AVR-Chat

Hi all,

Well I have to make 100 units (and pot them in Epoxy Resin) of an octopus lure 
I designed for a proto run.

I am now thinking SERIOUSLY about building my SMD oven (as it is mainly SMD 
only 4 through hole solder connections and 2 through hole non solder 
connections (fishing line to hold the lure in the pot))

I also have a lot of "other" projects including a run of 200 units for my 
speed alarm unit for the Au Targa Rallys.

So I need a circuit for Type K to AVR. I know there was a design note in the 
Atmel applications Journal, unfortunately the WRONG schematic was placed in 
there :(

So if anyone knows of a good easy schematic (with cold junction compensation) 
I would love to see it. I do not need high accuracy, as solder does not mind 
if it is 310C or 315C so anything to within +/- 2.5C is fine (I think the over 
will have problems in coming up quick enough ;) (if so more elements and more 
insulation is in order ;)

This will be an OPEN SOURCE Design. FULL PCB artwork (in Gerber and Protel 
99SE format), Schematics, Photos, source code, etc. will be on my site.

I will also be recognising all who contribute to this design.

I know I can buy chips like the MAX6675 as used in the Elector Jan06 issue, 
but these are not at hand ATM and I am running out of time.

I will also use the over for post curing of the epoxy etc. so I would like to 
build something that can have MULTIPLE presets.

I will design around the Mega 128 (huge overkill, BUT I have them in stock ;)

-- 
Regards,

Kat.
---------------------------------------------------------------
  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
  For Everything Electronics 		   Phone: 0419 923 731
---------------------------------------------------------------


-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 17/03/2006

Kathy Quinlan wrote:

> Hi all,
> 
> Well I have to make 100 units (and pot them in Epoxy Resin) of an octopus lure 
> I designed for a proto run.
> 
> I am now thinking SERIOUSLY about building my SMD oven (as it is mainly SMD 
> only 4 through hole solder connections and 2 through hole non solder 
> connections (fishing line to hold the lure in the pot))

I meant to add, I have ONLY had the oven still in its box, never opened for 4 
years ;) So I think it is time to move on this project or the SO will want it 
for the Kitchen ;)


-- 
Regards,

Kat.
---------------------------------------------------------------
  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
  For Everything Electronics 		   Phone: 0419 923 731
---------------------------------------------------------------


-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 17/03/2006

Kathy Quinlan wrote:
> Hi all,
> 
> Well I have to make 100 units (and pot them in Epoxy Resin) of an octopus lure 
> I designed for a proto run.
> 
> I am now thinking SERIOUSLY about building my SMD oven (as it is mainly SMD 
> only 4 through hole solder connections and 2 through hole non solder 
> connections (fishing line to hold the lure in the pot))
> 
> I also have a lot of "other" projects including a run of 200 units for my 
> speed alarm unit for the Au Targa Rallys.
> 
> So I need a circuit for Type K to AVR. I know there was a design note in the 
> Atmel applications Journal, unfortunately the WRONG schematic was placed in 
> there :(
> 
> So if anyone knows of a good easy schematic (with cold junction compensation) 
> I would love to see it. I do not need high accuracy, as solder does not mind 
> if it is 310C or 315C so anything to within +/- 2.5C is fine (I think the over 
> will have problems in coming up quick enough ;) (if so more elements and more 
> insulation is in order ;)
> 
> This will be an OPEN SOURCE Design. FULL PCB artwork (in Gerber and Protel 
> 99SE format), Schematics, Photos, source code, etc. will be on my site.
> 
> I will also be recognising all who contribute to this design.
> 
> I know I can buy chips like the MAX6675 as used in the Elector Jan06 issue, 
> but these are not at hand ATM and I am running out of time.
> 
> I will also use the over for post curing of the epoxy etc. so I would like to 
> build something that can have MULTIPLE presets.
> 
> I will design around the Mega 128 (huge overkill, BUT I have them in stock ;)

I haven't done cold-junction stuff, but only read about it.

I think you could amplify and lowpass filter the thermocouple output with
an opamp, then feed into the avr ADC. Connect an ambient temperature measuring
device to another ADC input, and subtract the effect of ambient temperature
from the thermocouple reading.

http://www.sensorsmag.com/articles/0203/temp/main.shtml

Russell Shaw wrote:

