This circuit is from General Electric from the 80s, using a relay with high current contacts (20 A). The transistor admits equivalent, and any phototransistor can be used as a sensor.
This circuit converts pulse frequency to current, which is indicated on an analog instrument. The...
Based on an LM317T, this circuit found in Popular Electronics works with signals of frequencies up to...
The Texas Instruments LM5178 Buck-boost controller is capable of operating in the 4.2 to 55 V (60...