This circuit came out in a publication called Electronics Handbook of 1993. The circuit shows how to implement a good common telephone line protector.
This TTL instructional circuit appeared in the February 1972 issue of Radio Electronics magazine. 5 V...
Using the HA2400 this circuit has its output voltage digitally programmed from the references...
We found this circuit in a European publication from the 1970s. The transistor is made of...