Resistance and Inductance of Motors and Controller Parts.

[texaspyro]

Luke, I am biased AGAINST computer connected instrumentation. Sooner or later you goof up or the circuit goofs up. At the voltages we are working with, and with potential ground loop problems, the probability of FUBARing the laptop is just too high in my opinion. The dollar value may be the same, but I have invested way, way too much time in the software, files and system build on my laptop.

Most of the better benchtop meters have optically isolated protection between the analog section and the digital section. Not too much to worry about blowing the computer (and even not-so-old laptops can be had for 50 bucks).

 

[texaspyro]

I need one of these LCR meters. It's officially on the EBay shopping list.

I used to be able to snag them for fairly cheap... lately they have gone ballistic. One sold for around $700 a couple weeks ago. But then Tucker still sells them for $4000+ I've been unable to buy any off Ebay for a reasonable price in years (and they don't show up very often any more).

You need to be careful about choosing them. The monitor is a bit of a sore point. All the problems that I have had with these machines have been video monitor related. I have another one right now (that I was going to ship to Luke since it was cleaner than the one he got). When I originally got it, it had a flakey connection to the CRT filament in the CRT socket. I've "fixed" it a few times. The last time it lasted for a couple of years... thought it was good to go. When I was packing it up, it went flakey again. I need to just replace the CRT socket... it takes forever to get to it. Or perhaps just add an external video connection.

 

[texaspyro]

I do not have a set of good kelvin leads like yours. I ordered them, but they have yet to arrive. I made my own "almost kelvin" leads up. The reference point is a couple of inches upstream of the clips.

Actually those are the semi-not-crappy Chinese Kelvin clips off Ebay. (Hint, when buying them, look at the photos carefully. Some sellers don't color code the heat shrink on the clips). Also, buy them pre-wired... it helps to be lazy. The Chinese clips close the jaws with a metal spring. The GOOD kelvin clips use o-rings or surgical tubing to close the clips. The lack of metal in the clips helps when measuring pico and nano whatsits. Tegam will sell you a pair for over $500. Agilent has them on a set for $170 (but has banana plugs). The Chinese clips are dirt-freakin'-cheap and work well. Luke did have to adjust the meter to zero out the reading offsets on the low end.

 

[HumboldtRc]

I was wondering if the HUG 1000uF caps were the best cheap capacitors to add to my electric pit-bike. I will be using them with the 100A Super Brain esc's. (Using 12s) (2 esc's)

http://parts.digikey.com/1/parts/41839-cap-1000uf-63v-elect-vr-radial-uvr1j102mhd.html

Stock ones with fried legs. This esc survived and still works, but the other went up in smoke. I have a replacement on the way... So i will be needing to add some good caps this time...

Any other cheap cap choices, that are still worth using...? Or are the HUG's the best cheap option...?

My pit-bike
http://endless-sphere.com/forums/viewtopic.php?f=12&t=22888

 

[amberwolf]

You can possibly prevent or minimize the fried legs on caps simply by using larger gauge copper wire to run to the leads on the caps, and solder to the leads right at the base of the cap, so there is virtually no cap lead length being used as conductor outside of the cap.

Most of the cheap caps have steel legs, just plated/tinned, and they heat up and melt easy under these loads.

Also, keep all the leads to all the caps as close to the same length as possible, so that resistance/inductance/etc is the same between all caps to the ESC. It may help with load distribution.

 

[AussieJester]

Nice bench there Luke, if you find you do want to make the benchtop bigger, dropping a larger top over the existing one and glue/nailing it in place would be easy fix.... LoL@ CNC machine and bench being in your house though, still haven't had a lil lady move in with you i gather LoL...

KiM

 

[katou]

Looks like a the beginnings of a good little lab there LFP. I am going through a little "reorganization" myself. I have determined that a minimal workbench-like shelf of about 18-20" deep on most walls is more valuable than traditional 30" deep workbenches. I'm replacing my 2 workbenches (32" deep) with one, and two wall mounted "shelves" (18-20" deep). It seems that I get more use out of having horizontal surface to hold tools and projects, rather than truly "working" on the bench. This leaves more floor space in the middle for a movable project assembly/worktable.

Time spent on workbenches and such, I have never felt I wasted. I also scored a bunch of kitchen cabs (uppers and lowers with drawers) that revolutionized my workshop. Pegboard is evil. (JMHO)

Oh, one suggestion. Your long shelf looks like it might sag if loaded right up. If you add a piece running along underneath on edge, (say 1x2) there will be no sag. You probably already thought of that, but, there you go anyway.

Keep up the good work, keep pushing the envelope. It inspires me to keep on trucking too.

Katou