My homebrew stirplate

[Yorg]

Getting closer.
Tossed the fan and got another. It now starts from zero.
However, it throws all but my smallest bar quite low speed.
I have one magnet on the hub, so will try another on top and see.
Thanks for your suggestions.

 

[RobertHSmith]

inspired by this thread, I made two with just a pentometer, fan and old blackberry power supply for each and som glad tupperware type containers.

I originally was using harddrive magnets, but switched to some ceramic ones from lowes that were 7/8 x 1 7/8 x 3/8 (may be different it's been about a month since I bought them).

I purchased a 2" stir bar that kept getting thrown with the harddrive magnet. I bought the magnets from lowes that come in a 2 pk. I put two together end to end and taped them together, then taped them to the center of the fan to have a larger magnetic field.

I am only using the pentometer to control the speed, but they work when you pulg them in at full speed, unplug them, then put the starter with stirbar on centered as best as you can. Eventually the speed slows enough for the bar to stop rattling around and center it's self. When it centers I have to plug it in quickly and then slow the speed with the pentometer.

I've done 3 starters so far and they have worked great

thanks for the inspiration.

 

[brewjunky]

I wish someone would draw this circuit out for those of us that are not electronic engineers.

I have problems following the schematic. If it were drawn out in terms of connect this wire here to this wires it would be easier.

I am not good at reading schematics that were meant for an electronic Engineer.

This is definatly not worded for the weekend warrior.

 

[BlindLemonLars]

I wish someone would draw this circuit out for those of us that are not electronic engineers.

I have problems following the schematic. If it were drawn out in terms of connect this wire here to this wires it would be easier.

Wow, it's your lucky day! Check out this thread by hexmonkey, from earlier today. Seems to be exactly what you're asking for.

Detailed step-by-step stirplate speed control

 

[waterkc]

wow, that is the best layout of a how too in a long time. Very well done.

Thanks

 

[Ben25]

All I used for mine was:

Project Box
12v Fan
switch
Rheostat (25 ohm)
2 rare earth magnets from ebay
12v transformer


I'm ok with electronics, but I don't understand the need for capacitors and all that other stuff when this works perfectly...

 

[hexmonkey]

All I used for mine was:

Project Box
12v Fan
switch
Rheostat (25 ohm)
2 rare earth magnets from ebay
12v transformer

I'm ok with electronics, but I don't understand the need for capacitors and all that other stuff when this works perfectly...

The site I linked in the other thread explains a bit about why the "advanced" circuit uses the components it does (and it sounds like the capacitors may be somewhat unnecessary). Basically, the problem is that some fans spin pull more current than others, so a random fan with the same 25 ohm rheostat gives predictably random results. Using a circuit that you know will put out a specific voltage range from a given starting voltage allows you to use whatever fan you want.

In your example, 25 ohms is not a very high value, so the difference from full-off to full-on is not particularly high. In my circuit I used a 120mm fan rated for 12V at 20 mA

voltage drop = amps x ohms = 0.20 x 25 = 5v
12v max - 5v = 7v
So full range of circuit for the 25 ohm rheostat is: 7v to 12v

This means the 25 ohm rheostat only dropped the voltage to 7V when turned all the way down. I had to flick the on/off switch to get the fan moving slowly enough not to throw the stirbar, because even turned all the way down, it was moving too fast to start. Not what I would call "working perfectly" in this setup.

In comparison, the "advanced" circuit is specifically designed to give a range of ~1.2V to 12V, which is well enough to start really slowly and get it up to speed without throwing the stirbar. Now I can just set the flask down, turn it on and adjust the speed, and it just works with no fiddling.

 

[hexmonkey]

I just noticed a good point for those of you looking to make this without the advanced circuit: use Ben25's parts list, but switch to a 6v power supply.

On this site:

Wort-O-Matic: Articles

Erik uses the same parts list as Ben25, including a 12v fan, but he lists a 6v power supply instead of a 12v power supply.

In my previous post, I noted the voltage drop for the fan and rheostat:

voltage drop = amps x ohms = 0.20 x 25 = 5v

This is independent of voltage, so it's a 5v drop for 12v or 6v supplied. Using a 6v power supply means the range is much better (1v - 6v). The fan will never spin at full speed, but for most fans this won't be a problem at all.

 

[Kelsch]

Wort-O-Matic: Articles

PRECISELY what I was looking for!

Thanks!

 

[Cookiebaggs]

Or just use the 25 ohm rheostat with an adjustable voltage AC adapter. The adjustable voltages allow you to set a speed and the rheostat gives you a speed control within the given voltage.

 

[Ben25]

I personally am happy I went with the 12v power supply. I don't think it would spin fast enough with a 6v. As it is, I can get the vortex down to the bottom on a 2000ml starter.

With a new starter, I have to start it on low, and slowly turn it up to high. It does not throw the bar unless I start it on medium to high.

