Hi Guenther,

Glad you are involved in examinating the circuit’s improvements !

When looking in the 1205 box, I discovered a PNP Germanium transistor without resistor !

To distinguish between Ge and Si transistors, the new Germanium transistor Modules have a Ge marking.
It was included with the OpAmp experiment set. I thought I hadn’t one.

I will try your circuit out today and wil report.

Concerning the 0,1µF capacitor, it was needed in my setup or the the thyristor got triggered when powering on.

It works as follows :

When power is applied, the capacitor starts charging. Since there’s a current flowing through it when charging, it momentarily shorts the Base of the NPN transistor to Ground.

This is a kind of POR (Power On Reset) and prevents false triggering of the Thyristor.

Glad to see that you seems not needing it. Have you tried several times reconnecting the power without having the problem that the lamp starts to light up immediatly ?


  • This reply was modified 2 years ago by LectronFan.