Found in a Popular Electronics from the 90s, this shield is activated by a 20 mA current. The inverter is an Open Collector TTL type. The power is 5 V.
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...