find anything that uses a ground signal. So I had to come up with one.
The parameters of the circuit are that the input signal has to be a ground, the circuit power has to be 12V, and I am trying to stick to transistors (I could probably use CMOS, but I'm trying to design the entire thing using transistor logic - it's been a great learning experience). This inverter is also powered by solar/battery, so current draw (particularly when active and LED is out) is important. The best I can do is 213.26 uA. Here is my design:
All 3 transistors seem to go into saturation mode when they are forward biased, and go into cutoff mode when they are not. I'd like to reduce the current draw, but I don't think it's possible and still maintain exactly 10 mA on the LED when it is lit. Is there a simpler design that I am missing? Am I overlooking the obvious (yet again)?
As always, any help is sincerely appreciated. I can't wait to finish this design and start building it.