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digital pid temperature controller

petercl14

Nov 6, 2020
7
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Nov 6, 2020
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Hi all, This is what I have made. It is an ATMEGA 328P controller. The user has only to input to a lcd display via up/down buttons. The display shows the current temperature and the desired temperature which starts at 20c. The user sets his desired temperature by using the up/down buttons. If for example 20c is set the controller will apply full mains voltage to a heater at the ambient 20c. Proportional power is applied between 20c and 21c turning off the power at 21c and above.
The prototype at the moment is a mass of wires. I need a manufacturing partner to make the device. This would involve making a printed circuit etc. Is anybody on the forum interested in doing this?
Had no luck with the my project. Did not understand what they meant by banner etc so I am posting here.
 

Bluejets

Oct 5, 2014
6,860
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Oct 5, 2014
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6,860
Get onto one of the online pcb manufacturers who will have free software (e.g. EasyEda) to design your circuit diagram and from there generate a pcb layout.
The gerber files are then uploaded to the manufacturer who makes and delivers at least 4 boards for a couple of dollars plus whatever postage.

First might be a study into demand, as most have already been designed and market flooded with $2 knockoffs.
If you think you might make some bucks, think again.
 

petercl14

Nov 6, 2020
7
Joined
Nov 6, 2020
Messages
7
Get onto one of the online pcb manufacturers who will have free software (e.g. EasyEda) to design your circuit diagram and from there generate a pcb layout.
The gerber files are then uploaded to the manufacturer who makes and delivers at least 4 boards for a couple of dollars plus whatever postage.

First might be a study into demand, as most have already been designed and market flooded with $2 knockoffs.
If you think you might make some bucks, think again.
This is where you are dead wrong. I have been looking for a simple pid controller for yonks. There is nothing as simple as the one I have designed anywhere. They all have very complicated sets of instructions which the ordinary person could not be bothered with. Have a look at the one from BERM instrument company made in China. I bought it and have never used it because the instructions are mind boggling. Have a look yourself.
Then another one from inkbird I found on ebay. Claims to be a pid controller but I don't think it is. It uses a SSR which is a solid state relay. Same with the Berm. A pid controller doesn't use a relay which is an on/off device. Have asked the inkbird source how I can get pid control over 1c from 18c to 19c. I don't expect any positive answer from him.
Please suggest a pid controller which you claim have flooded the market. I will show you that it is either not a pid controller or has such complicated instructions that your ordinary Joe Blow could not understand or would not be bothered with understanding and using. Compare with my very simple user interface.
 

kellys_eye

Jun 25, 2010
6,488
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6,488
Really depends on what the heating application is. PID is overkill for anything that has 'mass'.
 

Bluejets

Oct 5, 2014
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This is where you are dead wrong
Well, could be wrong to some degree but "dead wrong" insinuates on all fronts.
Go ahead and build some and see if you can re-cover your costs.....let alone make any profit from the venture.
Too easy these days for people who want a certain thing is make their own. (cheap as chips too).
Anyhow...go for it and find out the hard way.
 

danadak

Feb 19, 2021
723
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Feb 19, 2021
Messages
723
A pid controller doesn't use a relay which is an on/off device.

There is nothing that prevents a PID control loop from having a sampled data
structure in its control path .....

A relay does not magically, necessarily, force a topology into non PID.....

Google "sampled data pid control loop"


Regards, Dana.
 

petercl14

Nov 6, 2020
7
Joined
Nov 6, 2020
Messages
7
Well, could be wrong to some degree but "dead wrong" insinuates on all fronts.
Go ahead and build some and see if you can re-cover your costs.....let alone make any profit from the venture.
Too easy these days for people who want a certain thing is make their own. (cheap as chips too).
Anyhow...go for it and find out the hard way.
I don't have the technology to build a commercially acceptable unit. For instance my MCU is a 28 pin dip. A commercially made one would be tiny. Don't recall now what the word is for making these very small microcontrollers but they would need specialised equipment. Had hoped to find such a manufacturer on this site as the name suggests that they make things.
I don't intend to spend my own money as a manufacturer would have a ready made market and self interest would take over.
I am still looking for a simple, easy to use digital controller for my heaters. I am already using an analog controller for my pid controlled heaters which I designed myself. The design is so simple that it is easy to use with my heaters unlike the birds nest of wiring I have with my lcd digital design. Temperature setting is by a potentiometer calibrated in centigrade degrees.
I use a watt meter to read the pid power my heaters are using. For instance a maximum 500 watt heater used in a small bedroom is usually only consuming 250 watts as it would be too hot for the full 500.
 

petercl14

Nov 6, 2020
7
Joined
Nov 6, 2020
Messages
7
Here is what I mean by incomprehensible instructions that come with all pid controllers that I have found. That is why I made my own very simple user friendly pid controller. Note in this one the itc-106vh it is not even clear what it is supposed to do. It doesn't appear to provide temperature control of a heater element but who knows in that mass of incomprehensible instructions it may somewhere.
 

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