My Stirplate... Cheap and Easy Build...

[iluvmysh]

Greatest stir plate enclosure ever...I'm looking every time I hit a thrift store!

do you have to blow on it to make it work?

 

[TANSTAAFB]

do you have to blow on it to make it work?

That's fu@#in funny!

 

[Hovik]

This is a fool proof wiring diagram. All parts is obtainable from your local Radio Shack.

This will allow for perfect speed control. Using just a potentiometer will work at first but wont last and last. You wont get good speed control and using lower volt DC adapters for speed control is silly. Don't do it, build it right.

Also checkout this handy link: http://www.stirstarters.com/instructions.html

If you like DIY then build one if not just order one from here, it is much easier and only marginally more expensive than parting and building it yourself.

Cheers to happy yeasty beasties!

Hi Guys,
I have built 2 stir plates using this schematic. The first stir plate worked perfect. I couldn't be happier. The second stir plate works but the potentiometer basically is off when turned down and if you turn it a little bit the fan goes from off to full speed.

I read and re-read this schematic, checked it against my wiring and everything looks right. I swapped pots, switches, and power supplies (one used a 12v and the other a 5v) but none of those were the problem. It's somewhere in the circuit but seemingly not the wiring. I am thinking it might be a bad resistor but I am totally out of ideas. Can anyone think of what component or area of the circuit might be the problem to cause a pot to have no adjustability in this circuit?
Thanks in advance.
Hovik

 

[brewman !]

Great thread.

I bet somewhere along the way a major stir plate manufacturer happened upon this thread, did a "D'oh !" and forehead slap and said "so this is where our stire plate sales have been going" !

 

[TripleHopped]

It also looks like my next upgrade is a 3L or 4L flask because my 1 gallon jug doesn't have a flat interior bottom.

I only use 1 gallon jugs that don't have flat bottoms and they work fine for my stirplate starters.

 

[misterbk]

Great thread.

I bet somewhere along the way a major stir plate manufacturer happened upon this thread, did a "D'oh !" and forehead slap and said "so this is where our stire plate sales have been going" !

If you think about it, we're not really building these for less money. We're just not assigning a dollar figure to the time we spend assembling. If someone asked to pay you to spend all day building these, the dollar figure would go up a bit!

 

[Starrider]

If you think about it, we're not really building these for less money. We're just not assigning a dollar figure to the time we spend assembling. If someone asked to pay you to spend all day building these, the dollar figure would go up a bit!

When it is a hobby and you are doing it for fun, you can't count your time as cost. That's part of the hobby. How many hobbies do you know where there can actually be a cost savings?
Between the DIY projects for equipment and the fact that the end product is cheaper than I can buy it in the store, this is the greatest hobbie on earth!

 

[Starrider]

Hi Guys,
I have built 2 stir plates using this schematic. The first stir plate worked perfect. I couldn't be happier. The second stir plate works but the potentiometer basically is off when turned down and if you turn it a little bit the fan goes from off to full speed.

I read and re-read this schematic, checked it against my wiring and everything looks right. I swapped pots, switches, and power supplies (one used a 12v and the other a 5v) but none of those were the problem. It's somewhere in the circuit but seemingly not the wiring. I am thinking it might be a bad resistor but I am totally out of ideas. Can anyone think of what component or area of the circuit might be the problem to cause a pot to have no adjustability in this circuit?
Thanks in advance.
Hovik

Since you say you swapped the pot, then the only thing left is the voltage regulator. Have you tested the output with a meter?
My first thought would have been the pot. Either it is bad and going from off straight to full on, or the value is not what you think it is. If the pot is bigger than you think, that is exactuly what it would do.
If the pot checks out, put the volt meter on the output (without the fan) and watch the voltage change as you turn the pot.
Another thing to check is that the terminals are correct on the 317 regulator. If the input and output are swapped, that might cause the problem too.

According to Mellow52, a pot alone wont last and last. I'm not sure why, I've never heard that before. I'm not an engineer so if there is a reason that current control is not as good as voltage control, I would like to understand. Functionally, they both see to be the same.

Most DIY's if heard of have been with a pot alone. In my case, I used a transistor and pot combination because I couldn't find the right sized pot locally. Same effect as a pot alone but mine seems to be holding up just fine.

