Back in Class, New Projects

I haven’t been sitting around since my last update. 2B has slowly started, and I have a new side project to keep myself busy in addition to the Co-op job hunt and Formula Electric work.

The new project is a portable soldering iron controller, powered by laptop power supplies and using Hakko soldering pencils. A good soldering station with a display instead of just a blinking LED costs about $200, and they’re pretty heavy to lug around because of integrated power supplies. There are already solutions on Ebay etc. as kits with exposed PCBs, which look fairly bomb like to carry around. The price point on the existing hobby-grade controllers makes sense for their purpose of controlling higher grade irons without the cost of an associated controller. The goal of my project is to repackage the existing state-of-the-art into a nice enclosure, and add a few features. A secondary goal is possibly to do a Kickstarter to see if anyone actually wants to buy one after I finish a product, although I won’t be disappointed if the whole market consists of me.

Anyway, constraints on the project include:

  • Input voltage of 12-24v DC from a laptop power supply or anything with a barrel jack
  • Control Hakko/Weller irons up to 80W, interfaced through a 5 pin 240 degree DIN connector
  • Temperature tolerance of 20 degrees Celsius
  • Controls temperature up to 800 degrees C
  • Operates in degrees Fahrenheit and Celsius

And criteria:

  • Fit in a standard enclosure with minimal machining
  • Be as compact as possible
  • Be safe to operate
  • Automatically detect the type of thermocouple in the iron connected
  • PID temperature control
  • Detection of an idle iron, reduce temperature or shut down to extend tip life and enhance safety
  • 16×2 LCD user interface using momentary push buttons

Given that the enclosure should be robust, commercially available, and compact, I chose a Hammond Manufacturing Model 1590B enclosure. It’s an aluminium die cast box with just enough room to fit an LCD and 2 panel mount buttons on a front panel. In my mind, the control circuity should not exceed the footprint of the LCD. This is the box with cutouts and components modelled in SolidWorks:

1

 

The 2 front panel buttons will be used for temperature adjustment and menu scrolling. Additionally there are 4 buttons on the bottom for menu selection and temperature presets and a hole pattern on the side for a flanged din connector:

2

 

The whole point of modelling this in SolidWorks was to ensure nothing would interfere inside the case. Everything will be a snug sit:

3

 

Yesterday night I got bored of solving differential equations so i made a drawing and headed to the machine shop.

4

 

About an hour later I had a machined box with everything mounted:

IMG_20140923_232601

 

 

Since this is a prototype and I didn’t have a PCB or complete circuit laid out yet, wires are dangling out the DIN connector hole going to an Arduino for now. Personally, I like the enclosure and if everything will fit in the enclosure it’ll be great. Only changes would be countersunk screws for the LCD so the heads sit flush and an additional window insert for the LCD since it is recessed. So far so good.

IMG_20140923_232611

In terms of what’s happening next, I need to may out a circuit and check that everything works, order some PCBs, and put together a user interface on the LCD. Hopefully I’ll have that done for the next update on this project.

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