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Messages - JohnBurton

1
General discussion / Re: Solder Paste?
November 18, 2016, 01:38:49 am
Just wanted to say thanks!

I tried just putting some ordinary solder on the pads with a soldering iron and then reflowing (after putting lots of liquid flux on the board) and it worked pretty much perfectly. My test board just had 8 0805 LEDS and 8 0805 resistors but I figure if they all solder perfectly then everything else is likely to.

Now to use it to build my "real" reflow controller instead of it being hacked together with various things plugged together :)
2
Hardware projects / Re: An STM32F042 development board
November 16, 2016, 01:48:34 am
I decided to make one of these :) I presume as you put the board schematics up it's ok with you to simply send the design to seeed or whoever to get some boards made?

I have a project in mind that I'd making my own board (very slowly designing it) but figured that making of of these would 1) Test my construction skills on a similar sized project and 2) actually be something where I'd make use of the finished product.

(Just thought you'd like to know there is interest in your work so you might be encouraged to keep posting things like this!)
3
General discussion / Re: Solder Paste?
November 15, 2016, 03:04:59 pm
ah i see. i just assumed you used paste.
i shall try what you do some more. it took a long time but i suppose practice helps.
4
General discussion / Solder Paste?
November 15, 2016, 04:15:41 am
Hello,
I'm interested in what solder paste you use for your reflow oven or any observations on it.

I built a reflow oven project inspired by your projects a while ago. Mine is quite a lot more primitive and only exists as a collection of bits plugged into a plugboard thing... but it seems to work well enough. I can put ordinary solder on the PCB with an iron and put a component on top and it reflows well.... but if I have to manually put solder on every pad with an iron I might as well just hand solder!

So I have major problems with solder paste.
I bought a tube of paste, but it was so hard that I could hardly squeeze any out of the tube. Following advice I heated it a little which helped a bit but even then it was so stiff I struggled to get any out and certainly couldn't spread it.
I bought a second tube, this was thinner but seemed to have somewhat separated into a fluid and hard pieces that wouldn't stick to anything.

Both were tubes I bought from ebay so I think it likely I bought bad solder paste :) Live and learn...

I'm just wondering what experiences other people had though, and what they bought and where from?
5
General discussion / Re: Eagle and Kicad
May 09, 2016, 02:20:35 am
I find that ALL PCB board software I've tried has difficult to learn and infuriating user interfaces, the only thing you get to choose it which set of boneheaded decisions you have to live with :P

I want to to make a PCB for my reflow oven controller so I've been looking at various bits of software.
I tried Eagle free version. I couldn't get on with it. Nothing seemed to work as I'd expect and I really just found it hard to use and gave up eventually. I was also concerned for future use about the board size limitations on the free version, and the cheap pay versions didn't seem to resolve that for me.

I tried Altium Circuit Maker after it was suggested here. In many ways it's very good. It's fairly simple to use and probably has the easiest to learn user interface. There are a number of things about it I didn't like but mostly a matter of taste. What really broke it for me though was the online stuff. I wanted to use it on my laptop when traveling as well as on my main PC and without internet access you just can't. Also, on more than one occasion it just stopped working. Components I could find in the online search tool were there one day and not there the next, at least I couldn't find them. Sometimes it would find NO components and then two hours later be working again.

Eventually I tried kicad. I like this the best. It takes a little time to learn to use it but I found that once I put the time in to learn the user interface it was the easiest to use for me. I think Circuit Makes is easier to get into, but after 10 hours of use both are about equal. There are some issues though. I gave up using the component library. The parts are not the ones I wanted, and frankly the library system is incomprehensible. But it's pretty easy to make my own components for the schematic and layout and I only have to do it once ever for each component.

So I'm using kicad now.  it has a lot of rough edges like some commands only working in opengl render mode and some NOT working in opengl render mode with no reason or explanation but I like it best out of the ones I've tried and hope to have a board made soon.
6
Well, I already had a solid state relay so I've used an incredibly cheap stm32f prototype board and a themocouple input module and a bluetooth module to hack together a controller and a breadboard. It's amazing what you can do with about 4 parts :P
I guess it's inspired by your first reflow project although I'm using a bluetooth module to control it like your second because it's such a easy way to interface to a project now :)

I'm doing some very basic PID control to work out the 'strength' of the heat needed at any given time and then each 6 seconds turning on the heater for 1-6 seconds depending on the strength required. The temperature fluctuates a bit but seems to remain within a few degrees of my target overall.

I've made a few simple SMD boards with just some 0805 leds and resistors on as a test and they seem to have worked perfectly :P

I don't like turning the heater on and off so often though, apart from the fact that it makes exact control impossible I'm sure it won't do the heater any good.

I guess my plan is to get the current breadboarded version working well enough that I can use it to build a more advanced second version. I'm lacking confidence in using mains power directly safely but I expect like anything else, I can carefully learn.

Thank you for your projects, as well as being useful to me directly, they have inspired me to do a lot more with my hobby than I might otherwise have done :)
7
I found what the problem was, I had connected up the thermocouple chip to my microcontroller wrongly. Frankly I don't understand how it was working at all.

I'm finding that I have to turn the oven on and off fairly frequently to maintain accurate temperature control. For example making a decision to turn it on or off every second.  I worry that the fan and heater are going to be damaged by doing this several hundred times over the space of making a single PCB.
Has this been a problem?

8
Hello,
I'm building myself a similar project and I'm in the testing phase.
I am reading a thermocouple on my microcontroller and it seems to work once I figured out the SPI settings.
The temperatures look plausible.

However I find that the thermocouple takes a very long time to cool down.
Even if I remove it from the oven it seems to only cool at the rate of one degree every few seconds, taking maybe 3 minutes to cool from 150 degrees to 50.
Does this seem normal?
9
Thank you for the comprehensive writeup! I'm going to need to get this working for my project :)

I also ran across http://www.emblocks.org/web/ which looks like it might be an interesting alternative.
It appears to use the same compilers etc so hopefully your library would work with it?

I'm going to investigate anyway as it looks a bit more "lightweight" than eclipse which I never quite got on with very well.