DC motor circuit

[RogerA00]

Hi, I' trying to adapt a motor from an overhead door to another use. I removed the circuit board and would like to insert a switch to permit intermittent operation in either direction. It uses AC power fed through a transformer, and there are two leads from it and two leads and a ground from the motor.
My research said to use a DPDT toggle switch and an "H" circuit. I tried that and it only buzzed in one direction, nothing in the other.
I had tested the motor using the circuit board, and it ran in one direction. Even if it had worked in both directions, it would not provide the control I need.

So can anyone offer another approach to try? Thanks.

 

[waross]

The circuit board controls the motor in both directions.
You may have to use a NO/NC push button to interrupt the stop circuit when you release the run button.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[theode]

Seems like your circuit board converts from ac to dc.
If your motor is permanent magnet field you will need a rectified supply.
Reversal is obtained by changing polarity on the motor leads.
It would be easier to use the motor with the board,assuming that comes out easily.
Its already configured for up (forward) and down (reverse).Just needs adapting.
Other way is to use a bridge rectifier with a suitable switch.
Check the dc current rating on switch is high enough.

 

[RogerA00]

There are a couple reasons that using the circuit board is not practical. The door head was discarded because something was wrong with the board and it was judged simpler to replace the entire unit. Second is that I would not be using all the components, such as the stop sensor. I need to be able to operate the motor for short runs that I control directly.

So if it means a bridge rectifier and switch, how do I determine their parameters and where do I obtain them?
This is not a commercial project, its a garage project.

The switch I found at Home Depot says 10A 277 VAC/20A 125 VAC 1.5 HP 125-250 VAC, on-off-on, Motor Rated. It is very stiff, so I am hoping to eventually find a rocker switch.
The motor is a 24V DC, and said to be 1/2 HP (not on the label)

 

[BrianPetersen]

Find out what kind of motor you have.

Get all the transformers and switches out of the system, they are just complicating matters. Connect two car batteries in series (Out of the cars!) to get 24 volts DC and apply that directly to the motor leads (leave the ground unconnected), and see what happens. Then reverse the connections and see what happens. (Actually, as a first test, I'd just do it with jumper cables from one car battery. You're not running the motor under load, it should spin with no load even on 12 volts, and this is all you need to know right now.)

I betcha the motor will turn in one direction when connected one way, and reverse when connected reversed. This would be indicative of a permanent-magnet motor with an ordinary commutator.

If this works correctly then your power supply and switching arrangement needs to emulate that - just like the original garage door opener power supply circuit did.

If the motor works correctly when connected to the batteries directly but didn't work correctly when connected to your power supply and switch circuit ... you know what that means.

 

[theode]

Rough calculation makes your motor about 15 1/2 Amps running current.
Your switch is rated ac only so is not suitable.
You could try an automotive store or breakers yard for dc switches and relays.
Batteries are your easiest bet for the supply because you'd need a transformer and rectifier plugged in at the house mains otherwise.
It should run at 1/2 power from your 12 volt car battery for experimental purposes.

 

[RogerA00]

OK, well I could not move the motor with either a battery charger or a single battery. I decided to try connecting it to my working overhead door in my garage, which happily is the exact same make and model. When I connected ONLY the motor, and hit the door button, it moved about a half turn, then stopped. Hitting it again repeated the motion, bit I think it may have been in the same direction. By the time I devised a way to get closer, it had stopped moving when I hit the button.

I may try taking it to a garage and see if they can help with a double battery, but I feel there is a reasonable level of comfort that the motor is basically working. Agree?

If so, I only need a rectifier (it has a transformer with 24V AC output) and a DC rated switch.
So can any of you suggest a place (link) of where to go to get these components, and how to designate them? Thanks

Of course, I may still need help in connecting them, but that can wait.

 

[ScottyUK]

Get hold of a 24V relay designed for a truck. Use it handle the motor heavy current switching.

It seems odd that a motor designed for 24V DC won't turn over on 12V with no load.

 

[OperaHouse]

I would suggest a picture. I have a hard time believing this is a DC motor.

 

[waross]

When I connected ONLY the motor, and hit the door button, it moved about a half turn, then stopped. Hitting it again repeated the motion, bit I think it may have been in the same direction. By the time I devised a way to get closer, it had stopped moving when I hit the button.

Throw that piece of junk away and start over with a good motor.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Skogsgurra]

I was just going to question the whole thread - it isn't exactly an "engineering discussion" and it doesn't convey much more than confusion. Bill was quicker than me. And more direct. There are lots and lots of geared motors available. Get one of those.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[BrianPetersen]

A DC motor that won't spin when DC is applied to it is NG.

There is a possibility that your tampering with it made the smoke come out. Electronic stuff only works as long as the smoke stays inside ... LOL ...

 

[flexoprinting]

What if it's an AC motor and direction is changed by capacitor leads? Does the motor have brushes? Name plate data?

Chuck

 

[waross]

I have never seen an AC motor with two leads that could be reversed, save for shaded pole motors which may be reversed by disassembling the motor and reassembling it with the stator reversed.
There are a lot of small reversing motors with three leads, common, forward and reverse.

and there are two leads from it and two leads and a ground from the motor.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Skogsgurra]

Remember this, Bill?
thread237-370926

Two wires, can start forward or reverse. But you will never know in advance...

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[waross]

I had forgotten that one, Gunnar. Possibly because I have never encountered on of those. All the small synchronous motors that I have encountered had a shading coil so as to always kick it off in the proper direction.
I still wonder how those motors develop starting torque if they come to rest in the electrical equivalent of "Top Dead Center".

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Skogsgurra]

I think I'll have to send you ona...

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[flexoprinting]

Hi Bill

I agree, but you never know anymore it's all about perspective. The OP stated two leads and a ground, ever seen a ground wire on a small DC motor? And look at this, I know it's out in left field a bit but I had to post this cheesy application.

https://www.google.com/search?q=sma...Fhow-do-i-reverse-my-electric-motor;2592;1552

Chuck

 

[roydm]

The owner said 2 wires plus a ground, I suspect it might be 2 wires plus a neutral and a regular split phase with a capacitor, I too doubt it's a DC motor.

 

[RogerA00]

Thanks.