Homebrew PCBs

AD595AQ Thermocouple amplifier, laser trimmed to match K type but can be recalibrated for other thermocouples. 10mV/C
<http://www.analog.com/en/temperature-sensing-and-thermal-management/digital-temperature-sensors/ad595/products/product.html>

$11.76 each from Digikey.
<http://parts.digikey.com/1/parts/498915-ic-thermocouple-amp-w-comp-14dip-ad595aq.html>

Sparkfun article on using it with a 16F88 to turn a toaster-oven into a reflow solder oven with schematic and C code:
<http://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=60&page=>

Steve Greenfield

A solder paste supplier recommended on one of the messages on an Instructables:
http://www.zeph.com/zephpaste.htm

Steve Greenfield
________________________________

From: Steve Greenfield <alienrelics@...>

AD595AQ Thermocouple amplifier, laser trimmed to match K type but can be recalibrated for other thermocouples. 10mV/C
<http://www.analog. com/en/temperatu re-sensing- and-thermal- management/ digital-temperat ure-sensors/ ad595/products/ product.html>

$11.76 each from Digikey.
<http://parts. digikey.com/ 1/parts/498915- ic-thermocouple- amp-w-comp- 14dip-ad595aq. html>

Sparkfun article on using it with a 16F88 to turn a toaster-oven into a reflow solder oven with schematic and C code:
<http://www.sparkfun .com/commerce/ tutorial_ info.php? tutorials_ id=60&page=>

Steve Greenfield

Steve Greenfield <alienrelics@...> writes:
> AD595AQ Thermocouple amplifier, laser trimmed to match K type but can be recalibrated for other thermocouples. 10mV/C
> <http://www.analog.com/en/temperature-sensing-and-thermal-management/digital-temperature-sensors/ad595/products/product.html>
> 
> $11.76 each from Digikey.

Alternatively, MAX6675ISA+ thermocouple to SPI chip, also K, $14 at
digikey.  Outputs absolute degrees C (has its own internal cold
junction compensator).  I used one of these to convert my laminator to
digital, the hookup was trivial as was talking to it.

A few extra dollars for the convenience seemed to be worth it, no need
to add any analog parts or rely on an MCU's internal ADC.

http://datasheets.maxim-ic.com/en/ds/MAX6675.pdf

Runs on 3.3v or 5v too.

> Sparkfun article on using it

I went with SF's article on hotplate reflow, seems to work for me as
long as I can keep my boards flat enough to get even contact.

Steve Greenfield <alienrelics@...> writes:
> A solder paste supplier recommended on one of the messages on an Instructables:
> http://www.zeph.com/zephpaste.htm

Goodie!  Thanks for the tip.

--- In Homebrew_PCBs@yahoogroups.com, DJ Delorie <dj@...> wrote:
>
> 
> Steve Greenfield <alienrelics@...> writes:
> > AD595AQ Thermocouple amplifier, laser trimmed to match K type but can be recalibrated for other thermocouples. 10mV/C
> > <http://www.analog.com/en/temperature-sensing-and-thermal-management/digital-temperature-sensors/ad595/products/product.html>
> > 
> > $11.76 each from Digikey.
> 
> Alternatively, MAX6675ISA+ thermocouple to SPI chip, also K, $14 at
> digikey.  Outputs absolute degrees C (has its own internal cold
> junction compensator).  I used one of these to convert my laminator to
> digital, the hookup was trivial as was talking to it.
> 
> A few extra dollars for the convenience seemed to be worth it, no need
> to add any analog parts or rely on an MCU's internal ADC.
> 
> http://datasheets.maxim-ic.com/en/ds/MAX6675.pdf

The AD595AQ has internal cold junction compensation, too. And is laser trimmed for K junction to 1C accuracy, with J junction in the AD594, and either can have external resistors added to either trim closer, or change to work with the other junction. I'm not too worried about relying on a PIC's ADC.

But thanks for the tip. I see it has a 12 bit ADC.

Steve Greenfield

Yeah, they're both good, I was just pointing out the convenience of
"read spi value, that's the temperature".  No calibration in the mcu,
no having to test to see if you got it right, no analog circuitry at
all.  Just read the SPI and use it as-is.  To me that was worth a few
dollars.

I can definitely see the convenience in that, it skips the step of calibrating the ADC necessary with the National chip. It also means you can use the most bargain-basement PIC or other uController, since no ADC is required.

I've got some LCD displays, a convection toaster oven, some PICs, some thermcouple wire... I'm missing time. Maybe I should suggest this as a project in my class. Might as well get credit if I'm doing it anyway.

Steve Greenfield

--- In Homebrew_PCBs@yahoogroups.com, DJ Delorie <dj@...> wrote:

>
> 
> Yeah, they're both good, I was just pointing out the convenience of
> "read spi value, that's the temperature".  No calibration in the mcu,
> no having to test to see if you got it right, no analog circuitry at
> all.  Just read the SPI and use it as-is.  To me that was worth a few
> dollars.
>

"Steve" <alienrelics@...> writes:
> I've got some LCD displays, a convection toaster oven, some PICs,
> some thermcouple wire... I'm missing time. Maybe I should suggest
> this as a project in my class. Might as well get credit if I'm doing
> it anyway.

I can post schematics if you're interested, but it's such a trivial
project... ;-)

I would appreciate it. ... Rookie at this that I am!

http://www.delorie.com/electronics/laminator/laminator.pdf

J1 is used to program the R8C; J3/J4 connect the two boards together -
I put the high voltage (120vac) stuff on its own board.