This commercial receiver from the year 1958 uses two AA cells as Power supply. The circuit is intend to receive MW station and the transistors are germanium types not easy to find today.
This circuit was found in a 90s Popular Electronics. The sensors can be common speakers that reach...
This circuit indicates when a 28 V lamp burns, lighting a neon lamp with higher voltage. The...
This circuit was obtained from an American 80's documentation. The operational ones can be...