Alt-BEAM Archive
Message #03216
To: beam@corp.sgi.com
From: Wilf Rigter Wilf.Rigter@powertech.bc.ca
Date: Wed, 12 May 1999 10:07:40 -0700
Subject: [alt-beam] FW: My Pagerbot
content-type: text/plain;
Hi Nigel.
> Here is a little reworked FLED circuit I call the XLED (cause it's a cross
> of many prior FLED circuits ) . I have not tested it but it should work
> . The 1K resistor can be adjusted for motor (size) inrush current
> requirements and the 10K resistor can be adjusted more or less
> independendly to set the sensitivity. Using a diode makes the dropout
> voltage about 1.5V and the LED about 2.1V
>
regards
> <>
> Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
> tel: (604)590-7493
> fax: (604)590-3411
>
> -----Original Message-----
> From: Wilf Rigter
> Sent: Tuesday, May 11, 1999 5:55 PM
> To: 'Nigel Joyce'
> Cc: 'rigter@cafe.net'
> Subject: RE: My Pagerbot
>
> Sorry for the delay Nigel,
>
> The pot goes between the cathodes and the anodes go to gnd. The switches
> go across the PDs. The PD no operates in the reverse leakage mode and the
> PD with the highest leakage (light) will cause that SE to fire first. The
> 2.2K resistor has two effects during charging it acts like a load resistor
> for the FLED and the current through the FLED must reach 2.5mA before
> enany current is supplied to the base of the 2N3906. After the 2N3906
> turns on and also turns on the 2N3904 then the 2.2K resistor supplies the
> base current for the 2N3906.You can improve the performance by replacing
> the 2.2K with a 1K resistor in series with a diode and a parallel 10K
> resistor in parallel with both. The cathode of the diode goes to the
> collector of the 2N3904. Now the loading during charging is set by the 10K
> resistor and the base current for the 2N3906 is set by the diode and 1K
> resistor to inprove saturation and drive bigger motors. I will send you a
> little schematic of that in a couple of hours.
>
>
> Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
> tel: (604)590-7493
> fax: (604)590-3411
>
> -----Original Message-----
> From: Nigel Joyce [SMTP:nigel.joyce@qr.com.au]
> Sent: Monday, May 10, 1999 6:30 PM
> To: Wilf Rigter
> Subject: Re: My Pagerbot
>
> Wilf,
> So the pot would go between the anode sides of the PD's which are
> in
> parallel with the feeler switches?
>
> Oh, one other question, I have not come across a site explaning the
> function of the 2.2k resistor on a SE, do you know of a site that
> explains
> this as I really want to understand the effect of small changes to
> SE's to
> suit different requirements.
>
> Thanks &
> Blue Skies
> ---Buzz---
>
> > yes, you need the pot for adjusting the FLED thresholds.
> > Let us know the result OK?
> >
> > regards
> >
> >
> > Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
> > >
> > > Ok, thanks, I will try it tonight, do you still use the pot?
> > > Blue Skies
> > > ---Buzz---
> > >
> > > > I don't know what the value of the pot is or what photodiodes
> (PD) you
> > > use
> > > > but try this: place the PDs reverse biased in parallel with
> the
> > > switches.
> > > > This means the cathode (stripe) is facing up. Depending on the
> > > sensitivity
> > > > of the PD, this should work quite well.
> > > >
> > > > enjoy
> > > >
> > > > Wilf Rigter
> > >
> > > > > OK Guy's
> > > > > Here's the problem, I have to use a FLED photopopper circuit
> because
> > > of
> > > > > the shortage of 1381's in this part of the world };-) the 1
> I used
> > > looks
> > > > > like this.
> > > > >
> > > > > << File: FLEDPV.gif >>
> > > > > In the picture from my previous post on this thread, you see
> the
> solar
> > > > > panel, it is from a calculator and produces about 2.3v. now
> the FLED
> > > > > won't fire at that voltage or the charge rate is too slow to
> fire
> > > > > the FLED, combined with that is the "eyes" (in the above
> pic, the
> eyes
> > > are
> > > > > next to the pot), which are in series with the FLED raising
> the
> total
> > > > > threshold voltage to about 3.1v (about 2.4v for the FLED +
> about
> 0.7v
> > > for
> > > > > the IR Detecting Diodes) Now as you can see that won't work
> because
> > > the
> > > > > solar panel never reaches that high. Is there any way I can
> Lower
> the
> > > > > threshold voltage to about a total of 2.0v ?
> > > > > Note: I may not have the jargon right, but I know what I
> mean };-)
> > > > > Thanks and
> > > > > Blue Skies
> > > > > ---Buzz---
> > > > >
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