reversing polarity using momentary or latching relays

[RAL]

With enough relays, you can do pretty much anything.   
 
So, the first pulse turns the actuator on (call that the forward direction).  The second pulse reverses the direction.  What happens next?  Is there a third pulse to turn it off?  Or does a limit switch turn it off?
 
Once it is off, does the next pulse turn in on in the forward direction again?  i.e. when it turns off, there is an implied reversal back to the forward direction.
 
What should happen if power is lost mid cycle?  When power is restored, should it continue in the direction it was going in?  Or default to the forward direction?
 
Finally, how long are the pulses from the OP2?  Milliseconds vs seconds could make a difference in the design.  If the pulse is too short, it might not be able to trigger a relay directly.

 

[LarrylLix]

It appears with no membership we cannot access your file.
 
There is a method with a latching relay and some capacitors that flip a relay back and forth each time it is energised.
 
The train relay I referred to was totally mechanical. There was a mechanism that toggled each time it was activated. Think ball-point pen.

 

[cestor]

With enough relays, you can do pretty much anything. 
 
So, the first pulse turns the actuator on (call that the forward direction).  The second pulse reverses the direction.  What happens next?  Is there a third pulse to turn it off?  Or does a limit switch turn it off?
 
Once it is off, does the next pulse turn in on in the forward direction again?  i.e. when it turns off, there is an implied reversal back to the forward direction.
 
What should happen if power is lost mid cycle?  When power is restored, should it continue in the direction it was going in?  Or default to the forward direction?
 
Finally, how long are the pulses from the OP2?  Milliseconds vs seconds could make a difference in the design.  If the pulse is too short, it might not be able to trigger a relay directly.

 
The way that it should work is that when a power pulse is applied, it goes forward until the limit. The next pulse should reverse the direction. If there is a power cut it should continue in the direction of travel. The OP2 pulses are configurable - it could actually be a 10-second "pulse" if needed.

 

[cestor]

Here is the circuit I am currently using -without the X10 element and without the limit switches which are built in to the actuator
[sharedmedia=gallery:images:928]

 

[pete_c]

Googling last night found a few adjustable RF remote controls and base dual relay motor controls for ~$10.00.  I do not think you would have an issue modding one of these for your use either wired or wirelessly.
 

 
 
 
 
 
 

 

[LarrylLix]

I assume your actuator is for window blinds?
 
How about two modules. each with an ac adapter to run up and one for down? All purchasable parts without messing around with circuitry.
 
You state your actuator has limits, how about when you want your blinds half way up or down? You will need to send timed pulses to achieve that.

 

[Del91574]

How about a ratchet relay?

 

[RAL]

DEL's suggestion of a ratcheting relay is a good one.  I had been thinking along similar lines after reading your answer to my questions, and the ratcheting relay would give you the capability you want.
 
The ones I have come across require higher coil currents than what an OP2 output can drive.  But you could use the output of the OP2 to drive a low current relay, like an Elk 924 (or Altronix RBSN), and then have the 924 drive the coil of the ratcheting relay.  Not elegant, but simple to implement.
 
An Omron G4Q is one ratcheting relay to consider.  The bad news is it isn't cheap ($180 or so).
 
A less expensive solution would be to use an electronic ratcheting relay, like an Altronix RBR1224, or this one on eBay.   But I don't believe either one will remember its state if power is lost.   That's an advantage of a mechanical relay like the Omron.
 
[Edit]
 
One other option would be to use latching relays.  This particular relay has 2 coils, one to latch and a second to unlatch.  You could use a pair of them, one to reverse the power to the actuator, and the other to switch the OP2 output from the latching coil to the unlatching coil.
 
This other board mounts both relays on a single board. 
 
Both versions of this relay board remember their state if power fails.
 
The input current for the relay coils is 50mA according to the spec sheet and needs to be pulled low. To drive both relay coils, you would be right at the limit of what an OP2 output can provide.   As with the Omron, I would use the OP2 to drive an Elk 924 and then have the 924 drive the latching relay coils.

 

[cestor]

The ratcheting relay is a good idea but too expensive for this particular application.
Will adding a single latching relay into the current circuit be sufficient? If so, can anyone help me with a circuit diagram..? 

 

[Del91574]

Wire 2 relays back to back and then have them latch upon the first change. Put a 3rd relay/contact between the latching feed to allow a reset. Then again $20 for a real ratchet relay vs. 2 relays at $15, with a 3rd dry contact to allow a reset (making a total of 3) I don't see how that's economical.

 

[RAL]

Here's a bargain price on a  P&B S89R11DBD1-12 ratcheting relay on eBay.
 
The coil on this relay requires more current than the OP2 output can provide (533 mA), so you'll need an intermediate relay to interface the OP2 output to the ratcheting relay.   Since the total load for all devices powered by the OP2 needs to be less than 1 Amp, you may need an auxiliary power supply to provide the 12V for this relay.
 
Here's a wiring diagram.
 
http://cocoontech.com/forums/gallery/image/930-ratcheting-relay-wiring/

 

[cestor]

thanks - thought the ratchet relay was going to be $180. Will try this solution

 

[mikefamig]

It appears with no membership we cannot access your file.
 
There is a method with a latching relay and some capacitors that flip a relay back and forth each time it is energised.
 
The train relay I referred to was totally mechanical. There was a mechanism that toggled each time it was activated. Think ball-point pen.

 
I once repaired my father's Lionel train that was built in the 40's that had the wires between the engine and coal car all detached. They were the circuit that controlled the reversing relay switch that you're talking about. If  remember correctly the switch had a wheel that rotated on an axis to switch the wires to the motor. If memory serves me it would rotate 45 degrees with each pulse of switching current. One pulse forward, next pulse off, next pulse reverse and next pulse off again.
 
I remember scratching my head for a while trying to figure out where the wires need to go and then it occurred to me to build a truth table like I learned to do in a binary logic course that I had studied in college. I'm sure that i don't remember how to do that now but it was fun to apply a skill that I never thought I would use for anything and it was a very neat device in it's time.
 
Mike.

 

[LarrylLix]

I once repaired my father's Lionel train that was built in the 40's that had the wires between the engine and coal car all detached. They were the circuit that controlled the reversing relay switch that you're talking about. If remember correctly the switch had a wheel that rotated on an axis to switch the wires to the motor. If memory serves me it would rotate 45 degrees with each pulse of switching current. One pulse forward, next pulse off, next pulse reverse and next pulse off again.

That would be a crude stepping relay, of sorts. The one I remember had a solenoid type armature that pulled a U shaped bar in and out. Each time it retracted a plastic weird shaped piece of nylon would turn up an opposite side  hook that would catch the U shaped metal bar so that it would toggle back and forth. It didn't rotate but rather just rocked  back and forth. Obviously, there must have been contacts on it. I was probably about 7 or 8 years old so it's a little foggy.