Author Options:

How to use & wire relays, speed controllers, timers, micro switches, etc. with a DC motor.? Answered

I would like to use a 110 volt, 1/2 hp (more or less), DC ( or AC ) reversing motor to move and close a horizontal, heavy (approx. 200 lbs.) fabric, thermal, curtain blanket and then to move and open back the blanket in a greenhouse. There are very expensive commercial greenhouse systems that exist to perform this task. Since I have a hobby greenhouse that is 30 ft. wide by 80 ft. long by 13 ft. tall, I need a much more affordable system. Horizontal wires or very large monofilament fishing line  (spaced 12" to 18" apart)  will run the length of the greenhouse at approximately the 8 ft. height. These wires or lines will be used to support the blanket and for it to slide on (the blanket will have grommets or similar devices used on a shower curtain to  keep the blanket running straight, etc. ) when mechanically closed and reopened. My idea is to use a DC or AC motor to perform this task with modifications to work in the greenhouse. The motor will consist of the 110 volt, 1/2 hp (more or less), DC or AC reversing motor, that will be connected to a small cable drum spool on the motor shaft, The motor  can be attached at one end wall of the greenhouse at 8 ft. high below or above the blanket and at the other end of the greenhouse also will have a cable drum spool with a pipe for rotation an be appropriately attached to the end wall. Attached to these 2 cable drum spools would be say 175 ft. ( 2 x 80 ft. plus initial amount on spool) of say 3/8 inch aircraft cable. The curtain blanket will have a say a 30 ft. long 1/2 inch or so horizontal metal bar or pipe attached to it on the leading edge. The aircraft cable will be attached to the blanket bar or pipe.The other end of the curtain blanket will be attached to the non motor end wall. As the motor turns the 2 cable drum spools  by wrapping and unwrapping the aircraft cable, the attached curtain blanket will be pulled the 80 ft. length of the greenhouse in each direction.
What I want to accomplish is as follows:                                                                                                                                                        . 1. Be able to slowly, if possible, (say over 20 - 30 minutes) close (move forward) the blanket with the motor at a preset time in the evening and for the motor to stop when the blanket is fully pulled to the motor end of the 80 ft. greenhouse.
2. Be able to slowly, if possible, (say over 20 - 30 minutes) reopen (move backward) the blanket with the motor  at a preset time in the morning and for the motor to stop when the blanket is fully pulled back to the non motor end of the 80 ft. greenhouse. To accomplish this, this reversing DC or AC motor will need to reverse direction to reopen the blanket.                                                                                      3. The shaft of a motor will probably be too short to clamp a cable drum spool to. How do I attach the spools?                                                                                        
4. What is best to use a DC or AC motor?
I tried extensively to research on the internet how to accomplish the above, but everything described similar processes in vague and technical terms of using various types of electromechanical timers, electromechanical relays, limit switches, microcontrollers, MOSFET circuits, transistors, arduinos, bridge rectifiers, etc. I have no  knowledge of all of these electronic devices and am totally confused. However, I am pretty good at say basic home electrical wiring. The closest thing on the internet to what I am trying to accomplish is an automatic chicken coop door, but not enough specifics for my project.

I need some very, specificsteps, specificproducts and where they can be purchased to be able to accomplished this. What type of motor, types of electronic devices, etc. Also, since it appears I will need a timer, a speed controller, relays or limit switches, etc. how in the world to  wire these to the motor in laymen terms. Thanks so much for anyone that can help me!!!



I'd go for a mains AC motor.

It sounds to me like you are only struggling with the electrics, not the mechanics.

With some educated guesses:

Lets use a 4" diameter tube for your pulley. 80 feet in 20 minutes is all of 0.8 inches/second.

I'd buy one of these


And one of these.


Which are the best sizes I can find right now. The second item is a motor driver.

You'll have to get a 4:1 reduction off the motor to the drum to come off at 4RPM, which is your slow-motion.

Basically, find a 4RPM, heavy duty motor and gearbox - 0.25 HP, 200W at least. I've erred on the high torque side.

Does this sound like you can handle it ?

I will research your suggestions. Thanks so much! Do you feel that a .25 HP motor will be large enough to move say 200 lbs. horizontally?

You're aiming to move it very very slowly, which, given a typical motor is spinning at 1500 RPM or so, when you want 3-4RPM out of the thing after the gear box, means you have increased the torque by 1500/4, so you will have OVER 400 ft lbs of torque.

You MIGHT find a single motor / gearbox combo that gives 3-4RPM out, and uses a 1/4 to 1/2 HP motor (200W...400W), but other wise you'll have to do a bit of final reduction with a chain drive.

I might think too simple now but did you consider going to the scrap yard for some garage door openers?
They do work with limit switches on the internal drive but it is quite easy to wire those to external switches to indicate the open and close position directly on the curtain or rope.
If that is out of the question you can look into the systems used on trucks to cover the trailers, it is a curtain system that is hand operated by you can adapt the principle for a motor drive.
The motor itself is not your issue as you don't need much power.
A gearbox is required to get the low speed you need so you need to look for the torque needed to pull your entire system, best to add at least 15% to that.
Again a garage door opener for a bigger door should be able to provide enough power for the job and already has all the components you need included.
Maybe one for the roll up doors that goes into the rolled up door would be suited for your cable drums as the motor is mounted on the axle and the drive gear could be mounted on the drum.

I have looked at garage door openers. The limiting factors of trying to use them is 160 ft. plus of cable or chain and trying to set the limits of travel. I also looked at truck cover motors, but could not figure out how to make them work in my project. I live in a small rural area and doubt there is any electrician with significant experience with electronic devices.

You can have the cable running with a clip on it, like a cable joiner.
Feed the cable through two holes and have a switch checking the cable for the clip that switches the motor off.
Of course the best option would be to use end switches on the rails where the blanket runs through.
Another option is to get someone over who has a bit of electrical and mechanical knowledge.
Your task is not hard but requires some mods and parts.

You don't say where you are in the world. It helps to point you in the right direction for components.

Without wishing to diss your skills if you really need chapter and verse on connecting such a system up you will be better of getting an electrician in to do the job for you.

Your going to need timers, plenty of electro mechanical plug in timers around. Most will deal with 10 amps easily.

Some way to connect your motor to your blanket, without being able to see this it is very hard to tell you how.

I think you may need to mount up the hardware to pull the blanket to and fro and then drive it with some kind of drive belt from your motor.