Synchronous Motor for Project, Must Go Just One Direction
09/21/2023 4:16 PM
I made an "equatorial mount" put a solar panel on it and I intend to move it at 15 degrees per hour to follow the sun. I use gradually increasing air pressure to lift a float in a can and move the solar panel. (originally I was going to do a solar cooker first).
I got a synchronous motor 4 watts, 45 seconds for a rotation, and use it to lift the float that controls the pressure.
It is geared much too high so I used a gearbox from an old office fan but the speed is still over twice too fast.
To get the speed to the perfect speed, I bought a plug in timer that can stop and start for set times over the course of the day.
I set it to one minute on and 2 minutes off based on the speed that the solar panel was moving. But there is a problem, I thought these motors were like the ones in mains wall clocks and only rotated in one direction, but almost every time it stops and starts, it will go in the opposite direction. So it doesn't work because I can't fine tune the speed with the plug in timer. Here is the solar panel on equatorial mount for the demonstration.
This actually works to rotate the solar panel mount. And the other part works as a timer but it is too fast without the plug in. So where can I buy a motor, about 1 rpm or a bit slower, that only goes in one direction and that I can fine tune with that plug in timer? My air pump waters the planter behind and also waters 2 greenhouses etc but there is plenty of pressure left to run the solar panel mover etc. The airlift pumps in the greenhouse, etc. use about 2 ft water pressure and the pump still has available 3 ft water column pressure even with them all running. The timer unit for the solar panel also is currently set to use 2 ft of water column too.
When all the air goes to that plastic wine fermenter, it pushes the float up fast enough to move the solar panel through about 6 hours of rotation in 2 minutes. So If I had the identical set up for a bunch of other solar panels, (or solar cookers on equatorial mount, I have enough air to run 180 of them from that one timer air pump combo! The plan is to make it better and run 2 or 3 solar panels and a couple of solar cookers as a proof of concept. And also because it is kind of an analogue timer, I was going to use it with the float idea, to switch things on and off in the greenhouse. For instance, I could use a float to open an air valve (that lets the main air pressure move stuff) to move winter curtains, and maybe close air vents and stuff like that. Other people could use a solar panel with photo diodes as normal solar trackers to power the air pump to move itself and other solar devices on the same system. Again, only one of the panels needs a tracking device and it can run everything else. I have a couple of videos on youtube but I have already changed things a lot and will make more changes too. I fully admit that the current setup is hokey but I will make it more sturdy once I find the right motor and taller buckets, etc. So please give me advice on a motor to use that can switch on and off and still maintain the same direction. Thanks Brian White
Re: synchronous motor for project, must go just one direction.
09/21/2023 9:57 PM
Thank you. I thought CCW/CW was a model number. DUH it means it can go either clockwise or counterclockwise. And on your link I can see that there are some others that are unidirectional (which is what I want).
Re: synchronous motor for project, must go just one direction.
09/22/2023 9:25 AM
Hopefully, one of these little motors will work. I'm sure you've thought of it, but counterweights to balance the shaft with the solar panel will minimize the work the motor has to do.
Re: synchronous motor for project, must go just one direction.
09/22/2023 2:11 PM
Oh, just to be clear, the motor just lifts the little float in the 4 inch pipe in the "air pressure controller", The low pressure air coming from a little air pump (gradually increasing pressure over the course of the day after it passes through the pressure controller/regulator) lifts another much bigger float and moves the panel. The plan is to have 3 or 4 solar cookers and solar panels all driven by floats that are lifted by the air from the air pump. I did find a motor that should work! It looks like it will fit straight into my crappy coupling too. It's supposed to come on Sunday and is supposed to run just anticlockwise. Sorry Counter ClockWise.
Re: synchronous motor for project, must go just one direction.
09/22/2023 10:34 AM
I'm pretty sure, since it only has 2 wires, and says CW/CCW, that this motor will run an un-predictable direction each time it starts, just as the turntable on my microwave oven does.
It might be possible to put a one-way clutch on the output shaft coupled to a switch, such that any time it turned the undesired direction, it would actuate that switch and turn itself off momentarily. Unfortunately, at 1 RPM, it would take a significant time to actuate the switch.
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Re: synchronous motor for project, must go just one direction.
09/22/2023 1:34 PM
Check out the link provided above.
Last image on the page.
It will reverse only when overloaded..this might be useful for auto reverse,return to start position??
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Re: synchronous motor for project, must go just one direction.
09/24/2023 2:57 AM
Thank you, That's exactly the problem I had. I have bought a CCW only motor as a replacement and hopefully it will work as I want it to. It's supposed to come tomorrow. Yesterday, I made the controller part smaller and much easier to adjust. Today, I tried to fix a few physical bugs in the system, and found thinner rubber tubing for the valve part and put the squirter hole from a saline nose dropper in one tube as a damper and the whole thing is working much more accurately. Unlikely to get it running tomorrow because the delivery will probably be late.
Re: synchronous motor for project, must go just one direction.
09/21/2023 5:30 PM
I made a motor driven equatorial mount for a Dobson telescope some years ago. It needs to be much more accurate than driving a solar panel, but maybe there may be a few ideas here you can use.
