This bench circuit was found in Radio Electronics magazine from June 1958. The circuit does not have an external power supply. The circuit generates signals from 12 Hz to 180 kHz in 4 bands.
In the figure we have a negative power circuit for SCR and unijunction transistor suggested by...
We found this oscillator in a documentation for radio amateurs from the 1970s. The circuit can use...
This 5 V power supply for TTL, Shields and microcontrollers is old, and the components can be...