Sprinkler Controller Indicator

[dminott]

I am using a Hunter Pro-C sprinkler controller and I need to add a device to indicate that a cycle has completed. there is 24 V.A.C. available
at the start of the cycle, and it stays active for the duration of one zone cycle (approx 20 mins.) I envision the voltage generating a single pulse, which is then fed to an electomechanical counter (for simplicity). I don't need any presets or reset. I do have a Durant Unipulser, which takes 15 VDC to advance the counter. Possible I could feed this with a one-shot.
Any help would be appreciated, and I am a "life member", so a schematic in an upcoming issue would be nice!<p>Many thanks,
Dave

[toejam]

I would try a light bulb in series with tha counter. Initally the current through the counter would be high enough to pulse it,but after the filiment heats, it would be limited so it does not overheat, use the lowest watt 12 volt bulb that will pulse it.

[dminott]

Thanks for the suggestion. I am waiting for a reply from the company to see what is the maximum current drain. <p>Dave

[Engineer1138]

The problem with this is that if the Unipulser's input isn't protected, the negative-going side of the 24VAC may damage it.<p>A simple solution may be a diode rectifier followed by a capacitor filter and a zener to limit the voltage. I made a simple diagram with Microsoft Paint and put it on my site at www.geocities.com/ivdsoft/rect.jpg
hope it's legible.<p>Assuming it's a positive-edge driven counter, you will get one pulse every time the sprinkler cycles on.<p>I don't know how much current the pulser requires, so I didn't show component values or types.<p>
<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by toejam:
I would try a light bulb in series with tha counter. Initally the current through the counter would be high enough to pulse it,but after the filiment heats, it would be limited so it does not overheat, use the lowest watt 12 volt bulb that will pulse it.<hr></blockquote>

[dminott]

To all,<p>Many thanks for the useful information.
I will go with the rectifier/zener solution, as I do have the necessary components in stock.
I'm surprised that a controller as sophisticated as the Hunter Pro-C doesnot have something as simple as this feature! I suggested to them that they could just flash the "day" indicator at a 1:3 duty cycle to show a completed cycle!
By the way, they suggest limiting the current to a max of 550 ma.<p>Thanks again,
Dave

[Chris Smith]

Tap off the signal to water solenoid, it will give you what you need. Light bulb, Led and resistor, latching relay, logic circuit, buzzer, what ever?