DIY Fail...

[kgx2]

So I've tried to make my own stir plate but after getting everything together and soldering it up nothing works. I'll be the first to say I know little to none about electric wiring but can build anything with good instructions (especially with diagrams). This seemed to be a very simple project so I figured I'd give it a shot. I tried switching the power wire on the potentiometer and that didn't help either. Using a 6V 1A power supply, old pc case fan 120mm 12V .6A, potentiometer, power inlet connector (no idea real name) & and a toggle on/off switch.

I know the power supply is lower than the fan but I tired another supply and still nothing so I don't think it's the supply. There seems to be very few things I could do wrong here as it really is a pretty simple circuit right?

Any help would be great! I'm going to get another new fan and see if this one was just dead as it did come from a retired pc.

Here are some pics of the project and components.

 

[theck]

You try hooking the fan up to the power supply directly to see if it actually works first? What's that extra item you have in the first picture?

 

[Powhatan]

How many wires does your fan have?

 

[LLBeanJ]

Yeah, what theck said. Connect the fan direct to the power supply and make sure it spins. Once confirmed, start working out from there.

Also, the toggle switch (first pic) looks like it might be wired incorrectly.

 

[johngaltsmotor]

IIRC you have the potentiometer wired as always being full resistance. You want to use one end and the center pin. The two ends always go full resistance so you want one end to the variable middle. Which end you pick just determines if 100% is full clockwise or counterclockwise.

 

[atoughram]

The switch is wired wrong - out of six places to solder, pick one center and one end on the same group of three. In other words, move one of the wires to the opposite side center terminal.

Also - depending on the power rating of that potentiometer, you might have a smoke producer there. Put a jumper from one side terminal of the pot to the center - it's doing absolutely nothing the way it's wired.

 

[evanmars]

If that is your power ON switch in the first pic, I think you have it mis-wired. The wire from the power supply should be on one of the middle connections, and the wire to the fan should be on the normally open connection on the same side of the switch.

 

[Flboy]

Yeah, what theck said. Connect the fan direct to the power supply and make sure it spins. Once confirmed, start working out from there.

Also, the toggle switch (first pic) looks like it might be wired incorrectly.

Agree!! FYI toggle looks like a ganged double throw double pole-looks like you are jumping gangs. Ganged is two switches in one. Three posts to a gang, outer post to inner post is a switch
Pot also looks to be wired wrong. looks to be wired across the pot. middle leg is the variable.
As said just jump both switch and pot, paper clip fine, and work backwards from there

 

[kgx2]

The first pic is the power switch.

Fan had 4 wires. I checked a site that said the right wire would be ground on the right most side then power wire just left to it.

I changed the potentiometer red wire to that post cause the middle post wasn't doing anything so I thought I'd try the other post. Nice to know I had it right the first time.

How would I know the power rating of the potentiometer? I got it at a gadgets store in a bin labeled 25ohm I think. (No idea what an ohm is &#128563

I'll change the incoming red power wire to the middle post of the on off switch and the red wire going to the potentiometer to the bottom most but on the same side as the incoming power wire?

What's a pot? Potentiometer?
Does the incoming power look wired correctly?

Thanks all!

 

[Flboy]

The first pic is the power switch.

Fan had 4 wires. I checked a site that said the right wire would be ground on the right most side then power wire just left to it.

I changed the potentiometer red wire to that post cause the middle post wasn't doing anything so I thought I'd try the other post. Nice to know I had it right the first time.

How would I know the power rating of the potentiometer? I got it at a gadgets store in a bin labeled 25ohm I think. (No idea what an ohm is &#128563

I'll change the incoming red power wire to the middle post of the on off switch and the red wire going to the potentiometer to the bottom most but on the same side as the incoming power wire?

What's a pot? Potentiometer?
Does the incoming power look wired correctly?

Thanks all!

Yes, pot = potentiometer. I'm am unjuneer, not a speller! FYI, rat world--am sitting in the data center there as I type! For now just bypass everything till you know you are good.

 

[kgx2]

Is this wired right?

 

[kgx2]

I can answer my own post. Yes it was cause we have power!

Fan works but only 1 speed? Pot only turns it on or off with the power switch on. No speed settings/control?

Need a better fan still?

 

[theck]

I can answer my own post. Yes it was cause we have power!

Fan works but only 1 speed? Pot only turns it on or off with the power switch on. No speed settings/control?

Need a better fan still?

Maybe your power supply is underpowered? Does it spin fast at one speed? Not an expert but when I swapped mine for a bigger supply 12v but more amp I think? it worked much better.

 

[Flboy]

Pot most likely burned out, very possible on these DIY builds. What is really needed is what is called a VPM (variable pulse modulator)..OH crap! Ya, better solution, cheap too, I got one on ebay, 3 bucks- with shipping, off hand do not remember the link to it. That pot looks light duty. to explain, we have to get back into that 'ohms' thing. Ohm is resistance, so the pot is a restriction. Ohms law, 25 ohm pot, 6 volt supply equals a lot of power/watts. plus a pot is a passive load and the fan is inductive, reason for that VPM thingy. it basicly turns the fan off and on quickly. 99% of the stir plates use potentiometers and are fine, pot may run hot tho. Trick is to use a large enuff potentiometer if you go this route. My guess, check parts list that have been proven. FYI, at 6 volts with a 12 volt fan, you may not need anything other than that switch. See if it throws the bar.

