- Joined Nov 5, 2016
I put together this common astable multivibrator circuit and powered it from my power supply at 5v and it worked fine. I wanted to use it by plugging it in to a wall socket. So I used the voltage divider to drop the voltage to around 10 volts and utilized a zener to provide a steady voltage. With the center tap not connected to anything I read 9.9 volts. But when I connected it to the zener resistor, it immediately dropped to 4.85v with the zener output at 4.53v. And when I connected it to the multivibrator, the zener output dropped to 3.59v and the multivibrator wouldn't work. I've had this kind of trouble before when trying to use a voltage divider. What am I doing wrong? I had to draw the circuit in the 'Paint' program, I hope you can read it allright.