[darryl]

Help!!! Trying to reverse wire a wiper motor. I understand how to reverse it with a on-off-on switch, which I have done. It works great, I just can't stand there and flip the switch all night. What I have is a FCG on a track. The FCG platform moves left and right on a track via a long garage door opener worm gear, which is turned by the wiper motor. What I need is two switches, one at each end so that when the FCG reaches it's end of travel the platform will flip a switch. I figure I need either a push button or roller lever switch. Maybe wire it like a three-way light? but I can't figure out what kind of switch a three way light is (SPDT, etc.)
I'm know there has to be some simple solution rather then a PROP 1 as a timer or something. Any help greatly appreciated as usual. Thanks Darryl

 

[Otaku]

darryl,
Use lever switches to energize latching relays at each end of the track. A latching relay will remain in the position it was in when power was removed from the coil. Wire the relays such that the polarity of the wiper motor power is reversed when the relay switches position. When the FCG contacts and closes the lever switch, the polarity change will reverse the motor direction. Hopefully, this will not require you to use two power supplies - I'd need to do a wiring layout to answer that question.

 

[bourno]

EDIT: Never mind below, I thought the track motor was on the platform. The methods below could still work for you, but it would require long cords being run.

Otaku idea on using a latch relay would be simpler as the coils just need pulsed to switch the points and they would stay in that position until the other coil was pulse to switch directions.

Back in March, you posted this link on MOM
http://www.internationalmeccanomen.org.uk/MMB/MotorControl/motorcontrol1.htm

Under Motor Control - Direction of Rotation Part 2a there is a Figure 28 which I think would work well for your application. Figure 28 just needs a regular toggle switch and relay to make the DC motor change rotation. This method would require the switch to be on the moving platform.

Or you could use a DPDT toggle switch like shown in Figure 22 to swap the polarity going to the motor. This would be the simplest way. Again, the switch would be mounted on the moving platform to get tripped/flipped near the end of the run to make the platform run in in the other direction until the switch got flipped back again.

Hadn't seen or heard anything on the FCG platform in some time, thought maybe it didn't work out. Good to hear you have got it running manually at the moment.

 

[darryl]

Thanks guys, the latching relay sounds good, the only problem is I wouldn't know how to wire them. Have been doing research online for about a hour but still no luck. Will keep going.
Might need to just try bourno's idea with the switch in the middle, just will have to figure out what to do to run the wires.
Thanks again!!

 

[gmacted]

What you're trying to do is a little tricky. You don't want to simply use a single DPDT relay for the following reason. Since all you're doing to reverse the direction of the motor is to swap the + and - leads of the power supply, there is a potential to short out the power supply using a single relay. The other thing you need to be careful with is that when you swap the + and - leads on the motor, the motor casing will become hot/live since the motor casing is connected to the - terminal. You will want to open up the motor and disconnect the - terminal from the casing. If you don't do this, you could run the risk of electrocuting anyone who touches it. I don't think you want this effect.
To be safe, I would use two time delayed relays (somewhat expensive) with a latching relay (somewhat expensive) and two limit switches (one on each end of the worm drive). The reason I would use two time delayed relays is you want a "break before make" connection. This means, you want the motor to stop moving in one direction before you want it to start in the other direction. It's similar to the switch you have already wired in an on-off-on configuration. You turn the switch to the "off" position before you turn it to the "on" position (break before make). A DPDT relay is a break before make, but the contacts are so close and you will basically have +12VDC and GND very close together, you have a potential for a "welding shut" effect that will essentially cause a direct short on the power supply. You'll most likely just blow the fuse, but it won't be pretty.

 

[mrklaw]

Rick Polizzi had a hot air balloon that would go back and forth automatically. It was featured in the "Extreme Halloween" show that was on HGTV. I've never seen a howto though

 

[darryl]

Thanks gmacting. I understand what you are saying, but I don't understand how to wire them. Does anyone have any good tutorials earmarked in their favorites? I just might have to order them and then go for it I guess.

 

[darryl]

gmacting, been doing some homework. Let me see if I understand this. I would have one time delay relay and one limit switch at each end of the track. When the ghost got to one end it would hit the limit switch energizing the timer relay. The timer relay would hesitate for what time I set it for then send power to the latch relay which would reverse the motor. When the ghost would reach the opposite end it would then do the same.
Just need to find the parts online. I'm quessing I would need 2 power supplies. One for the timer relays and one for the latch relay?
Thanks again if you get time to answer.

 

[gmacted]

gmacting, been doing some homework. Let me see if I understand this. I would have one time delay relay and one limit switch at each end of the track. When the ghost got to one end it would hit the limit switch energizing the timer relay. The timer relay would hesitate for what time I set it for then send power to the latch relay which would reverse the motor. When the ghost would reach the opposite end it would then do the same.
Just need to find the parts online. I'm quessing I would need 2 power supplies. One for the timer relays and one for the latch relay?
Thanks again if you get time to answer.

