Hi, just checking by to ask if anyone has knowledge of fitting a variable speed rotary switch such a fan heater controller to vary wiper speed . Down under we are required to have 2 speed wipers in a scratch built car. As these simple wipers only have 2 wires ,I could not think of another way to control speed . We will be running the lazy Susan tandem type connector arm to run 2 wipers and one motor. Please you rainx fans restrain from input. While I have used it many times ,and anti fog.
I have a two speed, variable and with auto park switch for my Newport wipers. These switch boxes are available but I can't remember the brand I used. It might have come with the wipers. Best to ask Newport. Also, I think a special type of motor has to be used with this type of switch. I could be wrong there, but you should check your motor's specs with the available switches and a manufacturer like Newport Wipers.
Check out this company. this is what I'm using with an American Bosch two speed wiper motor. With it being as small as it is, the shipping cost to Australia should not be much.
I'm not too sure how that's supposed to work. Diodes pass voltage/current one way, and block it the other way. This also shows three wires from the motors, it appears his only has two. The 1 amp fuse size is suspect too, if accurate that's a very small motor. May be a stretch to expect it to run two wipers. And is Radio Shack still around down under? They're defunct here... The other thing to keep in mind is if you drop voltage to slow the motor, it will draw more current if the load is unchanged, sometime a lot more. More current means more heat, heat is the enemy of electrical systems. I'll throw out one more idea. Pretty much all small DC motors are 'timed' for maximum power/speed in one direction. If you reverse them, they run slower. Whether or not it will be slow enough to satisfy your inspector I can't say, but it may be worth checking. All you need for this is the switch shown above. In any case, I wouldn't run the wipers on slow speed for any time as the motor will very likely get pretty hot and it will probably shorten it's life. I've never seen a single-speed wiper motor run like this; all the two-speed ones I've seen have dedicated windings for each speed.
Those diodes have a forward voltage drop of 1 volt, so putting five of them in series might give you around 8 volts or so at the motor, which should drop the speed roughly in half. It's a more accurate way to drop voltage than using a resistor...the drop does not depend on the load.
Maybe the down under diode numbers are different but after a few hours making the circuit board and trying different connection combinations,it went frustratedly into file 13. Bought a NOS heater blower 3 speed switch on eBay . On the bench it seems perfect for 5 minutes running, it did not seem to get hot at any speed. It was something like 9v 10.5v and 12v .
Does your existing motor have the auto park function ...... does NZ rego require it. Intermittent wipers can be achieved with the VW/AUDI relay method if that's needed too.
If that wiper switch has a built-in resistor (it will get warm/hot on "low"), and only in the positive line, you should be fine. It just means your wiper motor is getting a lower voltage on "low" (maybe around 9V, so the other 3V is across the resistor). This is the basic circuit that will work , you just need a resistor of enough resistance to slow it down enough, and of a wattage rating to dissipate the "excess" voltage.
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