This circuit is from an old American documentation and its use in motorcycles with 12 V is suggested to power 6V radios. The transistor can be the BD136 and BC548.
Found in older documentation this setting applies to modern components, noting that the power...
This circuit can send signals in both the VHF and FMN bands with a range of a few tens of meters. The...
This circuit indicates when the voltage of a 12 V battery is low. With changes, for example, the...