How to switch a transistor between gnd and floating?

tpny said:

But your previous design (with positive feedback to the pnp) is also ok right? Since you did assign 5mA going into the base of the relay npn to turn it ON..

Click to expand...

It should be OK. I thought the design was a little flaky, with little room for component tolerances, but I never tested it for that.

I like the fet design, less resistors and no current is wasted on switching the transistors ON.. Which leads me to think: if I'm using the transistor strickly as a switch, choose fet over bjt

Click to expand...

It's a short jump to CD4000 series logic gates instead of FETs in parts of the circuit, which could result in reducing the component count even more.