WOW! This is interesting. I have a sega naomi system in a HS-5 cab that I thinking about converting over to MAME. So, if I understand this right this would replace the 15/32k manual switch on the naomi system.
Yeah pretty much.. Do you know what monitor/chassis is in the machine? The remote board for my chassis is
this one. Scroll down to "Toshiba Remote Board and Toshiba PCB-D SUB Connector Board".
If you have the same remote board, I'd be pretty confident that you could simply copy exactly what I have done. If you have a different remote board, it should still be doable, you'd just need to modify my breadboard circuit to match what your remote board does..
Assuming it does much the same thing as mine (it simply takes an input voltage (12v), feeds it though some resistors and then you end up with a different voltage at the end (31kHz = 10.16v, 24kHz = 6.03v, 15kHz = 2.14v), which then gets sent via the ribbon cable to the monitor to tell it which mode to run at.