Alt-BEAM Archive
Message #09136
To: beam@sgiblab.sgi.com
From: "Ben Hitchcock" beh01@uow.edu.au
Date: Thu, 13 Jan 2000 23:34:04 +1100
Subject: [alt-beam] Re: my first robot
Hi,
>From: Jonathan D Rogers
>Date: Thu, 13 Jan 2000 15:34
>
> Well, I just breadboarded Ben's FLED solarengine circuit with those nifty
> motors I found, and ti works beautifully.
Fantastic! I was starting to get a bit worried there when David said that
his didn't work. I really think that his problems are to do with using 6.9k
resistors instead of 3.3k. (By the way, David, did you try putting two
6.9k's in parallel to give 3.45 K?)
> Then, I built my first
> photovore, free-form. Unfortunately, it doesn't move despite my checking
> all my connections several times. After checking several spots with a
> voltmeter, it seemed like the circuit wasn't getting enough
> power...odd...
I had this problem too. It turned out that my 3.3 K's were connected to the
wrong position.
> But, I'm sure if I fool around with it I can get it to work!
For sure!
Here are a few tips that I discovered when building Fred:
1) Check the FLED polarity. I put one in backwards when building Fred.
Easy to do, difficult to find.
2) Check the main cap polarity. This will limit your voltage if installed
backwards.
3) If the main cap voltage is holding steady at some voltage (below 2.2 V)
but the motors aren't spinning or ticking:
The first thing to note is that it's easier to debug one SE at a time than
both at once.
Disconnect the 3.3 K resistor (only unsolder ONE side of it, of course!)
from one of the BC327's. See if the voltage level changes. If yes, then
this side is faulty. If no, then repeat for the other side.
If the voltage still doesn't change with both 3.3K's disconnected, then you
definitely have a wiring error. Check that the 337's are in the right way.
When you have determined which side is faulty (or both!) then follow this
procedure:
Check where the other end of the 3.3K and the 10K resistor goes. It took me
half an hour of doing this to realise that I had mistakenly attached the
3.3K to the earth side of the BC337!
4)
If all else fails, print out the circuit, and get a big black felt-tip pen.
Start at the solar panel, and check _everything_ about each component before
crossing it off and going to the next one. Do this for the connections as
well - as in, the base of the 327 should go to the 3.3K, and the 4.7 uF, and
nothing else!
It's tedious, and might take you an hour to do properly, but that's an hour
spent that will definitely get you a working popper at the end of it!
Remember to go over each component THOROUGHLY, and mark your +V and -V rails
with a bit of tape. It's pretty easy to mistakenly attach a component to
the wrong rail (I did that too.)
> Thanks a lot for a great circuit, Ben!!
Hey no worries! I'm glad that someone found it useful.
I'm sure that you just made a simple mistake on the construction (I made
about six when building Fred) and you'll kick yourself when you find it.
You know that the circuit works on the breadboard, so it should work inside
a popper... (Famous last words I think!)
Cheers,
Ben
9137 Thursday, 13 January 2000 6:31 Re: microcore experimentation kit beam@sgiblab.sgi.com George Rix
> What if (as someone suggested) i reate a small circuit board complete w=
ith
a
single schmitt inverter and either a plug to put in your own resistor or =
an
adjustable pot built in. Plus a plug to add your own hysteris. A SMD LED =
is
on board. It would connect to a breadboard (or protoboard) with some PCB
pins, a little like the BASIC STAMP. With this you could easily grab a fe=
w,
plug them in, connect them in your own pattern an you have a microcore.
Would people be intrested in such a thing? I could start a production of
them. Keep in mind though they may be rather expensive compared to buying=
a
17HC14 and individual parts. This is just because the parts themselves ar=
e
rather expensive. (A single schmit inverter is 68 cents).
>
>David
I would certainly be interested...
Can I have fourteen trillion? To go? =3D)
Peace out!
Rob Rix
No doubt it will all make sense when we're older =8B Calvin and Hobbes
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