Alt-BEAM Archive
Message #10501
To: beam@sgiblab.sgi.com
From: SG sparkyg@seark.net
Date: Sun, 20 Feb 2000 12:07:14 -0600
Subject: [alt-beam] Re: walker dying
Mike,
put those .01 caps back on the motor leads.
also, it could be one of your power leads is moving where it is soldered
to the circit. Sounds like a short to me.
my walker did this and it turned out to be a looly soldered female battery
connector.
-hope this helps.
Sparky
At 03:27 PM 2/20/00 GMT, you wrote:
>I finished a walker last night, but for some reason, after everytime I turn
>it on, it slows down stops altogether after about 10 seconds. The indicator
>LED's also glow less bright. And I know its not the battery, because its
>brand new... Here are the specs: Does anyone know what's wrong?
>
>- Master-Slave Bicore with reverser (Ian's complete walker circuit)
>- 74HC240
>- 2 h-bridges
>- 2 Lithium 3V batteries in series
>- 7805 voltage regulator (bicore gets 5V, motors get 6V)
>- 4 Green indicator LEDs
>- 1 Red LED to show when the tactile sensor is turned on
>- 2 .22 uF caps for each neuron = .44 uF per neuron
>- Front and rear motors are different... but both efficient and alike in
>performance.
>- No filtering caps (o.1 uF across IC and/or motors)
>- Entire circuit on a pcb (flux scraped off)
>
>and thats about it.... thanks for the input, and especially for that on the
>pager motor and fan.
>
>______________________________________________________
>
10502 Sun, 20 Feb 2000 14:07:33 -0400 [alt-beam] Re: newbie electronics questions alt-beam@egroups.com michael.hirtle@ns.sympatico.ca (Michael Hirtle) Hi.
You will need a solar cell that provides more current then 1.4mA
it should at least be 8mA.
for the capacitor it should be anywhere from 1000uF to 1F depending on what
you want to build.
4700uF is the most common capacitor for solar engine use.
the capacitor should be 6.3V that is the lowest voltage you can find except
for a 0.33F cap which is 2.5V and the 1F caps can get as low as 2.5V also.
You can find solar cells at www.solarbotics.com or www.adaptobotics.com
walkau wrote:
> i have some small 3v motors kicking around (i don't know what the
> current draw is) and some small 3v 1.5 ma solar cells with which i would
> like to build some SE.
>
> what rating of capacitor should i be using? i am not sure of the
> significace of the farad rating on the capacitor. i understand the need
> for the voltage rating on it.
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