Alt-BEAM Archive

Message #07831



To: beam@sgiblab.sgi.com
From: JVernonM@aol.com
Date: Fri, 19 Nov 1999 02:53:26 EST
Subject: [alt-beam] Re: 1381


In a message dated 11/19/99 1:46:38 AM Eastern Standard Time,
gpowell@engr.uvic.ca writes:

> i am still having great difficulties with the 1381
Hi Greg,
Have you tried reversing the transistors or trigger to see if they are
backwards? This is a common mistake. Do you have enough light to fire the
sucker (assuming you have a solar cell there)? How large is the cell (i.e.-is
the voltage level higher than the trigger). Are you using the 2.2k resistor?
Some have reported better results with a smaller value (2.2k has always
worked for me). If you have one that works, compare it part for part and
connection for connection. Something HAS to be different in those non working
ones. Have you tried freeforming one following one of the online tutorials?

See ya,
Jim
http://www.geocities.com/SoHo/Exhibit/8281/beamart.html



7832 Fri, 19 Nov 1999 09:13:47 +0100 [alt-beam] Re: 1381 beam@sgiblab.sgi.com Thomas Pilgaard Nielsen Hi Greg,

what are you using the cap for? If you mean the one soldered to the
solarcell you might want to check the capacity once again : .047uF and
.0047uF caps don't hold a lotta juice for the entire cirquit. Instead
try using a 4700uF (or larger) cap.

If I've !completely! missed the point here, I apologize.

Cheers,

Thomas, Denmark

Greg Powell wrote:
>
> i am still having great difficulties with the 1381. i find it hard to
> believe that so few people have had problems getting them to work. i have 3
> circuits in front of me. one is breadboarded and works and the other is on a
> pcb identical to the breadboard version and doesn't work. the third is
> identical to the pcb and breadboard version except that it has a 0.0047uF
> cap instead of a 0.047uF capacitor. i have checked components, replaced
> components and resoldered till I finnaly had to give up. i did find that the
> 2N2222 are better than 2N3904.
> so to recap:
>
> pcb with 0.047uF -> not working
> breadboard with 0.047uF -> works
> pcb with 0.0047uF -> works
>
> i am clueless, i think that when my chloroplast components get here i am
> going to scrap the 1381. okay, i won't scrap it but i will give it a rest.
>
> Grumpy till I find a solution,
> Greg

--
---
"Fremtidens computere vejer maaske ikke mere end halvandet ton."
Popular Mechanics 1949



7833 Fri, 19 Nov 1999 03:18:27 EST [alt-beam] Re: 1381 beam@sgiblab.sgi.com JVernonM@aol.com In a message dated 11/19/99 3:15:33 AM Eastern Standard Time,
ascii@hum.auc.dk writes:

> check the capacity once again : .047uF and
> .0047uF caps don't hold a lotta juice for the entire cirquit. Instead
> try using a 4700uF (or larger) cap.
Yep, that one went right by me. You want at least 2200uF there and 4700 is
common.

See ya,
Jim
http://www.geocities.com/SoHo/Exhibit/8281/beamart.html
ICQ# 55657870



7834 Fri, 19 Nov 1999 00:44:04 -0800 [alt-beam] Re: 1381 beam@sgiblab.sgi.com Greg Powell At 02:53 AM 11/19/1999 EST, you wrote:

>Have you tried reversing the transistors or trigger to see if they are
>backwards? This is a common mistake.

yup, done it a couple of times but not this time.

>Do you have enough light to fire the
>sucker (assuming you have a solar cell there)? How large is the cell (i.e.-is
>the voltage level higher than the trigger). Are you using the 2.2k resistor?
>Some have reported better results with a smaller value (2.2k has always
>worked for me). If you have one that works, compare it part for part and
>connection for connection. Something HAS to be different in those non working
>ones. Have you tried freeforming one following one of the online tutorials?

I have tried bigger cells, ie. the biggest 5.5V solarbotics sells, they are
interchangable without difference. I have tried V-triggers from 2V to just
under the panel rating. I have used exactly the same components as on the
solar speeder kit. the testing is done under the same lighting conditions
and motor loads. I have actualy had a working breadboarded circuit with I
transfered onto the pcb and it stopped working. I thaught perhaps it was the
pcb but I checked it. I have the pcb on my web page if you have the time to
look. I am going to get a friend to look things over in case it is just me
going mad. The main problem is that I just can't let go of it. I am supposed
to be studying for finals but this is so much more entertaining :). Thank
you very much for your time Jim.

Greg
http://www.engr.uvic.ca/~gpowell/

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