good MAX6675 but difficult to get at my local electronic shop here, any info
for use 877A produce PWM to a SSR to control the heater ? for temp senser, I
found application note for LM335 with cold junction compensation "K" or "T"
type TC wire, VDC reading fed back to the 877A ADC input,



-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Matt Pobursky
Sent: Sunday, June 20, 2004 3:10 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PIC]: using 877A to controllor the temprture upto 300deg.C


On Sun, 20 Jun 2004 11:47:47 +0800, CL Low wrote:
> yes, I was thinking of replacing costly temperature controller by using a
> PIC, and display reading in LCD, I know how to drive a alphanumeric LCD,
but
> I don't have a proper T type TC wire amplifier schematic ? I've LM335
temp.
> sensor but it desn't goup to 300deg.C

Look at the Maxim MAX6675 for one easy way to do it. It's an 8 pin
package that includes cold junction compensation, has a simple SPI
interface and direct connection to the thermocouple. 0 to 1000 degree C
temperature measurement with a standard K-type thermocouple with 12 bit
resolution. With software calibration you can get accuracy to <1 degree
C.

Matt Pobursky
Maximum Performance Systems

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