Alt-BEAM Archive
Message #13119
To: "'beam@sgiblab.sgi.com'" beam@sgiblab.sgi.com
From: Wilf Rigter wilf.rigter@powertech.bc.ca
Date: Fri, 7 Apr 2000 12:42:11 -0700
Subject: RE: Transistor switching time question
Good question Justin,
The turn-on time of a transistor is generally faster than the turn-off time.
In fast switching circuit such as a bicore head that can be a problem. A 6
transistor h-bridge, used together with a bicore, causes a nasty current
spike every time it switches state which wastes power and generates noise on
the supply lines . The problem disappears when the same h-bridge is used
with a microcore which has an inherent delay between the active outputs . So
you can see the kernel of a solution. You must design the circuit so that
the turn-on of transistors is delayed with respect to the turn-off or so
that a transistor on state is interlocked with the off state of the other
transistor. This can be done with some clever connections or by adding some
caps, resistors or diodes depending on the application.
regards
wilf
> -----Original Message-----
> From: Justin Fisher [SMTP:jaf60@cantva.canterbury.ac.nz]
> Sent: Friday, April 07, 2000 1:56 AM
> To: beam@sgiblab.sgi.com
> Subject: Transistor switching time question
>
>
> I'm planning a circuit part that acts like a SE-triggered switch, using
> transistors. When the SE signal hits, it'll both turn off a 3906 and turn
> on a 3904. However, like an H-bridge, if both 3906 and 3904 are on at the
> same time, it shorts the main cap. As this needs to be an efficient
> circuit, I wondered at the possibility of a difference in transistor
> switching times - something that could result in an extremely brief short
> each time it triggers. Is this a realistic concern? Should I put in a
> small
> cap or something to add a tiny delay to the 3904 switch-on Just In Case?
13120 Fri, 7 Apr 2000 15:52:12 EDT Re: Parts??? beam@sgiblab.sgi.com BUDSCOTT@aol.com In a message dated 4/6/00 9:39:28 PM Central Daylight Time,
fett3_14159@hotmail.com writes:
<< Sorry, this is a little off topic but i'm curious. You have Culvers too?
They are mainly in Wisconsin(where I am) and a few others in like 3 other
states. Where do you live? >>
Illinois has them to, i'm by chicago, but far enough away so that we don't
get too much of the effects! Rockford, what can I say, it sucks! Yeah, a
little off topic, but what the heck!
-Spencer
<http://www.botic.com/users/beamstop>
not a robot scientist
not a college major
not a grad student
not a professor
not a very organized person
just Spencer (isn't that impressive enough?)
13121 Fri, 7 Apr 2000 15:55:16 EDT Re: biped beam@sgiblab.sgi.com BUDSCOTT@aol.com This is a function of the brain in the cerebellum if i remeber correctly,
balance is probably the hardest part in all walking robots, good luck!
-Spencer
<http://www.botic.com/users/beamstop>
not a robot scientist
not a college major
not a grad student
not a professor
not a very organized person
just Spencer (isn't that impressive enough?)
13122 Fri, 07 Apr 2000 12:56:23 PDT Re: crab, crab, crab again beam@sgiblab.sgi.com "Timothy Flytch" >From: "John A. deVries II"
>And, of course, an autonomous submarine is usually called a
>torpedo. Idon't get why we have to strain at the seams to invent new words
>when existing words work really quite well.
>Z
A torpedo???
You mean we should build things that blow up and sink ships???
Timothy...
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