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Controlling a 12v Wiper Motor? Answered

Hi all,

I'm a bit of a noob with electronics and wondered if anyone could help me with a project, I would like to control the speed of a wiper motor for use in a small powered saw.

Ideally using mostly the upper end of the motors speed, are there any cheapish products I can buy off the shelf to wire together to give me (UK) mains power going in and the max safe voltage/amperage out to run the motor, plus speed control.

I say max voltage/amps as I have read elsewhere that the motor can handle a bit more than just 12v.

I have searched a good few electronics kit sites and found things that sound like what I want, but I guess I'm just not sure if it actually is.

As always I would be grateful for any help.

14 Replies

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rickharris (author)2016-09-21

https://www.amazon.co.uk/6V-90V-Pulse-Width-Contro...

try this, Your not giving the current rating for the motor but this provides 15A so may well do and at 2:77 isn't going to break the bank.

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Squibo (author)rickharris2016-09-21

Wow that really is cheap thanks.

Would this power supply suffice do you think?

https://www.amazon.co.uk/switch-transformer-SODIAL-Power-Supply/dp/B018RQZ4HW/ref=sr_1_11?ie=UTF8&qid=1474477873&sr=8-11&keywords=12v+15a+power+supply

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rickharris (author)Squibo2016-09-21

probably, again your not specifying the motor current which is important but 15 amps should do it - I assume you have retained the mechanism on the wiper motor.

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rickharris (author)rickharris2016-09-21

Try it with a car battery first

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Squibo (author)rickharris2016-09-21

Thanks again for your help, I have tried it on a car battery and it runs fine, but the body has no info other a cryptic part no and 12v printed on it.

I have kept the whole mechanism and the plug, but it will need to be pretty heavily modded to work as I would like.

I did some research online ( the US use rakes of these in Halloween prop automation it would appear) and it looks like the amps ramp up under load and should max out at around 14 amps, that's just before stalling.

I'm hoping it should work, it won't be the quickest, but they have a fair bit of torque so if I aim to reduce mechanical friction as much as poss (except the bit where I want loads of it) it might just work :)

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iceng (author)Squibo2016-09-23

The reciprocating mechanism will fail early because the saw load is much more then the intended design of sliding rubber on glass.

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Jack A Lopez (author)2016-09-21

What is this thing you call "wiper motor"?

I have heard that phrase used to describe the actuator, consisting of DC electric motor plus speed reducing gears, that drives a cars windshield wiper.

https://en.wikipedia.org/wiki/Windscreen_wiper

But you say you're using it in a "small powered saw".

So that made me think, that maybe you are using the word "wiper" to mean more generally something that wipes, like commutator brushes, like found in a "brushed DC electric motor"

https://en.wikipedia.org/wiki/Brushed_DC_electric_...

so that a "wiper motor" is actually "brushed motor", "motor with brushes".

I was just curious about that. Sometimes I just have no clue about the jargon you kids use these days, especially for peeps who speak a dialect other than FUSE (Former United States English).

;-)

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user

In English English, the wipers are the windshield wipers.

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user

Thanks for clarifying that.

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Vyger (author)Jack A Lopez2016-09-21

Yeah, I also am mystified. And I cannot see any connection between a saw and a windshield wiper. perhaps it is used on a face shield to keep the flying dust off. I don't get the connection at all. And there is no way a windshield wiper motor could work as a saw ----- well maybe attached to the handle of a hand saw to pull it back and forth ???

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Squibo (author)Vyger2016-09-21

Bingo, motorised hacksaw, it's an old fashioned way to cut steel but I can essentially build it for the price of the controls, you don't even need speed control but I thought it would be nice.

Check YouTube there are some really nice examples, I'm going to try with a wiper motor, should that fail I have a 1/4 hp motor to upgrade with, believe it or not this is one tool where more power won't really help.

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Squibo (author)2016-09-21

Apologies, for clarity I am referring a vehicular windshield wiper motor.

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Jack A Lopez (author)Squibo2016-09-21

So it is a windshield wiper motor, and you want to use the reciprocating motion to push a hacksaw back and forth. I can almost picture it.

I think RickHarris is on the right track recommending a PWM type driver to sort of throttle the power to it.

Actually, this is the same strategy used in typical design for a battery-powered, variable speed, power tool; i.e. battery, plus PWM driver, plus brushed DC motor, plus geartrain.

In one of my old instructables, in Step 5,
https://www.instructables.com/id/Generator-Demonstr...

I took a picture of an old cordless drill with the cover off, that sort of shows these blocks, {battery, PWM driver, motor, geartrain}, all in one picture.

PWM drivers are actually kind of ubiquitous, considering there's pretty much one in every battery-powered power tool, so they should be inexpensive, because they're not rare.

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Yonatan24 (author)2016-09-21

You need to click "reply" when posting a reply, so they'll get notified.

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