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parallel port valve controler

Or something like that. Bear with me, I'm a software kinda guy.

I've got eight valves I would like to put under computer control. These valves are 12 volt DC latching (pulse). Or so they say on their labels. I do know that there is a black wire and a red wire comming out of them. If I put a red wire on the postive terminal of a battery and the black one on the negative terminal, the valve will open. If I reverse the wires, the valve will close.

I'd like to find something that will control these valves via the parallel port on an old pc. What I would like to find is some like store.qkits.com/moreinfo.cfm/QK165 but that will able to reverse the polarity of the signals.

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Frank Stutzman
Reply to
Frank Stutzman
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That kit will work, but you have to get 2 of them, or 16 relays. You will use 2 relays per valve. You would connect the contacts as follows:

Relay1: (+12)--------(Wire1)--------(0) Relay2: (0)--------(Wire2)--------(+12)

Here is a similar cheaper kit or you can search eBay for "relay board".

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There are relays that have dual contacts on them, so you would use 1 relay per valve, but I couldn't find one cheaper than $250. These relays are DPDT Relays. If you want to make your own, look for part number JW2SN-DC12V at digikey. This is the cheapest that I could find. Search for it here:

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It costs $2.33 USD each. RadioShack has a similar one for $5.29 each, look for part number 275-249.

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The most important thing if you make your own is the diode that is connected to the relay. This diode is there to protect the transistor from back EMF from the relay. If you forget to install it, the transistor could short circuit taking your printer port and your motherboard with it. See the Datasheet at MPJA site on how it's done, very simple.

Reply to
Someone

It would be cheaper to have one DPDT polarity-determining relay in charge of the entire bank and a single pulsing (on/off) relay for each valve -- 9 relays, and cheaper ones to boot. The software would only be slightly more complicated.

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Reply to
CJT

Below are some pages I made that have some parallel port stuff that might be of use.

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Reply to
Si Ballenger

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