DIY SMD reflow Toaster-Oven Controller Kit.

[kreutz]

A few years ago I designed and built a toaster oven controller for SMD reflow for a 100 prototype order. The oven worked so beautifully I kept it and all my prototypes from then on have been soldered on that oven.

It features local and RS232 remote control and programming, profile setup and storage, manual control, (adjustable) PID temperature control with a modified Bresenham algorithm based power control (for more efficient heating). RS-232 optional PC data adquisition (for oven profile comparison and graphic oven temperature vs profile display) in real time, etc.

Now I am going to retrofit a few more ovens for production using the same design. So decided to offer a DIY kit with the basic components including the programmed micro-controller and PCB, the KIT will be sold at $39.95. The rest of the components including optional local LCD display and a 4x4 matrix Keyboard, could be locally obtained by the user. I will also provide complete schematics and Step by Step instructions.

Here are some photos of my SMD work.

[JonLed]

Count me in for one.

Jon

[kreutz]

Originally Posted by JonLed Count me in for one. Jon

Thanks,

Kreutz.

[keebler303]

Kreutz

How does your kit compare to this:

http://www.sparkfun.com/commerce/pro...products_id=81

1) Obviously yours needs to be assembled by the purchaser.

2) LCD is not included but is plug and play by end user if desired?

3) How does it control the heater? Relay? Triac?

4) Are you planning a standard serial connection? If so, might I recommend an FTDI FT232R. I have a UB232R whic uses that chip and let me tell you, it is much, much nicer to have USB, especially with the lack of serial ports nowadays.

5) Would you include some basic PC software for specifying ramp and soak times to send to the controller and to record the actual temperature profile?

6) How much will the tuning vary from oven to oven? How difficult would it be to include some tuning software to optimize the profile on "dummy" board before actual use.

I think you could have a barebones kit (as specified in your original post) plus one or more addons which would enhance the quality and ease of use of the oven. Keeping things simple (plug and play) would be best.

http://www.articulationllc.com/main.sc

Something between the sparkfun board and the below link would be ideal in my opinion. There is quite an open price range for this type of kit as well.

Regards
Matt

[keebler303]

One more link for a similar unit:

http://thesiliconhorizon.com/store/p...products_id=48

Matt

[kreutz]

Originally Posted by keebler303 Kreutz How does your kit compare to this: http://www.sparkfun.com/commerce/pro...products_id=81 1) Obviously yours needs to be assembled by the purchaser. 2) LCD is not included but is plug and play by end user if desired? 3) How does it control the heater? Relay? Triac? 4) Are you planning a standard serial connection? If so, might I recommend an FTDI FT232R. I have a UB232R whic uses that chip and let me tell you, it is much, much nicer to have USB, especially with the lack of serial ports nowadays. 5) Would you include some basic PC software for specifying ramp and soak times to send to the controller and to record the actual temperature profile? 6) How much will the tuning vary from oven to oven? How difficult would it be to include some tuning software to optimize the profile on "dummy" board before actual use. I think you could have a barebones kit (as specified in your original post) plus one or more addons which would enhance the quality and ease of use of the oven. Keeping things simple (plug and play) would be best. http://www.articulationllc.com/main.sc Something between the sparkfun board and the below link would be ideal in my opinion. There is quite an open price range for this type of kit as well. Regards Matt

Hello Matt;

The controller includes only the basic components, nevertheless the optional components are completely plug and play and easily available from all mayor distributors. I will provide a complete schematics and B.O.M. including the optional parts.

I don't consider the first link a real "apple to apple" comparable, my control system is a real PID precision temperature control system with power distribution on a PID cycle based on a modified Bresenham algorithm, all power switching is done on zero crossings of the AC signal and there is no conduction angle modulation of the AC signal, so there is no power line noise associated with the system, and the power factor is = 1. The power switch is Solid State Relay. Because of the difference between our systems, is probably why their crude toaster oven control approach failed to give quality reflows to their own boards, as their own web page says.

