PID Incorporation Into Inexpensive Hot Air Stations and Preheaters  - Page 1
Forum section: electronics / projects

author: Dawn
author_rank: Regular Contributor
timestamp: June 23, 2012, 03:05:14 am
content: I've seen articles,videos,and blogs that describe kits or industrial PID modules being incorporated into toaster ovens and hotplates. I don't believe I've seen one yet that attempts to add profiling capability into any of the inexpensive hot air stations or preheaters like their hyperexpensive industrial brand name counterparts. I would think that this would be an interest instead of monitoring temperatures with makeshift DMM thermocouple probes and a timer. Has anyone read or seen article attempting to automate the process?

author: JVR
author_rank: Regular Contributor
timestamp: June 25, 2012, 07:35:32 pm
content: Never seen a project like that, but it would not be too hard to implement, good sensor and a lekker microcontroller and you'll have it going in a few minutes

author: SeanB
author_rank: Super Contributor
timestamp: June 25, 2012, 08:08:08 pm
content: I did PID a fridge, as I was unhappy with the existing mechanical controller ( it was getting dodgy, and i had a PID controller spare along with the Pt100 probe) so did it, and set the off time constant to 5 minutes ( save the compressor) and pressed autotune. After a week read out the autotune values, and it had basically defaulted to a simple on off control with a 2C hysteresis. I then replaced the PID Omron controller with a slightly cheaper one that only has a setpoint, off and on time control and a hysteresis setting. Uses less power as well, a whole 1W saving...... The display fridge uses 1kW when cooling, 100W otherwise in circulation fans. I dropped the power 200W by removing the shorted 200W drain pan heater mat, replaced it with a fan to provide the required evaporation, as I do not think it will ever be cold enough to freeze, and the discharge piping in any case does a few turns in the tray to provide extra cooling to the hot gas. Must remember to wash the evaporator coils this month with cleaner, and clean the fans as well.

author: robrenz
author_rank: Super Contributor
timestamp: June 25, 2012, 08:15:32 pm
content: Many of the small ovens/ toaster ovens dont have the thermal capacity to follow the profile anyway. Make sure your oven's full on deg/sec rise is fast enough for the profiles you have in mind. Otherwise it will be a waste of time.

author: Dawn
author_rank: Regular Contributor
timestamp: June 25, 2012, 11:43:44 pm
content: I would believe there is a real need to see automated profiling capability on lower end hot air units. It's a given with IR stations in the $300 range from China, But to my knowledge, there isn't a complete preheat/hot air integrated station solution like Weller,OK, or Hakko have had. I don't see the need for an IR station or the footprint/separate power circuit that goes along with such a station, I'm not reballing computers or game consoles with the need for a large worksurface, just the occasionall, small BGA that one finds on smaller consumer and commercial equipment that a hot air station would be enough.Sunko, Aoyue/Blackjack and some other preheaters that do have a primative preprogrammed warming cycle using accessory thermocouple probes. The top end Aoyue and Sunko have the ability to store a single hot air profile for reflow ramp up,reflow,and cooldown. None of these operate as an automated and intergrated system like for example Weller's andHakko's little stations do.If these Chinese companies can impliment 5 step PID preheat,reflow,and cooldown cycle control as part of their IR products, there's no reason the hot air products can't. The game boards are full of empiracally arrived time/temperature profiles that have to be monitorored and physically adjusted, so there is a demand. Most all the newer multi feature stations use pic PID controllers. Interconnectivity of their companion preheaters would be a no brainer and would guarantee companion sales of thier own products. Typical prices of the two larger Aoyue/Blackjack preheaters such as the 863,883 with profiling is well over USD$250. Hot air stations with the profile cabability; 270x types are USD$275; about $100 over the more advanced Hakko derivative clones like the 968 and 852 series.Surely they could incorporate and umbilcle cord solution like Hakko or Weller with little effort if they can do it with their all-in-one IR stations.

author: MickM
author_rank: Regular Contributor
timestamp: June 26, 2012, 10:48:45 pm
content: Hi;maybe you could adapt this:http://dangerousprototypes.com/forum/viewtopic.php?f=56&t=2457Arhi has several PID things on DP.Mick M