For the first couple years I drove pre-fliptronic flippers using raw power. It’s not the safest way to do things, but it worked for my needs. The time came, however, when I needed a more robust modern way to drive fliptronic flippers.
There were a few things I wanted in a driver board: Direct switch button access, CPU switch activation, and power enabling via CPU without the need of large relay switches. After lots of R&D (and component burnouts), I finally came up with a working design that satisfies my requirements. I call it the LinFlip-Duo. It can handle 2 flippers.
The flipper buttons are not part of the switch matrix. They are managed directly on this driver board. This gives the player a nice feeling of direct control, not worrying about matrix/CPU latency. The EOS switch is also directly managed on this board so, again, there is no potential latency when needing to disable the high power solenoid. The CPU can directly enable either the high or low power solenoids, so the CPU can safely enable the low power circuit if the EOS switch isn’t working.
One thing I’d like to change in the next revision is how power is distributed to the flippers. Right now there isn’t really a good consistent power source feeding the high power flippers… TBD I suppose.