 

[kgx2]

Trying to glue the stupid magnets in place but I'm not letting it dry I guess cause it keeps throwing them... using a poker chip a buffer between the fan magnet and the rare earth magnets. One of each polarity facing up to spin the bar in place hopefully.

 

[kgx2]

Yeah the pot needs replaced cause even with a hard drive magnet it still throws the stir bar.

Off to the shack I guess....

 

[HopinJim]

Need to use a voltage regulator to drive the fan. The pot is probably not rated for tha current draw of the fan. use the circuit below. This is the circuit used by Stir Starters and is the one I used to build mine. The regulator takes the fan load on and the pot merely is an input to the regulator to adjust the voltage to the fan. Radio Shack has the parts. The part no. there is LM317T.

 

[atoughram]

http://www.amazon.com/dp/B00GL4JGOA/?tag=skimlinks_replacement-20
http://www.amazon.com/dp/B008F0CTBA/?tag=skimlinks_replacement-20 <-- The one I've got...
http://www.amazon.com/dp/B005F7R8Z8/?tag=skimlinks_replacement-20

 

[kgx2]

Thanks for the links but why would I buy a stir plate when I'm talking about making one in the DIY section?

 

[monkeeroot]

I had alot of problems with the bar being thrown when I built my first stir plate. I was using just a power supply and potentiometer like your setup. This just isn't the best way of controlling speed IMHO.
After going through many unsuccessful modifications, I ended up building a voltage regulator like the one mentioned by HopinJim. With a 13VDC power supply hooked up, it gave me much better speed control and now I don't throw the bar at all.
Just something to keep in mind. Throwing the bar frustrated me for awhile.

 

[kgx2]

HopinJim thanks for the info. I found the item on their website. As I stated my electrical knowledge isn't much though so I've no idea how to read the diagram you posted. Any chance you coud post a picture of how you wired yours?

 

[monkeeroot]

I don't remember where I got this drawing from, but this might help you out.

 

[TNugent]

Thanks for the links but why would I buy a stir plate when I'm talking about making one in the DIY section?

Because this....

HopinJim thanks for the info. I found the item on their website. As I stated my electrical knowledge isn't much though so I've no idea how to read the diagram you posted. Any chance you coud post a picture of how you wired yours?

 

[GrizzAndFish]

MODS: I think this should get stickied. Even though it started as asking for help, it has a lot of very helpful hints about building stir plates in just a few pages.

 

[atoughram]

Because this....

Exactly - Save yourself some frustration and money.

 

[evanmars]

Exactly - Save yourself some frustration and money.

http://www.bevmo.com/Beer
http://www.megabev.com/main.asp?request=search&sel_category=556&type=B&

No need to make your own beer....

 

[fartinmartin]

I brewed today , laid yeast on water for 15mins , stir a bit for 15 mins , pitched the yeast, air lock going in 2.5 hours. Stir plate ?

 

[atoughram]

http://www.bevmo.com/Beer
http://www.megabev.com/main.asp?request=search&sel_category=556&type=B&

No need to make your own beer....

Nope - there isnt

 

[atoughram]

The point of my latter posts are this: I don't try and DIY a auto transmission rebuild - I've taken everyone I've had to do to a shop. Why? Because I don't have the knowledge, skills, abilities, or tools to do the job and for me to obtain all that, it would cost more than it does to just have someone else do it. I have the knowledge, skills, abilities, and tools to build my own stir plate - but I didn't - because my time is worth money to me and it was cheaper to buy it.

Making your own stir plate is cool - but when it turns out dangerous - it's not cool.

I hope this has been helpful.

 

[LLBeanJ]

I brewed today , laid yeast on water for 15mins , stir a bit for 15 mins , pitched the yeast, air lock going in 2.5 hours. Stir plate ?

Sounds like you severely overpitched, since there was no real growth phase taking place. Ideally, with a proper pitch you shouldn't see visible signs of fermentation for 12-24 hours.

But, yeah, your point is valid as long as you are happy with the limited choices of available dry yeast strains and you don't mind buying fresh yeast every batch (assuming you are not harvesting and re-pitching slurry into the next batch while viability is still high). Granted, even if you do need to make a starter, a stir plate is not necessary, though it is very helpful and will yield more cells, and is therefore more economical, than a starter made without one.

I use liquid yeast exclusively because I like the greater variety of strains that are available. I also reuse my yeast many times over, often starting with as little as 20B cells that were harvested maybe 6 or 8 months prior that needs to be propagated to the proper pitching size. For that my stir plate is worth it's weight in gold and since I'm reusing yeast rather than buying fresh, I'm sure my stir plate has paid for itself, given that a typical starter's worth of DME is around $1.00 and a new vial is ~$8.00.

