Sciencemadness Discussion Board - [Nurdrage] Make Sodium Metal with Menthol - need help with DC motor

[Nurdrage] Make Sodium Metal with Menthol - need help with DC motor

razor0109 - 15-3-2020 at 04:40

I ran into a problem with my crappy magnetic stirrer (12V DC 1A) as the magnesium ribbon pieces (where the shortness of each piece is a function of my patience) clumped together too much, and the stirrer bar ended up being dislocated all the time.

I have a more powerful motor from a food processor that got fried out. It's rated for 230V DC circuits. I checked and there is voltage generated between the leads while turning the motor manually, although I'm not sure if the motor could otherwise be damaged. I have almost zero experience with building circuits, and I would need to make this motor turn with variable speed / get another, more powerful magnetic stirrer.

I have an Arduino Uno, with an L9110 DC Motor Driver.

Any guides, tips, even discouragement for planning to play with high current without reading a lot about the subject first would be much appreciated!

EDIT: could just a longer stirring bar solve the problem (reaction vessel would be an Erlenmeyer flask), and cutting the magnesium to really small pieces? Also, the motor must run continuously for about 40 hrs. And, I do have a heating solution, I use an aluminium pot to contain the reaction vessel, which has a PID controlled heating tape wrapped around it.

Motor type: BOSCH MMR150PLUS, which came from a Bosch MMR08A1 food processor.

URL to Nurdrage's video: https://www.youtube.com/watch?v=BsNoiFj3wlw

My stirrer: https://www.ebay.ca/itm/INTLLAB-Magnetic-Stirrer-Magnetic-Mi...

Arduino kit: https://www.ebay.com/itm/Adeept-Ultimate-Starter-learning-Ki...

[Edited on 15-3-2020 by razor0109]

Endo - 15-3-2020 at 10:57

Unfortunately that motor will not work with the L9110 motor driver. The driver you have will supply from 2.5 to 12 Volts. It also maxes out at 800 milliamps. This means that the most it could supply to this motor is ~ 5% of it's rating. Not sure if you could even get any rotation out of it at that low of an input. Further issue with the motor is it's duty cycle, running an intermittent duty motor for two or three days will lead to overheating and destruction of your motor.

There are solutions out there, involving a stepper motor, appropriate power supply, and a stepper driver with appropriate hardware to supply it with a timing signal. You can check out this thread for example SciMadness stirrer thread

The second part, the process outlined by Nurdrage is at elevated temperature. I doubt that you will see much of a reaction at room temperature.

By the time you go through all of that, and determine how to heat the pot too I think you might consider a new or used hotplate/stirrer combo.

Good luck!

NaK - 15-3-2020 at 14:26

Well I actually tried the menthol method from the video and have to strongly advice against it: Quantities are very limited because you have to use a lot of mineral oil for a small amount of reagent, otherwise the sodium globules won't collapse and you won't be able to extract anything and also stirring a mineral oil solution with sodium pieces possibly unattended for multiple hours seems like a pretty bad idea.

I also didn't find a way to reuse the mineral oil or even dispose of it because there is no way of getting the magnesium oxide out.

I think the thermochemical way in the metal can is far superior, the yields are not as good but sodium hydroxide and magnesium are cheap and you won't have to deal with all that mess. Only drawback is that you need dioxane but that's pretty easy to make from OTC chemicals

[Edited on 15-3-2020 by NaK]

[Edited on 15-3-2020 by NaK]

Sulaiman - 15-3-2020 at 19:04

I use a similar motor for my diy overhead stirrer
https://www.youtube.com/watch?v=ziRxiFSaZsA

d.c. motors have two main characteristics;
. speed proportional to voltage
. torque proportional to current

so even when operated at low speed, full rated torque is available.
(if power supply is adequate and the motor does not overheat)

I think that it will make an excellent stirrer motor.
- but consider the sparking of the commutator brushes as an ignition source.
_____________________________________________________________
P.S. providing the variable voltage for the motor can be achieved in many ways,
but first you need to know approximately what voltages and currents are required.
I guess that something like
https://www.ebay.co.uk/itm/Adjustable-AC-DC-Power-Supply-Ada...
or, more expensive but with many uses
https://www.ebay.co.uk/itm/LW-K305D-30V-5A-110V-DC-Power-Sup...
or
try a 5V usb charger, an old laptop charger, ac/dc plug-pack etc.

The flexible coupler is not necessary, but I think it is better than a rigid coupler.

P.P.S. making your mixture easier to stir is the cheapest solution,
and a larger stirbar will help.

P.P.P.S. lots of chemistry procedures rely upon your patience

[Edited on 16-3-2020 by Sulaiman]

wg48temp9 - 15-3-2020 at 19:10

There are various mains powered motor controllers available on eBay for controlling 240/120V DC brushed motors.

For example for about £8 https://www.ebay.co.uk/itm/AC-Input-220V-DC-Output-10-210V-2...

draculic acid69 - 15-3-2020 at 23:05

Just buy a hotplate/mantle/stirrer off eBay for 100$ is the easiest solution.also if you're food processor was fried it's probably the motor that's fucked so do you know if it even works

razor0109 - 19-3-2020 at 04:30

Quote: Originally posted by wg48temp9

There are various mains powered motor controllers available on eBay for controlling 240/120V DC brushed motors.

For example for about £8 https://www.ebay.co.uk/itm/AC-Input-220V-DC-Output-10-210V-2...

