Here's a Pelco VS512B twelve input electronic switch for multiple camera security monitoring systems. Operation is more or less identical to the simplest of analog sequencers, though instead of each stage passing a DC voltage corresponding to a potentiometer setting, each stage passes signal. Bandwidth is presumably up into the MHz, since it must carry video signal, low frequency has yet to be tested since the unit as stock is loaded with BNC connectors. Hole placement on this looks to be too congested for 1/4" jacks, so I may have to settle for RCA connectors on this thing.
Overall there seems a pretty light parts count here, considering. The twelve switching input sections at upper left, room for eight more. I believe far left is a gain recovery/buffer stage for the output. Power supply at right. Halfway into the frame is the rate pot, function switches below.
Input at left. Those diodes may play hell with signal integrity in the audio range, I'll leave them be for now. Red stripe actives are MCR102 Thyristors, presumably in a bistable daisy chain which translates to sequential switching. The locally (single channel) charged Thyristor could then tickle the PN3638A into conduction, sluicing the local input into the gain recovery stage for output.
Just speculation: The "ring" of Thyristors are the oscillator, cycle rate is dictated by the voltage supply charging up caps. Lock stepping this to an external sync pulse may be troublesome, but there is only one way to find out. Onto the pile with it.
