Small Ac Motor Wireing - DIY Chatroom

outback · 11-04-2009, 10:13 PM

I need help wireing this little electri motor. It has 3 wires, Blue/Red/Yellow. At the moment I have it wired up with only 2 wires. Red/Blue, It will run if I spin the shaft and get it started first. The motor came of of a Old Film Projector. I need this for a project. Here is a photo of the motor.

Also their was a double transformer in the box with it, and a small round filter/ I just have it straight wired at the moment.

Apreciate your help.
Thanks

nap · 11-04-2009, 11:08 PM

the small round "filter". are you sure it is a filter and not a capacitor to start the motor?

it says right on the motor it needs a cap. the 10/7.5 mfd is the size required.

(the 10 is for 50 hz power and the 7.5 is for 60 hz power)

it also says it is reversible. I would think one of the lead you are using (I don't know which one offhand) and the one that is currently not being used would cause the motor to run in the opposite direction.

outback · 11-04-2009, 11:29 PM

Your probly right about the start cap, it must not be a filter. Heres a better picture of it. I tryed looking it up but could not find out for sure.
I should have payed more attention when takeing it apart, and made a wireing diagram, I just was in a hurry, and thought it would be simple. LOL

I'm thinking the power supply is not for the motor, but for the other electronics that was in it.

Now if this is a starter for the motor, maybe someone will know what wires to connect to it.

Thanks for your help.

outback · 11-04-2009, 11:34 PM

I just wired it up, as to what I thought maybe right? I'm not going to plug it in till I'm sure, I just did this as a potentioal example.

Houston204 · 11-05-2009, 01:56 AM

Do you have an ohm meter?

Common to Run = a lower reading
Common to Start = a much higher reading
Start to Run = the sum of your other 2 readings.

The cap wires between Start and Run.
Power connects to Common and Run.

outback · 11-05-2009, 10:10 AM

I have a craftsman multimeter.

That is pretty much Greek to me. I can just bairly understand it. Please explain it a little more detail. As this only has three wires. Do I need to used the motor as a ground when checking the wires?
O' yeah the motor had a Green chassis ground but I took it off.

outback · 11-05-2009, 04:57 PM

Quote:

Originally Posted by Houston204

Do you have an ohm meter?

Common to Run = a lower reading
Common to Start = a much higher reading
Start to Run = the sum of your other 2 readings.

The cap wires between Start and Run.
Power connects to Common and Run.

I figured it out, works great, now the motor starts up like it's supost to.. Thanks

Houston204 · 11-05-2009, 08:25 PM

Yeah, I could improve my communication skills. I should have introduced my post more like...

These three wires are actually common, start, and run. There is a technique for determining which wire serves each function with an ohm meter.

Measure orange to blue, orange to yellow and blue to yellow and write down your readings.

The set with the lowest reading will include your common and run wires.
The set with the highest reading will include your start and run wires.
The remaining set will include common and start.

So, in other words...
Common to Run = a lower reading
Common to Start = a much higher reading
Start to Run = the sum of your other 2 readings.

The capacitor wires between Start and Run.
Power connects to Common and Run.

In my defense, it was 1:00 in the morning (local time) when I posted that.
I'm glad you figured it out

Yoyizit · 11-05-2009, 11:16 PM

Quote:

Originally Posted by outback

I figured it out, works great, now the motor starts up like it's supost to.. Thanks

Take readings everywhere so you know what's "normal" voltages, currents and resistances for this motor.

outback · 11-06-2009, 11:15 AM

I used Houston204 First directions, and just keept thinking about what he said, and used that to come up with the wireing. I have never ever wired an 3 Wire AC motor with a Cap Start before, it was pretty hard to understand. But now I know. Thanks Guys.

O' I was makeing a Coin Tumbler, thats what the motor is on. I also installed a Dimmer Switch in between the main power wires. Works great.

beenthere · 11-06-2009, 05:04 PM

That is NOT a start cap.

It is a run cap.

A start cap needs to have a method of removing it from the circuit after the motor has started.

outback · 11-06-2009, 07:25 PM

O.K run cap... Yeah I had saw something mentioned about the Start cap, it's like a breaker, or selinod right?

Yoyizit · 11-06-2009, 07:33 PM

"Run capacitors are rated in a range of 3-70 microfarads (mfd)"

"Start capacitors have ratings above 70 microfarads"

beenthere · 11-06-2009, 07:34 PM

No.
It is just a start cap. But, another device is also used to remove it from the circuit. So as not to burn up the motor, or start cap.

start caps are much higher micro farads then run caps.