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Unread 31-01-2012, 13:27
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Matt Krass Matt Krass is offline
"Old" and Cranky. Get off my lawn!
AKA: Dark Ages
FRC #0263 (Sachem Aftershock)
Team Role: Mentor
 
Join Date: Oct 2002
Rookie Year: 2002
Location: Long Island, NY
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Re: Why not integrate Jaguars with Diodes?

Quote:
Originally Posted by EricVanWyk View Post
Crowbars are things like shunt diodes that short out the power input in an attempt to blow an upstream fuse before exploding. These make me nervous: It is a protection against incorrect wiring that assumes that the rest of the robot is correctly wired. In particularly badly wired robots, they can make the situation worse. I typically use crowbar protection in more controlled environments.
I was actually just toying with this solution last night in our lab, given the rather unnerving ratcheting click noise coming from the PD board, I thought it served as a fair indicator to turn the robot off immediately while saving the Jaguar, I also used a fairly beefy power rectifier to do it, so heat wasn't an immediate concern. I'm more concerned with the effects of repeatedly shorting the thing out rapidly.

Just curious, because I'm sure there's an angle I haven't thought of, what kind of incorrect wiring are you anticipating causing a crowbar to be an ineffective solution?

(I am mostly toying with idea out of build season curiosity, since I don't believe the current electrical rules would permit such a protection circuit in competition use).

Matt
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Matt Krass
If I suggest something to try and fix a problem, and you don't understand what I mean, please PM me!

I'm a FIRST relic of sorts, I remember when we used PBASIC and we got CH Flightsticks in the KoP. In my day we didn't have motorized carts, we pushed our robots uphill, both ways! (Houston 2003!)