This circuit is from American documentation from the 1980s. The transistors are general purpose types and the relay can be 6 or 12 V depending on the supply voltage.
Unlike the previous circuit, this circuit from Electronics Now, October 1993, has the load...
For the component values used in thisf this circuit, the frequency can be adjusted between 740 Hz and...
We found this circuit in the 1982 Selezione Radio magazine in Italy. The circuit uses an...