This shield circuit is from a 1968s Motorola documentation. The relay is according to the supply voltage. R1 can be reduced to lower trigger voltages.
Found in National Semiconductor publication from the 1980s. This gain-100 circuit can be...
We found this configuration in a 1975 publication. It can be implemented easily, as it uses only...
The high number of transistors on this radio for the medium wave range is an indication of its...