This power supply for model railroad was found in a February 1961 Radio Electronics Magazine. The transistor must be mounted on a heatsink and the transformer is a 1,5A secondary winding.
This circuit produces the sound of percussion such as blocks, drum, bell, etc. The frequency...
We found this oscillator in a publication from the 1960s. The frequency is around 600 Hz with the...
Found in a Popular Electronics from 1992, this circuit uses a PLL567 in an audio meter bridge that...