New Giveaway - Wort Monster Conical Fermenter!

Home Brew Forums > Home Brewing Beer > DIY Projects > Stirplate - 12v too much, 6v won't turn it on???




Reply
 
LinkBack Thread Tools Display Modes
Old 01-22-2011, 01:07 PM   #31
MalFet
/bɪər nərd/
HBT_LIFETIMESUPPORTER.png
Feedback Score: 1 reviews
 
MalFet's Avatar
Recipes 
 
Join Date: May 2010
Location: NYC / Kathmandu
Posts: 8,143
Liked 1196 Times on 789 Posts
Likes Given: 533

Default

Quote:
Originally Posted by Kayos View Post
Most of us NEED this site because we aren't in the electronics field and have no idea how this stuff works or is even figured out. That's why the DIY's posts are SOOOOO helpful. I never would have been able to build the stirplate without an exact step by step process. I have no idea how the ohms on a pot are figured. I will help out everywhere I can, but I need someone like you guys to help me with the electronics stuff and just tell me where to solder and to what. I had to do it just as the build suggested because I have no idea how much of a difference a 25 ohm pot is vs a 25K ohm pot or where you would use the two. Fact is, I really don't care. I just want a stirplate that works. It saved me $40. Got a little education along the way as well. Bonus!

P.S. My fan is 12v - not sure if that matters or not

Thanks for all the help guys, and thanks for dealing with the ignorant one (mirror )
Sure thing! And I got no gripes about any of that. I hope that post didn't come off as impatient; I just kept seeing all these different people with different problems, nobody was posting enough detail to help them, and the only thing in common seemed to be that everyone had a 1-25ohm pot.

Your 6V charger isn't working because it's not giving your fan enough juice. Computer fans are typically built on motors that will spin at a fixed RPM for a fixed voltage. If you bump the voltage up, it will spin faster, and if you bump the voltage down, it will spin slower. It's not so simple, though, that you can say 0V = zero speed, 6V = 50% speed, and 12V = 100% speed. All fans have an operating voltage range, and will only spin at all if given power above a certain threshold. A potentiometer works by introducing variable resistance to the circuit, which causes a voltage drop, which in turn causes the fan to spin slower than its maximum speed.

The problem is that you know how much of a voltage drop you want, but you can't know how much of a voltage drop you're going to get from any particular resistor without knowing how much current your fan draws. This should be listed on the label...something in the ballpark of 0.5A (or 500mA). So a 1-24ohm pot will cause one range of voltage drops for a 0.5A fan, and another range for a 1A fan, and yet another range for a 0.25A fan.

There are a couple solutions, but first you want to make sure that your device is wired properly. You say that it's much too high, even at the lowest setting. This probably just means that you've got a relatively powerful fan, and that even 25ohms of resistance isn't enough to get you down to a workable range. Just to make sure you're wired right, though: does the speed of the fan change at all when you adjust your potentiometer?

So solutions:
1) go to radioshack and buy a relatively large range potentiometer (say, 0-200ohms, rated for 10W) and know that this will work for 95% of fans. The down side to this is that you'll have a very narrow "sweet spot" of useful range on your potentiometer, so you'd have to be gentle with it to find a useable setting.

2) build something more like this: http://www.homebrewtalk.com/f11/my-homebrew-stirplate-8850/ It looks more complicated than it is, but this design has the added benefit that it will work with pretty much any 12V fan.

3) post more detailed specs of your fan (particularly current draw in amps or nominal power usage in watts) or a part number and we can speculate about what kind of pot would work better for you. It would be only speculation, though, because the addition of those magnets means that your fan isn't behaving as described in its datasheet anymore.

...and let us know how it goes.

@dzlater - if you are happy with your speed range, you could get the same 1-25ohm pot but just make sure it has a higher rating than 3W. 6W or 10W should be fine.


__________________
MalFet is online now
 
Reply With Quote Quick reply to this message
Old 01-22-2011, 01:37 PM   #32
dzlater
Feedback Score: 0 reviews
Recipes 
 
Join Date: Apr 2008
Location: New Jersey
Posts: 1,030
Liked 23 Times on 22 Posts
Likes Given: 105

Default

Quote:
Originally Posted by MalFet View Post
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>
@dzlater - if you are happy with your speed range, you could get the same 1-25ohm pot but just make sure it has a higher rating than 3W. 6W or 10W should be fine.
Thanks this stuff gets pretty confusing for those of us who are electronically challenged.


