Battery controlled switch (CB8708E)

This circuit was found in a 90s Popular Electronics. It can be used to control a triac from the low voltage of an ordinary battery.

Flasher with Transistors (CB5210E)
We found this circuit in an American 1980s documentation. The transistors can be equivalent as BC548...
Voltage Doubler (MSB021E)
Figure 1 shows a hal-wave voltage doubler operating with the Power-supply voltage. Output current...
RIAA Equalizer Amplifier (CB25696E)
This preamplifier circuit for turntable cartridges was found in the March 1994 issue of...