I used 5 lb 7/16 magnets.

 

[hexmonkey]

I personally am happy I went with the 12v power supply. I don't think it would spin fast enough with a 6v. As it is, I can get the vortex down to the bottom on a 2000ml starter.

With a new starter, I have to start it on low, and slowly turn it up to high. It does not throw the bar unless I start it on medium to high.

I used 5 lb 7/16 magnets.

I definitely had trouble starting with 12v and the 25ohm rheostat. I wonder if maybe your magnets are stronger than mine? I don't know how I'd measure the strength, they're just out of a hard drive.

Do you happen to know what amperage your fan is? That's really the only other variable...

 

[Ben25]

The fan is a .3 amp...

 

[hexmonkey]

The fan is a .3 amp...

That might just do it. That .1 amp amounts to an extra 2.5v drop, making the range 4.5v - 12v.

voltage drop = amps x ohms = 0.30 x 25 = 7.5v drop

 

[BarleyWater]

I discovered a great source for magnets. At Petsmart you can get a magnetic aquarium cleaner. I had the smaller size for my old aquarium, so I dug it out, busted open one side, and inside were two of the strongest magnets I've ever found, stronger than the rare earth magnets I got from mcmaster. In the other piece there are two more of the same magnets. They are attached to a metal bar, perfectly spaced. Just centered it up, turned on the fan, and it worked like a charm.

 

[schweaty]

Would an 80mm fan work?
Masscool
I have a bunch of these laying around. Newegg had a sale going and I bought a bunch.

 

[schweaty]

Well I got this thing working using a 1/2 inch stir bar in a 1000ml bottle. The vortex in the middle wasn't very large though. I'm wondering, the bigger the stir bar the larger the vortex? Is it possible for the magnets to slow down the fan too much and not create a large vortex? Is it because I'm using a 80mm 12v fan and not a 120mm? Please, someone who knows about this stuff please help me out. I wanted to brew on Monday!!!

 

[hexmonkey]

Well I got this thing working using a 1/2 inch stir bar in a 1000ml bottle. The vortex in the middle wasn't very large though. I'm wondering, the bigger the stir bar the larger the vortex? Is it possible for the magnets to slow down the fan too much and not create a large vortex? Is it because I'm using a 80mm 12v fan and not a 120mm? Please, someone who knows about this stuff please help me out. I wanted to brew on Monday!!!

It's not the stirbar size but the speed it moves at.

The vortex size doesn't mean too much, as long as you have movement it's doing its job and the yeast will grow.

How did you make your stirplate? What voltage? Any rheostat?

 

[schweaty]

It's not the stirbar size but the speed it moves at.

The vortex size doesn't mean too much, as long as you have movement it's doing its job and the yeast will grow.

How did you make your stirplate? What voltage? Any rheostat?

12v DC adapter
80mm 12v DC fan
Project box
On/Off Switch
2 Magnets from harddrive

I didn't use a rheostat because I didn't need one. The stirplate starts slow enough to where the bar won't get thrown at the beginning Once it gets to full speed its not throwing the bar either. I tried using a 1 inch bar it it works much better for me than the 5/8. Tried a 2 inch but the magnet in it is too strong and won't even let the fan turn. I've only tested it in water and it gets going pretty good. Is there another substance that might have the consistency that wort does?

 

[keithd]

If you're not too handy soldering or just don't feel like messing with electronic components, you can use a Zalman Fan Mate 1 or Fan Mate 2 instead of the LM317 circuit, since it's pretty much the same thing.

I bought mine at CompUSA years ago for something like $10, I think the Fan Mate 2 is around $4 at newegg.

I use it with a 6V 500ma wall-wart and a 120mm 12V .35a fan that has a large hub, and it'll spin 5L with a 1" stirbar. Just make sure your magnet's magnetic axis is well-centered along the fan's rotational axis and it won't throw the stirbar. And if your fan has a hard time starting at lower voltages, you have to space the magnet away from the fan hub. I'm using an exceptionally powerful magnet pulled from a 15k rpm server drive, and the fan won't spin up at lower power with the magnet right against the fan hub.

OBTW - testing with a digital multimeter, I saw 4.7v low to 7.6V high output with the Fan Mate, and 9V without it on the 6V rated wall-wart. You might could rig a 3-way switch - off, thru Fan Mate, and bypass for faster speeds.

You could use an 80mm, but make sure the fan motor hub is appropriately sized for the magnet you use, and be aware that 80mm fans usually spin at MUCH higher rpms than 120mm fans.
-keith

edit - oops, sorry about resurrecting a zombie thread. I found it through another thread link earlier today...

