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FW: [DPRG] tutebot brain breadboard layout question

Subject: FW: [DPRG] tutebot brain breadboard layout question
From: Dan Miner miner at centtech.com
Date: Mon May 15 22:54:16 CDT 2000

-----Original Message-----
>From: Dan Miner 
Sent: Monday, May 15, 2000 12:08 PM
To: 'olio'
Subject: RE: [DPRG] tutebot brain breadboard layout question


> > OK, now your robot stops, and begins to back up.  This causes SW1
> > to open.  What happens?  R1/R2 cause the charge on C1 to "slowly"
> > drain away.  How quickly this happens is adjustable with R1.
> 
> the drain is actually pretty good without the pots.  it reverses for
> aprox 5-7 secs.  and i can live with that for now. 

That will depend on the type of cap you have there.  Some
will take longer than others to drain the charge.  It's a cap.
specification called "leakage".

> > drains the charge away.  Your robot will back up for a LONG time!
> 
> but you said LONG time enough to make the question if 
> something is wrong
> with my set up cause it actually isn't reversing for such a 
> long time. 
> well, are we talking long in elephant or gnat years? :^)

5-7 sec. is reasonable with electrolytic caps.  
However tantalum caps. could take much longer.

OH WAIT! - I just realized that the transistors will also
drain off come of the charge through the base.
That's why it's not really a LONG time.

> > What difference in behavior will you get with 2 switches instead of
> > the single one shown in the book's schematic?
> 
> well i expect to see differential turning/steering.  i plan 
> on making it
> a three wheeler - third just as  a go-along wheel.  maybe even S3 & S4
> connected to S1 & s2 (to have bumpers for the rear of the bot 
> in case it
> gets backed in somewhere.)

Sounds good.

				- Dan


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