I have an interest in the controller that Dave reviewed but the 240V requirement is difficult for me, especially finding an oven.
I found this controller on eBay. It uses an SSR to switch the oven's element, is programmable in terms of the temperature ramp-up and down, and otherwise looks like it may do the trick. What do you guys think of this? There are some other controllers that are even cheaper but less programmable.
http://www.ebay.com/itm/PID-TEMPERATURE-CONTROLLER-W-30-RAMP-SOAK-SSR-OUTPUT-/110627498979
This one is cheaper but doesn't seem to have any ramp and soak timing options:
http://www.ebay.com/itm/New-Universal-Digital-PID-Temperature-Controller-SSR-Control-output-1-alarm-/110862594914
Or why not try the OSPID controller from
ospid.com?
I've detailed most of my reflow experience with it, including hacking it, on
this post at the ospid forum's 'Setpoint Profiles (for Reflow et al)' thread.
It did take some experimenting to get a JEDEC compliant profile working:
Click on the image to view full res images.I started out and failed, trying to use a cheap hotplate, (way too much thermal mass) before eventually settling on the four bar
9 litre Elgento E048, available from Amazon and ASDA at least, in the UK.
In the end I also decided against using PID control. PID, as I discovered is a science, not a black art. Determining PID settings by the wild-assed-guess (WAG) method is only fun for about an hour. From my limited experience, a PID controller using one P, I and D setting, is great for a steady state system such as a coffee machine or incubator, but ideally a controller needs a range of PID tuning parameters over the entire temperature range of the connected oven, to ensure it can actually achieve the rates required by a reflow profile.
So, inspired by mikeselectricstuff's simple yet elegant manually controlled and timed 'power ON' cycles to achieve a reflow profile, (detailed in one of the videos linked to earlier in this thread) my solution was to hack up another couple of profiles to use with the ospid controller.
Firmware is here:
https://github.com/hairykiwi/osPID-Firmware.git, and software for the monitor here:
https://github.com/hairykiwi/osPID-Front-End.gitThe new profiles simply automate the process of setting a power setting for a), a given period, or b) until the required temperature is attained. The only prerequisite is that you determine, by experiment, the maximum rate of change of temperature achievable by the oven at each phase required by the reflow profile. After a short period of experimenting, you're then in a good position to wild-ass-estimate the power output required to achieve a required rate as each phase; much easier than WAGing PID settings - and as an added benefit a much a smoother temperature profile can be achieved more easily.
As for evidence of sucessful application, the last profile in the collection above was recorded during (PB-free) reflow soldering the prototype open source
OTM-02 watch module:
Click on the image to view more full res images.