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up vote 6 down vote favorite

I don't have much experience with electronics, but I think what I want to do could be cobbled together from a Radioshack.

I have a Dig 5006-IP automatic sprinkler controller. It controls 24V DC valves. It has two "SENSOR" terminals, that when closed will put the unit in bypass mode. Basically a rain sensor is attatched to this, and is normally open. When it rains, the circuit goes closed and trips the rain mode.

Unfortunately, the Hunter Rain-Clik I bought is normally closed, and goes into open mode when it rains. Its more designed to be used inline with the valve. Something I don't want to do.

So how can I reverse this? How can I swap rainclik's signal, so that when it's closed, the dig sees it as open. And when its open, it sees it as closed? I have a soldering gun and basic knowledge of putting things together.

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2 Answers

up vote 7 down vote

Use a old school 24VDC relay, that has NC (normaly closed) and NO (normally open), then the put that like a inverter in the middle.

That way when the circuit is closed, the relay is open, and vice verse.

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2  
Just about what I was going to say. Do make sure you don't end up switching any power to ground with out a resistor inline, I have seen this happen when people play with relays. – Kellenjb May 5 '10 at 15:11
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Also, you might want to check out this page (it is the opposite of what you want but might help you out): instructables.com/answers/… – Kellenjb May 5 '10 at 15:14
he needs to invert the sensor signal not the power signal to the valves. – Mark May 5 '10 at 17:13
This is more along the line of what I was thinking about. A quick note: It appears to be 24V AC ( not DC ). Max output amps is .83. On the controller box, I have two Common terminals, and then the two Sensor terminals ( along with the 9 valve terminals ). I think I can use the box's common to power this: radioshack.com/graphics/uc/rsk/Support/ProductManuals/… And hook up the NO side of that relay to the Sensor terminals ( the extra set to my own LED showing 'rain mode' as on ). Do I need to mess with Diodes/Resistors for this? It all seems in 'range' to me. – Frank May 5 '10 at 19:53
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Assuming you can get access to DC somewhere you can do this with a single MOSFET transistor. – Mark May 5 '10 at 22:19
up vote 0 down vote

There are a lot of ways you could solve this. I think a decent solution would be to buy a cheap, simple microcontroller like the Arduino and use it to watch the rain sensor, and then close a relay that's attached to the sprinkler. That would be the fun way to solve the problem.

I can imagine a few other possibilities. I suspect that it would be cheaper and easier to just buy the right sensor. There may also exist some sort of relay inverter that's designed for this type of situation. I've never actually seen one, but I bet it exists. (Edit: see Johan's answer for confirmation that this exists!)

If you're interested in the fun solution, you can find out more about Arduinos here: http://www.arduino.cc/

You might also take a look at this example: http://www.glacialwanderer.com/hobbyrobotics/?p=9

Good luck!

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And interesting idea. I am more of a programmer and this is enticing. The extra bells and whistles I could add would be cool. I think for now, i'll work on just using an old school DPDT relay. Then maybe later integrate it with this, or PIC, or something, and tie the watering system to other data ( like output from my PC ). – Frank May 5 '10 at 20:51
You might also take a look at the Garduino: instructables.com/id/Garduino-Gardening-Arduino But I do think a relay is a decent choice. There's a lot to be said for simplicity. – pingswept May 5 '10 at 20:54
Better link: garduino.dirtnail.com – pingswept May 5 '10 at 20:55

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