 

[RedOctober]

http://img33.picoodle.com/img/img33/3/11/16/f_starter2m_0f0f1ad.jpg



Materials:

Old Plastic VHS case
Old Phone Charger
Rheostat from Radio Shack
Switch from Radio Shack
Control Knob from Radio shack
Old PC Fan and magnet salvaged

done for 8 bucks

 

[skipdog]

I'm interested in a stir plate if you have any more. You can email me at [email protected]

 

[humann_brewing]

So I recently cleaned out the garage and one of the things I threw out were really old hard drives and I am kicking myself now.

So if I had to get some Neodymium Magnets at a local store, where should I go?

 

[Sumo]

I just did my first starter with His stir plate. it worked like a charm. I bought expired yeast from my LBS for 2 bucks. I got Wyeast London ESB (I don't remember the number) It was a lager yeast. I used a 2 liter flask, I bought the starter kit from Morebeer for 15 bucks and used a 2" stirbar. It took 48 hours for the expired yeast to catch on but once it did the flask looked like it was filled with milk. I cold crashed it and had a huge starter on my hands. I will brew the beer tomorrow night. I can't wait to pitch the starter on it. The starter can sit in the fridge for 5 days no problem in the fridge once its done. Just make sure you cap it off with plastic wrap and a rubber band. BTW You can buy magnets online for 8 bucks. I got the 12lb pull magnets. they work great.

 

[humann_brewing]

I just did my first starter with His stir plate. it worked like a charm. I bought expired yeast from my LBS for 2 bucks. I got Wyeast London ESB (I don't remember the number) It was a lager yeast. I used a 2 liter flask, I bought the starter kit from Morebeer for 15 bucks and used a 2" stirbar. It took 48 hours for the expired yeast to catch on but once it did the flask looked like it was filled with milk. I cold crashed it and had a huge starter on my hands. I will brew the beer tomorrow night. I can't wait to pitch the starter on it. The starter can sit in the fridge for 5 days no problem in the fridge once its done. Just make sure you cap it off with plastic wrap and a rubber band. BTW You can buy magnets online for 8 bucks. I got the 12lb pull magnets. they work great.

I have everything but the earth magnets. Where did you get those?

I think I may need to use a bigger fan, mine is only a 80mm

 

[Sumo]

I ordered them from here:

MAGCRAFT® Neodymium Magnets

Product ID: NSN0641
ProductName: Rare Earth Magnet - Disc - D0.500 x T0.250 - Package of 8
Description: Rare-Earth Neodymium-Iron-Boron (NdFeB) Disc Magnet Size - Diameter 0.500" (12.70mm) x Thickness 0.250" (6.35mm); Grade N40; Pull Force - 10.69lb/4849g

These had a really strong pull and they are round and small. The case I used was too big and I had too much head space between the fan and the top of the case so I double stacked the magnets and used 4 total. As for the small fan, that is the beauty of using that large metal washer.. Gives you a little more space to move the magnet around. Trust me it works well. Let me see if I can figure out how to post the pics I took.
I hope this helps you out. Buying the magnets was easier for me. Dealing with HD's can be a bitch. I am lazy and would rather spend 16 bucks and not have to deal with taking them apart.

 

[StirStarters]

edited message-no longer valid

 

[Catt22]

 

[Sumo]

I just did my first starter with His stir plate. it worked like a charm. I bought expired yeast from my LBS for 2 bucks. I got Wyeast London ESB (I don't remember the number) It was a lager yeast. I used a 2 liter flask, I bought the starter kit from Morebeer for 15 bucks and used a 2" stirbar. It took 48 hours for the expired yeast to catch on but once it did the flask looked like it was filled with milk. I cold crashed it and had a huge starter on my hands. I will brew the beer tomorrow night. I can't wait to pitch the starter on it. The starter can sit in the fridge for 5 days no problem in the fridge once its done. Just make sure you cap it off with plastic wrap and a rubber band. BTW You can buy magnets online for 8 bucks. I got the 12lb pull magnets. they work great.

I just wanted to say that I am a huge fan of starters now. The starter I made took off in 3 hours and more importantly I feel I had better results with a starter then not using one.

 

[MajorWoody]

Just wanted to say thanks to everyone who contributed to this thread. Finished my own stirplate last night. It was CHEAP and pulls a strong vortex right down to the bottom.
Materials:
--Radio shack project box
--Illuminated toggle (had this)
--Radio shack potentiometer and knob
--12 v case fan from dead computer
--Pair neobdenum magnets 10mm from ebay, dirt cheap
--1000ml Ehrlenmeyer flask from LHBS, $15
--1" stirbar off ebay, cheap
--Variable voltage 3-12V wall wart free from the computer technician's junk closet here at work

This will pay for itself with the first three packs of yeast. I will just culture the three that I use most often, keep them in the fridge in baby food jars, and keep right on re-using. Most importantly, I can pitch a big starter every time.

And also it is just cool to watch. I never even knew these things existed until I read about them here.

Thanks everyone.