SSR voltage leak

[terodox]

Hello All!

I'm fairly new to Raspberry Pi, but I'm a fairly old hat at electronics. Here's what I'm doing:

I have a kegerator with 4 taps. I also have two young children (one of whom just figured out how to open the taps). My basic plan is to have 4 solenoid valves that will prevent beer flowing unless an appropriate password is entered via a website hosted on my pi.

I have everything working to enable the gpio pin and automatically disable it after 2 minutes. The issue I'm having now is on the other side of this circuit. The SSR I'm using ( http://www.amazon.com/gp/product/B009EQG1UY/?tag=skimlinks_replacement-20 ) is allowing some voltage (2.3-2.5 v ish) to leak through even when the SSR is not powered from the input side. The power supply is 12v so that's close to 20% of it's max flow coming through.

My concern is for the health of the solenoid valve if it being given a trickle of power over a long period of time. Is there a way to draw down this voltage before it reaches my valves? Should I not be using this tpye of SSR? Is there a better solution to this whole problem that I've simply overlooked?

Any and all help/advice would be wonderful.

Thanks in advance!

 

[flars]

You could use a mechanical breaker to cut the power at the battery.

 

[terodox]

Can you expand on that at all? Do you mean using a mechanical relay? An electromagnetic relay for example?

 

[flars]

I'm not an electrician. I need to reference Caldwell to do any wiring. I meant a switch that would physically break the connection. Could be as simple as wall switch for 110V AC.

 

[terodox]

For this application I need to have the DC voltage constantly available so when I send the pin on the Raspberry Pi hi to trigger the SSR all the valve will open and beer will flow. I'm trying to avoid a physical switch if at all possible.

 

[mxrob]

Sounds like a pull down resistor circuit may be what you need. Do a goggle search for "pull down resistor"... lots of example diagrams on the web.Just make sure your current load for your valves isn't more than what your SSR is capable of handling.

Sent from my GT-P5113 using Home Brew mobile app

 

[Brumateur]

What is your valve power consumption?

 

[day_trippr]

[...]The SSR I'm using [...] is allowing some voltage (2.3-2.5 v ish) to leak through even when the SSR is not powered from the input side. The power supply is 12v so that's close to 20% of it's max flow coming through. [...]

Do you have a load on this SSR yet? The SSR's leakage current may be extremely low and with an actual load the voltage may drop near zero..

Cheers!

 

[AngryMonk]

Do you have a load on this SSR yet? The SSR's leakage current may be extremely low and with an actual load the voltage may drop near zero..

Cheers!

I was about to write same answer. There is some voltage leak, but current very minimal. You valve is safe.
I'm all for DIY and gadgets, but what about a lock on the tap ?

 

[day_trippr]

[...]I'm all for DIY and gadgets, but what about a lock on the tap ?

Practically speaking, I suspect solenoids would actually be easier to implement than mechanical faucet locks without making a mess of things...

Cheers!

 

[terodox]

Hello All!

I had a quick discussion about this same topic over on the raspberry pi forums: http://www.raspberrypi.org/phpBB3/viewtopic.php?f=37&t=72100&p=520282#p520282

The end conclusion is that this particular SSR has a large leakage allowance. The solution is to use a different SSR rated closer to what I will actually be utilizing with a leakage allowance of only 1 mA.

opto22 DC60S3 with a leakage current of 1 ma.

Datasheet:
http://www.opto22.com/documents/0859_Solid_State_Relays_data_sheet.pdf

Amazon Link:
http://www.amazon.com/gp/product/B0058UY8M8/?tag=skimlinks_replacement-20

 

[Brumateur]

If you valve consumes less than 2.5 Amp you can use ULN2003A IC. It's. cheap (<$1)but requires some soldering.

 

[terodox]

The other option is an n channel mosfet, but I like the convenience of screw based connectors. Worth the extra money to me.

 

[FuzzeWuzze]

Practically speaking, I suspect solenoids would actually be easier to implement than mechanical faucet locks without making a mess of things...

Cheers!

For the Perlick faucets the locks cost $15 more than the actual faucets themselves.

4 faucets and you just turned a 150 dollar perlick keezer into a 350 dollar one.

 

[terodox]

In total this project is going to cost me about $130. However, it will also give me the ability to add raspberry pints into the mix for virtually nothing.

I'm in the final stages of testing this with direct power via an override switch, and once it's all implemented I'll do a build wrote up post.