> Kathy Quinlan wrote:
> 
>>Hi all,
>>
>>Well I have to make 100 units (and pot them in Epoxy Resin) of an octopus lure 
>>I designed for a proto run.
>>
>>I am now thinking SERIOUSLY about building my SMD oven (as it is mainly SMD 
>>only 4 through hole solder connections and 2 through hole non solder 
>>connections (fishing line to hold the lure in the pot))
>>
>>I also have a lot of "other" projects including a run of 200 units for my 
>>speed alarm unit for the Au Targa Rallys.
>>
>>So I need a circuit for Type K to AVR. I know there was a design note in the 
>>Atmel applications Journal, unfortunately the WRONG schematic was placed in 
>>there :(
>>
>>So if anyone knows of a good easy schematic (with cold junction compensation) 
>>I would love to see it. I do not need high accuracy, as solder does not mind 
>>if it is 310C or 315C so anything to within +/- 2.5C is fine (I think the over 
>>will have problems in coming up quick enough ;) (if so more elements and more 
>>insulation is in order ;)
>>
>>This will be an OPEN SOURCE Design. FULL PCB artwork (in Gerber and Protel 
>>99SE format), Schematics, Photos, source code, etc. will be on my site.
>>
>>I will also be recognising all who contribute to this design.
>>
>>I know I can buy chips like the MAX6675 as used in the Elector Jan06 issue, 
>>but these are not at hand ATM and I am running out of time.
>>
>>I will also use the over for post curing of the epoxy etc. so I would like to 
>>build something that can have MULTIPLE presets.
>>
>>I will design around the Mega 128 (huge overkill, BUT I have them in stock ;)
> 
> 
> I haven't done cold-junction stuff, but only read about it.
> 
> I think you could amplify and lowpass filter the thermocouple output with
> an opamp, then feed into the avr ADC. Connect an ambient temperature measuring
> device to another ADC input, and subtract the effect of ambient temperature
> from the thermocouple reading.

I am probably wrong, but I thought cold junction was needed to make the 
circuit accurate ??

-- 
Regards,

Kat.
---------------------------------------------------------------
  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
  For Everything Electronics 		   Phone: 0419 923 731
---------------------------------------------------------------


-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 17/03/2006

Russell Shaw wrote:

> http://www.sensorsmag.com/articles/0203/temp/main.shtml

Damn now I am wondering if an RTD would be better :S I have an RTD in a smoke 
machine (that is in bits) and it may be a better option (it has glass braided 
wires so I guess it should be ok in the temp range I wish to use it in)


-- 
Regards,

Kat.
---------------------------------------------------------------
  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
  For Everything Electronics 		   Phone: 0419 923 731
---------------------------------------------------------------


-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 17/03/2006

Have you found a suitable oven for SMD work, I tried a toaster oven of a
brand commonly available in AU and found that it was a little slow coming up
to temp, and the temp distribution was poor (hot spots). There was a lot of
heat loss "no insulation" the outside covers were nearly as hot as the
inside of the oven and due to lack of time and the desperate need for a SMD
oven lost interest for the time being.
Have you been able to find an oven that looks like it would do the job?
Owen.

-----Original Message-----
From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf
Of Kathy Quinlan
Sent: Sunday, March 19, 2006 3:42 PM
To: AVR-Chat@yahoogroups.com
Subject: [AVR-Chat] Type K inputs on AVR

Hi all,

Well I have to make 100 units (and pot them in Epoxy Resin) of an octopus
lure 
I designed for a proto run.

I am now thinking SERIOUSLY about building my SMD oven (as it is mainly SMD 
only 4 through hole solder connections and 2 through hole non solder 
connections (fishing line to hold the lure in the pot))

I also have a lot of "other" projects including a run of 200 units for my 
speed alarm unit for the Au Targa Rallys.

So I need a circuit for Type K to AVR. I know there was a design note in the

Atmel applications Journal, unfortunately the WRONG schematic was placed in 
there :(

So if anyone knows of a good easy schematic (with cold junction
compensation) 
I would love to see it. I do not need high accuracy, as solder does not mind

if it is 310C or 315C so anything to within +/- 2.5C is fine (I think the
over 
will have problems in coming up quick enough ;) (if so more elements and
more 
insulation is in order ;)

This will be an OPEN SOURCE Design. FULL PCB artwork (in Gerber and Protel 
99SE format), Schematics, Photos, source code, etc. will be on my site.

I will also be recognising all who contribute to this design.

I know I can buy chips like the MAX6675 as used in the Elector Jan06 issue, 
but these are not at hand ATM and I am running out of time.

I will also use the over for post curing of the epoxy etc. so I would like
to 
build something that can have MULTIPLE presets.

I will design around the Mega 128 (huge overkill, BUT I have them in stock
;)

-- 
Regards,

Kat.
---------------------------------------------------------------
  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
  For Everything Electronics 		   Phone: 0419 923 731
---------------------------------------------------------------


-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 17/03/2006


 
Yahoo! Groups Links

OWEN-A wrote:

> Have you found a suitable oven for SMD work, I tried a toaster oven of a
> brand commonly available in AU and found that it was a little slow coming up
> to temp, and the temp distribution was poor (hot spots). There was a lot of
> heat loss "no insulation" the outside covers were nearly as hot as the
> inside of the oven and due to lack of time and the desperate need for a SMD
> oven lost interest for the time being.
> Have you been able to find an oven that looks like it would do the job?
> Owen.

