This circuit can activate a powerful lamp or call system when a telephone call occurs. Suitable for hearing impaired or noisy places it was found in American documentation in the 90s.
This circuit from an old documentation uses an operational amplifier that is no longer used. The...
This circuit is the basis of a symmetrical 15 V supply. MC1468 can also be used. They are not...
This tuned circuit was found in a 1966 Electronic Circuit Handbook. The transistor can be any...