pic: burnt up TETRIX motor

[Mark McLeod]

There is this FIRST legal option for development, but not competition:
http://www.legoeducation.us/store/de...2&s=32&ID=2135

Use the promo code FRCT3340 (thanks Travis!) and it's $9.

[PhilBot]

Originally Posted by Al Skierkiewicz

A 5 or 6 amp fuse in line with each motor might be a good protection. If installed properly with insulation, etc., I do not see any rule that would prevent it. The stall current on the motor is listed at 7 amps I believe.

Pitsco sells just such a modified motor power wire:

It's hugely expensive for what it is, but it's clearly 100% legal (since it's a standard TETRIX part) and it's ready to go for those not wanting to do soldering.

http://parts.ftcrobots.com/store/det...&c=1&t=0&l= 0

[Chris is me]

Does smoke = no longer competition legal motor?

We failed both our motors this way with less than 1 second of stall, and it's quite disappointing - but if the smoke is just the thermal breaker tripping and it happened to reset, then hey, we don't have to spend $60.

I'm almost certain we will be direct driving our minibot now not because it's fastest but just to avoid stall even though I think it will still happen.

[wilsonmw04]

Originally Posted by Chris is me

Does smoke = no longer competition legal motor?

From my experience, no, smoke does not not make the motor illegal. I can also say that smoke does not mean the motor is bad either. We have used every motor we have "smoked" again in competition. In face, I think we still have all the motors we started with 3 years ago. The only real problem we have is that we snapped two posts before they made the new adapters.

[Jonathan Norris]

We have had both our motors burn up so far... I opened up one of ours yesterday and shorted the burnt resistor, planning on putting a new resistor on the outside. Does anyone know what resistance the resistor is supposed to be??

If these motors burn out this easily mini bots are going to get expensive very quickly...

[billbo911]

Originally Posted by colin340

Al why do u think it is a inductor? just to quiet the brush noise?

also any idea on value of the inductor?

I honestly can't prove if it is a resister or an inductor. One thing I can say is it is a series device, not a shunt device. The cap is in fact a shunt.

That being said, it makes perfect sense that it is an inductor. The inductor and cap create an LC low pass filter, thus keeping the higher frequency noise from being radiated or conducted to other components or systems.

[Al Skierkiewicz]

I will see if the motor I have open at work can CSI'd.

[Teched3]

Now that you see there is a problem, time to engineer a solution. Shouldn't be too difficult to design a way to turn off motor power when you strike the target.

[billbcc91]

Al says that is an inductor and he is usually right. But it does look like a resistor to this mechanical engineer who remembers just about nothing from my EE courses 20 years ago. So I could very easily be mistaken.

Somebody asked about the value of part. If it is a resistor, you can tell by the color of the bands. I can't tell what the inner 2 bands are from the photo due to the crispiness. Maybe somebody who has cracked a motor open can post what the band colors are. Here is a link about how to decode the color bands to a value.

http://www.electronicsteacher.com/tu...a-resistor.php

I would expect there may be an equivalent code for inductors?

[Al Skierkiewicz]

Originally Posted by Mark McLeod

There is this FIRST legal option
http://www.legoeducation.us/store/de...2&s=32&ID=2135

Use the promo code FRCT3340 (thanks Travis!) and it's $9.

Mark,
Thanks for the link unfortunately it is not currently part of the allowed list of Tetrix parts. Please standby...

[artdutra04]

Originally Posted by Al Skierkiewicz

Mark,
Thanks for the link unfortunately it is not currently part of the allowed list of Tetrix parts. Please standby...

They are listed on the third page of the TETRIX product catalog linked to in Minibot section of The Robot rules.

http://www.tetrixrobotics.com/Buildi....aspx?moid=533.

[Al Skierkiewicz]

OK,
I will check on this. I have a doc that is the allowed parts for inspectors. I cannot load the Tetrix page, it appears to be having an issue. My doc does not list the thermal protectors.

[Teched3]

In Team Update 3, FIRST gives a 2nd link to Lego Education, FRC Tetrix parts, which is notably expanded over the Pitsco catalogue in the original manual.

www.legoeducation.us/FRC

That link should take you to a 9 page catalogue of additional Tetrix acceptable parts.

[Al Skierkiewicz]

TecheD,
There in lies some of the confusion. The lego link is not in the Team Update. It is a place that can be used to obtain parts. From TU#3
Please note that the Rule <R92> only allows Tetrix components. While Tetrix components are a subset of FTC components, it is essential to realize that not all FTC parts are Tetrix parts. As such, not all FTC parts are permitted on the MINIBOT. Please be sure to vet your components against the above list before constructing your MINIBOT.
I am receiving a corrupt file error when trying to access the Tetrix page. Therefore, I cannot compare it to my file.

[caffel]

Thanks for the G2 on this motor and the implication that we must have a limit switch.
Hopefully someone, perhaps you yourself, will put this up in the Q&A so we can get a clarification.
Have you seen the resister stripes of a new one ?
Like what is the resistor rated at ?
Maybe we could use a small cricuit braker in series (they go down to 3 Amps, although hard to source in that rated size)