No idea, I bought a brevile one a few years back, I hope it will do the job lol.

-- 
Regards,

Kat.
---------------------------------------------------------------
  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
  For Everything Electronics 		   Phone: 0419 923 731
---------------------------------------------------------------


-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 17/03/2006

Kathy Quinlan wrote:

> Russell Shaw wrote:
> 
> 
>>http://www.sensorsmag.com/articles/0203/temp/main.shtml
> 
> 
> Damn now I am wondering if an RTD would be better :S I have an RTD in a smoke 
> machine (that is in bits) and it may be a better option (it has glass braided 
> wires so I guess it should be ok in the temp range I wish to use it in)
> 
> 
Well as I can not find an RTD in RS or Farnell that is cheap and will do the 
job (most have very short leads, and long lead ones do not have the upper temp 
I want (I want to get to ~300C for safety Margin)

So I will stick to Type K thermo couple, and just wait for my MAX6675 to arrive :)

-- 
Regards,

Kat.
---------------------------------------------------------------
  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
  For Everything Electronics 		   Phone: 0419 923 731
---------------------------------------------------------------


-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 17/03/2006

On Sun, 19 Mar 2006, Kathy Quinlan wrote:

> 
> I meant to add, I have ONLY had the oven still in its box, never opened
> for 4
> years ;) So I think it is time to move on this project or the SO will
> want it
> for the Kitchen ;)
> 

When I was in college, one branch of the EE Department was doing 
experiments with photosynthesis.  They made their own PMT tubes in a 
special oven. One night, some student made a pizza in the oven.  Ruined it 
for any further use in making tubes.  I remember hearing about when the 
professor in charge went livid when he found out.

Zack

Zack Widup wrote:

> On Sun, 19 Mar 2006, Kathy Quinlan wrote:
> 
> 
>>I meant to add, I have ONLY had the oven still in its box, never opened
>>for 4
>>years ;) So I think it is time to move on this project or the SO will
>>want it
>>for the Kitchen ;)
>>
> 
> 
> When I was in college, one branch of the EE Department was doing 
> experiments with photosynthesis.  They made their own PMT tubes in a 
> special oven. One night, some student made a pizza in the oven.  Ruined it 
> for any further use in making tubes.  I remember hearing about when the 
> professor in charge went livid when he found out.
> 
> Zack

I think PCB work in an oven used for food would not be too bad, but I would 
not want to use food in an oven that has been used for making PCB's :(


-- 
Regards,

Kat.
---------------------------------------------------------------
  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
  For Everything Electronics 		   Phone: 0419 923 731
---------------------------------------------------------------


-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 17/03/2006

Kathy Quinlan wrote:
> OWEN-A wrote:
> 
>> Have you found a suitable oven for SMD work, I tried a toaster oven of a
>> brand commonly available in AU and found that it was a little slow coming up
>> to temp, and the temp distribution was poor (hot spots). There was a lot of
>> heat loss "no insulation" the outside covers were nearly as hot as the
>> inside of the oven and due to lack of time and the desperate need for a SMD
>> oven lost interest for the time being.
>> Have you been able to find an oven that looks like it would do the job?
>> Owen.
> 
> No idea, I bought a brevile one a few years back, I hope it will do the job lol.
> 
If you really want something in a hurry and you charge yourself for development 
time then a COTS thermocouple adapter is also an option. This can provide 0-10V 
or 4-20mA to feed into the Mega128 ADC. Total cost < 2 manhours, finished, 
calibrated, accurate, no grief.

I used to use a Sunbeam toaster oven for a while, still available for ~AUD70. 
Fold some alfoil around the walls & the lower 75% of the door. This makes an 
incredible difference to the "cold sink" near the walls. Cook a few A4 sheets of 
paper to see what the heat distribution is like. The unit had an external PID 
controller with ramp/soak driving an Opto-SCR module which was built into the case.

There is a small Sunbeam unit with a fan as well now but I don't know how it 
would suit the application.

The unit had 2 bars ea on the top & bottom & had no probs generating a good 
reflow profile.

