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Double-R 01-29-2011 12:15 AM

PWM..Show us How
 
Been looking an waiting, Pretty sure i'm not the only one wondering,[LEFT]how do you build/make one. Some say get a PWM , you dont need a PID setup . SO I ask . HOW..

wyzazz 01-29-2011 05:20 AM

http://home.highertech.net/~cdp/boilnew/boilnew.htm

freddyb 01-29-2011 02:14 PM

Buy this: http://www.bakatronics.com/shop/item.aspx?itemid=383
Replace C1 with a 2.2uF capacitor to lower the frequency.
Use a 12V wall wart as a power supply to the PWM board.
Connect the output of the PWM board to a SSR to control your boil.

This is how I did it and I'm very happy. Cheap, easy, responsive control.

wyzazz 01-29-2011 02:57 PM

Interesting! Very Nice!

SpottedDogBrewing 05-06-2011 05:03 PM

Quote:

Originally Posted by freddyb (Post 2596087)
Buy this: http://www.bakatronics.com/shop/item.aspx?itemid=383
Replace C1 with a 2.2uF capacitor to lower the frequency.
Use a 12V wall wart as a power supply to the PWM board.
Connect the output of the PWM board to a SSR to control your boil.

This is how I did it and I'm very happy. Cheap, easy, responsive control.

Can you show photo's of your unit with the wiring schematic:ban:

freddyb 05-06-2011 05:35 PM

Quote:

Originally Posted by SpottedDogBrewing (Post 2900498)
Can you show photo's of your unit with the wiring schematic:ban:

Here's a diagram I made. I tried to keep it simple. Hopefully it's enough to get you going. It's easier to understand once you get your hands on this stuff and start piecing it together.

http://img804.imageshack.us/img804/3433/pwmboil.jpg

Homercidal 05-06-2011 05:48 PM

I have one of those PWM boards and it was very easy to build. I connected to a 12V and watched it smoothly run from Zero to full speed through the whole range of the dial.

Adjusting for a heater element is extremely easy.

Once the board is built, and you have your 12V connected, simply run the output to a Solid State Relay, and connect the Relay to the heater element.

The PWM controller turns the relay on and off faster for more heat, and slower for less. Think of it as controlling PULSES of electricity to the element. The faster the pulses come, the hotter the element will get.

Inodoro_Pereyra 05-06-2011 06:00 PM

Quote:

Originally Posted by Homercidal (Post 2900643)
The PWM controller turns the relay on and off faster for more heat, and slower for less. Think of it as controlling PULSES of electricity to the element. The faster the pulses come, the hotter the element will get.


Hmmm...no. A real PWM controls the heat by varying the time the element is active, in relation with the total pulse time. The pulse frequency never changes. What changes is the part of the total pulse the element is receiving power. The wider the active part of the pulse, the more heat produced (hence the "pulse width modulation" name).

wyzazz 05-06-2011 06:07 PM

^^What he said^^

The PWM doesn't modify the amount of heat the element puts out, that is static based on the wattage/voltage. It just modifies the amount of time the element stays on.

Homercidal 05-06-2011 07:23 PM

Yeah, now that I re-read my post I have no idea why I posted it like that. I guess that's what happens when you are trying to install Exchange Server and figure Mash Adjustments while reading and posting on HBT...

The image above has a very good sample of the frequency showing the hotter vs the cooler pulse widths. It's more about the time per pulse that the element is on vs the time per pulse that it's off.


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