The bottom line is that you're right. None of us needs a stir plate to brew beer. But it does become a necessity once you make the decision to stop wasting money on new yeast and to start reusing yeast you've already paid for.

 

[atoughram]

The only reason I bought a stir plate was so that I'd only have to buy one tube of yeast instead of two.

Washing and storing yeast - in my opinion - add's complexity and another failure avenue to my process - I'll just buy new yeast every time except when I'm going to pitch the same yeast into different worts - which I do with WLP001. Then I'll pump new wort onto an existing yeast cake.

BUT - I'm not criticizing those who wash, store and re-propagate yeast - each to their own.

 

[monkeeroot]

The point of my latter posts are this: I don't try and DIY a auto transmission rebuild - I've taken everyone I've had to do to a shop. Why? Because I don't have the knowledge, skills, abilities, or tools to do the job and for me to obtain all that, it would cost more than it does to just have someone else do it.

Not too sure how an auto transmission relates to this situation at all. If you do something wrong with a transmission you are risking your life and the life of others. If you do something wrong with a stir plate you basically just run the risk of having less yeast to pitch. I don't believe that any person on this forum started brewing with expert knowledge and equipment. We all took the plunge and learned how to do it.

I have the knowledge, skills, abilities, and tools to build my own stir plate - but I didn't - because my time is worth money to me and it was cheaper to buy it.

That was a decision that you made. You don't know what he has lying around the house that will make building one much less expensive. I built mine for $2.00 because I had almost everything in my garage for example.

Making your own stir plate is cool - but when it turns out dangerous - it's not cool.

I don't think that there are many situations where people have died from 12VDC. There is a much greater risk of being injured while handling several gallons of boiling liquid and we all take that risk.

I'm not too sure why this post has even gone off topic in the first place. The main purpose of this post was someone asking for help with a DIY build. There was never the question as to whether or not he should buy or build one.
Encouraging someone not to try something because you wouldn't do it is not what this forum is about.

 

[toddnaud]

this guy's site, along with the links he posted at the bottom of his blog, helped me:
http://biohazardbrewery.wordpress.com/instruments/brewery-stirplate/

 

[atoughram]

I don't think that there are many situations where people have died from 12VDC.

Probably why we dont see many electrical fires in automobiles...

and I was encouraging the OP to do the safe thing - and get help or buy one already made, no matter what you may believe, 12Vdc will burn your house down just the same as 120Vac.

 

[monkeeroot]

Probably why we dont see many electrical fires in automobiles...

and I was encouraging the OP to do the safe thing - and get help or buy one already made, no matter what you may believe, 12Vdc will burn your house down just the same as 120Vac.

I stand corrected. But, this is why seeking help for projects will help prevent this sort of mishap.

 

[IslandLizard]

I brewed today , laid yeast on water for 15mins , stir a bit for 15 mins , pitched the yeast, air lock going in 2.5 hours. Stir plate ?

That's dry yeast, the cell count is quite high already when re-hydrated properly, and the yeast is ready to take off. Now 2.5 hours must be a new record, never seen or heard that before.

For liquid yeast, the stir plate is a real gem and a reasonable necessity.

 

[kgx2]

Success! Sort of...

So i got it all together and running thanks to the advice and diagram. I learned how to tell the positive side of a capacitor in the process which is always a plus to learn something new! Tested it with my 1L flask and some water and it worked well. Not a lot of speed control but enough. Guess the fan isn't very good?

I say sort of because i pit my first starter on the plate last night and the bar rattles like crazy even though with just water it was fine. I'm guessing stronger magnets are needed to stabilize the bar?

Here's a pic of the finished product in action.

 

[tracyk]

Congrats on your success!! I have made several stir plates for myself and friends and here is what I have found that works best for the ones that I made. An old 80mm computer fan, of course your switch (12v), a 25 ohm 3watt pot (from rat shack), and usually a 6 volt 500Ma power supply. I found that a 300Ma power supply would work, but they were more finicky to get right. With a 6V 500Ma power supply I can do as little as 1 liter up to 5 liters without any problem. With the 1 liter I have the pot turned all the way down. I usually am stirring a 2 liter starter.

If you are using an old hard drive magnet or rare earth magnets those would be strong enough.

 

[abeasst]

Success! Sort of...

So i got it all together and running thanks to the advice and diagram. I learned how to tell the positive side of a capacitor in the process which is always a plus to learn something new! Tested it with my 1L flask and some water and it worked well. Not a lot of speed control but enough. Guess the fan isn't very good?

I say sort of because i pit my first starter on the plate last night and the bar rattles like crazy even though with just water it was fine. I'm guessing stronger magnets are needed to stabilize the bar?

Here's a pic of the finished product in action.

Make sure you bring the sitr plate up to speed slowly. Don't just crank it all the way to high as sometimes this can cause the stir bar to just vibrate and not actually spin.

 

[kgx2]

Yeah i tried doing both and adjusting the flask on the plate but the bat still rattles like crazy.