The second link is a similar approach more comparable to my own. I don't know about their implementation, but it seems more solid.

PID tuning is done on trial an error, as any manual PID tuning. There is a Manual mode that allows graphically finding some of the tuning parameters for known PID tuning methods, I will give some step by step instructions too.

Tuning is dependent on the oven chosen for the job. My oven is a 1500Watt Black and Decker. I don' recommend anything less than that power.

My circuit also handles the fan control on the forced convection ovens by means of a second low power SSR.

RS232 communication is used for remote control, as well as for calibration and data acquisition, in order to display and store batch to batch oven quality control data, which might help fine tuning the PID parameters. Automatic mode is controlled by means of "profiles". You can store 4 profiles and call them at any time, or work from an on the fly made profile in RAM. You can also change PID parameters on the fly just before running a profile.

So far the remote communication protocol is command based, and commands could be sent from any terminal application like the Hyper-Terminal. Oven data could be received the same way. There is an optional local mode where commands are entered on the keyboard and displayed on the LCD screen (two line, 20 characters per line, character LCD module), the circuit handles the -5 v bias required on some of the displays by means of a charge pump circuit that can be optionally populated by the user. Both modes (Remote and Local) can work concurrently.

Best regards,

Kreutz.

[kreutz]

Originally Posted by keebler303 One more link for a similar unit: http://thesiliconhorizon.com/store/p...products_id=48 Matt

This link seems like a more comparable product, but completely assembled. I haven't seen it before, Thanks!.

Kreutz.

[Khalid]

Kreutz..u are really the Genious...Thanks for providing low cost tools which we can't think of buying...

[kreutz]

Originally Posted by Khalid Kreutz..u are really the Genious...Thanks for providing low cost tools which we can't think of buying...

Hello Khalid;

I am only trying to provide opportunities for people that don't have the financial means to access professional quality tools, but show interest into learning and developing skills, by their own means, in order to pursue a better future. Or, at least, provide some of the opportunities that were not there when I was a student a looong time ago...long before Internet was available. Some of the DIY tools and designs I publish were developed, out of necessity, for my own use.

Thanks,

Kreutz.

[keebler303]

Kreutz

I was not looking for an "apples to apples" comparison. I was more giving you the opportunity to show why yours was a better value over similar commercial offerings.

For the tuning I was thinking of something like a plot of the temperature response. So you could qualitatively say you need to increase damping if you have excessive overshoot, etc. Just something more than "feel" to make it easier for newbies to wrap there heads around what each part of a pid controller does. Users could also post their response plots and others could help them with tuning. Tuning may not be terribly important as it seems that even at full blast, most toaster ovens can barely keep up with the recommended reflow profile. Many have had success with manual control just going full bore to the max temp. and then shutting it off.

Cheers
Matt

[kreutz]

Originally Posted by keebler303 Kreutz I was not looking for an "apples to apples" comparison. I was more giving you the opportunity to show why yours was a better value over similar commercial offerings. For the tuning I was thinking of something like a plot of the temperature response. So you could qualitatively say you need to increase damping if you have excessive overshoot, etc. Just something more than "feel" to make it easier for newbies to wrap there heads around what each part of a pid controller does. Users could also post their response plots and others could help them with tuning. Tuning may not be terribly important as it seems that even at full blast, most toaster ovens can barely keep up with the recommended reflow profile. Many have had success with manual control just going full bore to the max temp. and then shutting it off. Cheers Matt

Matt;

I am working on a little applet to do what you want, it is really not necessary, but it is convenient (faster) because the data acquisition capability already let me import data into Excel and see the curves profile vs actual temperature.

Nevertheless I will include the Windows application with the basic kit. It will also allow to download profiles stored into the PC and real time monitoring. The command interface will also stay, for those who want to develop their own interface software.

I like comparisons, it is good to see how we are doing and what could be improved, there is so much to learn...

Best regards,

Kreutz.

[bharbour]

I would like one of these kits.

Bob Harbour