Solid State Stir Plate

[podz]

Crap .... I just threw out an old motherboard that had a tiny fan on the cpu.

Never, ever throw away working electrical motors! From anything!

 

[Sudz_Makenzie]

Yeah .... the SWHMBO has me tagged as a hoarder and was nagging the bejeebus outta me, so I reluctantly tossed it

 

[kcmobrewer]

I found some 30mm fans on newegg if you're looking for one. Don't know much about them though, dunno if they would work. They're dc.

Here

I'm gonna be obsessed with this until I get one made lol. I found the Hammonds clear project boxes, but can't find one with smooth sides like the OP had. Just doing some reading I think I would want to make one with a LCD display for a stopwatch. So you know how many hours/days it's been on the plate. With just a push button to start the timer. Also a potentiometer if I can mange to make it work. Although if I can just program it to spin at a certain rpm I would be ok with that as well. Kinda overboard I know but sounds really fun! Looking forward to buying my kit and getting started.

I assume the custom PCB an essential part of this? I kinda figured just an adruino couldn't accomplish this. That seems like it'll be way over my head, and something I just can't read up on and figure it out. Maybe the OP would be willing to share the design?

Otherwise maybe I can just use one of those motors that come with the kits to spin a set of rare earth magnets.

 

[kwikfivo]

I'll try to get a video with the potentiometer up this evening.

I think any fan would work, but my goal is to keep the moving parts inside the flask. I think an aluminum heat sink sized properly should pull enough heat off of them.

I like your ideas for using an LCD, I need to find one of those so I can track some key variables.

The custom PCB is not necessary, I just did it to clean up the circuit. My original setup consisted of a bread board with a lot of wires. I would recommend using a solderless breadboard for all of your projects until you get the circuit figured out (it is a lot easier to relocate a wire or component on a breadboard than to buy another custom PCB).

The fan with magnets is always a good fall back option, it might be a good place to start if you want a beginner level electronics project.

Cheers!

 

[MrNatural]

Way cool. Almost like a maglev for brewing.....

 

[bu_gee]

I think any fan would work, but my goal is to keep the moving parts inside the flask. I think an aluminum heat sink sized properly should pull enough heat off of them.

I like your ideas for using an LCD, I need to find one of those so I can track some key variables.

Try out that tanking circuit. You might be able to get away with just passive cooling if you can reduce the power draw. Do you have a schematic of your circuit posted anywhere?

If you're looking at getting a screen, here is some maker stuff I've been working on for my company:

[ame]https://www.youtube.com/watch?v=5Dc3u0rnO48[/ame]

It only costs about $5 if you make it yourself. It very similar to an OLED board you can get at sparkfun for about $20.

I've been needing incentive to post more about it. If you're interested, I can get you more info.

 

[bu_gee]

Wow. I didn't expect it to import the video.

 

[kwikfivo]

So I was going to take a new video for someone on here who was curious how the potentiometer worked in the system, but I had a minor electrical meltdown.... I had my scope hooked up and was watching the waveform and the probe arced from one of the outputs to ground, and it literally blew the center of the h-bridge chip out, time to figure out how I protect those circuits. Once I get the board repaired I'll post a new video.

bu_gee, I'm interested in the display you have. Where can I find one? Do you have a data sheet for it, how I can make it work? Since I'm running the arduino pro-mini I don't have a lot of I/O left, not sure if this will be able to control that or not.

 

[passedpawn]

Very cool. I know what I'm doing with the broken sprinker valves I have in the garage.

Whoever said you should add a fan to keep them cool made me laugh. Add a fan and you don't need the electromagnets at all.

I messed with emags some at one time. They do suck a bunch of current and get warm.

I wonder if the current through them is dependent on load... I'm guessing yes, just like any other winding. If so, you could add some feedback (haptic control) to measure the current and then manage the speed in order to not lose synch with the stir bar.

 

[bu_gee]

So I was going to take a new video for someone on here who was curious how the potentiometer worked in the system, but I had a minor electrical meltdown.... I had my scope hooked up and was watching the waveform and the probe arced from one of the outputs to ground, and it literally blew the center of the h-bridge chip out, time to figure out how I protect those circuits. Once I get the board repaired I'll post a new video.

bu_gee, I'm interested in the display you have. Where can I find one? Do you have a data sheet for it, how I can make it work? Since I'm running the arduino pro-mini I don't have a lot of I/O left, not sure if this will be able to control that or not.

I've blown out H-bridge ICs with spectacular results before. If you can put a small resistor on your supply through the H-bridge, you'll limit the current and make it less likely to blow. That isn't always doable so the other option is a fast blow fuse or a polyfuse like they have on the Arduino.

As for the display, it has an I2C interface (2-wire) plus one extra pin for external control. The biggest problem you're likely to run into is that these displays aren't 5V tolerant and a 3.3V level is right on the cusp of working for the Arduino so it could prove a bit of an issue although, others claim that they've used it with no trouble.

I'll work on getting the docs an sort posted on my wiki and I'll let you know.

 

[kcmobrewer]

Whoever said you should add a fan to keep them cool made me laugh. Add a fan and you don't need the electromagnets at all.

That was me and thankfully the one I build will be for me and not you. I didn't say he should add it, I asked if it would work. He didn't say the goal was to keep the moving parts inside the flask until after that. My goals do not have to be the same.

I don't know anything about this... I just thought it would be a fun project.



Sent from my iPhone using Home Brew

 

[kcmobrewer]

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[passedpawn]

That was me and thankfully the one I build will be for me and not you. I didn't say he should add it, I asked if it would work. He didn't say the goal was to keep the moving parts inside the flask until after that. My goals do not have to be the same.

I don't know anything about this... I just thought it would be a fun project.

I wasn't making fun of you. It's just that most stir plates are fans with magnets mounted on them. Mine is. The fact that there is no fan makes this one unique around here.