__________________
dzlater is offline
 
Reply With Quote Quick reply to this message
Old 01-22-2011, 02:08 PM   #33
Kayos
disclaimers are sissy
HBT_SUPPORTER.png
Feedback Score: 0 reviews
 
Kayos's Avatar
Recipes 
 
Join Date: Dec 2006
Location: Santa Clarita, SoCal
Posts: 1,372
Liked 7 Times on 7 Posts
Likes Given: 7

Default

Quote:
Originally Posted by MalFet View Post
...and let us know how it goes.
I think I'm happy with it now. Thanks for the education, if I build another one, I'll definitely do it a but different. I am going to hook up the 12v plug again to so I don't have to have the pot cranked all the way up the whole time. Mybe Add a bit bigger pt, also. What size do you think would work better with the Anthony Lopez setup?
__________________
Being Dealt (kegged): Carbed Crystal light lemonade for the boys, Delta Bravo IPA, Applewinder
Primary: Climbing stout
Primary #2: ESB
Big Blind: Pucker Bitter
Small Blind:
Tasty Remembrances: White 'N Nerdy, Dynamite Red (Hop bursted), APA, The Bonaduce (irish Red), runners stout, ridgeback brown,

from my big ass computer sitting on my floor
Kayos is offline
 
Reply With Quote Quick reply to this message
Old 01-22-2011, 02:17 PM   #34
MalFet
/bɪər nərd/
HBT_LIFETIMESUPPORTER.png
Feedback Score: 1 reviews
 
MalFet's Avatar
Recipes 
 
Join Date: May 2010
Location: NYC / Kathmandu
Posts: 8,143
Liked 1196 Times on 789 Posts
Likes Given: 533

Default

Quote:
Originally Posted by Kayos View Post
I think I'm happy with it now. Thanks for the education, if I build another one, I'll definitely do it a but different. I am going to hook up the 12v plug again to so I don't have to have the pot cranked all the way up the whole time. Mybe Add a bit bigger pt, also. What size do you think would work better with the Anthony Lopez setup?
The whole point of my last post was to explain why I have absolutely no way of answering that question without knowing the answers to the questions I asked you.
__________________
MalFet is online now
 
Reply With Quote Quick reply to this message
Old 01-22-2011, 09:56 PM   #35
Kayos
disclaimers are sissy
HBT_SUPPORTER.png
Feedback Score: 0 reviews
 
Kayos's Avatar
Recipes 
 
Join Date: Dec 2006
Location: Santa Clarita, SoCal
Posts: 1,372
Liked 7 Times on 7 Posts
Likes Given: 7

Default

OK, no prob. I have no intention of taking the whole thing apart to find out the fan info. I did splice both the 12v and 9v wires together and now can plug in either one I choose depending on the size and viscosity of the starter.

__________________
Being Dealt (kegged): Carbed Crystal light lemonade for the boys, Delta Bravo IPA, Applewinder
Primary: Climbing stout
Primary #2: ESB
Big Blind: Pucker Bitter
Small Blind:
Tasty Remembrances: White 'N Nerdy, Dynamite Red (Hop bursted), APA, The Bonaduce (irish Red), runners stout, ridgeback brown,

from my big ass computer sitting on my floor
Kayos is offline
 
Reply With Quote Quick reply to this message
Old 09-29-2012, 03:58 PM   #36
bd2xu
HBT_SUPPORTER.png
Feedback Score: 0 reviews
 
bd2xu's Avatar
Recipes 
 
Join Date: Jul 2012
Location: Atlanta, GA
Posts: 753
Liked 26 Times on 24 Posts

Default stirring a 1.5L starter in a 2L flask

I built my stir plate with a cigar box, fan, two hard drive mags, and 9V power supply. Don't have a pot on it yet. When i tested it with a 1" stir bar in a 4 cup (1 L) measuring cup, it was perfect. vortex all the way tot he bottom. Now though I'm doing the maiden voyage with a 1.5 L starter (this is the second step) in a 2L flask. The 1" bar spins it but the vortex doesn't go very far down, still getting lots of good stirring though. I tried the 2" bar and couldn't get it to spin. The liquid is not clear so I couldn't see what it was doing, but looked like no spin.

