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Old 07-01-2011, 02:07 PM   #1
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Default REX-C100 PID (cheapest PID on ebay)

These PIDs have been discussed on here recently in several threads because they cost so little. You can literally find these for $0.99 and free shipping in auctions on ebay.

The auction listings are always misleading (meaning "false") in that they indicate that they have a 12V pulse output suitable for driving an SSR. There are models of the REX-C100 that do have the SSR output, but I have never seen anyone selling them on ebay. All of the ebay ones have a mechanical relay output and not an SSR control output.

They also usually have "F/C" in the title, which can lead you to believe that they display in either Fahrenheit or Celsius. Not true. They only do Celsius.

A friend of mine bought one of these after falling for the false advertising. Not only was the product equipped with a relay output and displayed Celsius only, but it also was broken. The temp probe input (K-type thermocouple only) has some sort of problem. With no probe connected, it reads about 3000*C. With a temp probe connected, it reads "EEEE".

Long story short, the ebay seller was a douchebag and would only refund half of his money AFTER my friend left POSITIVE FEEDBACK. My friend just gave me the PID to play with.

I popped the case on that thing open last night to see if I could figure out what was wrong with the temp input. I didn't see anything obvious, and I didn't have time to really tinker with it, but I did realize as I looked at it that this thing can EASILY be hacked to make it drive an SSR.

There is a small relay soldered down near the output terminals. There are a couple of voltage controllers on the board, one delivering 12VDC and one delivering 5VDC. I couldn't tell which one of those supplies ended up ultimately feeding to the relay control coil, but it's irrelevant. The point is that the relay is receiving a DC control signal to activate it, and that signal is either 5V or 12V.

Most SSRs that I have seen require a control signal between 3VDC and 32VDC, so 5 and 12 are perfect.

So... with a couple of wires and a soldering gun, you could tap onto the bult-in relay's control signal and bring those wires out of the controller. Connect them to an SSR. Done.

The internal relay would still be clicking and clacking, which isn't great for it, but the good news is that if the relay ever died, you wouldn't even care or notice.

A cleaner solution would be to actually remove the built in relay and jumper the signals that are used to control the coil straight to the output terminals that used to be switched by the relay. Then you wouldn't even need the extra wires coming out of the back of the PID for the SSR. You could just use the screw-down terminals that are on the back.

I *really* want to try this out as an experiment, but since the REX-C100 I have is busted, I can't do it. I am going to try and snag one of the $0.99+free shipping PIDs off ebay to see if I can do this and have it work well.

Alternately:
If anyone bought one of these and got stuck with it, and if you don't want it, PM me. I would like to hack that thing and would be willing to pay a tiny bit for something that you might be considering as junk.

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Old 07-05-2011, 11:32 PM   #2
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Default Conversion of the REX c100

I tried the conversion of the c100 to SSR output. I opened the unit, found two holes somehow intended for a diode and soldered two wires to the 12 volt signal to the relay (rated for 10 amps, by the way) and ran the wires out the back. Setting the P to the default 30 and plugging it in, it ran just as suggested.

It is true the ad on eBay is deceptive. it says SSR and it implies F but it is not there. The vendor offered a $10 refund on a $18 purchase so I have a functional unit for $8. There is no adjustment for the duty cycle for SSR but the relay setup is just fine.

I did not see $.99 and free shipping or I would have gotten that. If I do spot such a deal, I will pounce on it as that would be the cheapest PID controller in the world. If you decide to get one of these, expect to dispute the sale through eBay. If you get one for $18 like me, the seller will offer you $8 but hold out for a complete return since you wanted SSR output and didn't get it. The seller will come back with $10. That is where I just accepted the deal. Maybe you can do even better? If you have never had a dispute through eBay, do not click the problem resolved button until you have the money back in PayPal. I did it early and it took special calls and got "scolded" twice for being a dummy from the folks at eBay.

Also, the instructions that come with this are great if you can read chinese. I did find a good complete set in English with a google search of REX C100 so i was saved from having to learn a new language.

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Old 07-06-2011, 02:37 AM   #3
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I bought one of these and according to the instruction manual it has a 0-12 volt ssr relay output.

After studying the instruction manual more, I don't think it does have an ssr out. The model no, has letters after the C100 that you have to match up to a legend to see what features you actually have. I think I can still make to work with an old cell phone charger to trigger my ssr and then switch over to my PWM to controll the boil. I'm still waiting on my SSR and heat sink to put this thing together and try it. I'll probably have one of the instructors at school look at the design in case I'v overlooked something.

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Old 07-06-2011, 12:38 PM   #4
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I bought one of these and according to the instruction manual it has a 0-12 volt ssr relay output.

After studying the instruction manual more, I don't think it does have an ssr out. The model no, has letters after the C100 that you have to match up to a legend to see what features you actually have. I think I can still make to work with an old cell phone charger to trigger my ssr and then switch over to my PWM to controll the boil. I'm still waiting on my SSR and heat sink to put this thing together and try it. I'll probably have one of the instructors at school look at the design in case I'v overlooked something.
If you got it off ebay, it does not have SSR output. I can 99.99% guarantee you of that.

The phone charger through the built in relay will work to drive the SSR, but I don't know how long it will last for you. For a HERMS or RIMS system, the thing will be turning on and off pretty rapidly. The relay will eventually crap out.

Earlier I made a claim that these could be found for $0.99 and free shipping on ebay. And, indeed, at that time I had ebay watches on no less than 10 of them for that price. I let the first couple go past with winning bids between $2 and $3. Then suddenly, all of those auctions I was watching were yanked down.

I can't find them for $0.99 and free shipping anymore.
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Old 07-06-2011, 03:25 PM   #5
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The relay will not be switching thet much untill I switch to the pwm to controll th boil. I will run it in auto mode like a thermostat through my mash, and ramp it up to 212f then go to the pwm once it starts boiling. I wouldn't think that would any harder on the relay than a pwm only. I'm also going to build another pwm in case of some kind of electrical failure on brewsay.
I may go in side the pid and see how much voltage is switching the 220 relay and use it if if it is what I can use for the ssr.
I'v been watching those cheap pids on ebay for weeks and bid on probobly 50 up to $12 trying to get one for less than $18 and always got outbid in the last seconds. I think it's rigged.

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Old 07-06-2011, 03:28 PM   #6
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I am not talking about the SSR when I say "relay". I am talking about the mechanical one built into the PID that you are going to run your DC power through.

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Old 07-06-2011, 03:42 PM   #7
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Yeah, I got hosed by one of these. I haven't even installed it or anything. First off, I ended up with the 240V version for some reason. And no, there is no ssr output. I haven't had time to deal with the problem resolution thing on ebay, but it may not be a bad idea... any way of getting this thing to work with 120v? I can't imagine it actually uses that kind of juice!

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Old 07-06-2011, 03:47 PM   #8
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Yeah, I got hosed by one of these. I haven't even installed it or anything. First off, I ended up with the 240V version for some reason. And no, there is no ssr output. I haven't had time to deal with the problem resolution thing on ebay, but it may not be a bad idea... any way of getting this thing to work with 120v? I can't imagine it actually uses that kind of juice!
The PID actually runs on anything from 90VAC to 250VAC. It will work fine on 110V.
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Old 07-06-2011, 03:53 PM   #9
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Really? cuz I couldn't get it to power up!

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Old 07-06-2011, 03:54 PM   #10
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Then you probably have a busted one.

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