Telephone Line Tester (CB21266E)

We found this circuit in a Radio Electronics from the 90s. The circuit is for conventional analog lines. All components are common nowadays.

| Clique na imagem para ampliar |

Temperature sensor shield (CB5093E)
This circuit was found in an old publication and can be adapted for use with modern...
Servo Test (CB11388E)
The circuit presented generates pulses at regular intervals with the duration controlled by a...
Volume Expander (CB19809E)
The LS150 is an uncommon high-performance operational amplifier today. The circuit is from old...