-- 
Cheers

Don

Don Ingram wrote:

> Kathy Quinlan wrote:
> 
>>OWEN-A wrote:
>>
>>
>>>Have you found a suitable oven for SMD work, I tried a toaster oven of a
>>>brand commonly available in AU and found that it was a little slow coming up
>>>to temp, and the temp distribution was poor (hot spots). There was a lot of
>>>heat loss "no insulation" the outside covers were nearly as hot as the
>>>inside of the oven and due to lack of time and the desperate need for a SMD
>>>oven lost interest for the time being.
>>>Have you been able to find an oven that looks like it would do the job?
>>>Owen.
>>
>>No idea, I bought a brevile one a few years back, I hope it will do the job lol.
>>
> 
> If you really want something in a hurry and you charge yourself for development 
> time then a COTS thermocouple adapter is also an option. This can provide 0-10V 
> or 4-20mA to feed into the Mega128 ADC. Total cost < 2 manhours, finished, 
> calibrated, accurate, no grief.
> 
> I used to use a Sunbeam toaster oven for a while, still available for ~AUD70. 
> Fold some alfoil around the walls & the lower 75% of the door. This makes an 
> incredible difference to the "cold sink" near the walls. Cook a few A4 sheets of 
> paper to see what the heat distribution is like. The unit had an external PID 
> controller with ramp/soak driving an Opto-SCR module which was built into the case.
> 
> There is a small Sunbeam unit with a fan as well now but I don't know how it 
> would suit the application.
> 
> The unit had 2 bars ea on the top & bottom & had no probs generating a good 
> reflow profile.
> 

Time is not a concern ;) Money is, Although I have 2 customers right now, one 
wants the 100 proto done in 2 weeks, and I will have a wait time of 5 days 
from the upfront payment to the delivery of the PCB's, so I have time. The 
Customer with the speed loggers, will place an order later this year. So there 
is no urgent time.

Hell it would not take me more than 30 seconds with the hot air tool to solder 
the first batch, only a 7555, 4 resistors and a cap :)




-- 
Regards,

Kat.
---------------------------------------------------------------
  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
  For Everything Electronics 		   Phone: 0419 923 731
---------------------------------------------------------------


-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 17/03/2006

My oven is a Kambrook about 3 years old, I did do a run with it after I
purchased it and the procedure I used was to get the temperature stabilised
to about 140c to 150c with the board in the oven before turning up the
temperature for the solder melt phase.  I found that most of the SMD
components skewed due to misplacement of the solder paste, this dragged them
between pads and most had to be reworked it seems that the solder paste has
to be precisely placed on the pads and perhaps components glued down.  The
board was milled not etched and perhaps solder mask on the board may help
but I think accurate placement of the solder paste is the most important or
perhaps tinning of the board with solder and using a liquid flux may work.

Owen. 

-----Original Message-----
From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf
Of Kathy Quinlan
Sent: Sunday, March 19, 2006 4:44 PM
To: AVR-Chat@yahoogroups.com
Subject: Re: [AVR-Chat] Type K inputs on AVR

OWEN-A wrote:

> Have you found a suitable oven for SMD work, I tried a toaster oven of a
> brand commonly available in AU and found that it was a little slow coming
up
> to temp, and the temp distribution was poor (hot spots). There was a lot
of
> heat loss "no insulation" the outside covers were nearly as hot as the
> inside of the oven and due to lack of time and the desperate need for a
SMD
> oven lost interest for the time being.
> Have you been able to find an oven that looks like it would do the job?
> Owen.

No idea, I bought a brevile one a few years back, I hope it will do the job
lol.

-- 
Regards,

Kat.
---------------------------------------------------------------
  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
  For Everything Electronics 		   Phone: 0419 923 731
---------------------------------------------------------------


-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 17/03/2006


 
Yahoo! Groups Links

On Mar 18, 2006, at 8:41 PM, Kathy Quinlan wrote:

> Hi all,
>
> Well I have to make 100 units (and pot them in Epoxy Resin) of an  
> octopus lure
> I designed for a proto run.
>
> I am now thinking SERIOUSLY about building my SMD oven (as it is  
> mainly SMD
> only 4 through hole solder connections and 2 through hole non solder
> connections (fishing line to hold the lure in the pot))
>
> I also have a lot of "other" projects including a run of 200 units  
> for my
> speed alarm unit for the Au Targa Rallys.
>
> So I need a circuit for Type K to AVR. I know there was a design  
> note in the
> Atmel applications Journal, unfortunately the WRONG schematic was  
> placed in
> there :(

SparkFun Electronics went through this process themselves, as did I.

I found that the toaster ovens were a bit slow, but if you doubled up  
the elements (i.e. buy 2 ovens, parallel elements) it helped.

You can use an AD595 thermocouple amplifier if you want.

Here's Sparkfun's schematic of their toaster oven controller:

http://www.sparkfun.com/datasheets/Tools/Reflow-Toaster-v2-Schematic.pdf

Sparkfun decided that an electric skillet was even better:
http://www.sparkfun.com/tutorial/ReflowToaster/reflow-hotplate.htm

You could do a simple bridge amplifier and do the cold-junction  
compensation yourself using a separate temperature sensor (for  
instance, you could use a Tiny45 which has an on-chip differential  
amplifier, and an on-chip temperature sensor).

