Alt-BEAM Archive
Message #03222
To: "Wilf Rigter" Wilf.Rigter@powertech.bc.ca
From: "Nigel Joyce" nigel.joyce@qr.com.au
Date: Thu, 13 May 1999 11:23:37 +1000
Subject: [alt-beam] Re: My Pagerbot
content-type: multipart/alternative;
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Hey Wilf,
So to take that circuit you sent, and add the stuff you told me about earli=
er the =
improved FLED photovore would look like this?
Sorry about the quality, I have to draw and scan.
Is this what you meant with the reverse leakage of the photodiodes?
Thanks for all your help
---Buzz---
> Hi Nigel.
> =
> > Here is a little reworked FLED circuit I call the XLED (cause it's a cr=
oss
> > of many prior FLED circuits ) . I have not tested it but it should wo=
rk
> > . 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
> > The pot goes between the cathodes and the anodes go to gnd. The switche=
s
> > go across the PDs. The PD no operates in the reverse leakage mode and t=
he
> > PD with the highest leakage (light) will cause that SE to fire first. T=
he
> > 2.2K resistor has two effects during charging it acts like a load resis=
tor
> > 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 t=
he
> > base current for the 2N3906.You can improve the performance by replacin=
g
> > 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
> > 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.
> > =
> > ---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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>
src=3D"cid:00b201be9cdf$3a532480$8d3e580a@qrail.com.au">
Sorry about the quality, I have to draw and scan.
>
Is this what you meant with the reverse leakage of the =
photodiodes?
Thanks for all your help
---Buzz---
> Hi Nigel.
>
> > Here is a little r=
eworked =
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
&g=
t; =
> . The 1K resistor can be adjusted for motor (size) inrush current
&=
gt; =
> requirements and the 10K resistor can be adjusted more or less
>=
> =
independendly to set the sensitivity. Using a diode makes the dropout
&g=
t; =
> voltage about 1.5V and the LED about 2.1V
> >
> =
regards
> > Wilf Rigter
href=3D"mailto:wilf.rigter@powertech.bc.ca">mailto:wilf.rigter@powertech.bc=
.ca
size=3D2>
> > The pot goes between the cathodes and the ano=
des 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 (ligh=
t) =
will cause that SE to fire first. The
> > 2.2K resistor has two ef=
fects =
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
> > b=
ase =
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
&g=
t; =
> resistor in parallel with both. The cathode of the diode goes to =
the
> > collector of the 2N3904. Now the loading during charging i=
s 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 bigg=
er =
motors. I will send you a
> > little schematic of that in a couple=
of =
hours.
> >
> > Wilf Rigter
href=3D"mailto:wilf.rigter@powertech.bc.ca">mailto:wilf.rigter@powertech.bc=
.ca
> > Wilf,
> > So the pot would go betwee=
n the =
anode sides of the PD's which are
> > in
> > parall=
el =
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 o=
f =
small changes to
> > SE's to
> > suit different =
requirements.
> >
> > ---Buzz---
> >
> &=
gt; =
> yes, you need the pot for adjusting the FLED thresholds.
> > =
> =
Let us know the result OK?
> > >
> > > regards
&=
gt; =
> > Wilf Rigter
href=3D"mailto:wilf.rigter@powertech.bc.ca">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
> > > >
> > > > &g=
t; =
> OK Guy's
> > > > > > Here's the problem, I have t=
o use =
a FLED photopopper circuit
> > because of
> > > > &=
gt; =
> the shortage of 1381's in this part of the world };-) the 1
> &g=
t; 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 f=
rom 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, combi=
ned =
with that is the "eyes" (in the above
> > pic, the eyes =
are
> > > > > > next to the pot), which a=
re 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) No=
w as =
you can see that won't work
> > because the solar panel never reac=
hes =
that high. Is there any way I can
> > Lower the
> > > =
> =
> > threshold voltage to about a total of 2.0v ?
> > > &g=
t; =
> > Note: I may not have the jargon right, but I know what I
> =
> =
mean };-)
> > > > > > Thanks and
> > > >=
; =
> > Blue Skies
> > > > > > =
---Buzz---
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Groups.com/group/alt-beam
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