With an 18 V input, this regulator was found in Philips documentation from the 60's. The transistors are from that time. The power transistor must have a heatsink.
This timer circuit was found in a 1980s American documentation. Transistors and SCR support modern...
This configuration appears at several points in this section, obtained from different sources....
This metering bridge circuit uses one power supply only. The operational ones depend on the...