Ned Konz wrote:
> On Mar 18, 2006, at 8:41 PM, Kathy Quinlan wrote:
> 
> 
>>Hi all,
>>
>>Well I have to make 100 units (and pot them in Epoxy Resin) of an  
>>octopus lure
>>I designed for a proto run.
>>
>>I am now thinking SERIOUSLY about building my SMD oven (as it is  
>>mainly SMD
>>only 4 through hole solder connections and 2 through hole non solder
>>connections (fishing line to hold the lure in the pot))
>>
>>I also have a lot of "other" projects including a run of 200 units  
>>for my
>>speed alarm unit for the Au Targa Rallys.
>>
>>So I need a circuit for Type K to AVR. I know there was a design  
>>note in the
>>Atmel applications Journal, unfortunately the WRONG schematic was  
>>placed in
>>there :(
> 
> 
> SparkFun Electronics went through this process themselves, as did I.
> 
> I found that the toaster ovens were a bit slow, but if you doubled up  
> the elements (i.e. buy 2 ovens, parallel elements) it helped.
> 
> You can use an AD595 thermocouple amplifier if you want.
> 
> Here's Sparkfun's schematic of their toaster oven controller:
> 
> http://www.sparkfun.com/datasheets/Tools/Reflow-Toaster-v2-Schematic.pdf
> 
> Sparkfun decided that an electric skillet was even better:
> http://www.sparkfun.com/tutorial/ReflowToaster/reflow-hotplate.htm

AAARRGGGHHH Another choice ;)

I actually think this may be the best Idea, as one of the problems was the 
sides burning arms, I can hack the sides off with the dremal (best tool in an 
Electronics Butcher.. I mean Engineers Tool Case ;)

But still has a problem with uniform heating.....

hmmm I wonder what would happen if I got a steel plate ~10mm thick, gave it 4 
ceramic feet and ran a long element under it with parallel lines and about 
10mm Center to center on the element, I only need a heating plate of 300x 200mm

Hmmm what can I come up with...

Gas would be good also, maybe a new plate for the BBQ just for PCB's...

So many crazy thoughs so little time to play ;)


-- 
Regards,

Kat.
---------------------------------------------------------------
  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
  For Everything Electronics 		   Phone: 0419 923 731
---------------------------------------------------------------


-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 17/03/2006

I've been using a cheap toaster oven for a while. It has two heater 
elements, top and bottom. It's 600 W, which is just enough.

When I got it, I ran a few tests and noted down the temp curve at 
several points, with the plan of making a controller with and AVR.
But, the runs showed that the oven was fairly similar to a real reflow 
oven, and that there was no need for a controller.
I simply out in the board, and set the timer for 2 minutes. The board is 
then up at about 120-130 deg C. I then leave it for about 1-2 miutes so 
the flux can do it's job, then finalize it all by turning the oven on 
for another 3 minuts. This will take it over the top at about 230-240 
deg. Open the door and let cool. Serve with a chilled chardonnay.
Works great, have made quite a lot of boards now with no problems, even 
though I suspect heat distribution withing the oven isn't all that great.
So, you may not need to make a controller after all.

But, back to the type K question. I did another project with a type N, 
which is similar. Thermocouple input was amplified 200 times with an 
opamp, so it would suit the A/D.
I used a Dallas DS18B20 as a temp reference, mounted where the connector 
to the thermocouple entered the board.

/Jesper

Kathy Quinlan wrote:

> Hi all,
> 
> Well I have to make 100 units (and pot them in Epoxy Resin) of an octopus lure 
> I designed for a proto run.
> 
> I am now thinking SERIOUSLY about building my SMD oven (as it is mainly SMD 
> only 4 through hole solder connections and 2 through hole non solder 
> connections (fishing line to hold the lure in the pot))
> 
> I also have a lot of "other" projects including a run of 200 units for my 
> speed alarm unit for the Au Targa Rallys.
> 
> So I need a circuit for Type K to AVR. I know there was a design note in the 
> Atmel applications Journal, unfortunately the WRONG schematic was placed in 
> there :(
> 
> So if anyone knows of a good easy schematic (with cold junction compensation) 
> I would love to see it. I do not need high accuracy, as solder does not mind 
> if it is 310C or 315C so anything to within +/- 2.5C is fine (I think the over 
> will have problems in coming up quick enough ;) (if so more elements and more 
> insulation is in order ;)
> 
> This will be an OPEN SOURCE Design. FULL PCB artwork (in Gerber and Protel 
> 99SE format), Schematics, Photos, source code, etc. will be on my site.
> 
> I will also be recognising all who contribute to this design.
> 
> I know I can buy chips like the MAX6675 as used in the Elector Jan06 issue, 
> but these are not at hand ATM and I am running out of time.
> 
> I will also use the over for post curing of the epoxy etc. so I would like to 
> build something that can have MULTIPLE presets.
> 
> I will design around the Mega 128 (huge overkill, BUT I have them in stock ;)
>

