Here's a circuit I'm trying to get working :
I have two digital signals (B and C in the diagram) coming from a CD40174 flipflop. I use these to light up two LED's.
I also use these as the input for a transistor based NOR gate the output of which I call A.
I also need to be able to drive an LED from A
The problem is that if I calculate R11 (the base resistor for the LED driving transistor) correctly (about 5K) the voltage at A is significantly less than 9V.
I am using A elsewhere and it needs to be as near 9V as possible. Also I'd like to draw as little current as possible from the flipflop outputs.
If I raise R11 to 100K I get a nicer, very nearly 9V at A, but the current through the LED (on pin 8) is significantly less than 20mA
Can someone tell me how to resolve this?