HBT 2014 Big Giveaway - 4/10 Re-Draw Winners Posted!

Home Brew Forums > Home Brewing Beer > Electric Brewing > Slow PWM using hacked LED dimmer




Reply
 
LinkBack Thread Tools Display Modes
Old 09-15-2013, 06:09 AM   #1
alien
Feedback Score: 1 reviews
Recipes 
 
Join Date: Apr 2012
Location: Philadelphia, PA
Posts: 1,229
Liked 61 Times on 55 Posts
Likes Given: 61

Default Slow PWM using hacked LED dimmer

Turn an inexpensive LED dimmer into a PWM timer for an electric element by swapping out a single capacitor:

Blog post: http://smokedprojects.blogspot.com/2013/09/led-dimmer-pwm-hack.html



alien is offline
 
Reply With Quote Quick reply to this message
Old 09-15-2013, 12:15 PM   #2
danb35
Feedback Score: 0 reviews
Recipes 
 
Join Date: May 2012
Location: Hartsville, SC
Posts: 131
Liked 18 Times on 14 Posts
Likes Given: 1

Default

Very clever! Should be pretty easy to feed this into an SSR and presto! Manual power control.



__________________
danb35 is offline
 
Reply With Quote Quick reply to this message
Old 09-16-2013, 04:10 AM   #3
alien
Feedback Score: 1 reviews
Recipes 
 
Join Date: Apr 2012
Location: Philadelphia, PA
Posts: 1,229
Liked 61 Times on 55 Posts
Likes Given: 61

Default

Exactly!

I have a spare so if anyone wants the 1.5 Hz PWM timer it is $10 shipped within the USA. Contact me via PM.

alien is offline
 
Reply With Quote Quick reply to this message
Old 09-17-2013, 01:59 AM   #4
cank
Feedback Score: 3 reviews
Recipes 
 
Join Date: Nov 2012
Location: Jonesboro, Arkansas
Posts: 381
Liked 18 Times on 17 Posts
Likes Given: 14

Default

Great idea. I just ordered 2.
Thanks for sharing. I post how it goes.

__________________
cank is offline
 
Reply With Quote Quick reply to this message
Old 09-17-2013, 02:12 PM   #5
alien
Feedback Score: 1 reviews
Recipes 
 
Join Date: Apr 2012
Location: Philadelphia, PA
Posts: 1,229
Liked 61 Times on 55 Posts
Likes Given: 61

Default

Good luck! Desoldering the original cap was the hard bit (for me anyway).

There is a lot of electronics in one of these little dimmers for $4 or however much they are.

alien is offline
 
Reply With Quote Quick reply to this message
Old 10-10-2013, 12:47 PM   #6
cank
Feedback Score: 3 reviews
Recipes 
 
Join Date: Nov 2012
Location: Jonesboro, Arkansas
Posts: 381
Liked 18 Times on 17 Posts
Likes Given: 14

Default

Alien,

I received my two dimmers but the circuit board is different. I have watched that video and looked at your pics and think I found which capacitor to switch but thought I should ask you first. Is there a way to verify which I one using just a normal multimeter? If my phone can upload pics I'll attach one of the boards.
I think it's C4?


image-3432809859.jpg

__________________
cank is offline
alien Likes This 
Reply With Quote Quick reply to this message
Old 10-12-2013, 05:49 AM   #7
alien
Feedback Score: 1 reviews
Recipes 
 
Join Date: Apr 2012
Location: Philadelphia, PA
Posts: 1,229
Liked 61 Times on 55 Posts
Likes Given: 61

Default

I have a couple of spares knocking around. I opened them up and they are different again! The PCB is neither green nor blue, but maroon -- and all the components are very helpfully labelled part with numbers and values, as on yours.

One of the 8-pin chips should be marked NE555. Orient the chip so that the bar is at the top, and count the pins from the top left (1) to the bottom left (4) and back up the other side from the bottom right (5) to the top right (8). There might be a dot next to pin 1. The timing capacitor should be connected to pin 1 on one end (ground) and pins 2 and 6 on the other end. Some of the connections may be visible on the PCB, some may be underneath the chip and not visible.

On that basis it looks very much like C4 as you say, which has the same value that mine did (0.1uF), so swapping it for 47uF or 100uF should get you in the ballpark. Good luck!

__________________
Magic Smoke brewhouse and grill

Arduino PID controller - Automatic Smoker - Cooler MLT - Counterflow Chiller - SSR demo - PWM timer - Folding Brew Table
alien is offline
 
Reply With Quote Quick reply to this message
Old 11-07-2013, 10:22 PM   #8
cank
Feedback Score: 3 reviews
Recipes 
 
Join Date: Nov 2012
Location: Jonesboro, Arkansas
Posts: 381
Liked 18 Times on 17 Posts
Likes Given: 14

Default

Finally got around to trying this. My desoldering skills are quite lacking and I ended up just pulling the pads and everything off the board. I even thought there was some stray solder in the masking to I tried to pry it off, turned out it was some of the metal from the circuit, so I soldered the leg of the capacitor to pin 2 of the 555 chip and a bridge to the closest resister.


Hooked it up to a SSR and a pencil sharpener motor. Everything seemed to work great. I could vary the pulse from off to full on. One thing I noticed is that when I first plugged it in, even if the pot was in the off position it would send one small pulse to the motor and then stop.

Thanks for this great little gem. Now I gotta find time to try it out for an element.



__________________
cank is offline
alien Likes This 
Reply With Quote Quick reply to this message
Old 11-07-2013, 11:54 PM   #9
alien
Feedback Score: 1 reviews
Recipes 
 
Join Date: Apr 2012
Location: Philadelphia, PA
Posts: 1,229
Liked 61 Times on 55 Posts
Likes Given: 61

Default

With the lid on nobody will know. Actually I pulled one of the pads off mine and had to scratch away part of the mask to solder to the ground plane.

__________________
Magic Smoke brewhouse and grill

Arduino PID controller - Automatic Smoker - Cooler MLT - Counterflow Chiller - SSR demo - PWM timer - Folding Brew Table
alien is offline
 
Reply With Quote Quick reply to this message
Old 01-08-2014, 08:28 AM   #10
alphaomega
Feedback Score: 0 reviews
Recipes 
 
Join Date: Jul 2013
Location: , Sweden
Posts: 150
Liked 62 Times on 27 Posts
Likes Given: 56

Default avoid desoldering

Hi!
Sorry for reviving the thread, but I have some info to add if someone else finds this later.
I found this thread (and magic's page) after I already reverse engineered a similar dimmer and modded it to SSR freq. for a cheapo RIMS system I'm planning.
I also found that a 100uf cap got me in th 1Hz range.
The tip I have is, if you want to decrease freq. by adding capacitance, you can avoid desoldering the smd cap and risk damaging the pcb. You can just solder the new cap in parallell. This makes it easy to undo later as well.
I just cut the legs of the electrolyte to appropriate length, pretinned, added some fresh solder to the pads and soldered it in.
Cheers!



__________________
alphaomega is online now
alien Likes This 
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
Have we been hacked or is it only me?????? C-Rider Beginners Beer Brewing Forum 22 06-03-2011 01:53 AM
AC Dimmer w/ DC fan??? carrotmalt DIY Projects 5 08-27-2010 05:17 PM
Has How to Brew been hacked? Revvy General Beer Discussion 10 01-31-2009 03:28 PM