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Re: Video circuit working but dark
Hi,
Nice to hear good news..;-)
Check the cabling to prevent ground loops. This can be the cause of the
noise you have.
Good luck,
Dan
----- Original Message -----
From: "Paul" <groups@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Saturday, May 24, 2003 2:30 PM
Subject: RE: [ukha_d] Video circuit working but dark
> Excellent!
>
> Thanks Dan, that did the trick. Perfect output now (a miniscule amount
of
noise but that's due to the fact that the circuit is on a breadboard I
think)
>
> Paul.
>
> > -----Original Message-----
> > From: Dan [mailto:dtoma@xxxxxxx]
> > Sent: 24 May 2003 12:19
> > To: ukha_d@xxxxxxx
> > Subject: Re: [ukha_d] Video circuit working but dark
> >
> > Hi Paul,
> >
> > Have you checked the form of the sugnal with an oscyloscope?
> > The black level can be to low comparing with the original or the
signal
is
> > attenuated in your circuit.
> > In my opinion, R8 and R9 are to big for this circuit.
> > They must be maximum 1K.
> > You must have an output impedance of the circuit near 0 in order
to
> > increase
> > it at 75 ohm using the R10-R12 resistors.
> > Try to decrease the value of R8 and R9 to 1K and see what's
happen.
> >
> > BR,
> > Dan
> > ----- Original Message -----
> > From: "Paul" <groups@xxxxxxx>
> > To: <ukha_d@xxxxxxx>
> > Sent: Saturday, May 24, 2003 12:38 PM
> > Subject: [ukha_d] Video circuit working but dark
> >
> >
> > > Having played a lot with the resistor values - I've got a
working
> > circuit
> > but it still lacks overall brightness (has a 'greyish' quality to
the
> > picture). Increasing the gain washes out whites but the overall
picture
is
> > still reasonably dark. Saturation of colours is good though.
> > >
> > > Any ideas - Keith?
> > >
> > > Paul.
> > >
> > > > -----Original Message-----
> > > > From: Paul [mailto:groups@xxxxxxx]
> > > > Sent: 23 May 2003 22:35
> > > > To: ukha_d@xxxxxxx
> > > > Subject: RE: [ukha_d] Heeeeeeeeelp! - got somewhere!
> > > >
> > > > Got a picture but it's quite 'grey' and needs to be
brighter. How
much
> > of
> > > > this might be down to long lead lengths (as it's on
breadboard)? The
> > > > capacitors between the power supply pins of the op amp
and GND are
> > close
> > > > to the IC but have quite long leads to GND - would this
make a
> > difference?
> > > >
> > > > As to shielding of the incoming/outgoing signal cables
- should they
> > be
> > > > connected to AC GND or the common of the PSU?
> > > >
> > > > Should they also be shielded as close to the PCB as
possible?
> > > >
> > > > Ta,
> > > >
> > > > Paul.
> > > >
> > > > > -----Original Message-----
> > > > > From: Frank Mc Alinden [mailto:fmcalind@xxxxxxx]
> > > > > Sent: 23 May 2003 22:20
> > > > > To: ukha_d@xxxxxxx
> > > > > Subject: Re: [ukha_d] Heeeeeeeeelp! - got
somewhere!
> > > > >
> > > > > Hi Paul
> > > > > What exactly are you making ?? sounds
interesting..
> > (nosey
> > > > > frank) ;-))
> > > > >
> > > > > Frank
> > > > > ----- Original Message -----
> > > > > From: "Paul" <groups@xxxxxxx>
> > > > > To: <ukha_d@xxxxxxx>
> > > > > Sent: Saturday, May 24, 2003 7:17 AM
> > > > > Subject: RE: [ukha_d] Heeeeeeeeelp! - got
somewhere!
> > > > >
> > > > >
> > > > > Ahhh - I did have one of the transistors connected
wrong - the
> > datasheet
> > > > > from RS was the wrong one!
> > > > >
> > > > > Now I need to fine tune the output which is a bit
odd brightness
and
> > > > > colour
> > > > > wise.
> > > > >
> > > > > I've got a tant cap on the input side and a 5K
trimmer instead of
> > 2K5 -
> > > > > will
> > > > > this make a difference?
> > > > >
> > > > > Thanks Keith and Dan!!!
> > > > >
> > > > > Paul.
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: Paul [mailto:groups@xxxxxxx]
> > > > > > Sent: 23 May 2003 21:34
> > > > > > To: Dan
> > > > > > Cc: ukha_d@xxxxxxx
> > > > > > Subject: RE: [ukha_d] Heeeeeeeeelp!
> > > > > >
> > > > > > When I disconnect pin 1 (pin6 on the old
part) (output) - it's
at
> > > > 10.5V
> > > > > -
> > > > > > is this what you'd expect?
> > > > > >
> > > > > > Paul.
> > > > > >
> > > > > > > -----Original Message-----
> > > > > > > From: Dan [mailto:dtoma@xxxxxxx]
> > > > > > > Sent: 23 May 2003 21:11
> > > > > > > To: Paul
> > > > > > > Subject: Re: [ukha_d] Heeeeeeeeelp!
> > > > > > >
> > > > > > > Hi Paul,
> > > > > > >
> > > > > > > It seems to be a problem with the
transistors.
> > > > > > > Disconnect pin 6 of the CI and check if
then it is at 0V.
> > > > > > > If yes, then you must check the two
transistors.
> > > > > > > Usually they must be pairs (the same
beta factor and the same
> > > > > > > characteristic in order to correctly
balance the push-pull
> > output.
> > > > One
> > > > > > > good
> > > > > > > indication that something is wrong with
them is that the
> > resistance
> > > > > > > bewteen
> > > > > > > E-C is measurable (it must be allmost
infinite if the base is
> > not
> > > > > > > connected).
