This an old commercial receiver found in a year 1958 magazine. The circuit uses some transformer available that timer and the transistors are germanium types. The circuit is intended to receive MW stations.
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...