----- Original Message ----- 

From: "Jesper Hansen" <jesperh@telia.com>
To: <AVR-Chat@yahoogroups.com>
Sent: Sunday, March 19, 2006 10:50 AM
Subject: Re: [AVR-Chat] Type K inputs on AVR


> I've been using a cheap toaster oven for a while. It has two heater
> elements, top and bottom. It's 600 W, which is just enough.
>
> When I got it, I ran a few tests and noted down the temp curve at
> several points, with the plan of making a controller with and AVR.
> But, the runs showed that the oven was fairly similar to a real reflow
> oven, and that there was no need for a controller.
> I simply out in the board, and set the timer for 2 minutes. The board is
> then up at about 120-130 deg C. I then leave it for about 1-2 miutes so
> the flux can do it's job, then finalize it all by turning the oven on
> for another 3 minuts. This will take it over the top at about 230-240
> deg. Open the door and let cool. Serve with a chilled chardonnay.
> Works great, have made quite a lot of boards now with no problems, even
> though I suspect heat distribution withing the oven isn't all that great.
> So, you may not need to make a controller after all.
>
> But, back to the type K question. I did another project with a type N,
> which is similar. Thermocouple input was amplified 200 times with an
> opamp, so it would suit the A/D.
> I used a Dallas DS18B20 as a temp reference, mounted where the connector
> to the thermocouple entered the board.

I've got a similar oven (Hinari 620W), it cost me 20 GBP from Argos. I 
haven't used it yet, though. I was going to make a controller for it but 
I'll try your technique first.

Leon

Leon

Troops,

Don't want to seem overly self righteous but if you are going to ship these to 
paying customers I would look a bit more at quality control and a bit less at 
what you can get away with. Teensie bit more measurement & process stability, 
lots more consistency in deliverables. Many more happy customer chappies. Lots 
more predictability in food on the table.

Speaking of righteous, anyone seen the eye on larry at the moment?  925 & 
falling, spent the day shifting pot plants & everything else outdoors.

http://www.theweatherchaser.com/maps/index.html?lat=-17.476432197195518&lon=149.17236328125&zoom=10&lid=106

Happily I am now on the outer edge of it ( breathes out & relaxes )

Cheers

Don


Kathy Quinlan wrote:
> Ned Konz wrote:
>> On Mar 18, 2006, at 8:41 PM, Kathy Quinlan wrote:
>>
>>
>>> Hi all,
>>>
>>> Well I have to make 100 units (and pot them in Epoxy Resin) of an  
>>> octopus lure
>>> I designed for a proto run.
>>>
>>> I am now thinking SERIOUSLY about building my SMD oven (as it is  
>>> mainly SMD
>>> only 4 through hole solder connections and 2 through hole non solder
>>> connections (fishing line to hold the lure in the pot))
>>>
>>> I also have a lot of "other" projects including a run of 200 units  
>>> for my
>>> speed alarm unit for the Au Targa Rallys.
>>>
>>> So I need a circuit for Type K to AVR. I know there was a design  
>>> note in the
>>> Atmel applications Journal, unfortunately the WRONG schematic was  
>>> placed in
>>> there :(
>>
>> SparkFun Electronics went through this process themselves, as did I.
>>
>> I found that the toaster ovens were a bit slow, but if you doubled up  
>> the elements (i.e. buy 2 ovens, parallel elements) it helped.
>>
>> You can use an AD595 thermocouple amplifier if you want.
>>
>> Here's Sparkfun's schematic of their toaster oven controller:
>>
>> http://www.sparkfun.com/datasheets/Tools/Reflow-Toaster-v2-Schematic.pdf
>>
>> Sparkfun decided that an electric skillet was even better:
>> http://www.sparkfun.com/tutorial/ReflowToaster/reflow-hotplate.htm
> 
> AAARRGGGHHH Another choice ;)
> 
> I actually think this may be the best Idea, as one of the problems was the 
> sides burning arms, I can hack the sides off with the dremal (best tool in an 
> Electronics Butcher.. I mean Engineers Tool Case ;)
> 
> But still has a problem with uniform heating.....
> 
> hmmm I wonder what would happen if I got a steel plate ~10mm thick, gave it 4 
> ceramic feet and ran a long element under it with parallel lines and about 
> 10mm Center to center on the element, I only need a heating plate of 300x 200mm
> 
> Hmmm what can I come up with...
> 
> Gas would be good also, maybe a new plate for the BBQ just for PCB's...
> 
> So many crazy thoughs so little time to play ;)
> 
> 


