Convertor from AC to DC for Skylight operation


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Old 03-08-14, 08:40 AM
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Convertor from AC to DC for Skylight operation

I'm looking to find a device that would convert 24v AC to 24V DC which can then be connected to a switch to operate a skylight motor.

Some background - In my house there was a wall switch that controlled a single skylight. The switch contained a switchboard which essentially was fed by 24v AC current - my regular 110v house current was transformed to 24v prior to the switch. The switch then essentially converted it to 24v DC current and allowed for operation of the skylight motor. They no longer make this switch. I sent it out to be refurbished but it could not be fixed. To replace the entire system - new motor, new transformer, switch, etc is fairly cost prohibitive especially to operate a single window. Is there some type of device which could essentially take the place of this switch - convert the 24v current to 24v DC & then be wired to a simple switch i.e a toggle switch that could then operate the motor? The device would have to be able to fit into a single gang box.
 
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Old 03-08-14, 08:52 AM
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Do you still have the old switch mechanism? What you need to find out is how many amperes the window motor needs.

Isn't the switch a 3 position switch for open and close with off in the middle? It needs to reverse the polarity (positive/negative) so the motor reverses direction. This is similar to a "4 way light" switch except it needs a positon in the middle where neither set of travelers is energized.
 
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Old 03-08-14, 08:59 AM
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It may not be that simple. Is this a Velux system ?

A make and model of what you are trying to replace would be helpful.
The transformer currently in use should have ratings on it. Maybe 24vac 20va or 30va
 
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Old 03-08-14, 09:22 AM
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It is absolutely solvable, all information, photos and info about labels etc may help.
Is it on the wall, or in a box, where are the transformer located, how may wires in and out, + ground???

dsk
 
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Old 03-08-14, 11:47 AM
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Ok. System is a Sentry 2000.

The motor says 40 Watts on it. I do not see any Amperage. There are two wires in the wall box from the transformer (Red & White) that attach to the blue wires on the switch. The other two wires in the wall box attach to the switch via the set screws and travel up to the skylight where they attach to the wires on the motor.

Truth Hardware manufactured the system. I've attached Front/Back/Side views of the switch & two photos of the motor.
 
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Old 03-08-14, 12:29 PM
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Google gives a lot of relevant hits on: sentry 2000 skylight
Seems pretty expensive to use original parts, but the switch contains some advanced electronics to protect against over current and other trouble. A rectifier and a toggle switch like this DC Motor Motor The Manually Reversing Switch Knob Toggle Switch | eBay should do the job, if you release the switch at the right position, and not keeps it running. A fuse protecting it would help. A B Allen Bradley 1492 GH015 Ser B 1 5A Single Pole Circuit Breaker | eBay and rectifier could be de- soldered from the old unit or like this: KBU1010 KBU 1010 10A 1000V Single Phases Diode Rectifier Bridge Single | eBay. And of course you need a box.

Still not the original security, but quite normal.

dsk
 

Last edited by d_s_k; 03-08-14 at 12:52 PM. Reason: links error
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Old 03-08-14, 12:35 PM
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You can't use tinypics for hosting and hot linking here.
 
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Old 03-08-14, 02:35 PM
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The wires from the transformer would attach to which item? How would that then connect to the toggle switch?
 
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Old 03-08-14, 04:06 PM
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When you wire your own manual switch there will be no motor protection and automatic operation.


Switch.... the switch is double-pole double-throw center off/momentary (DPDT-CO) (on)-off-(on)
Fastronix Solutions--Performance Automotive Electrical Components


The bridge rectifier and capacitor are available everywhere. The switch is somewhat of a specialty item as you want a switch that rests at off and that you have to hold in the open or closed position.

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Last edited by PJmax; 03-08-14 at 05:26 PM. Reason: added pic
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Old 03-08-14, 10:47 PM
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Great diagram!
In addition I would consider putting the 1.5 Amp circuit breaker, it is slightly undersized, but a very slow acting protection. It may save the motor in case of holding the switch in a position to long. The breaker could be put in any wire after the rectifier/capacitor and before the motor.

dsk
 
 

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