You would need two time delay relays. One for each direction. The time delay is needed to ensure that one relay has turned off before the other one turns on. One latching relay would be needed with two limit switches. The limit swiches would connect to the latching relay to control when to turn on and off the direction relays. You could do all of this with one 12 VDC supply. Are you using an old computer supply? If your interested I can probably draw something out for you over the weekend.

 

[gmacted]

Just took a quick look at mouser.com. The cheapest 12 VDC time delay relay (with socket) I could find was ~$50 each. The latching relay was ~$20. The snap switches would be ~$1 each. Still interested?

 

[.id.]

Something like this should work..... It uses 2 DPDT relays (choose a coil voltage comperable with the motor), 2 momentary Normally Open microswitches, and 2 momentary Normally Closed microswitches (the switches are the same kind, you just wire to different terminals of the switch).

One pole on each relay is used to latch the relay (in conjunction with the NO switch). The other pole is used to reverse the motor (similar to the switch that you had already wired up). Hopefully this is understandable in the pic......

The hardest part is the Normally Closed switch on the one side and the Normally Open switch on the other side have to be activated at roughtly the same time. Mounting them might be tricky, but if you put one above the other, the motor/moving FCG part should have enough momentum to to keep is going a little farther after it has hit both switches....

The parts I looked at on Mouser were:
Two - 528-976B-5D - PC Board Relays DPDT 5VDC coil 5A contacts - $4.17 each
Four - 6115-V7-1B17D8-263 - Basic Switches SPDT 11A @ 277VAC contacts - $2.90 each

Hope this helps (rather that hinders).....

 

[gmacted]

Something like this should work..... It uses 2 DPDT relays (choose a coil voltage comperable with the motor), 2 momentary Normally Open microswitches, and 2 momentary Normally Closed microswitches (the switches are the same kind, you just wire to different terminals of the switch).

One pole on each relay is used to latch the relay (in conjunction with the NO switch). The other pole is used to reverse the motor (similar to the switch that you had already wired up). Hopefully this is understandable in the pic......

The hardest part is the Normally Closed switch on the one side and the Normally Open switch on the other side have to be activated at roughtly the same time. Mounting them might be tricky, but if you put one above the other, the motor/moving FCG part should have enough momentum to to keep is going a little farther after it has hit both switches....

The parts I looked at on Mouser were:
Two - 528-976B-5D - PC Board Relays DPDT 5VDC coil 5A contacts - $4.17 each
Four - 6115-V7-1B17D8-263 - Basic Switches SPDT 11A @ 277VAC contacts - $2.90 each

Hope this helps (rather that hinders).....

.id.,

I also thought of something like this, but I agree that the mounting would be very critical and very tricky. You would have to rely on there being enough momentum in the motor to trip both switches. I think that may be a very big assumption. It may be worth looking at in an experiment before building anything, however.

I do have a few problems with your circuit, however.

First lets look at the DPDT relays. Lets say the FCG starts in the middle of the worm drive. All microswitches will be in their normal state. The coils will energize and immediately de-energize because one of the NC poles is suppling GND to the coil. It will then immediately re-energize. It will proceed to turn on and off rapidly until either you turn off the power or the relay wears out. See the problem.

The second problem I have is with the components you chose. The DPDT relay has a 5A rating at 30 VDC under a resistive load, but only a 2A rating under an inductive load. A motor is definately an inductive load. This relay will probably not be able to handle the current needed.

The other potential problem is with the microswitches. They have an 11A rating at 277 VAC. I can't find their rating at DC voltage. They should be ok since they are only activiating DC coils, but it still should be checked.

Don't get me wrong, I think it's a good idea, but I don't think it will work in it's current state. If I am incorrect in what I have stated please correct me. I like you, am only trying to help.

 

[.id.]

gmacted,
Sorry, you were correct, I hadn't drawn the relay connections correctly (or did a very good job documenting). I updated the picture....See if the updated one makes more sense.

I also thought of something like this, but I agree that the mounting would be very critical and very tricky. You would have to rely on there being enough momentum in the motor to trip both switches. I think that may be a very big assumption. It may be worth looking at in an experiment before building anything, however.

True....Although the switches could be mounted one on top of the other and using a piece of 12ga Copper wire, solder the two levers together so that the two switches act as one larger DPDT micro switch. Just to be clear, the NC switch on the left relay is tied to the NO switch on the right relay and both of these switches are placed at one end of the gantry. The NC switch on the right relay is tied to the NO switch on the left relay and both of these switches are placed at other end of the gantry.

First lets look at the DPDT relays. Lets say the FCG starts in the middle of the worm drive. All microswitches will be in their normal state. The coils will energize and immediately de-energize because one of the NC poles is suppling GND to the coil. It will then immediately re-energize. It will proceed to turn on and off rapidly until either you turn off the power or the relay wears out. See the problem.

