When the phone rings, a high-powered incandescent light comes on. This circuit can be interesting to obtain the remote call warning or to assist the hearing impaired.
This circuit is from a 1976 publication and can be assembled with more modern operational...
Common diodes when forward biased present a voltage fall of about 0.6 to 0.7 V. This voltage fall...
This 50's setup has a balance control. The transistors are germanium types of the time, and the...