-- 
Cheers

Don Ingram


Leading Edge Design

Mob:   +61 4 1877 5670
Ph :   +61 7 4942 5670
SIP: 899 060 4942 5670

Fax:   +61 7 4942 5680

23 Daniel St
North Mackay
QLD 4740
Australia

P.O. Box 10326
Mt Pleasant
QLD 4740
Australia

Don Ingram wrote:

> Troops,
> 
> Don't want to seem overly self righteous but if you are going to ship these to 
> paying customers I would look a bit more at quality control and a bit less at 
> what you can get away with. Teensie bit more measurement & process stability, 
> lots more consistency in deliverables. Many more happy customer chappies. Lots 
> more predictability in food on the table.
> 
> Speaking of righteous, anyone seen the eye on larry at the moment?  925 & 
> falling, spent the day shifting pot plants & everything else outdoors.
> 
> http://www.theweatherchaser.com/maps/index.html?lat=-17.476432197195518&lon=149.17236328125&zoom=10&lid=106
> 
> Happily I am now on the outer edge of it ( breathes out & relaxes )
> 
> Cheers
> 
> Don

This is what I am aiming for, repeatability :) no I think it will work, is why 
I am using a Mega 128 (I will be running 2 fans (1 to move the air (it is a 
convection oven) and one to suck cool air in for cool down (PWM'd DC fan)

I want to do this right, and get a nice temp profile, so if I need extra 
elements that is what it will get :)

-- 
Regards,

Kat.
---------------------------------------------------------------
  K.A.Q. Electronics     Website: www.kaqelectronics.dyndns.org
  IM: Yahoo: PinkyDwaggy MSN: katinka@kaqelectronics.dyndns.org
  For Everything Electronics 		   Phone: 0419 923 731
---------------------------------------------------------------


-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 17/03/2006

> Speaking of righteous, anyone seen the eye on larry at the moment?  925 & 
> falling, spent the day shifting pot plants & everything else outdoors.
> 

http://www.theweatherchaser.com/maps/index.html?lat=-17.476432197195518&lon=149.17236328125&zoom=10&lid=106

> 
> Happily I am now on the outer edge of it ( -22 deg S, breathes out & relaxes )

For the benefit of our US people who probably don't have the faintest idea of 
what I am rabbiting on about...

Off topic but great imagery, unless you live in Innisfail or Mission Beach that 
is...


http://forecast.mssl.ucl.ac.uk/shadow/tracker/static/EAUWV.html
http://www.bom.gov.au/cgi-bin/wrap_fwo.pl?IDQP0005.txt
http://www.bom.gov.au/products/IDQ65002.shtml
http://www.bom.gov.au/products/IDE00902.loop.shtml
http://mirror.bom.gov.au/products/IDR212.loop.shtml

This is all live imagery so by 2000 hours 19/3/06 or so it will all have 
disappeared.

Cheers

Don

> This is what I am aiming for, repeatability :) no I think it will work, is why 
> I am using a Mega 128 (I will be running 2 fans (1 to move the air (it is a 
> convection oven) and one to suck cool air in for cool down (PWM'd DC fan)
> 
> I want to do this right, and get a nice temp profile, so if I need extra 
> elements that is what it will get :)

Oops, my apologies, got focused on the hacking the pan apart bit & forgot the 
Mega128 ;-)

One of the commercial proto ovens uses this.  The hotplate forms the board 
support & substrate heater. The fans circulate the heat around the oven cavity 
from beneath the plate. Above the PCB is a set of quartz bars, pyrex window in 
the top.


-- 
Cheers

Don

Hi All,


Silicon Chip,August2002 had a project using op amps and a K type 
thermocouple
which may be of use if you go the op amp way. It uses a LM335 as the 
cold junction
temperature reference.

The link for the AVR journal with corrected schematic (Moyer project) is:-
> http://www.circuitcellar.com//library/print/0503/moyer154/index.htm
The max6675 is a much easier to use and I also felt inspired by the 
Elektor article
on SMD. No fiddly pots to adjust in the calibration process !!!!!

I have a couple of  6675 "samples" and have just bit bashed some 
assembly code
for a mega8 and have one happily reading temperatures from one of the cheap
Jaycar K type probes on a LCD.

Happy to make this code available if required.

Cheers

Rob Payne

Kathy Quinlan wrote:
> I think PCB work in an oven used for food would not be too bad, but I would 
> not want to use food in an oven that has been used for making PCB's :

   Well, that would depend on what kind of food.  Baking a pizza in a 
reflow oven could seriously impair the
usability of the oven for its intended purpose, at least until someone 
disassembled the oven and THOROUGHLY
cleaned it.  Vaporized grease, and smoke from strsay organic debris 
could easily contaminate the moltem
solder, compromising the integrity of the joints formed.

