How to set up a temperature profile - Page 1
Forum section: electronics / projects

author: Jane
author_rank: Frequent Contributor
timestamp: November 27, 2015, 06:38:31 pm
content: For my project I need to set up a temperature profile but the profile should NOT start from ambient temperature ,that can be as low as 20°C , but from a higher temperature, for example from 150°C.Also it should finish at that temperature 150°C.Will I need two PID controllers or one will be enough?And what kind of the controllers_ ALtec P410 or REX C100 or different?Thank you for help

author: billdlv
author_rank: Newbie
timestamp: November 28, 2015, 05:51:58 am
content: I have not used either controller you mention, but I have used many other types of temperature controllers. I had a look at the instructions for both, and the Altec P410 has profile capability while the REX C100 does not.I believe you would be able to do what you describe by using an alarm output and the appropriate temperature profile programmed into the controller. The alarm output would trigger the temperature profile to start, and when finished you can have the controller set point stay at a little higher value than the alarm limit to prevent the profile starting again. Have a look at the instructions they actually are pretty good for a low cost controller. This controller also has an autotune facility which will make tuning for the PID constants much easier.What are you trying to do with your project? It's a little unusual to run a profile the way you describe.I noticed by doing a search for the controller model number you have posted this question to a number of other forums. Hopefully you get the help you need. I think you should post your conclusion to all the forums so all can benefit.

author: Jane
author_rank: Frequent Contributor
timestamp: November 28, 2015, 06:15:35 am
content: Thanks for your reply.I need to solder items that need only about 10 seconds to be heated and soldered ( no longer)The starting temperature can not be ambient (20°C)temperature because it is not technically possible to heat up ( large) soldering tip to about 220C during those 10 sec. So I must already start from a higher temperature, say 150C. That temperature is lower than melting point of tin but high enough that soldering tip CAN reach the melting point during those 10 sec. After those 10 sec, I need to a soak period to cool down the soldering tip but ONLY to those 150 C from where I started (and I can solder other items)Will I need 2 controllers, 2 pcs of TC or only one?Thank you

author: billdlv
author_rank: Newbie
timestamp: November 28, 2015, 06:45:26 am
content: Quote from: blueskull on November 28, 2015, 06:24:46 amI don't have much experience soldering SMD devices so I can't comment on the above. Sounds like bluesskull has some experience and data points to work with. I know in the soldering videos Dave has posted he does not seem to be concerned too much with getting components too hot when using an iron for the soldering. I think for doing oven work that is a different story since the profiles are usually for longer durations of time.You should be able to do what you ask using 1 controller and 1 thermocouple. With the controller in normal mode you would change the set point to the 150 C and prepare everything. Once the iron is at the 150 C you would start the profile which would ramp at the rate you desire to the 220 C and run the profile. When complete, the profile can set the iron back to the 150 C and it will cool down and you can start again. You will have to perform some tests to see what the cool down rate is and what the maximum transition rate will be with the iron. It will be tricky to mount the thermocouple in a way to give you an accurate temperature reading. If you were being very rigorous then you would also mount thermocouples on the parts being soldered and monitor their temperature during the soldering process to ensure they don't exceed the temperature limit.Whether this is the best thing for what you are trying to do I don't have enough soldering experience to say for sure.

author: Seekonk
author_rank: Super Contributor
timestamp: November 28, 2015, 08:28:44 am
content: I've used PID controllers of that type and have a couple comments. Autotune is pretty much a joke. Most uses never get beyond the P proportional unless a large thermal mass is involved. In P the power starts at 100% at the lower temperature and goes to 0% at the set point. These controllers are cheap $15 and pretty but I have often felt I could do better with a dozen lines of code in a micro.

author: Jane
author_rank: Frequent Contributor
timestamp: November 28, 2015, 09:36:16 am
content: Thank you for replies@billdlv: Yes, it should work as you described but how can I set up a loop, so that the temperature 150C remains regardless of how many soldering cycles I will use ( without heating up from ambient temperature first)?

author: tggzzz
author_rank: Super Contributor
timestamp: November 28, 2015, 09:56:40 am
content: For amateur or one-off boards, consider using a modified skillet method.I've had success using a saucepan with sand in the bottom and a glass lid, plus a non-contact thermometer. The sand heats the board first (i.e. before the components), acts as a thermal buffer preventing hotspots, and allows controllable temperature rises. The glass lid keeps a little heat in, thus heating the topside components a little, and allows you to see the solder melting so that you can carefully lift the board when it has melted. I've found thin lifting wires hooked through holes on the PCB corner are necessary and sufficient when removing the PCB.As with any new technique, a little experimentation will enable you to control the rate of temperature rise just by turning the gas up and down.

author: billdlv
author_rank: Newbie
timestamp: November 28, 2015, 07:39:44 pm
content: Quote from: Jane on November 28, 2015, 09:36:16 amOnce the profile is finished you have the option of keeping the last set point at 150C. The controller will keep the iron at that temperature until you start the program again. Have a look at the instructions for the controller they explain the profile operation pretty well.