Thread: Wiper motor controller circuit

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Hi all,
I finished a wiper motor controller that I've been working on for a few weeks. The circuit allows the motor to perform two 180° rotations with a pause in between the cycles. I'll be using this to open and close a coffin lid, but it has other applications such as extending/retracting a linkage, opening/closing a door etc. Here's a video of the circuit in action:

Wipermotor.flv - Video - Photobucket - Video and Image Hosting

The circuit is triggered by a 9VDC pulse from a PIR. At the end of the two 180° rotations, the circuit waits for the next trigger. Here's a link to the circuit drawing and parts list:

HalloweenGallery.com - Documents/Motor controller rev 2

HalloweenGallery.com - Documents/Part list rev 4

For some reason the circuit picture doesn't display in the window, just click on the "view full size image" to display the pic.

If anyone has questions please let me know. I'll get pics of the opto reflector attachment up in the next couple of days.

Interesting -

I have something planned like this, but I was just planning to use limit switches and reverse the motor after 180 deg or so.

I should add that the circuit uses two adjustable timers - one for the total length of the sequence and another for adjusting the pause time between the 180° rotations. The total length timer is a simple R/C circuit; the pause timer is a 555 astable oscillator which momentarily disables the opto sensor to allow the motor to start rotating. The PIR trigger (9VDC pulse) could be changed to a dry trigger by substituting a monostable 555 circuit.

Great Job Otaku!

I also have two PDFs showing the opto reflector and opto mount hardware and the 10 amp outboard relay wiring. I can't attach them here - the file sizes are too large. PM me if you're interested and I'll email the files to you.

I have a mechanical question that someone may have an awnser to.
I'm using a wiper motor to lift an arm but it's not strong enough and reverses before it gets to the top. Here's my question:
If I had a two foot arm pinned at one end and wanted to lift it with the least energy. Which of the three would be the best choice:
1- push up on the arm 6" from the pinned end.
2- extend the arm 6" past the pined end & pull down.
3- add a 4" cam or pully/wheel at the pinned end with a chain to pull the arm up.
I really don't want to use springs or rubber bands to do the trick. I just need to get a little more lifting power then pushing up on the arm.
Thanks.

Try getting a power supply with more current, you may just be running out of juice during the lift. Wiper motors are very beefy and you must be lifting a lot of weight.

Otherwise I would suggest just adding a small spring to assist in the lifting.

mechanically, if the fulcrum is closer to the object being lifted, the easier it will be lifted.

Originally Posted by goober

I have a mechanical question that someone may have an awnser to.
I'm using a wiper motor to lift an arm but it's not strong enough and reverses before it gets to the top. Here's my question:
If I had a two foot arm pinned at one end and wanted to lift it with the least energy. Which of the three would be the best choice:
1- push up on the arm 6" from the pinned end.
2- extend the arm 6" past the pined end & pull down.
3- add a 4" cam or pully/wheel at the pinned end with a chain to pull the arm up.
I really don't want to use springs or rubber bands to do the trick. I just need to get a little more lifting power then pushing up on the arm.
Thanks.

in terms of mechanical advantage 1 and 2 are the same, sorry I don't really understand 3

Yay!! Another great product from Otaku Inc. (You should start your own company.)
Will this circuit only work for controlling a wiper motor? Or will it work on any DC motor?
It looks like a very useful item. Thanks for sharing it.

Originally Posted by DaveintheGrave

Yay!! Another great product from Otaku Inc. (You should start your own company.)
Will this circuit only work for controlling a wiper motor? Or will it work on any DC motor?
It looks like a very useful item. Thanks for sharing it.

LOL! Thanks Dave!
The circuit will work for other motors provided they have very little "overrun" when the power is cut. If the motor rotates the reflector past the view of the opto, it will restart power to the motor. The circuit is independent of the motor, so it will also work on an AC motor. Gearmotors are probably the best application since they move fairly slowly - the motor in the video is running on low speed with a 5VDC power supply, about 15 RPM. You can see a bit of "overrun" which will probably go away when the motor gets a load on it. I plan to use this for opening a coffin lid, holding it open while the corpse inside speaks to the TOTs then closing it again. It'll be triggered with the 9VDC pulse from a Quorum PIR. The repeatability is pretty good - I ran it for several hours on a 30 sec. repeat cycle and it always stopped within ~ 5 degree range. Not as good as a stepper motor, but a whole lot cheaper.
An astable timing circuit controls when power is sent to the motor and the length of the pause between the two 180° rotations. The pause time (6-12 secs) can be adjusted with a trimpot. After running the two 180° rotations, it waits for the next trigger.
The sequence is started by momentarily disabling the opto emitter which closes a relay, sending 12VDC to the output terminals on the board. The 5VDC motor power is actually switched by an off-board relay that is controlled by the 12VDC output from the circuit. I tried using that output to run the motor, but ran into noise difficulties; I got a lot of relay bounce. Also, the on-board relay contacts are just 2A and the motor uses a 5A supply.