Hi Bob,
Thanks for your thoughts and questions. This controller was designed to use only a wee bit of juice in the circuit itself. I'm aware of the two wiper motor designs...to power or to ground. In this case, I don't believe it will matter since the relay operates just as a switch would. I've tried the motor and touching the correct wire to 12v + with the same approximate speed of the relay switch causes it to go through one motion cycle and park without issue. So at this point the only question remaining is will the 2 sec delay give enough time. Said a different way "will the 2 sec delay send another pulse to the motor before it completes the sweep?" Because that won't be the best plan. If not, adjusting will be easy. In fact I originally thought of using 4 tiny variable resistors which could each be adjusted as desired...but I didn't have them and thought it might be over-complicating without need.
Yes, I think most switches work that way. In this case the switch will be sitting on top of the dash, however. I can of course wire it any way at all...I'm just thinking of what will be the easiest and most logical to use. Probably just a matter of getting used to it. I doubt many owners of these trucks would be letting other people drive them in the rain. Maybe we should take a switch position poll?
As for the circuit, yes...you're on the right track. It is the simplest RC circuit I could think of...cobbled mostly from a light sensitive circuit I created around the same time you were taking your last circuits class. Did I flip the base/collector/emitter? I've been known to do that and I'll tell you the two transistors I had here...one was different. One was CBE and the other was EBC in orientation. I'm not looking at the schematic now but I will later today. The original diagram was drawn hastily, modified as resistance values needed to be changed and then cleaned up a bit. If I made a mistake, that's when it happened. The 10k resistor was put in there to add a bit more resistance before the switch started selecting individual resistors. This is a way of saying it helped make the after-switch resistance values closer to what I needed plus it seemed to me if I needed to adjust upward the time delay of one speed, I'd need to adjust upward the delay time of all of them and using a single resistor before the switch would be the easy answer. Hopefully that makes sense. Once I receive the switch I've ordered I'll be able to hook this all up and try it. Right now it is working with a single resistor and seems to be spot-on.
I considered using the 555 IC and that would work fine, but I'd still have to have a selector switch, different resistor values, etc. Plus I didn't have one handy the afternoon I started working on this.
Intermittent vacuum wipers? Don't you just step on the gas pedal for that, Bob?
