Regenerative circuit for two sensors (CB8266E)

Found in a 1967 American publication, this circuit with feedback for two transistors has a gain of 20 times. Phototransistors are types of the time.

| Clique na imagem para ampliar |

Parallel Port Interface for PC (NI021E)
This application is not modern since few computers have parallel ports. But you can use this...
Second Order Unity Gain Filter (CB25817E)
Using a 741 op-amp this circuit high-pass to 10 kHz was found in the February 1995 issue of...
Precision sample and hold (CB8882E)
Found in a 1969 EEE, this circuit is based on an operational amplifier of the time and on old type...