This variable gain circuit for analog video signals was found in a 90s Linear Technology documentation. The circuit has an adjustable gain between -12 and +8 dB.
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This is an old test circuit for integrated TTL counters, feeding a Nixie tube, common at the time....
This traditional crystal radio circuit, but which has a modern version with diode, was found in an...
This headphone amplifier using a pickup coil can be used as an extension for devices such as TVs,...