Ttelephone tone encoder (CB10150E)

This keypad telephone encoder circuit was found in ancient American documentation. The components used are common and are not difficult to obtain.

| Clique na imagem para ampliar |

Transistor Intercom (CB16408E)
This circuit was found in a 1980 publication. It uses only 3 easily obtainable transistors. It is a...
Multi Range Ammeter (CB10543E)
This circuit was published in an English magazine from 1977, but remains current, as we can...
Cable Tester (CB16567E)
The circuit shown is intended for cable testing, providing status indication via LEDs. The number of...