I am trying to build a TRNG using avalanche breakdown for randomness. I am developing a circuit as looks like this.(<https://web.jfet.org/images/rng-circuit.gif>)

Before I complete the circuit i wanted to be sure that my transistors generate random voltages. So I tested the avalanche breakdown voltage with a digital multimeter.

[![this is the circuit that i build and test for.](https://image.ibb.co/czXa7b/rng_circuit.gif)](https://image.ibb.co/czXa7b/rng_circuit.gif)

I checked the voltage from the red points in picture. But when I tested it, there was only a constant voltage of 8V. I thought it should be randomly changing between 8-0 volts. Is this normal ?