How does a toaster oven work? - Electronic Circuits Projects Diagrams Free

dknguyen · 30th May 2006, 09:43 PM

Does anyone know how a toaster oven works inside? I wanted to try and convert one for solder reflow, but mainly for curing things which requires a temperature of 50C-60C. The problem is that ovens don't go that low and I was wondering if it could be done with a custom temperature control.

THanks.

rockin_rick · 30th May 2006, 10:02 PM

I know have any specific knowledge of toaster ovens, but perhaps this will help:

http://www.sparkfun.com/tutorial/Ref...ow-toaster.htm

Rick

dknguyen · 30th May 2006, 10:42 PM

That helps a bit. my problem is not so much with the electronics or temperature control part. It is more with the actually how the oven switches on and off. I'm pretty sure a normal oven only turns completely on or off depending on the temperature inside the oven. I'd like to see if it's possible to turn the heating elements on "part-way" similar to speed control in a motor vs. on/off.

I don't know the mechanism used to switch the heating elements on and off and whether or not the heating elements can be PWM'd to have them be on part-way (I'm not sure if PWM even has any meaning with VAC and even if it does, I'm not sure if a MOSFET can be used to PWM a VAC signal).

**Nigel Goodwin** · 30th May 2006, 10:46 PM

I suspect you'll probably find it's usually a crude mechanical thermostat - I would forget PWM or anything, it's NOT need for AC heater control. If you want variable power you use 'burst fire' control, which is easy to do with AC, and perfectly fine for heaters.

dknguyen · 30th May 2006, 10:50 PM

I'm a bit worried about overheating the chips since I use lead-free solder and it seems that the two temperatures are really close. I figure I could minimize overshoot if I could get it to be continuously variable power.

Do reflow ovens use on/off with knowledge of how fast the element heats up? or do they have variable power heating elements?

30th May 2006, 11:54 PM

Try http://www.elektor-electronics.co.uk...th=1&art=52955 This is article explaining the whole process.

dknguyen · 31st May 2006, 08:38 AM

Well I have found a very nice digitally-controlled infrared-convection toaster oven. Hopefully the digital part of it will allow me to tap my PCB directly into the drivers and relays so I won't need to splice into the high-voltage line.

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30th May 2006, 09:43 PM	(permalink)
dknguyen	How does a toaster oven work? Does anyone know how a toaster oven works inside? I wanted to try and convert one for solder reflow, but mainly for curing things which requires a temperature of 50C-60C. The problem is that ovens don't go that low and I was wondering if it could be done with a custom temperature control. THanks.

30th May 2006, 10:02 PM	(permalink)
rockin_rick	I know have any specific knowledge of toaster ovens, but perhaps this will help: http://www.sparkfun.com/tutorial/Ref...ow-toaster.htm Rick

30th May 2006, 10:42 PM	(permalink)
dknguyen	That helps a bit. my problem is not so much with the electronics or temperature control part. It is more with the actually how the oven switches on and off. I'm pretty sure a normal oven only turns completely on or off depending on the temperature inside the oven. I'd like to see if it's possible to turn the heating elements on "part-way" similar to speed control in a motor vs. on/off. I don't know the mechanism used to switch the heating elements on and off and whether or not the heating elements can be PWM'd to have them be on part-way (I'm not sure if PWM even has any meaning with VAC and even if it does, I'm not sure if a MOSFET can be used to PWM a VAC signal). Last edited by dknguyen; 30th May 2006 at 10:45 PM.

30th May 2006, 10:46 PM	(permalink)
Nigel Goodwin	I suspect you'll probably find it's usually a crude mechanical thermostat - I would forget PWM or anything, it's NOT need for AC heater control. If you want variable power you use 'burst fire' control, which is easy to do with AC, and perfectly fine for heaters. __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

30th May 2006, 10:50 PM	(permalink)
dknguyen	I'm a bit worried about overheating the chips since I use lead-free solder and it seems that the two temperatures are really close. I figure I could minimize overshoot if I could get it to be continuously variable power. Do reflow ovens use on/off with knowledge of how fast the element heats up? or do they have variable power heating elements? Last edited by dknguyen; 30th May 2006 at 10:54 PM.

30th May 2006, 11:54 PM	(permalink)
Paul Obrien	Try http://www.elektor-electronics.co.uk...th=1&art=52955 This is article explaining the whole process.

31st May 2006, 08:38 AM	(permalink)
dknguyen	Oven Well I have found a very nice digitally-controlled infrared-convection toaster oven. Hopefully the digital part of it will allow me to tap my PCB directly into the drivers and relays so I won't need to splice into the high-voltage line.