This circuit was found in a 80’s American documentation. The adjustment trimpot is from 47k to 100k. The diodes are general-purpose types use and the supply voltage depends on the relay.
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...