Relays and logic glitch

You need a double pole, double throw relay, that's all. For motors and your amperages, you can also buy what is called a "reversing contactor". Which is the same thing, except made beefier and designed to avoid shorts etc.

Just an addition, but it is possible for both channel relays to be active at the same time. Can that may cause a problem?

You need two relays. One, a DPDT wired as a polarity reverser which is activated by one of the Rx channels. The other is an SPST or DPST which simply serves as a motor power switch and is activated by either Rx channel (connect the relay coil to the two channels through diodes).

Jerry

It'll depend on if you have limit switches and how they are set up. Garage door openers usually use only one channel. If there are other channels on the remote they might control lights, etc. There is not usually an "open" button and a "close" button, just a "change state" button.

If door is closed and control is asserted, start opening. Then, if control becomes unasserted, keep opening until open limit is reached

-- except if control is reasserted, in which case stop or reverse.

The logic for closing is similar.

Another option is a latching relay... Power to it once and it will reverse...Power again foward...

Hi Jenny

Can you locate two relays that will have contacts that will handle the motor current and be activated by the "control channel" voltage? Each relay will need 3 sets of contacts.

I might be a supplier of free relays (and sockets). I can certainly draw you a schematic to show how two relays will satisfy your "logic" problem.

Jerry

Hi Don,

This is not a garage door opener. It is a stand alone rolling code Rx-Tx set.

The key chain Tx has two buttons that activate two channels on the Rx board, hence the button to open and button to close.

The Rx board has a reset for each channel. I have replaced the two NC limit switches on the sat-actuator with two NO switches which reset the appropriate channel and drop the relay at the end of each direction's travel.

All I need now is to have channel One drive the gate open, the NO will close and trip the reset and stay there. Channel Two will close the gate, the NO will close and trip it's reset and stay there.

I need a flip-flop relay to reverse direction of the motor from open to close, BUT as an adjunct to the first post, it is possible to have BOTH channels activated.

I have just been testing a bit and if the reset for one channel is held closed, then that channel cannot be activated, so the flip-flop relay needs to also short the reset for the "other" channel to prevent both being in the on-state at the same time.

Getting out of the truck to unlock the gate is not sounding so bad. LOL I am going to make this work though.

Hi Jerry,

The old satellite controller was rated at 36v and 4A for the actuator so pretty easy to find relays for that range. The relay coils can be

I'd appreciate the schematic to be available to all on the group for archive purposes though, so if you have a website where you could post it that might be handy. Thanks for the supply offer, I do have a box of assorted relays here. Later today or tomorrow, I will check to see what is what. Even so they would be under 10-bucks at Mouser.

OK, but your application is a gate opener/closer as I understand it. A good way to arrive at a workable and reliable design is to clearly understand what you want the design to do (and not do) ... and then start accquiring or adapting what you have to make it do it.

According to :

O.K.

Just out of curiosity -- why not make the "close" button available to anyone at any time? That might simplify the logic somewhat, and if the gate is already closed, what harm will someone pushing the "close" button do -- other than eventually discharge the battery in the transmitter if you don't have supplied power?

All you need to control access to is the "open" button.

Enjoy, DoN.

snipped-for-privacy@d-and-d.com (DoN. Nichols) wrote in news:f0eek601g88 @news1.newsguy.com:

If you run the motor relay coil power through a set of NC contacts on the opposite direction relay, you can have only one relay coil active at a time.

i.e. power from remote board relay "close" goes through NC contacts on the "open" motor relay, then through the "closed" (NC) limit switch to the coil of the "close" motor relay. Power from the remote board relay "open" goes through a set of NC contacts on the "closed" motor relay, then through the "open" (NC) limit switch to the coil of the "open" motor relay. With this set-up, if the motor is at limit, no power can be applied to the motor contacts in that direction, and no power can be applied if the other relay is active. With both relays at rest, and neither limit switch made, the gate can be moved in either direction, but not both. Use another set of NC contacts on the motor relay to reset the remote board.

Pardon for coming in late on this, but (by the suggestions I saw) would you confirm that this is an AC or DC motor???

Richard

Assuming it is a DC permanent-magnet type, you reverse it by just swapping the leads. Given this, two relays with Form-C (change-over) contacts will do it. Connect the NO contacts of both relays to the +ve line, the NC contacts to the -ve line. The two moving contacts go to the two motor lines. Call those relays X and Y. The truth table is now:

Energised Motor None Stops (both lines -ve) X only Runs forward Y only Runs backward X and Y Stops (both lines +ve)

Yeahbut...

How many gates that size use DC motors??? Or - Do they all???

Richard

Easy as Jenny - go to a auto parts store, or an auto wrecler, buy a electric window relay....they come up surplus all the time. - and they work by reversing polarity to the window motor for up and down.

One button for open via a relay big enuff to handle the current

Other button drives window winder relay to close gate.....they handle

Andrew VK3BFA.

Jenny - easy as - not complicated. Go to an auto parts store, or find a wreck, with electric windows - use the relay that controls them. They reverse polarity to open/close the window...good for about 30 amps current, 12v coil.

Use one button and external relay (ordinary type relay, preferably switching both poles) to open the door Use the other remote button to operate the window winder relay to close the gates.

Go for it - dont get bogged down in theory.

Andrew VK3BFA.