I'm having to build up an audio amplifier to boost the signal from my DVD
player, connected in-line in the audio lead (phono) between the DVD player
and the TV. I gather that the normal signal level is 0.5Vrms and the input
impedance of the TV audio input should be 10k (presumably at 1kHz?). It
would be very convenient for me to leave the dc (around 6V wrt the signal
return) rather than connect via a capacitor....is the TV certain to have
it's own dc block? It is reading off-scale ohms on my DMM. The TV is a
United Kingdom PAL model,
combo, Ferguson, 14" new, with dual tuner (don't know the model without
uninstalling it from the cabinet which takes some time).

Many thanks for the help, David

I'm having to build up an audio amplifier to boost the signal from my DVD
player, connected in-line in the audio lead (phono) between the DVD player
and the TV. I gather that the normal signal level is 0.5Vrms and the
input
impedance of the TV audio input should be 10k (presumably at 1kHz?). It
would be very convenient for me to leave the dc (around 6V wrt the signal
return) rather than connect via a capacitor....is the TV certain to have
it's own dc block? It is reading off-scale ohms on my DMM. The TV is a
United Kingdom PAL model,
combo, Ferguson, 14" new, with dual tuner (don't know the model without
uninstalling it from the cabinet which takes some time).

Many thanks for the help, David



What kind of amplifier?
Is it a single transistor, in common emitter configuration?
Why can't you include a coupling capacitor from the collector?

Above all, why do you need it in the first place? Is there a level
discrepancy?

Graham.

%Profound_observation%

What kind of amplifier?
Is it a single transistor, in common emitter configuration?
Why can't you include a coupling capacitor from the collector?

Above all, why do you need it in the first place? Is there a level
discrepancy?

Thanks for your reply,

I live on a boat and have a number of things that I want to feed into the AV
input of the TV and the levels need tweaking. I'm just going to use a 741
op amp with suitable gain adjust and I have all the bits I need to do that
without ordering anything - except a suitable coupling capacitor. Where I
am, I would have to take a day out to buy one or mail order one from
Maplin - one capacitor is going to cost quite a lot and with the Christmas
post I won't get it working till Xmas Eve anyway! I rather suspect that the
TV audio input jack has a dc block because it reads infinity on my DMM but I
haven't played around with TV AV inputs for many years and I don't know what
the manufacturers are tending to do these days. Is the figure of 0.5V rms,
at Zi10k correct, do you know?