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.
This circuit was found in a French magazine Toute LÉlectronique from 1978. Transistors are not...
Any operational amplifier can be used in this circuit. The 741 is the most common. Power supply must...
September 2016 - It can be purchased by Mouser Electronics the new board from Texas Instruments...