Paul & Sabrina's cheap DIY 144v motor controller

[jyanof]

Getting the EV grin all over again!

I was wondering how removable this front panel is (or is it the back panel?). is it glued in place? with my new uController knowledge, I was thinking about putting together a quickie 4 sensor temperature probe. I'd take off this panel, wedge a thermistor into a gap so it touches a diode, another on a mosfet, glue one to a capacitor, and leave one outside the controller to measure ambient temp. They may not be perfectly accurate, but should be ballpark enough to get an idea what's goin on. I don't know anything about rs232 communications yet, but was thinking I could just have the readings cycle through on a 4 digit LED display.

Temperatures are my main concern and I think this could give us a little more insight into component temps. It could also help diagnose problems - if there are any!

I don't necessarily want to get way off topic with a whole discussion about this - just wondering if this panel provides access to the guts without dismantling the whole thing and if you see any problems with this plan.

I ordered some parts and'll hopefully put it together next week. I'll put a section in the wiki under 'testing' if it seems like it'll work.

[GrahamMc]

Looks nice. I am jealous.

[MPaulHolmes]

Hey Joe! I suppose you could solder the thermistor leads to the unused A/D conversion posts of the u-controller on the bottom of the control board. I think you should be able to get access without too much trouble. The dang control board will be soldered to the 10 gate resistors, which means it's sort of stuck where it is, but you would be able to bend it up on one side to attach the other temperature monitors underneath. It shouldn't be much trouble to get access to the various components either. hmm... I'll have to make a slight design change, but it's no problem at all. I hadn't thought of it until you mentioned wanting access. Thanks!

By the way, the serial port code is super super easy to do (in it's basic form). I haven't done the interrupt driven version yet. Adrian has some code on his RSVP thing (it's going to be OK paul... don't get angry) for a more robust serial communications code chunk.

[squiggles]

Originally Posted by MPaulHolmes

Paul,
Why are you using the fancy clips to mount the diodes and mosfets?

Also is the clear polycarbonate casing in the other images just a demonstration case?
Cheers.

[MPaulHolmes]

See those 2 indents that run horizontally across the mosfet clips? (it's hard to explain). Basically the clips clamp the mosfets down in two spots. The upper middle and lower middle, with quite a bit of force (like 15 or 20 pounds I think). Clamping through the hole just puts pressure at the top of the mosfets/diodes. Maybe that's fine, but another benefit is that you don't have to align them so the diodes and mosfets holes line up when you use clips. Later on, I'll probably use 12 diodes and 10 mosfets, since the mosfets can handle more current than the diodes. That would make alignment very difficult if I wanted to just have the diodes closer together.

The Lexan case is NO MORE! Well, maybe the endcaps for this go around. I don't know. hehe. Hondo made some enclosures out of pretty fancy heavy duty aluminum for free! and he even shipped them and they are on their way!

I'm learning some tricks to avoid some really really annoying things that can happen along the way. Holy cow.

Here's some pictures of the progress (I took 43 pictures this time, and 59 earlier today, so check out photobucket if you want to see all the details! MPaulHolmes on Photobucket):



This idea came to me as I was working on it. IN the next version I can get that B- bar even closer. Almost right underneath the mosfets! It shrinks the necessary space down for the PCBby about 0.25", and makes the MOSFETS/DIODES/CAPACITOR loop shorter! :





Joe, avert your eyes. below is my mistake. I'm sorry. See those bolts!? I turned them into screws. hehe. I'm so sneaky sometimes! I can hardly stand it!

[slurryguy]

For those that seem to need a convenient clicky linky thingy before they can find anything...

Here is Paul's Bucket-O-Photos

Clicky Linky Thingy



Warning... It's really easy to spend a few hours studying the pictures. Don't ask me how I know this.

[jyanof]

Originally Posted by MPaulHolmes

Hey Joe! I suppose you could solder the thermistor leads to the unused A/D conversion posts of the u-controller on the bottom of the control board.

i was planning to have a whole separate board, so it'd be completely independent of the controller control board. there'd just be some wires dangling out the front. keepin it simple.

diggin the progress!

[MPaulHolmes]

How do you know this?! hahaha!

Sort of almost done. Man, like giving birth to you-know-who! (Her name starts with an O, and ends with an H)



For More pictures, click HERE:

Oops, I put up the wrong link. hehe.

[squiggles]

I just remembered a PACE solder rework station that we had at one of my previous places of employment. We had it as we used to do board level repairs on most of our electronic kit.
The interesting thing was the hot air soldering tool that was intended for use with surface mount components (station included a 20x stereoscopic microscope, it was a cool toy). So anyway the point is that the soldering was done by painting solder 'paste' on the target region placing the component and then hitting with the hot air gun. The paste would turn into little balls of molten solder and when the temperature was right would form a very nice joint.
I am thinking that this may be a technique that would work with the heavier copper particularly if it was preheated. The problem with traditional soldering is that the heat is dragged very quickly out of a soldering iron tip, you basically need to use a very large tip if you are working on objects this size.
Soldering is quite an art, we endured considerable training to learn proper technique.....which I have not used for 10 years so probably lost most of the skill

[squiggles]

It also had an electroplating attachment that we used to gold plate terminals (and the odd copper coin ). Really good toy it was..