Wednesday, September 28, 2016

Low Profile Long Lead Thermistors

I put together some thin thermistors as a proof of concept. Aiming to get under 1/16" thick. Very few long lead thermistors on digikey are under this mark. 

I ordered some flat flex cable with connectors, Digikey offers inch increments between 2" and 8" and a variety of termination options, all as value add parts. The flat conductors inside are 0.05" wide on 0.1" pitch.

Digikey stocks 10k NTC thermistors all the way down to 0201 SMD package, but I went 0805 for two reasons. First, they're the same thickness as 0603 chips, but in an easier to handle and more robust package due to the larger area for solder to stick to. Second, 0402 and smaller won't reach across the space between conductors. The manufacturer of this wire makes it in 0.05" pitch as well, but the 2 conductor version isn't stocked at digikey.

 0805 NTC thermistor and flat flex cable

Saturday, October 3, 2015

Motor Controller Photo Dump

I realized that I never made an update to the motor controller post after someone messaged me about it. Here's a photo dump for now.

 Case from Rapid Sheet Metal

Monday, March 2, 2015

Motor Controller Packaging

Quick note: This post is a work in progress. Some sections are incomplete or missing.

1. Objectives

The motor controller used in the MY2015 will be based off of the Unitek Bamocar D3 modules used in the 2014 car. The D3 controller meets the electrical requirements for our tractive system (voltage, power, control scheme) but there is an opportunity to make significant improvements for use in our application by reducing size, weight, and installation complexity. To make the most of a redesigned housing, both control modules and will be integrated into a single package.

Thursday, January 22, 2015


Let's talk about Otto.

Otto is the result of a 25 person team working over the fall 2014 semester in the class 2.009: Product Engineering Processes at MIT. This is the mechanical engineering capstone class and as the name implies, it focuses on teaching about how products are made. Luckily, the faculty strongly believe in learning by doing.

Sunday, October 5, 2014

Tractor Anniversary

Here we are. A year since I started looking at those tempting domestic tractors on Craigslist.

Contrary to popular belief, I've actually made some progress on this thing. Let's take a look.

They make paint for tractors. Not something I had thought about but it makes sense in retrospect. It's oil base and supposed to be extra durable. It can be used with a hardener (which I used) for faster drying and supposedly greater durability. It can be brushed/rolled or thinned for use in a spray gun.

First order, degrease anything that gets paint. You can see that the end that had an oily engine on it is mostly rust free.

Thursday, May 1, 2014

The 6.115 Saga

I started work on this project almost a year ago. A majority of what follows happened over summer 2013, as of last week I finished the last task needed to get it to production.

This requires a bit of explanation.

There is a class taught by Prof. Leeb called Microcomputer Project Laboratory, or 6.115 in MIT speak. It runs each spring and students are taught how to work with microcontrollers and then are required to complete a sufficiently complex electronics project of their own design. To aid in this process, each student is given a briefcase size kit which holds protoboards, a microcontroller interface, power supplies, handheld tools, a bag of parts and whatever else they choose to use. It is highly encouraged that the kits be brought home so work can be done outside of class.

The 6.115 kit as used today and 10 years previous.

Wednesday, April 23, 2014

What I did on Marathon Monday

For this post I'd like to share the process I went though to make a prototype base plate for a teaching kit I'm working on. It turned out a bit like a guide, but I'm not necessarily saying this is how to do things. It's just what I did and it seemed like a natural way to write it.

Here's the short version of why I did this:
My UROP advisor teaches 6.131 Power Electronics Laboratory. After seeing what I did to his 6.115 kits he asked me to come up with something for this class as well. I'll get a post going for that project, but it's taking me a bit longer to write up because it's a doozy. There will also be a real update on what I've actually done to the 6.131 kit once it gets a bit more finalized and all my time isn't taken up by classes.

Fire up your favorite CAD program and get your part drawn out.