What does the "L" and "N" leads do on this PWM speed controller?

wg48temp9 - 19-3-2020 at 07:29

Quote: Originally posted by razor0109

Quote: Originally posted by wg48temp9

What does the "L" and "N" leads do on this PWM speed controller?

I would expect them to be the mains input which are the usual designations for Neutral and Live mains connections. The other two connections being for the motor. Ideally there will be connection instructions with the controller or to be certain ask the seller if it comes with them or what they are.

razor0109 - 21-3-2020 at 04:04

Quote: Originally posted by wg48temp9

Quote: Originally posted by razor0109

Quote: Originally posted by wg48temp9

What does the "L" and "N" leads do on this PWM speed controller?

I think i'm gonna go with your suggestion, and try with this PWM unit. Many thanks!

wg48temp9 - 21-3-2020 at 06:13

Quote: Originally posted by razor0109

I think i'm gonna go with your suggestion, and try with this PWM unit. Many thanks!

Your welcome.

razor0109 - 24-3-2020 at 06:18

Quote: Originally posted by wg48temp9

Quote: Originally posted by razor0109

I think i'm gonna go with your suggestion, and try with this PWM unit. Many thanks!

Your welcome.

Just one more thing; wouldn't I need to use an AC to DC rectifier, fitted on the output of the PWM for this? I have a DC motor!

wg48temp9 - 24-3-2020 at 07:19

Quote: Originally posted by razor0109

[

Just one more thing; wouldn't I need to use an AC to DC rectifier, fitted on the output of the PWM for this? I have a DC motor!

I would think it was obviously not required if you have read the description and spec (shown below) for the item.

AC Input 220V DC Output 10-220V
PWM 220V DC Brush Motor Speed Controller

Specifications:
Input Voltage: AC 220V
Output Voltage: DC 10-210V Linear Under Load
Maximum Current Load: 20A
Continuous Current: 10A
Speed Range: 0% -100%
Regulation Method: Potentiometer
Connection Mode: Fence Type Terminal
Size: 85x57x37mm/3.35x2.24x1.46"
Quantity: 1 Pc

RogueRose - 24-3-2020 at 08:17

Quote: Originally posted by Sulaiman

I use a similar motor for my diy overhead stirrer
https://www.youtube.com/watch?v=ziRxiFSaZsA

d.c. motors have two main characteristics;
. speed proportional to voltage
. torque proportional to current

so even when operated at low speed, full rated torque is available.
(if power supply is adequate and the motor does not overheat)

I think that it will make an excellent stirrer motor.
- but consider the sparking of the commutator brushes as an ignition source.
_____________________________________________________________
P.S. providing the variable voltage for the motor can be achieved in many ways,
but first you need to know approximately what voltages and currents are required.
I guess that something like
https://www.ebay.co.uk/itm/Adjustable-AC-DC-Power-Supply-Ada...
or, more expensive but with many uses
https://www.ebay.co.uk/itm/LW-K305D-30V-5A-110V-DC-Power-Sup...
or
try a 5V usb charger, an old laptop charger, ac/dc plug-pack etc.

The flexible coupler is not necessary, but I think it is better than a rigid coupler.

P.P.S. making your mixture easier to stir is the cheapest solution,
and a larger stirbar will help.

P.P.P.S. lots of chemistry procedures rely upon your patience

[Edited on 16-3-2020 by Sulaiman]

Nice stirrer! I have a similar motor (probably identical, it's a 200w hand blender motor) that I could use but I was trying to figure out how to control speed. What did you use? Are you running AC or DC? I'm guessing it's a universal motor?

I was thinking of using a router speed controller as it works on all universal motors I've tried, but it seems to have difficulty at lower speeds, say anything under about 30-40% power, and at that speed it sometimes makes some bad noises (with vacuum cleaners/motors).

Sulaiman - 24-3-2020 at 09:03

You have quoted sufficient relevant information in your post above.

razor0109 - 25-3-2020 at 04:13

Quote: Originally posted by wg48temp9

Quote: Originally posted by razor0109

[

Just one more thing; wouldn't I need to use an AC to DC rectifier, fitted on the output of the PWM for this? I have a DC motor!

Fair enough, I was distracted by some other items I found on ebay.

The mains power here is supplied with a voltage rating of 230 V @ 50 Hz.

If the input of the PWM takes 220 volts, wouldn't it get overloaded with 230 volts? I am trying to find a PWM rated for 230 volts.

wg48temp9 - 25-3-2020 at 05:40

Quote: Originally posted by razor0109

Unless a voltage rating specifies some like absolute maximum or even just maximum you should consider it a nominal rating.

For example.

fromAttachment: Explanation_230Volts.pdf (41kB)
This file has been downloaded 902 times

That means that something with a nominal 230V rating should be designed to operate correctly up to 253V. They are rms voltages the peak voltage would be 358V pk. In addition there are voltage spikes on mains supplies and from the motor load. So the maximum voltage rating of the control element for a 230V mains may be 500V or even 1,000V depending on how generous the designer is with is his design margins.

In short a 220V controller will probably work just fine on 230V.
Particularly so as it will be passing at most a few amps and it is rated at 20A pk 10A continuous so it will not get very hot. High temperatures tend to reduce maximum voltage ratings of electronic components.

PS: I have purchased one and I am in 240V land (UK) It will be controlling a DC brushed washing machine motor, probably a bit too powerful for a stirrer unless its stirring concrete.

[Edited on 3/25/2020 by wg48temp9]