The earth turns 15 degrees per hour or 1/4 degree per minute.
I coupled a 1 rpm motor to a 1/4" 20 thread/in steel threaded rod. This rod is meshed to a homemade gear to make a worm/gear drive. The gear is connected to the shaft which has to turn once per 24 hour day.
The homemade gear was made by cutting a circle of wood. The circumference of the gear has to be (24x60)/20 = 72" or 72"/pi = 22.918" in diameter. I bought some flexible nylon 1/4" x 20 threaded rod and wrapped it around the edge of the wood circle. I put JB Weld on the edge of the wood circle and underneath the nylon threaded rod. The JB Weld adheres to the wood but not to the nylon rod, and when it is set up, the nylon rod can be removed, leaving a gear that perfectly meshes with the steel threaded rod connected to the motor.
The motor and threaded rod can be hinged at one end so that it can be disengaged from the gear to reset the position of the solar panel.
Re: synchronous motor for project, must go just one direction.
09/26/2023 10:03 AM
A very original idea to make custom threads !
A GA from me!
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Re: synchronous motor for project, must go just one direction.
09/26/2023 10:01 AM
Very good original idea to make custom threads without a lathe!
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Re: Synchronous motor for project, must go just one direction.
09/23/2023 12:54 AM
To make a synchronous small motor like a clock motor a small leaf spring is used so that when the motor starts in the reverse direction the spring, mounted on the output shaft, is tensioned against a stop until the motor stalls and then the spring gives the rotor a flick in the correct direction to run the motor in the desired direction.
Maybe you could use a circuit to vary the frequency supplied to the motor. For the motor you could use one of those DC motors that were used in record players, with the contact governor on the shaft. The quicker the motor goes the more often the speed control contacts open and the motor slows down to below the required speed and then reboots. Of course a flywheel is needed to even out the pulses.
Re: Synchronous Motor for Project, Must Go Just One Direction
09/26/2023 10:04 AM
Here is a link to slow motors.You also might try a variable speed drill motor.
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Re: Synchronous Motor for Project, Must Go Just One Direction
10/01/2023 11:35 PM
Thanks for your help. I didn't have the materials needed to make it as I wanted but it works, using a synchronous motor that was a bit too fast and then bringing it back to the right speed with a timer worked like a charm. I made it for people in solar cooking communities but it is just easier doing it the first time with a solar panel. Plus it will probably be shared more widely because hopefully people will want to make cheap tracking solar panels. Brian
Re: Synchronous Motor for Project, Must Go Just One Direction
10/04/2023 9:50 PM
I would've used this set up. I don't think high precision is required for a solar tracker so a few degrees off would be acceptable.
A slit would allow the sunlight to enter a black box with two photo-sensors. When the sun hits one sensor, it will trigger the motor to turn one way and when the sun hits the other sensor, the motor will turn the other way. If the motor turns slowly enough, hunting or oscillating can be avoided.
When the sun sets, a separate switch will trigger the motor to turn the panel back towards the east in preparation for the next day.
This is just off the top of my head and I may have missed a few details but I think the basic principle will work.
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Re: Synchronous Motor for Project, Must Go Just One Direction
10/04/2023 11:05 PM
If those photosensors are photo-resistors (as opposed to any kind of on/off device), then the sum of the currents through the two can be used to control the speed (and direction, if necessary) of the motor, with no problem of hunting/oscillation.
A daytime approximate speed would be required, to avoid losing position when large clouds pass over.
With appropriate settings for minimum and maximum speeds, there should never be a need for the reverse sensor.
I believe return-to-start will require some kind of separate circuit; there are many possibilities, including physical switches, timers, capacitor charge, etc.
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Re: Synchronous Motor for Project, Must Go Just One Direction
10/09/2023 2:29 PM
May I use or adapt your diagram for those who want to go that route? I'll credit you if you want, if I use it publicly. Just tell me what to call you. I was told that hunting and oscillating can be a major problem and a huge waste of energy with the photo diode controlled panels, and it looks like your method solves that problem. I use an indoor set up to make the gradually increasing air pressure to move the solar panel on equatorial mount. But if one solar panel had the photodiodes and an air pump and valves, it could function as the controller, it would just control the valves to change air pressure and move itself and at the same time a bunch of zombie solar panels on the same type of mount in the same orientation as itself. Thanks, Brian
Re: Synchronous Motor for Project, Must Go Just One Direction
10/09/2023 8:02 PM
Sure, no problem. I'm sure this idea isn't new so no need to credit me.
Hunting becomes a problem if the mass of the moving structure is great enough that stopping it becomes difficult as the inertia of the structure wants to keep moving even if the motor has stopped. That's why I wanted the panels to move slowly.
My design uses gears to slow down the movement and also allows me to use a smaller motor. I'm considering using a brake to stop the movement instantly but I'm going to wait until I actually build the thing before deciding if I need it.
Good luck on your project.
regards,
Vulcan
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Synchronous Motor for Project, Must Go Just One Direction
Re: synchronous motor for project, must go just one direction.
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