Should I try putting a 12V power adapter back on? When I used the 12V in my testing with water in a measuring cup it was too fast and wouldn't spin.

__________________
bd2xu is offline
 
Reply With Quote Quick reply to this message
Old 09-29-2012, 05:31 PM   #37
bd2xu
HBT_SUPPORTER.png
Feedback Score: 0 reviews
 
bd2xu's Avatar
Recipes 
 
Join Date: Jul 2012
Location: Atlanta, GA
Posts: 753
Liked 26 Times on 24 Posts

Default

Update, using the 12 volt vs the 9 volt it throws the 1" and 2" ball every time. So I guess I need a 12 volt power with a pot to find that sweet spot between 9 and 12. Before I do that though I will stack a third hard drive mag on top of the other two to see if more mag power and making the mags closer to the lid will let me use the 12v as is. Thinking maybe with more magnetic power the stir bars will stick with 12 volts.

__________________

On Deck:
Primary: Centennial Blonde, Petite Saison D'Ete, Weizenbier
Secondary:
Carbing/Conditioning/Lagering: caramel apple cider
On tap: Cottage House Saison, Oaked English Mild, London Porter
Bottled: Vanilla Bourbon Imperial Porter, La Fin Du Monde Clone, Trench Pale Ale, Cottage House Oaked Saison with Chardonnay

Text to SWMBO: "Honey I'm having one more pint with the guys, be home in 20 minutes. If I'm not home by then, read this message again."

bd2xu is offline
 
Reply With Quote Quick reply to this message
Old 10-01-2012, 02:50 PM   #38
bd2xu
HBT_SUPPORTER.png
Feedback Score: 0 reviews
 
bd2xu's Avatar
Recipes 
 
Join Date: Jul 2012
Location: Atlanta, GA
Posts: 753
Liked 26 Times on 24 Posts

Default

Well I added a fourth magnet and now the 9 and 12 volt work great with the 1" bar but the 2" bar still gets thrown every time. So I'll just stick to the 1" bar and use either the 9 or 12 depending on the speed I need. Only thing I had to purchase for this project is the stir bars, had everything else!

__________________

On Deck:
Primary: Centennial Blonde, Petite Saison D'Ete, Weizenbier
Secondary:
Carbing/Conditioning/Lagering: caramel apple cider
On tap: Cottage House Saison, Oaked English Mild, London Porter
Bottled: Vanilla Bourbon Imperial Porter, La Fin Du Monde Clone, Trench Pale Ale, Cottage House Oaked Saison with Chardonnay

Text to SWMBO: "Honey I'm having one more pint with the guys, be home in 20 minutes. If I'm not home by then, read this message again."

bd2xu is offline
 
Reply With Quote Quick reply to this message
Old 10-03-2012, 07:24 PM   #39
zzARzz
Member
HBT_SUPPORTER.png
Feedback Score: 0 reviews
 
zzARzz's Avatar
Recipes 
 
Join Date: Jul 2012
Posts: 410
Liked 43 Times on 35 Posts
Likes Given: 4

Default

When I built my stir plate I had similar issues with 12 volts kicking off my stir bar. Fortunately I picked up a universal 300mA power adapter from RadioShack that allows me to adjust the voltage from 1.5V to 12V. I usually set it from 6V - 7.5V, depending on how large my starter is, and by turning the potentiometer on high to get the stir bar started and dialing it back down, I can adjust the vortex however I like. Runs for 2 days at a time with no problems. One of the rare instances where I've had a bit of foresight . This is the one I use:

http://www.radioshack.com/product/index.jsp?productId=3875402

I tied a knot in the cable just inside the project enclosure to prevent any wires from being pulled loose while moving it around and it seems to work well.



__________________
zzARzz is offline
 
Reply With Quote Quick reply to this message
Reply


Quick Reply
Message:
Options
Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
And one more DIY stirplate... -TH- DIY Projects 9 01-03-2012 08:05 PM
DIY Stirplate help chode720 DIY Projects 19 03-02-2011 03:19 AM
Stirplate power? Gumbys_Brew DIY Projects 16 11-18-2009 07:20 PM
diy stirplate lm317 help cryptonic84 DIY Projects 4 11-06-2009 05:25 PM
Simple Stirplate DRAGGER DIY Projects 2 01-05-2008 10:28 PM