A simple reflow soldering oven question.

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1

Hi Guys,

I have searched the web for ideas on making a reflow soldering oven. Most of the designs I've come across utilize special chips for temperature to digital conversion. The only chip I need to perform millivolts to a 0 to 5 full scale is an LM 358. The readouts utilize a graphic display when all I want to use is a 2 x 16 LCD. I'm basically a hardware guy and I'm still trying to get my head around C+. Let's face it all you really need to do is start the oven have the temperature go up to 250°C for 10 seconds and then shut down.

I've used this LM358 configuration before on a theatrical smoke machine. The output fed into a analog input pin of an ATmega8 chip. The working temperature from 0 to 800 degrees F. The output of the op-amp was 0 to +5vdc.

I would appreciate any help you guys can give me.

TNX Gary

TCBUF.jpg

2

What is your question ?
What kind of temperature sensor to you have ?

There is a library for an LCD display.

You can read analog signals

With a transistor or mosfet and a relay, or a relay module, you can turn things on and off using an output pin.

You have to convert the raw data from the analog input to a temperature. After that you can test the temperature for a certain value.

if (temperature > 250.0)     // temperature above 250 ?
  digitalWrite (pinRelay, LOW);   // turn off relay.

There are examples to use Arduino with reflow ovens. Some use a PID loop to control the temperature.

3

Hi
I am going to use a K type thermocouple fused at the end. K type thermocouples have an out put of 20mv @ 500C. A buffer is used to bring the voltage up to a readable level. With a gain of 213 and at 40 uv per degree this output will be 2.13 v @ 250C.
I was hoping I could get some help writing the program but I guess I'll stumble through it then post here and get some tips.

Gary

4

Writing a program is gathering pieces of examples. There are many examples.
If you have an Arduino board, start with the blinking led.
After that try to send something to the serial monitor (the serial monitor is a part of the Arduino IDE on the computer).
Next thing is to read an analog input and send that to the serial monitor.
Add the LCD, and output pin.

If you don't know how to continue, show us your sketch.