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Re: Video circuit working but dark
Some Pics Paul ;-)))
Well done Dan ;-))
Frank
----- Original Message -----
From: "Paul" <groups@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Saturday, May 24, 2003 9:30 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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