Peufeu's Electronic Stuff Unfinished projects since 1912

After being gouged by Spark Fun and their non-working reflow toaster controller, I got the one from Silicon Horizons :

techFX reflow 2.0 controller with PID control.

I got the cheapest toaster I would find, which turned out to be a DeLonghi for 40 €. I did not want to have cables everywhere so I attached the reflow controller to the side of the oven with a few spacers to keep it cool, as can be seen in these pics :

I used high-temperature silicon insulated wire for all connections to the oven. A soldering iron set to max power does nothing to this wire, so it should be safe. The reflow oven is thus self-contained.

The controller needs a PC (black cable is USB) and a 6V wall wart (orange cable) for operation.

The shop was out of static relays so I used some opto-triacs and triacs, also it was cheaper ! I put two triacs, for the upper and lower infrared heaters.

From top to bottom : power switch and LED, top heater switch and LED, bottom heater switch and LED, and override switch.
If set in the top position, the heater switches let the controller control the heaters. If set in the bottom position, the corresponding heater will either be on or off depending on the position of the "override" switch.

The oven's thermostat still works, on the top heater only, so it could be used without the controller, but for baking chips the controller gives a much more constant temperature.

For reflow, both heaters should be used, but for desoldering for instance, the board can be put upside down, and only the top heater used (to avoid frying the chips), once the board is hot enough they just fall on the aluminum plate.

I put a heatsink for the triacs, which turns to be useless since they don't heat that much. I used Arctic Silver thermal epoxy to attach those, screws are so passé.

I added a buzzer on the controller's "Fan" output, with a time constant, so when it's cooked, it beeps, just like a any oven should do ;)

I like the looks of this thing, it's quite ugly and looks like Frankenstein !

Here it is baking chips to remove the moisture prior to desoldering :

Note that with this controller a static relay or triac should be used, not a normal relay, because when maintaining a constant temperature as in this baking example, it sends frequent short pulses to the heaters, and a mechanical relay would not last long. Besides, solid state is much quieter !

The software has some little annoying issues and it lacks polishing, but those are acceptable since It works, it's cheap, and it's easy to use.

Testing the reflow toaster with Silicon Horizon techFX controller. Peak temp 210°C (a bit high), an old 4MB SIMM was sacrificed in the name of science in order to adjust the reflow curve :

So, I would recommend the techFX controller to anyone wanting a reflow oven.

Cost :
- Controller € 38
- Thermocouple € 9
- Oven € 40
- Other parts € 30

Total € 117

Not bad for something that does the job of a € 2500 oven !