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Laptop charger to run fan?
tag1260
Top  #1 Print Post
Posted on 04/15/2019 7:54 PM
Hi,

New guy here with questions.

Modifying my hot air popper (Popcorn Pumper) and while I have my heaters figured out I am having trouble with the fan.

I know it's a 18v DC motor but am unable to source the right transformer locally and reasonably but have read about using a laptop charger to run the fan. Now, is this a possibility? and where would you place a potentiometer to control speed? Would you just use a dimmer switch to control 120v input ? Or place a pot on the DC side?

Thanks
 
JitterzZ
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Posted on 04/15/2019 10:55 PM
Welcome
Until someone with direct knowledge weighs in, these links may be of some help:
"I took the diode bridge out and wired an IBM laptop charger that outputs 16 volts DC directly to the fan motor" https://www.reddi..._roasting/
https://www.home-...11841.html
https://www.engad...e-roaster/
https://www.instr...offee-roa/
Edited by JitterzZ on 04/15/2019 11:02 PM
 
renatoa
Top  #3 Print Post
Posted on 04/16/2019 2:33 AM
Not a pot, but a DC PWM dimmer:

https://www.ebay....2667035967
 
tag1260
Top  #4 Print Post
Posted on 04/16/2019 7:11 AM
Thanks everyone. With your help I might have it figured out. For some reason though, I cannot get the laptop charger to work. However, I found an old computer power pack that does. it's only 15 volt but for now it will have to work until I get a more powerful one.

When you sent the PWM speed control link, I realized that I actually had one of those in my stash for another project.

Cobbled it all together and it's running perfectly!!!!

Now to roast some beans later today!!!!

Thanks again
 
tag1260
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Posted on 04/19/2019 12:16 PM
burned up that speed control somehow. Using a 24v 15a power supply . Don't know if that would do it or not but back to the drawing board. Or maybe just buy a Fresh Roast hot air roaster.
 
Monarda
Top  #6 Print Post
Posted on 04/20/2019 12:56 PM
I used a laptop charger for the step-down transformer and it works fine. BUT, I have yet to re-wire to the DC side of the diode bridge for speed control. So, my question is, just how important is it to control fan speed? I'll be posting again in the roasting section- I can control the heat profile perfectly, but I am getting rather flavorless roasts- I think I am baking. Does controlling air flow speed really effect the roast if I am getting even roasts and good temperature profiles (including controlling the RoR profile)?
 
Wiz Kalita
Top  #7 Print Post
Posted on 04/24/2019 4:09 AM
When I first built my roaster I used an L298N circuit for PWM control. This is a problem with higher power motors because there's a 2V power drop in the driver, and at high currents that gives a lot of heating. Burned out a few of those cheap boards before I got a different controller. But for my purposes, always running at full power is ok. You need enough airflow to have good agitation, but not so much that you can't reach the right temperature, but I have a chimney and a chaff filter that put me in that sweet spot.
 
Fionakev
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Posted on 05/15/2021 6:44 AM
The truth, I believe, is with the processor. The CPU may become overheated while running, which is why this occurs. To lower your processor's temperature, look for a better model. However, rather than a laptop, I recommend that you buy a PC. This is determined by your budget and interests. You should use a laptop stand instead of replacing this laptop if you don't want to replace it. I was still searching for a laptop stand due to the pain in my neck. I found the right solution at smartlaptopstands.com I hope this information was helpful to you.
Edited by Fionakev on 05/18/2021 4:28 AM
 
renatoa
Top  #9 Print Post
Posted on 05/15/2021 10:09 AM
This thread is about using a laptop source for the roaster (popper) fan, no processor or laptop involved.
 
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