Ted S posted:
One concern I have with the module Leo recommended, is that in my case, the footswitch in the primary circuit is normally closed. When you press it changes to open. However, it seems like that module (and others like it) expects a default open circuit, and a trigger event of closing the primary circuit to start the timer function.
The key piece here (and the reason I'm afraid I'll need something like an arduino to control the relay), is that RELEASING the foot pedal in the primary circuit is also a trigger event. There are millions of switches and electrical devices that trigger on press. But the release (and restoration of continuity in the primary circuit) somehow has to be "sensed" which completes a logical loop that executes the remaining events. That sounds like computer logic to me.
Suppose you have a SPDT relay with COM, NO, and NC terminals on the output side. You could wire the foot switch to this relay so that it is energized in the normal, resting state. With the magnet energized, there would be a connection between the COM and NO terminals.
Now when you press the foot switch and break the connection to the relay, the spring in the relay will change it to make a connection between the COM and NC terminals. This would be your trigger.
There are other, better ways of doing this than using a relay but you get the idea. It's just a bit of negative logic.
I believe that anyone with a lick of sense can master the Arduino. It just takes time, patience and a good hookup to the Internet. There's a lot of information regarding this microprocessor and the things that it can do. I can help you with it if you get stuck. I would encourage anyone to jump in and get started. It's inexpensive, it can be utilized for a multitude of electronic projects and most of all, it's fun.
