This circuit is from an 80's publication. It makes use of small 6 V x 50 mA incandescent lamps. The diodes can be general purpose or even 1N4002. The transformer is 6.3 V with 100 mA or more current.
We found this test circuit in Radio Electronics magazine from July 1962. The circuit uses...
We found this circuit in an American publication from the 1980s. Equivalent modern operational amplifiers...
The transistors in this circuit can be the BC548. Capacitors determine the frequency and can be...