Microwave Forum

richy_64 · Administrator Beiträge: 198

Here is an example of a simple noise generator.
The quality of the picture is bad, so here are the parts again:

R1: 10k
R2, R5, R7: 1M
R3, R6, R8: 12k
C1-C5: 1n
D1: 5,6V Zener diode, you can also use a germanium diode like AA11x.
T1-T3: standard npn type, like BC547
Power supply: 9-12V should be fine.

Behind C5 you get a noise signal that is strong enough for our experiments.

The function: Diodes are never completely closed, there is always a little noisy current of some µA (in fact, in most cases this is undisired, but this circuit uses this side-effect).
The transistors T1-T3 amplifier the noise at the cathode of the diode by the factor of 1000000.
[I measured the noise voltage at a germanium diode, a got 10mV with frequencies up to some MHz]

@ imran: You can use this circuit instead of the µC i used.

Richard