R1 may be 10k and R2 100k. The transistor can be the BC548 and instead of the small lamp we can use a series LED with a 1k resistor. D1 is germanium and C1 is 10 nF. C2 can be 47 nF.
In the figure we have the way to increase the current capacity of an operational amplifier. The...
We found this circuit in a 1982 documentation, but the circuit can still be easily assembled, as the...
Found in an Electronics World of 1968 this circuit can use any SCR and diodes depending on the...