> > > > > > >
> > > > > > >
> > > > > > > BR,
> > > > > > > Dan
> > > > > > > ----- Original Message -----
> > > > > > > From: "Paul"
<paul@xxxxxxx>
> > > > > > > To: "Dan"
<dtoma@xxxxxxx>
> > > > > > > Sent: Friday, May 23, 2003 10:55 PM
> > > > > > > Subject: RE: [ukha_d] Heeeeeeeeelp!
> > > > > > >
> > > > > > >
> > > > > > > > Oh, and I'm not sure what you mean
by " check if one of the
R6
> > or
> > > > R7
> > > > > > > resistors is not interrupted"?
> > > > > > > >
> > > > > > > > Paul.
> > > > > > > >
> > > > > > > > > -----Original Message-----
> > > > > > > > > From: Dan [mailto:dtoma@xxxxxxx]
> > > > > > > > > Sent: 23 May 2003 19:40
> > > > > > > > > To: ukha_d@xxxxxxx
> > > > > > > > > Subject: Re: [ukha_d]
Heeeeeeeeelp!
> > > > > > > > >
> > > > > > > > > Hi Paul,
> > > > > > > > >
> > > > > > > > > Check the following points:
> > > > > > > > > - IC1-pin 2, 3 and 6 to be as
near as 0V as possible
> > (without
> > > > any
> > > > > > > input
> > > > > > > > > signal)
> > > > > > > > > - direct voltage on each of
the two diodes(D1 and D2)...
it
> > must
> > > > > be
> > > > > > > around
> > > > > > > > > 0.6V
> > > > > > > > > - check if one of the R6 or R7
resistors is not interupted
> > > > > > > > > - check the polarity of the
two diodes.
> > > > > > > > > If something different, send
me a mail.
> > > > > > > > >
> > > > > > > > > I don't know EL2244C... you're
sure that it is compatible
> > with
> > > > > > CA3100
> > > > > > > ?
> > > > > > > > > The rest of the substitutions
are not important.
> > > > > > > > >
> > > > > > > > > BR,
> > > > > > > > > Dan
> > > > > > > > >
> > > > > > > > > ----- Original Message -----
> > > > > > > > > From: "Paul"
<groups@xxxxxxx>
> > > > > > > > > To: <ukha_d@xxxxxxx>
> > > > > > > > > Sent: Friday, May 23, 2003
8:39 PM
> > > > > > > > > Subject: RE: [ukha_d]
Heeeeeeeeelp!
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > > I'm building the
following circuit:
> > > > > > > > > >
> > > > > > > > > > http://home.maine.rr.com/randylinscott/jan98.htm
> > > > > > > > > >
> > > > > > > > > > But with the following
substitutions:
> > > > > > > > > >
> > > > > > > > > > IC1 CA3100 (single opamp)
changed to EL2244C (dual opamp
> > > > > package)
> > > > > > > > > > Q1 2N3053 (Gen purpose
NPN transistor) changed to BC182L
> > > > > > > > > > Q2 2N4037 (Gen purpose
PNP transistor) changed to BC212
> > > > > > > > > > D1 1N914 (small signal
Diode) changed to 1N4148
> > > > > > > > > >
> > > > > > > > > > R3 is a 5K trimmer rather
than 2K5 specified (is this a
> > > > > problem?)
> > > > > > > > > >
> > > > > > > > > > I'm using an ATX PC PSU
as the +12V and -12V source with
> > the
> > > > > > common
> > > > > > > > > connection connected to the
ground points on the circuit
(is
> > > > this
> > > > > > > right?).
> > > > > > > > > The PSU has slightly different
voltages (+12V is something
> > like
> > > > > > +11.4V
> > > > > > > > > and -12V is actually -11.04V).
> > > > > > > > > >
> > > > > > > > > > When I connect up the
circuit, it doesn't work and the
> > > > > transistors
> > > > > > > and
> > > > > > > > > IC
> > > > > > > > > get very hot!
> > > > > > > > > >
> > > > > > > > > > I'm treble checking the
circuit. Any thoughts?
> > > > > > > > > >
> > > > > > > > > > Thanks,
> > > > > > > > > >
> > > > > > > > > > Paul.
> > > > > > > > > >
> > > > > > > > > > > -----Original
Message-----
> > > > > > > > > > > From: Dan [mailto:dtoma@xxxxxxx]
> > > > > > > > > > > Sent: 23 May 2003
18:14
> > > > > > > > > > > To: ukha_d@xxxxxxx
> > > > > > > > > > > Subject: Re:
[ukha_d] Heeeeeeeeelp!
> > > > > > > > > > >
> > > > > > > > > > > Hi Paul,
> > > > > > > > > > >
> > > > > > > > > > > Transistor from
what???
> > > > > > > > > > > Or ...just a simple
transistor?
> > > > > > > > > > > :-)
> > > > > > > > > > > Dan
> > > > > > > > > > > ----- Original
Message -----
> > > > > > > > > > > From:
"Paul" <groups@xxxxxxx>
> > > > > > > > > > > To:
<ukha_d@xxxxxxx>
> > > > > > > > > > > Sent: Friday, May
23, 2003 7:46 PM
> > > > > > > > > > > Subject: [ukha_d]
Heeeeeeeeelp!
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > > Anyone with
electronics experience – I need help
> > (please!)
> > > > > > > > > > > >
> > > > > > > > > > > > My transistors
are cooking!
> > > > > > > > > > > >
> > > > > > > > > > > > Anyone?
> > > > > > > > > > > >
> > > > > > > > > > > > Paul.
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > ** UKHA2004 BE
THERE! ** - start planning now.
> > > > > > > > > > > >
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