Upgrade heating element upgrade - digital unit

[Mr Walleye]

Alan

Certainly the theory of your findings seems correct in my mind. (my minds a funny place though!  ;D ) I wonder if you rerun the test with your Maverick sensor directly against the rear of the cabinet near the Bradley sensor if you would see more similar temps.

I have seen some temp sensors that are mounted in an insulator so the surrounding materials don't affect them. Ultimately, you want to measure the air temp for sure and this is probably the reason most people don't use the cabinet mount style sensor for the Auber PID.

Here's a couple of older posts regarding the same or similar subject.

http://forum.bradleysmoker.com/index.php?topic=19496.0

http://forum.bradleysmoker.com/index.php?topic=15591.msg185989#msg185989

[mschoonmaker]

Having a bit of a problem here.

If adding a secondary element requires more amperage (as it should), and this can be accomplished by adding a PID controller + solid state relay versus using the BDS controller output alone, why not simply allow the BDS controller to control a SSR to drive both elements (or the 900 watt)? This bypasses the PID and allows the BDS controller to (in)directly control both elements (or a 900 watt element).

Please educate me...


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[Mr Walleye]

mschoonmaker

You are absolutely right. We discussed this a few years ago but I don't recall anybody actually trying it. You would need a SSR with an input voltage that would handle the 110VAC that the DBS would be sending it to switch the power to the elements. The Auber SSRs are rated at an input voltage of 3 - 32 VDC which wouldn't work in this case. I wouldn't be surprised if you contact Auber that they may be able to get you one.

Mike

[mschoonmaker]

My point, however, is that the BDS controller is a PID in its own right, and should need only a SSR to take advantage of the 900 watt element OR dual 500 watt elements. No auber PID needed, at all.


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[Mr Walleye]

No it's definitely not any type of PID controller. It's simply an on/off type of controller. As I recall the DBS shuts off the power to the element when it reaches the set point. As the temp cools to 10 degrees below set point the DBS control switches the element back on. Unfortunately when the cabinet reaches the set point, the element is still red hot so the temp swings above the set point. Same problem but the reverse when the cabinet temp drops to 10 degrees below set point except now the element is cold and takes a minute or to warm up and the temp continues to drop a few mare degrees. Basically a PID anticipates the element lag times and applies a percentage of power to the element to eliminate or at least minimize the temp swings. You could set it up that way (with a SSR and no PID) and it should have no problem handling it because the DBS controller is simply switching the SSR. The SSR is handling switching the load.

Having the SSR controlled by a PID would have much tighter temp swings though.

Mike

[mschoonmaker]

Thanks much, I had not previously found anything that described the control implementation of the BDS, and if they were going to put a control engine of sorts in there, why not PID? After all, "it's just software" :)

[Alanfromwis]

Hi All,
  Have read recent posts on this issue, & am now doing 2 shoulder roasts & baby back ribs that I started this morning at 6am. I am using the BDS controller to turn SSR on and off with no PID. When BDS controller would turn on & off, this 120vac is fed to a small power transformer with a primary of 120 vac and a secondary of 9vac then a full wave bridge rectifier to produce 9 vdc. This then turns on & off the SSR The meat load is about 10 lbs. temp swings are less with meat in than when I tested it with no oven empty. I had some of the parts, but for $30 to $40 you should be able to get all new parts for this setup. Almost forgot to mention that I included a 120 vac neon indicator to show when element is on or off.
Alan

[mschoonmaker]

Hi Alan,

I'm curious why the transformer et al, instead of just using a SSR that switches a 120vac load with a 120vac signal direct from BDS?

[Alanfromwis]

Mschoonmaker,
  Not sure any of that configeration are available. However you could use a 9vdc wall wart, and I think with a current rating of 100 milliwats would be more than sufficient as the ssr takes very little current. I got my SSB from Auber for $15 plus shipping, & you shouldn't need heat sink for either 900 or 1000 watts. Should have fuse holder with about 15 amp fuse in input to ssr.
alanfromwis

[ChicaFeliz]

Hi ALanFromWis,

That is what I would like to do.
Possible for you to post a quick diagram on how to do this?
Or parts list with a detailed discription.

Thanks everyone for the input. I ve learned alot.

[mschoonmaker]

Amazon.com

http://www.amazon.com/Opto-22-Control-Optical-Isolation/dp/B0058UX17G/ref=sr_1_1?ie=UTF8&qid=1343841346&sr=8-1&keywords=solid+state+relay+120vac
Opto 22 120A25
120VAC load, 120vac control, 25 amp (way more than needed) $32.00

Alternate (better):
http://www.amazon.com/Opto-22-Control-Optical-Isolation/dp/B0058UX04U/ref=sr_1_4?ie=UTF8&qid=1343841346&sr=8-4&keywords=solid+state+relay+120vac
Opto 22 120A10
120VAC load, 120vac control, 10 amp (probably just about right: 1000 watts/120v = 8amps). The 900 watt element would only be 7 amps, so the 10 amp SSR would be OK.

[Alanfromwis]

Hi ALanFromWis,

That is what I would like to do.
Possible for you to post a quick diagram on how to do this?
Or parts list with a detailed discription.

Thanks everyone for the input. I ve learned alot.

ChicaFeliz,
  If you look at your message inbox, sent you a message.  What mschoonmaker said in his post will also work. I had all the parts for the mod that I did except the SSR. Tested it and it makes recovery time after opening door much shorter with the 900 watt. As for temp swings, they are more than with PID, but they even out somewhat over time. The IT is the main temp parameter anyway.
alanfromwis

[Alanfromwis]

http://s1076.photobucket.com/albums/w446/agkrans/900%20watt%20mod/?action=view&current=b80f73a3.jpg

[Alanfromwis]

Have been trying to add pics from photo bucket & am gaing on it, but still no pics. Alan

[Mr Walleye]

Alan

Here is a link that should get you hooked up to post pictures.
http://www.susanminor.org/forums/showthread.php?488-Answers-To-Bradley-Smoker-FAQ-s&p=768#post768

Here's you picture...



Mike