This circuit with unijunction transistors was found in a documentation from the 80's. The trigger times of the SCRs depend on the capacitors and are adjusted in the 5M (4M7) potentiometers.
Figure 1 shows a circuit than can be used as time stage in timers, and other applications....
This circuit is from a 1989 Electronics Handbook. The zener diodes are 9 V x 1 W and the...
We can use this amplifier with low impedance headphones with good performance. Possible...