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Another Duty Cycle Controller Option
allenb
A couple of years ago I needed a duty cycle timer that the on and off times could be independently adjusted anywhere from a few seconds to 5 minutes+ for controlling a home built pellet auger/burner (Treager style). The 555's could do it but seemed to get a little squirrely with the long timings.

I stumbled on this circuit and built it shortly after and became an excellent long and short period duty cycle controller.

http://www.edn.com/archives/1996/0328.../07di3.htm

The switch symbols (within the dashed boxes) are part of a 4016 quad bilateral switch chip. The other chip (4060) is like a souped up 555 with a few extra bells and whistles.

This circuit makes it easy to include several (10?) variable resistors on a board with a rotary switch for selecting them for the 'on' cycle. You can set them to allow each to be a 10% increment of 100% duty cycle which would allow you to dial a power level with 10 (or more) increments.

The reason I'm posting this is for anyone who can't put together or program a TC4 or could use another option for duty cycle timers in addition to the already proven 555 circuits.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
Dan
FYI, Those are also called programmable recycle timers. On and off times independently controlled.

Say, I have a Traeger grill/smoker. You?
allenb

Quote

Dan wrote:
FYI, Those are also called programmable recycle timers. On and off times independently controlled.

Say, I have a Traeger grill/smoker. You?


I've been using the old electric barrel smoker these days. A while back I built a DIY version of the Traeger which worked pretty well but I had a terrible time trying to get the timing right to achieve smoke without it quickly re-igniting. Very touchy timing. Hat's off to Traeger for figuring that one out!

One of these days I'm going to break down and buy one.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
JimG
I've been meaning to put my TC4/Arduino in charge of controlling the fan on my Hottop for a long time, but haven't gotten around to it.

Moving in the right direction, today I wrote a program for testing my planned drive system for the fan (PSU, optoisolator, Darlington pair, etc.). When I had this simple test program done, I realized that is was almost exactly the application being discussed in this thread.

So I added a few more lines of code, called it aPWM.pde, and posted it to the googlecode site.

As currently configured, this sketch, along with a potentiometer (or two) connected to the TC4's ANLG1 and/or ANLG2 headers, can be used to manually control a heater through an SSR, a DC fan through a Darlington pair, etc.

Here is a link to the readme file which explains things a little better:
https://tc4-shield.googlecode.com/svn...E-aPWM.txt

Here is a link to the program:
https://tc4-shield.googlecode.com/svn...M/aPWM.pde

Jim
Edited by JimG on 04/24/2011 8:33 PM
allenb
Jim, great work getting the TC4 able to do PWM. This will allow the TC4 to be a total control package instead of clunky separate add-ons to control the fan.

I need to get back to my TC4 and update with the latest programs and Kona so I can control my roasters without all the current baggage!

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
JimG
I've ordered a laser-cut lid for my RS project box from pololu.com that will accommodate the LCD/buttons/LED's, two pots, two TC jacks, an ON/OFF switch, and binding posts for the DC output signals. So I hope to finally move the fan speed control for my HT over to the TC4 using the routines in the aPWM sketch.

Jim
Edited by JimG on 04/27/2011 7:44 AM
bvwelch

Quote

JimG wrote:
I've ordered a laser-cut lid for my RS project box from pololu.com that will accommodate the LCD/buttons/LED's, two pots, two TC jacks, an ON/OFF switch, and binding posts for the DC output signals.
Jim


Nice! Maybe we need to start a thread / repository for enclosure ideas, info, templates (hint :-)
JimG

Quote

bvwelch wrote:
Nice! Maybe we need to start a thread / repository for enclosure ideas, info, templates (hint :-)

I am waiting on quotes and other info from Bud and Hammond. Eventually, I would like there to be a source for pre-made enclosures that fit the hardware we're developing.

Or at least a series of pre-made cover panels for a few common Radio Shack project boxes.

I am playing with a minor rearrangement of the LCDapter to facilitate this. But having anything useful to report is probably still a few weeks away.

Jim
Edited by JimG on 04/27/2011 4:20 PM
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