This circuit uses the LM2931 which is not a common component today. What it does is to activate a lamp causing it to blink at a frequency determined by the capacitor.
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In the proposed circuit, each pulse of light or infrared radiation that hits the photodiode...
This circuit with the CK722 has a small range. We found it in Radio Electronics magazine from...
We found this circuit in a 1972 publication. The circuit is indicated for the application of TTL...