Cheap automated blinds

[kd5crs]

Check this out, if you haven't seen it: (very cool, way to go senor biochemtronics): http://www.instructables.com/id/Build-A-Mo...roller-For-Les/

That piece got me thinking... all it takes to turn blinds is a battery powered DC motor hooked to a relay. Relay closes, motor turns. Lo and behold, there's even an x10 module which does that... the Universal Module, PUM01. I already use Indigo to control everything, so things like on/off timing are taken care of.

So with that setup, how can I reverse the polarity to turn the DC motor the other way (change from open to close and close to open)? The version used in the Instructables article is cool but relies on the microcontroller, which I am trying to leave out for simplicity and cost considering that most of its functions are handled by Indigo and the PUM01.

Is there something I can use that will change polarity whenever power is applied? It would have to hold the state while power is off, to be switched next time power is applied.

Thanks. I can picture what I need in my head, but I don't know what it is called.

 

[Lagerhead]

So with that setup, how can I reverse the polarity to turn the DC motor the other way (change from open to close and close to open)?

The usual mechanical way to do this is to wire a DPDT relay in a reversing configuration as in the picture. You get opposite polarity depending on whether the relay is energized or de-energized. Use Indigo to remember the last state.

EDIT: It turns out that this is what the Instructables project is doing anyway.

 

[kd5crs]

Thanks for the reply. I saw that in the Instructables page, how that is used to switch the polarity. But his means of energizing/deenergizing that relay is based on the internal logic of the microcontroller, right? Without the microcontroller, doesn't it reset once power is removed (x10 PUM01 relay opens)?

Or am I missing something simple?

 

[Lagerhead]

. . . doesn't it reset once power is removed (x10 PUM01 relay opens)? Or am I missing something simple?

Yea, looks like you will need another hardware interface. You could probably arrange some sort of latching, but still will need two distinct signals. Sorry I misunderstood your question.

 

[ceady]

In a similar type setup I used a momentary up down toggle switch (wired as Lagerhead has shown for the dpdt relay) attached to a latching relay. So when I pushed up on the button it gave a momentary +ve DC voltage and the relay latched one way, and when I pushed down it gave the relay a momentary -ve DC voltage and it latched the other way. The great thing about this is the relay only needs a momentary voltage to latch and will hold that state until the opposite voltage is received.

If you wanted to automate the above, an easy way to do it would be to replace the momentary push button with two relays, one would simulate the toggle up and the other the toggle down. This would require two separate signals though and you would have to make sure one relay was in the off position before the other relay was activated.

 

[kd5crs]

Thinking about it some more, I can use a second PUM01 to switch the DPDT switch. I knew there was a reason they put two receptacles on each outlet!

I think that's good enough for a proof of concept. I'll post back when it is complete.

 

[Quixote_1]

Thinking about it some more, I can use a second PUM01 to switch the DPDT switch. I knew there was a reason they put two receptacles on each outlet!

I think that's good enough for a proof of concept. I'll post back when it is complete.

I would be hesitant to use anything that uses X10. It's very slow and not very reliable.
I've been trying to figure out how to do the same thing and I'm thinking about using an Insteon EZIO device. It has multiple relays, inputs and outputs. If we were to use that, we could attach limit switches somehow and I'm even thinking that it might be possible to use the 1-wire input to read the light level outside and have the blind adjust accordingly.

 

[kd5crs]

I would be hesitant to use anything that uses X10. It's very slow and not very reliable.

I agree 100%. It is purely a matter of cost, right now. I can get two PUM01s for $20, whereas the cheapest Insteon relay controller is $100. Now it is true that the $100 gets me 6 relays, but I then have to run wires from those relays to the window blinds. When I'm ready to do that, I'll want to run power as well to free me from battery changeouts. All that wire running makes for a non-trivial amount of work.

Once I get to that point, I may use a wi-fi or bluetooth relay instead. Unless Smarthome comes out with a wireless Insteon relay any time soon... :+D