   Not surprising that academics would throw up their hands in despair, 
assuming the oven to be a complete
loss.  In the real world, an engineer would curse the fool who baked the 
pizza (and possibly take out a contract on
his/her life *evil grin*), and then get down to cleaning and 
refurbishing the oven for use.


tom

OK, I am sorry if this offends anyone, and I apologize to Kat for 
usurping her authority as list owner, but I
am growing weary of the excessive noise on the list.

   I refer not to the relatively few (and usually interesting, at least) 
off topic threads, but the the lack of editting on the parts of so many 
of the participants.

  It is neither NECESSARY nor DESIREABLE  to include **EVERY** line of 
the message to which you are
replying in your reply.  PARTICULARLY when you are replying to a thread 
with many, many previous messages.

   Learn to edit, people!  Redact superfluous information, and eliminate 
repetitive re;posting of "relevant"
information.  If you have been following a thread, and you see that the 
same paragraphs/sentences have already
been copied and reposted many times, ELIMINATE them from your response.  
We've all seen them severasl
times, and don't need to see them again. 

   Not only is this wasting network bandwidth (and uyes, the backbones 
ARE straining under the current traffic
loads), it wastes space and time for the individual users, when 
repetitive, and esecially repetitive USELESS
information is reposted and reposted, ad nauseum.  In particular, there 
is absolutely NO need to repost
all the Yahoo Groups crap at th e bottom of each message, when quoting 
from another participant.  All that
extraneous data clogs up the disk space of the participants, as well.

\rantmode off

Tom Keller

OWEN-A wrote:

{superfluous text removed for brevity]
>  I found that most of the SMD
> components skewed due to misplacement of the solder paste, this dragged them
> between pads and most had to be reworked it seems that the solder paste has
> to be precisely placed on the pads and perhaps components glued down.  The
> board was milled not etched and perhaps solder mask on the board may help
> but I think accurate placement of the solder paste is the most important or
> perhaps tinning of the board with solder and using a liquid flux may work.
>   
   Many hobby outlets (and, I would presume, commercial outlets as well) 
which sell soldering and PCB
suppliues also carry an "Electrless Tin Plating" system which is 
incredibly easy to use.  After etching
and drilling (and routing, if you do that), you simply soak the 
(cleaned) PCBs in the plating solution.
After a very few minutes, a thin layer of real tin has been deposited 
upon the copper, protecting it from
oxidation and corrosion, improving solderability considerably (the tin 
plate wets very nicely) and giving
your PCBs a more "finished" and professional appearance.

tom

On Sun, 19 Mar 2006, Kathy Quinlan wrote:

> Ned Konz wrote:
> >
> > SparkFun Electronics went through this process themselves, as did I.
> >
> > I found that the toaster ovens were a bit slow, but if you doubled up 
> > the elements (i.e. buy 2 ovens, parallel elements) it helped.
> >
> > You can use an AD595 thermocouple amplifier if you want.
> >
> > Here's Sparkfun's schematic of their toaster oven controller:
> >
> >
> http://www.sparkfun.com/datasheets/Tools/Reflow-Toaster-v2-Schematic.pdf
> >
> > Sparkfun decided that an electric skillet was even better:
> > http://www.sparkfun.com/tutorial/ReflowToaster/reflow-hotplate.htm
> 
> AAARRGGGHHH Another choice ;)
> 
> I actually think this may be the best Idea, as one of the problems was
> the
> sides burning arms, I can hack the sides off with the dremal (best tool
> in an
> Electronics Butcher.. I mean Engineers Tool Case ;)
> 
> But still has a problem with uniform heating.....
> 

Maybe you could make an electric hotplate work? I haven't tried one for 
that purpose, but I have used one to solder a copper or brass plate to the 
ground-plane side of a double-sided pc board used for microwave circuits.  
That 0.010" and 0.005" thick Duroid is pretty soft without extra support!

Also, most of the commercial boards I've seen with surface-mount parts 
have a tiny dot of some kind of glue to hold the part where you want it 
when you put the board in the oven.  It is very difficult to remove the 
part once it's there, though.  It's even dangerous if there are circuit 
traces running under the part. I've ripped a few of those off trying to 
remove faulty parts that have been glued with this method.

And I agree about the Dremel.  Also very handy to butcher ... er ... 
repair cars, darkroom equipment, etc. etc.  :)

Zack

--- In AVR-Chat@yahoogroups.com, Kathy Quinlan <kat-yahoo@...> wrote:
> I am now thinking SERIOUSLY about building my SMD oven ...

I am working on a similar project at the moment.  I have ordered an 
AD595 thermocouple amplifier (should be here this week) and I have a 
type K thermocouple.  According to the datasheet 
(http://www.analog.com/UploadedFiles/Data_Sheets/421725987AD594_5_c.pdf
) I should get 10mV/*C output from the amplifier.  This will result in 
a range of about 2.2V from room temperature to the peak oven 
temperature.

Don