Actually, as it was drawn, both Relays would have latched immediately and the motor wouldn't have done anything.
As it is drawn now, if it is started in the middle of the run, it will just sit there (not do anything) since the NO switches on each Relay are open and the relay latch is on the NO contacts as well. Neither relay will energize and the motor will remain in the off position.
To start it, you will have to hit one of the sets of switches. Once a set is hit, the NC switch on one relay will be opened (turning off an already off relay) and the NO switch on the other relay will close causing that relay to turn on and latch. The motor will turn on in one direction and run until it hits the other set of switches. At this point, the NC switch on the energised relay is opened causing this relay to shutoff and the motor to stop. At the same time the NO switch on the de-energized relay is closed causing that relay to energize and latch. The motor turns on in the opposite direction until it hits the other set of switches and the whole cycle starts over.

The second problem I have is with the components you chose. The DPDT relay has a 5A rating at 30 VDC under a resistive load, but only a 2A rating under an inductive load. A motor is definately an inductive load. This relay will probably not be able to handle the current needed.

The other potential problem is with the microswitches. They have an 11A rating at 277 VAC. I can't find their rating at DC voltage. They should be ok since they are only activiating DC coils, but it still should be checked.

Again, you are correct. I just did a quick look last night and neglected the DC inductive load amperage. The microswitches are going to be switching a very small load on the relay coil. The reader, however, would have to make sure that the relay contacts can handle switch the load of the motor. Perhaps the 817-FTR-F1CD012V, although it doesn't have any data on the inductive current capabilities. Another thought would be to get two SPDT power relays (a small one to handle the latching and a larger one to handle the power of the motor) and connect their coils in parallel in place of the DPDT relay.

Thanks for keeping me honest, gmacted!

 

[gmacted]

I agree that this configuration will work. The NC microswitch must be tripped first on each side of the worm drive. I still believe that the relay you have chosen will not be able to handle the current.

darryl,
i.d. has provided a cheaper alternative. You'll need some soldering skills. My solution, although more expensive, will be easier to implement. If you're interested, either i.d. or myself can provide you with a part number for a suitable relay (current wise).

This is what I like about this forum. It's member come up with different ideas and are willing to share them. Thanks to all.

 

[darryl]

Hey all. Just got back from a trip across Washington state for a wedding. Just got online to see what everybody has been up to while gone. Saw the long posts and just wanted to let you know I'm still here and interested in making this work, just have to wait till tomorrow to read and try to figure out what is being proposed here. Bad trip, blew a tire and broke down twice in the motor home that hasn't ever given my father-in-law any problems (so he says.) Well, we had to rewire almost the entire ignition system. Many burnt,crispy wires to be fixed. Up late all night and up early today and then caught a plane home and here I am needing to be at work in six hours. So anyway will reveiw these tomorrow and get back with you guys tomorrow. Sorry, I'm really excited about this but can hardly keep my eyes open. Until tomorrow...........

 

[darryl]

Sorry it took me so long, been working 12 hour days so far and with my wife and kids gone for 2 weeks I come straight home and work on the house until dark or later.
Just want to say thanks to both of you. If you both think that I.D.'s idea will work I'd have to go with that one simply due to funding. I can solder pretty well. I even think I have a pretty good grasp on what needs to happen and how to follow I.D.'s drawing, I just don't understand 2 things.
I hate to ask but could one of you help me pick the right parts, all that electroic stuff about loads and amps and such just makes no sense to me.
And second, on each of the 2 relays there is a circle. What part of the relay is that? I understand the diagram for the part that represents the "switch" but have never seen a schematic that has a circle in the relay.
Anyways, thanks for your patiance and the time spent so far on this and sorry it takes me so long to respond, but being out of town last weekend and being down one person in a 4 person company is wearing me out.

 

[.id.]

I just don't understand 2 things.
I hate to ask but could one of you help me pick the right parts, all that electroic stuff about loads and amps and such just makes no sense to me.

I'd probably defer to gmacted....I apparently have problems with that too... Otherwise, I can try to help you on that....What is the voltage and amperage on the motor?

And second, on each of the 2 relays there is a circle. What part of the relay is that? I understand the diagram for the part that represents the "switch" but have never seen a schematic that has a circle in the relay.

Sorry for the confusion.....The circle is the coil on the relay....That was the best I could do with Visio without drawing a custom relay pic.

 

[darryl]

no need to apoligize i.d. Thanks for your honesty and all the help you have put into this. It's a wiper motor out of a saturn so I'm assuming 12v, don't know the amperage.

 

[gmacted]

no need to apoligize i.d. Thanks for your honesty and all the help you have put into this. It's a wiper motor out of a saturn so I'm assuming 12v, don't know the amperage.

Sorry darryl I was out of town the last few days. Just trying to catch up. i.d.'s circuit should work fine. I'm assuming you have the Allelectronics motor. I'll take a look around and see what I can find.

 

[darryl]

Oh bless you!! Will be working on the house the next three days. Wife and kids are visiting grandparents while I paint around the house so I'm free to hop online when ever and check things out.