For a big project I need a strong and slow engine. As I gathered it is common get a used windshield wiper motor. I got a used one from my neighbor who fixes cars but the motor turned out to be something strange, not like any other wiper motor I can find on the internet (doesn't look like them either). I experimented with it to understand it. If I remember it has 5 connections and I guess two are for this auto-parking feature but I'm not interested in that. Leaves three connections and now to bizarre(to me).
Let me call them c1, c2 and c3. The possible connections that can be made with a power source (plus and minus) is listed here and what happens:
+c1 -c2 motor rotates one direction.
-c1 +c2 motor rotates the same direction (even though I reversed polarity).
+c3 -c2 motor turn the other direction.
-c3 +c2 motor turns the other direction (again, I reversed polarity and it spins the same, but at a different speed).
+c1 -c3 short circuits
-c1 +c3 short circuits
The thing about different speed I guess is for the different speeds of the wipers.
And the c2 should be the "ground", because it would be in touch with the rest of the metal of the car it was mounted in at the beginning.
I understood that I needed to control high currents with the arduino, but I didn't want a mechanical relay (the direction might be changing quite often, perhaps a few times per second). I bought a Parallax HB-25 Motor Controller
(bought it in fact before my strange wiper motor).
You might see the problem here, to control direction of a motor the HB-25 changes polarity of its output ports (M1 and M2). That wouldn't help me.
And now I'm getting out into the more deep waters, for me at least. I think that adding a few diodes might solve my problem.
I attach my suggestion. I hope people can tell me if this will do what I want. When the HB-25 puts positive on M1 and negative on M2 the motor rotates one way and when changing polarity of M1 and M2 it rotates the other way.
Second, I need help with selecting the diodes. I plan to buy from conrad.com, they have a big selection of diodes
. Is a "standard" diode okay? Or a Schottky diode? What I've tried to read other diodes aren't of interest here.
So... the voltage I guess will be around 13-14VDC and the motor might get stalled (high current draw). I don't know anything about the motor's power. But looking around there seems to be wiper engines in the range of 50-150 watt. So if buy diodes that are good for up to 15A, which should I buy? Or if the price would be the close for 25A I would take that (25A is the max continuous for the motor controller).