If you plan to spend money, you could also get one of ebay #
250337695389 (Or any other commercial temperature controller, used one
are cheaper as long as you get the right TC interface.).
I've used a similar controller for a SMD hotplate, and it works pretty well.
I've seen the MAX6675, and if one feels inclined to bother with the
SPI it looks nice, but personally i wish someone would make cheaper
analog interfaces (thermocouple to mV).
Analog devices makes them (forgot the number), but they are pretty expensive.
Anyway, everything will work. I chose the cheap solution with the
least number of parts for my laminator and it works fine, but there
are definite advantages to having a readout of actual temperature for
sure. Personally i would avoid the microcontroller route as long as
possible.
ST
On Wed, Dec 10, 2008 at 4:18 PM, DJ Delorie <dj@...> wrote:
>
> "Stefan Trethan" <stefan_trethan@...> writes:
>> Or you could simply use a thermistor, pot, transistor, and solid state
>> relay, throw that together and be done with it. If you think about it,
>> there really is no need for rocket science here.
>
> What's the working range for thermistors?
>
> I was thinking of using a MAX6675 chip, which goes from type K to SPI
> readout of degrees directly, with no extra math or hardware needed.
> An R8C MCU with an ADC pin reads the pot, and the LCD displays the set
> point and the roller temp in actual degrees (rather than just 0..10 :)
>
> I figure for $50 in parts (including power supply module) it lets me
> know it's set to the right temperature, something I see only in
> laminators costing hundreds of dollars. My thought is that I can set
> the desired temperature to a specific setting according to the specs
> of whatever I'm laminating, and know when it's at that temperature.
>
>> I know you like to play with software so it probably doesn't pain
>> you as much as me.
>
> There is that :-)
>
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