Electronic Circuits and Projects Forum

What are the outputs of the timer?

1. For instance, ON for a period of time and then OFF for a similar period of time (continuous)
or
2. ON (or OFF) for a brief moment at every period of time (pulsed).

OK. Though I'm still visualizing the sequence.

Will the timer be ON for the entire duration of the actuator's transition? Or just a portion? (In other words, how long does it take the actuator to complete one cycle).

Do you know how the actuator motor and limit switches are wired? If not, can you give me a Brand and Model #?

Reason I ask is that I'm not yet convinced you need a latching relay.

Will the timer be ON for the entire duration of the actuator's transition? Or just a portion? (In other words, how long does it take the actuator to complete one cycle).
It takes the actuator roughly 30 seconds to travel the entire distance, and yes the timer is ON for the entire duration and a little beyond.

Do you know how the actuator motor and limit switches are wired? If not, can you give me a Brand and Model #?
No, I don't know how they are wired. The model # is PA-02 with 14 inches of stroke from http://progressiveautomations.com.
As far as the actuator goes, I can keep it powered for as long as I want it will turn off after full travel is achieved. It will only travel in the other direction once I reverse polarity.
Thank you!

HansW,

It might be simpler and cheaper to get a timer that has a 12hr ON followed by a 12hr OFF function like this one. You might be able to find something cheaper or more readily available somewhere else)

It would power the DPDT relay for 12hrs and the de-power it for 12hrs, thereby switching the actuator polarity on that schedule.

Keeping the relay powered for that length of time won't be a problem (as a frequent customer of radio shack here, I don't know of any of them that aren't rated for continuous power on conditions).

I can give you the wiring diagram for hooking up all the components for this project, if you like.

Another relay just unnecessarily complicates the system, is all. Essentially, the timer is doing the part of the latch relay.

As for a power failure, without a UPS for the battery and timer, you'll have to manually restart/recalibrate the system. No other choice, really, that I can think of.

You might want to consider some manner of manual override for the door itself.

We could also add a momentary switch to re-cycle the actuator to the position appropriate for the time of day.

Here's a schematic:

12 VDC DPDT Timed Polarity Changer.JPG

Hope this helps.

Perhaps it will help to explain how the circuit I gave you works.

The timer/relay "unit" is the equivalent of a "latching relay". By definition, a latching relay is a device that, with the appropriate stimulus (a 12 hour ON signal from the timer, followed by a 12 hour OFF signal), toggles between two states: one (or more) contact group(s) of the DPDT relay are closed (ON), while the other(s) are open (OFF). Then, with the reverse stimulus, the opposite is true.

The timer/relay "unit", in such a configuration as depicted, performs that function.

So, in essence, what you are asking for is a "latching, latching" circuit, for which I do not perceive a need, if I have understood your task.

Below are examples of the two "states" the circuit has:

The Forward rotation state of the DPDT relay with the current path:

12 VDC DPDT Timed Polarity FORWARD.JPG

and the Reverse rotation state:

12 VDC DPDT Timed Polarity REVERSE.JPG

Here is the manufacturer's wiring diagram for a rocker switch hook-up (you would substitute the Timer/ DPDT unit for the switch). Note also that the battery polarity is reversed from my diagram. This has NO EFFECT, however, on functionality other than motor rotation direction. Change the battery leads as necessary to achieve the correct motor direction for your system.

Rocker swirch wiring PA-02 etc.JPG