Line powered audio switch, getting there it seems

OBones wrote:

Hi all

A few days ago, I started a thread to ask if it would be feasible to
create a line powered audio switch connecting one stereo output to
either of two inputs.
After a nice discussion with many people, I came up with a schematic
that is available at this address:

http://obones.com/index.php?module=article&view=7

Along with it is the detail the working principle, as I understand it.
Could anyone be kind enough to have a look at this and comment on it?
I would very much appreciate feedback from more experienced designers.
Click to expand...
Look Here !

You reckon you can draw 1mW from the audio line. Your loony 'active
rectifier' will *consume* more power than that - even if it worked - which
it won't

Nor is 1 mW capable of driving a relay.

Get real !

Bye bye......


Graham
 
I read in sci.electronics.design that Jonathan Westhues
<please-see-website@nospam.com> wrote (in
<QHcce.10233$BW6.1027249@news20.bellglobal.com>) about 'Line powered
audio switch, getting there it seems', on Thu, 28 Apr 2005:
The OP213 still draw 3 mA/amplifier. That corresponds to a 6 V drop
across R4...
Click to expand...
It's not a good choice. A TL062 might well be better, but there are
several even more economical.
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
I read in sci.electronics.design that Pooh Bear
<rabbitsfriendsandrelations@hotmail.com> wrote (in
<4271D294.CBF5BF87@hotmail.com>) about 'Line powered audio switch,
getting there it seems', on Fri, 29 Apr 2005:
You reckon you can draw 1mW from the audio line. Your loony 'active
rectifier' will *consume* more power than that - even if it worked -
which it won't

Nor is 1 mW capable of driving a relay.
Click to expand...
You have not taken the * energy storage* into account. 1 mW for 1000
seconds is 1 joule. Discharge 1 joule in 1 second and you have 1 watt.
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
John Woodgate wrote:

I read in sci.electronics.design that Jonathan Westhues
please-see-website@nospam.com> wrote (in
QHcce.10233$BW6.1027249@news20.bellglobal.com>) about 'Line powered
audio switch, getting there it seems', on Thu, 28 Apr 2005:

The OP213 still draw 3 mA/amplifier. That corresponds to a 6 V drop
across R4...


It's not a good choice. A TL062 might well be better, but there are
several even more economical.
Click to expand...
Ok, something like the LMV301, http://www.national.com/ds/LM/LMV301.pdf
Considering I'm using one with low input current, would the rest of this
work?
 
John Woodgate wrote:

I read in sci.electronics.design that Pooh Bear
rabbitsfriendsandrelations@hotmail.com> wrote (in
4271D294.CBF5BF87@hotmail.com>) about 'Line powered audio switch,
getting there it seems', on Fri, 29 Apr 2005:
You reckon you can draw 1mW from the audio line. Your loony 'active
rectifier' will *consume* more power than that - even if it worked -
which it won't

Nor is 1 mW capable of driving a relay.

You have not taken the * energy storage* into account. 1 mW for 1000
seconds is 1 joule. Discharge 1 joule in 1 second and you have 1 watt.
Click to expand...
Actually, I had considered it. To make use of the energy storage effect
you'd have to use one of those clever relays that only needs to be pulsed
to change state.

Anyone recall if they have a specific name ?

You've still got a problem with the op-amp consuming > 1mW. Even the low
power types I know of can't do that.

Graham
 
In article <42728916.51FCE746@hotmail.com>,
rabbitsfriendsandrelations@hotmail.com says...
John Woodgate wrote:

I read in sci.electronics.design that Pooh Bear
rabbitsfriendsandrelations@hotmail.com> wrote (in
4271D294.CBF5BF87@hotmail.com>) about 'Line powered audio switch,
getting there it seems', on Fri, 29 Apr 2005:
You reckon you can draw 1mW from the audio line. Your loony 'active
rectifier' will *consume* more power than that - even if it worked -
which it won't

Nor is 1 mW capable of driving a relay.

You have not taken the * energy storage* into account. 1 mW for 1000
seconds is 1 joule. Discharge 1 joule in 1 second and you have 1 watt.

Actually, I had considered it. To make use of the energy storage effect
you'd have to use one of those clever relays that only needs to be pulsed
to change state.

Anyone recall if they have a specific name ?
Click to expand...
Latching relay?

You've still got a problem with the op-amp consuming > 1mW. Even the low
power types I know of can't do that.
Click to expand...
SMoE. ;-)

--
Keith
 
I read in sci.electronics.design that Pooh Bear
<rabbitsfriendsandrelations@hotmail.com> wrote (in
<42728916.51FCE746@hotmail.com>) about 'Line powered audio switch,
getting there it seems', on Fri, 29 Apr 2005:

Actually, I had considered it. To make use of the energy storage effect
you'd have to use one of those clever relays that only needs to be
pulsed to change state.
Click to expand...
That's what the OP has.
Anyone recall if they have a specific name ?
Click to expand...
Trace the thread back.
You've still got a problem with the op-amp consuming > 1mW. Even the
low power types I know of can't do that.
Click to expand...
The op-amps run from the energy stored in the filter cap of the
half-wave rectifier. That's there all the time the audio is present,
after the initial charging period.
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
On Fri, 29 Apr 2005 08:08:01 +0100, John Woodgate wrote:

I read in sci.electronics.design that Pooh Bear
rabbitsfriendsandrelations@hotmail.com> wrote (in
4271D294.CBF5BF87@hotmail.com>) about 'Line powered audio switch,
getting there it seems', on Fri, 29 Apr 2005:
You reckon you can draw 1mW from the audio line. Your loony 'active
rectifier' will *consume* more power than that - even if it worked -
which it won't

Nor is 1 mW capable of driving a relay.

You have not taken the * energy storage* into account. 1 mW for 1000
seconds is 1 joule. Discharge 1 joule in 1 second and you have 1 watt.
Click to expand...
And what about those <<.1 Vf MOSFET rectifier simulators?

Thanks,
Rich
 
John Woodgate wrote:

Anyone recall if they have a specific name ?

Trace the thread back.
Click to expand...
Latching, it's indicated beneath it ;-)


You've still got a problem with the op-amp consuming > 1mW. Even the
low power types I know of can't do that.

The op-amps run from the energy stored in the filter cap of the
half-wave rectifier. That's there all the time the audio is present,
after the initial charging period.
Click to expand...
Actually, I was thinking, how could the C1 capacitor charge up if the
OpAmp is already pumping current?
Wouldn't it be better to add a 5.6V Zener diode in series opposition at
the exit of C1?
This way, if I'm correct, Vcc will only go from 0 to +5v (approx), when
the capacitor is charged enough.
Hum... That puts the risk of turning off the whole supply. I'm reaching
the limits of my low-power knowledge here. Could anyone help out?
Rest assured that I very much appreciate all the help I've gotten so far.

Cheers
Olivier
 
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