Negative ion detector (CB21001E)

This tube circuit was found in the magazine 73 for radio amateurs in an issue from the 1980s. Note the transformer used to power the circuit.

| Clique na imagem para ampliar |

TTL LED flasher (CB12764E)
This circuit allows the use of two triggers (inverters or NAND ports connected in this way) to...
Automatic Doorbell (CB16652E)
This circuit was found in a 1992 publication. Its purpose is to time the activation of a doorbell...
Fine Adjusted Power Supply (CB15781E)
A fine adjustment of the output voltage of a power source is achieved with this circuit, which...