Good Luck, let us know what you find

 

[Hovik]

Since you say you swapped the pot, then the only thing left is the voltage regulator. Have you tested the output with a meter?
My first thought would have been the pot. Either it is bad and going from off straight to full on, or the value is not what you think it is. If the pot is bigger than you think, that is exactuly what it would do.
If the pot checks out, put the volt meter on the output (without the fan) and watch the voltage change as you turn the pot.
Another thing to check is that the terminals are correct on the 317 regulator. If the input and output are swapped, that might cause the problem too.

According to Mellow52, a pot alone wont last and last. I'm not sure why, I've never heard that before. I'm not an engineer so if there is a reason that current control is not as good as voltage control, I would like to understand. Functionally, they both see to be the same.

Most DIY's if heard of have been with a pot alone. In my case, I used a transistor and pot combination because I couldn't find the right sized pot locally. Same effect as a pot alone but mine seems to be holding up just fine.

Good Luck, let us know what you find

Pot goes from 1.2 ohms - 4.95k ohms. This is very close to the performance of the pot in my working stir plate. Wall wort output is 5.10v. Input side of regulator shows 5.10v
Output shows 1.254vdc when pot closed, only 3.51vdc when is pot open but this is with the fan connected. If I need to desolder it to get a reading I can... let me know. Does this suggest any possible causes?
I checked and the volt regulator seems to be wired correct.

 

[bigken462]

Hey guys, I tore into a old hard drive this morning expecting to find some half moon magnets. All this one has looks to be a round one.

Any particular brand of hard drives that I need to look for?

 

[mrduna01]

That's not the magnet, but the actual disc that holds the data. The magnet should be under that arm that comes out to write on the disc if im not mistaken.

So many beers... so little time.

 

[bigken462]

That's not the magnet, but the actual disc that holds the data. The magnet should be under that arm that comes out to write on the disc if im not mistaken.

So many beers... so little time.

Lol, ok I knew what the disk was, but I thought the magnet was the smaller center part. Somehow I thought those was attached to the disk themselves.

Well, now the next question is, since these appear to be just as brittle as everyone said they would be, could I break off the larger unbroken magnet to match the other one I broke, or keep searching for another hard drive to destroy. lol Crap sake I barely put the needle nose pliers to them and it broke like glass.

 

[barrooze]

Lol, ok I knew what the disk was, but I thought the magnet was the smaller center part. Somehow I thought those was attached to the disk themselves.

Well, now the next question is, since these appear to be just as brittle as everyone said they would be, could I break off the larger unbroken magnet to match the other one I broke, or keep searching for another hard drive to destroy. lol Crap sake I barely put the needle nose pliers to them and it broke like glass.

What I did was stack mine. That way it doesn't matter if one is broken or not. Just try to center the magnet so it's field's center is at the center of your fan or what ever you're going to use to spin the magnet.

The below image is what I'm talking about.

 

[mojo2008]

Well, now the next question is, since these appear to be just as brittle as everyone said they would be, could I break off the larger unbroken magnet to match the other one I broke, or keep searching for another hard drive to destroy. lol Crap sake I barely put the needle nose pliers to them and it broke like glass.

I only used one on my stirplate and it's plenty strong. Just center it on your fan the best you can to minimize wobble.

 

[Hang Glider]

Two methods to remove those hard-drive magnets that seem to work:

1 - a paint-scraper type putty knife (stiff blade) and a gentle tap with a mallet
2 - bend the metal that it's on - and it will pop off

 

[Stealthcruiser]

As stated above......^^^^^, and also, soak it in a bit of Acetone, and the glue will soften up and quit playing.......

 

[mrduna01]

I used some pliers to bend the bracket and get the magnet separated slightly on the twisted end and it popped right off. My magnet seems smaller than some here however and seems to be very strong. Not brittle at all. I got it from the IT department so not sure what kind of drive it came out of.

 

[Starrider]

Pot goes from 1.2 ohms - 4.95k ohms. This is very close to the performance of the pot in my working stir plate. Wall wort output is 5.10v. Input side of regulator shows 5.10v
Output shows 1.254vdc when pot closed, only 3.51vdc when is pot open but this is with the fan connected. If I need to desolder it to get a reading I can... let me know. Does this suggest any possible causes?
I checked and the volt regulator seems to be wired correct.

I haven't been on in a while, sorry. If you are still struggling with this, I see a couple of things to look into. If you have a working stir plate with all the same components, it makes it a little harder.
First, you are starting at a max of only 5 volts. Most fans In my experience are designed for 12V. Reducing much below 5V and I think you would experience stalling (off) and then have to open it up to full speed to get it going again.
If you can up the power to 9 or 12V, that alone may be enough to solve your problem.
Also look at the fan itself. When comparing with your working plate, assuming everything else is the same, the fan could have different requirements. It's age and amount of use it has seen could also affect the power draw/requirement.

