Looking for a small wiper DC motor

Thread Starter

neowebmedia

Joined Feb 25, 2019
7
Hi all!

I am looking for a small 5v max DC motor with the ability to work like a wiper. The goal is simply moving a flag from left to right and right to left in a field of 160 degrees 60 movements per minute. It is possible? What I should look for? Thank you!

What I need?
 

MaxHeadRoom

Joined Jul 18, 2013
21,383
You may want to try a wiper motor that uses the three connections, common high and low, and run it on 5v on the high setting, I have never tried it, but a trip to any auto wrecker may produce one for testing.
Max.
 

MaxHeadRoom

Joined Jul 18, 2013
21,383
You need a slow operating oscillating motion, the wiper motor gear box may be a possibility even if the motor isn't.
5v for that operation is a little limiting I feel.
Max.
 

be80be

Joined Jul 5, 2008
2,049
I guess you have never looked at a wiper motor

You have Right Angle Gear Motor with a arm on it

You make a arm put that on the little motor I showed you and you have a wiper motor
Now to do what you want will take a little more thinking LOL.

 

djsfantasi

Joined Apr 11, 2010
6,786
Depending on how big the flag is, perhaps you could use a servo. Like the one I linked to above.

I’d drive it with a 555 based oscillator and switch in (with a MOSFET or BJT) different timing resistors. The two resistors would provide the correct pulses for 0° or 160°. Then, you’d need to alternatively drive the MOSFET/BJT to create the alternating action. Search for 555 based servo testers to get an idea of what I’m talking about.

Reading the specs, the servo should be able to drive the flag 60 times a minute. I calculate one back and forth motion with this servo is 0.79 seconds. If the flag speed is a little flexible, this might work for you. You could tune the alternate action to exactly 60 times a minute.
 

Yaakov

Joined Jan 27, 2019
1,612
Hi all!

I am looking for a small 5v max DC motor with the ability to work like a wiper. The goal is simply moving a flag from left to right and right to left in a field of 160 degrees 60 movements per minute. It is possible? What I should look for? Thank you!

What I need?
As other people have said, a wiper works mechanically. Without knowing the load the motor will have to move, and the total power you can provide (voltage isn't enough, amperage is also needed), it is very hard to say if it is practical to do. Once thing that is fairly clear, if you just want the waving action, the right way to do it is with a cam and arm arrangement.
 

djsfantasi

Joined Apr 11, 2010
6,786
Here is a circuit I quickly found online to demonstrate what I meant for the 555 control circuit.

I’d add a second 100nF capacitor so each resistor would have its own. I’d remove the buttons and add a logic level MOSFET (2N7000 for example) between ground and the cap/resistor combo.

Now you just need a timer that alternates connecting each MOSFET gate to 5V. Another 555 circuit, with a 50% (or close) duty cycle operating at 1Hz, can be used if you add a second MOSFET to one side, acting as an inverter.
 

Yaakov

Joined Jan 27, 2019
1,612
Here is a circuit I quickly found online to demonstrate what I meant for the 555 control circuit.

I’d add a second 100nF capacitor so each resistor would have its own. I’d remove the buttons and add a logic level MOSFET (2N7000 for example) between ground and the cap/resistor combo.

Now you just need a timer that alternates connecting each MOSFET gate to 5V. Another 555 circuit, with a 50% (or close) duty cycle operating at 1Hz, can be used if you add a second MOSFET to one side, acting as an inverter.
If reversing the motor is the method, there will need to be mechanical stops at the limits of travel possibly with buffers.
 

djsfantasi

Joined Apr 11, 2010
6,786
If reversing the motor is the method, there will need to be mechanical stops at the limits of travel possibly with buffers.
But that’s irrelevant with a servo. The servo only moves to where it’s commanded. No mechanical stops necessary. You just need one signal (and it’s inverse) to move the servo back and forth in a waving motion.
 

Yaakov

Joined Jan 27, 2019
1,612
But that’s irrelevant with a servo. The servo only moves to where it’s commanded. No mechanical stops necessary. You just need one signal (and it’s inverse) to move the servo back and forth in a waving motion.
I know how servos operate, but if he is using anything with mass at the end of a long arm, a 5V servo is probably going to need help decelerating the load before reversing. I have no idea how much mass he wants to fling around, but a flag has a long arm, and the flag itself is not massless.

I am mind reading, since he's not providing much information. If the load is small, I am wrong.
 

djsfantasi

Joined Apr 11, 2010
6,786
I know how servos operate, but if he is using anything with mass at the end of a long arm, a 5V servo is probably going to need help decelerating the load before reversing. I have no idea how much mass he wants to fling around, but a flag has a long arm, and the flag itself is not massless.

I am mind reading, since he's not providing much information. If the load is small, I am wrong.
Yep, I get that. That’s why in my first post about a servo solution I asked about the flag. It gets down to what the purpose of the flag is. You’re right about the length of the arm and the mass of the flag. But we just don’t know.

I built a similar device for a special effect in a theatrical production. The length of the arm was short and the “flag” was a 3”x5” recrangle of 0.08 thick styrene. It had a little mass. Just off the cuff, a 6”arm of 0.0625 brass and a 3”x3” rectangle of Mylar presents no problem.
 

djsfantasi

Joined Apr 11, 2010
6,786
I just can’t stop myself. With the materials I suggested in my last post, we can likely go to a 12” arm and the flag likely could be larger. Say 6”x6”

Heat the brass rod at one end and hammer it flat. Then drill it out so that you can bolt it to the servo arm.

Buy a Mylar balloon at a Dollar store. Cut out your flag and use the inside to face out. Using AAC glue (Superglue), attach it to the arm.

Build the circuitry on a perfboarf. Reserve room to attach the servo. Double sided tape is all that’s necessary.

Mount everything in a project box with a cutout in the side where the servo will project. Add a hole to supply power (that had a SPST switch to turn the unit on/off.

And you’d be close to a complete solution.
 

MaxHeadRoom

Joined Jul 18, 2013
21,383
But that’s irrelevant with a servo. The servo only moves to where it’s commanded. No mechanical stops necessary. You just need one signal (and it’s inverse) to move the servo back and forth in a waving motion.
Is this the usual reference to a RC servo or a servo mechanism in general?
Often this is not defined.
Max.
 

Yaakov

Joined Jan 27, 2019
1,612
What do you think about using a half gear on a low speed motor and a spring for moving back the flag arm?
It would help to know how big you expect the flag to be and how much current we’re working with. Voltage just isn’t enough information to know how much work we are doing. If you are talking about the 5V from, say, an Arduino, that’s not going to get you much. Or, from a USB port, well, same there. So, what’s the story with the size and power supply?
 
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