Uni-direction of small motor

Rainer Feyer · #1 08/21/2007, 07:13 AM

Hi all,

I purchased a small motor, 120V 2 turns per minute, to make a peristaltic pump with.

I have been able to make the parts for the pump, but, did not figure with he motor turning bi-directionally; i.e.: turns one way now, turns the opposite direction next time it is turned on. I like the motors dependability (use it with my swirlstein) and cost (less than $5.00) but, for a peristaltic pump it would have to turn one way only.

Any suggestions?

funman1 · #2 08/21/2007, 03:19 PM

120V motors like that start turning a direction based on where the poles ended up when it stoped.
The is no way to control it really..
The only hope is to make a device that you can attach to the motor shaft that will only turn one way. So when it sratrs you force it to turn only one way.

funman1 · #3 08/21/2007, 05:29 PM

Just remembered a good example of this is a microwave turn table, and most powerheads... They will start in random directions but with a mod can be made to start in a single direction.

customcolor · #4 08/21/2007, 06:40 PM

find a dc motor always same direction

funman1 · #5 08/21/2007, 10:18 PM

That's what a few of the "expensive" powerheads do..
Runs a DC motor, so it does not need to have special mods done to it to get it to start in the correct direction.

Rainer Feyer · #6 08/22/2007, 07:08 AM

Thank you all.

Would the modification have to be an electronic triger to stop and restart if it goes the wrong direction, or something like a mechanical 'block' which, I would think, would be a great strain on the motor and gears.

Customcolor, are D/C motors much more expensive?

funman1 · #7 08/22/2007, 08:07 AM

It would block one direction mechanically, but only for a moment because then the motor would start spining the other direction.
DC motors are pretty cheap on ebay.
Knowing how fast your motor is actually spinning before all the gears though is the tricky part to finding a replacement.

Rainer Feyer · #8 08/22/2007, 11:21 AM

funman1

Thank you - I found a couple of DC gearmotors on surpluscenter.com and will report back to see how they are. From what I heard in the past, D/C motors are very easy to adjust in terms of RPM, correct? Hope that they are strong enough to do the job.

As for the mechanical 'stop and turn', so to speak, do you or anyone have an example?

customcolor · #9 08/22/2007, 06:42 PM

rpm change on a dc motor is yes just that easy. i have seen tons of dc's on ebay and look for tourc(cant spell lol) but if its a geard motor it should be strong

funman1 · #10 08/22/2007, 07:46 PM

yeah the way you are geared about any motor will work because the motor will spin very fast and the gears will slow it down, but that also creates more power on the slow side of all the gears.

DC motors can be controller with a variable resistor (Pots / Potentiometer)

I think there's an example of a maxijet mod where you put a prop on the MJ and then you mod it somehow so it will only start one direction. I've never modded a MJ so I'm not versed in the subject, but if memory serves, they solved it somehow..

Rainer Feyer · #11 08/23/2007, 06:22 AM

Thank you for all the info!

The MJ mod is actually a very good DIY to do - I made several and they work great (and inexpensive).

Though, the MJ mod was more of a 'propellar spin' question, rather than a motor changing direction. The MJ resolution was: If the prop spins the wrong way, it will propell itself forward (pushing water backwards). A simple piece of Acrylic would stop the prop, thereby reverting the spin direction.

Still hoping to get a sample of a motor changing direction, I would still like to use the A/C motors in the future.

Anyone?