Another thing would be the relationship between the pot and regulator. To get an accurate reading, you would have to remove the fans so it doesn't add to the voltage drop. Watch the affect on the output voltage while you turn the pot. You might find that with very little movement of the pot, you see large swings in output voltage. You may also get that information from the data sheet for the 317 regulator.

I would try increasing the voltage first and see what happens.

I run mine with 12v. It's easy to turn up the pot to limit current or volts in your case but you can't add volts if you don't have them from the start.


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[Stormbringer]

I made this a few months ago. I had some parts on hand and It was a fairly easy build.
I used the rare earth magnets from Ace hardware and they work fine. I omitted the led since the switch i had didn't have one.
I made about 4 starters with it and I couldn't be happier.

 

[seckert]

.

 

[mrkrausen]

This is a fool proof wiring diagram. All parts is obtainable from your local Radio Shack.

This will allow for perfect speed control. Using just a potentiometer will work at first but wont last and last. You wont get good speed control and using lower volt DC adapters for speed control is silly. Don't do it, build it right.

Also checkout this handy link: http://www.stirstarters.com/instructions.html

If you like DIY then build one if not just order one from here, it is much easier and only marginally more expensive than parting and building it yourself.

Cheers to happy yeasty beasties!

ok, I'm not sure if it's just me but I can't find most of these items at radioshack. I was able to find the 5k potentiometer and the LM317T. However I wasn't able to find the 5 or 25 uf 25vdc capacitors, or the 240 ohm, 1/4 - 1 watt resistor. I ended up getting the 220 ohm, 1/4-watt resistor since it seemed the closest. Any suggestions? I think I did see a 4.7 uf capacitor but it wasn't 25vdc either.

 

[dirkomatic]

ok, I'm not sure if it's just me but I can't find most of these items at radioshack. I was able to find the 5k potentiometer and the LM317T. However I wasn't able to find the 5 or 25 uf 25vdc capacitors, or the 240 ohm, 1/4 - 1 watt resistor. I ended up getting the 220 ohm, 1/4-watt resistor since it seemed the closest. Any suggestions? I think I did see a 4.7 uf capacitor but it wasn't 25vdc either.

Save yourself a lot of effort and buy a fan which comes with the speed control potentiometer already:
http://www.newegg.com/Product/Product.aspx?Item=N82E16835200027

With code SUPSALE033, it's $5 shipped. It's a very easy build.

 

[mrkrausen]

so you're saying I won't need any other components electrically than that fan/pot combo, switch and power supply?

 

[dirkomatic]

Yes. That's all you need

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[mrkrausen]

Thanks! I'll order it tonight.

 

[wildcatman17]

Will any size fan work I have a like a two inch it seems to run fast enough. Trying to make it a inexpensive as possible...

 

[Hang Glider]

Will any size fan work I have a like a two inch it seems to run fast enough. Trying to make it a inexpensive as possible...

yes. Indeed, you don't even need the blades, just the motor. But the blade has that nice center hub to stick a magnet to...

 

[Feldmann]

I'm having trouble finding a Potentiometer/Rheostat. I live in Canada so shipping for everywhere I look bring the price to around $30 and I can't find any local shops that stock them. Any Canadians have a website that won't cost me an arm and a leg for shipping?

 

[uatuba]

I'm having trouble finding a Potentiometer/Rheostat. I live in Canada so shipping for everywhere I look bring the price to around $30 and I can't find any local shops that stock them. Any Canadians have a website that won't cost me an arm and a leg for shipping?

There's this really cool website called Amazon.ca.


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[misterbk]

I'm having trouble finding a Potentiometer/Rheostat. I live in Canada so shipping for everywhere I look bring the price to around $30 and I can't find any local shops that stock them. Any Canadians have a website that won't cost me an arm and a leg for shipping?

Newark has a Canada branch.

canada.newark.com

They'll get you something so precisely what you need, you'll probably learn something buying it.

What potentiometer value are you after? (Forgive me if I haven't read the same instructions you read.) If their site is too confusing I'll help you find one, and a knob to go with it.

Edit: Start --> Here <-- for potentiometers. (Passive Components / Potentiometers / Rotary Potentiometers)