AVR-Chat

----- 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