Bruno Putzeys' reference UcD amplifier

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nilsomat

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Joined 2005
Hello everyone, i found a really interesting information about Bruno Putzey's (inventor of UcD) own selfbuilt amplifier on the hypex homepage:

--snip--
Two UcD modules on a mainboard. Input buffering is fully discrete and dozens of LED's act as stable, low noise zener diodes. In fact, Bruno once said that he could read the newspaper by just lifiting the cover of the amplifier ;-)

There are no regular voltage regulators to be found inside. A couple of fully discrete circuits (lots of LED's) provide a very low noise, high PSRR power supply. Bruno found regular zener diodes to be far too noisy for this purpose.
--snip--

Does anyone know how to implement input buffering and voltage regulation with LEDs?? Hey, this might also look cool :)

Greetings,
Nils
 
G

ghemink

Member
Joined 2004
nilsomat said:
Hello everyone, i found a really interesting information about Bruno Putzey's (inventor of UcD) own selfbuilt amplifier on the hypex homepage:

--snip--
Two UcD modules on a mainboard. Input buffering is fully discrete and dozens of LED's act as stable, low noise zener diodes. In fact, Bruno once said that he could read the newspaper by just lifiting the cover of the amplifier ;-)

There are no regular voltage regulators to be found inside. A couple of fully discrete circuits (lots of LED's) provide a very low noise, high PSRR power supply. Bruno found regular zener diodes to be far too noisy for this purpose.
--snip--

Does anyone know how to implement input buffering and voltage regulation with LEDs?? Hey, this might also look cool :)

Greetings,
Nils
Click to expand...


About input buffering with LEDs I don`t know. However for voltage regulation, in a position where you would normally use a zenerdiode, you would put a number of LEDs in series until you get the desired voltage over that stack of LEDs.

Gertjan
 
Alfetta87

Alfetta87

Member
Joined 2003
revivalaudio.fr
nilsomat said:
Hello everyone, i found a really interesting information about Bruno Putzey's (inventor of UcD) own selfbuilt amplifier on the hypex homepage:

--snip--
Two UcD modules on a mainboard. Input buffering is fully discrete and dozens of LED's act as stable, low noise zener diodes. In fact, Bruno once said that he could read the newspaper by just lifiting the cover of the amplifier ;-)

There are no regular voltage regulators to be found inside. A couple of fully discrete circuits (lots of LED's) provide a very low noise, high PSRR power supply. Bruno found regular zener diodes to be far too noisy for this purpose.
--snip--

Does anyone know how to implement input buffering and voltage regulation with LEDs?? Hey, this might also look cool :)

Greetings,
Nils
Click to expand...

Why don't you ask Bruno directly? I'm sure he'll give some info
 
C

classd4sure

Disabled Account
Joined 2004
diyaudio.com
anant_narayan said:
LED's are used as a voltage reference. Combining with a transistor it forms a Constant current souce. This is a common scheme in any amplifier at the input stage where the compartor transistors need to be fed with a constant current source.
Click to expand...


I think that's just one example of its use as a voltage reference.

What we should look at it is why it's possibly a better voltage reference than say, a zener for instance. Is it better than better than a proper reference as well? Or possibly just a quick and easy/cheap way of attaining a reasonable reference, without say resorting to band gaps etc.
 
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T0kiman

Member
Joined 2005
If i'm not mistaking they wrote something about Bruno finding the zeners much to noise for the purpose they were used in. With this in mind i thought he must not be the only one thinking of this. I stumbled on an article of maxim where they use a zener as a white noise generator. The noise is created by the reverse breakdown process wich, for zeners with reverse voltages greater than 5.6V, is called avalanche breakdown. This is a random process of collisions of moving free carriers in the depletion region and fixed atoms. I can imagin that this process creates noise of some sort. I could be wrong to:).

Also maybe a good question to ask is how much the zener voltage is dependent of temperature and power supply changes comparing to a normal led.

regards,

Thomas
 
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nilsomat

Member
Joined 2005
Lenz mailed me (thank you!) an article about LEDs as a constant current source. Since the article is in german and even though i am german i hardly understand it i probably shouldn't be the one to translate it here. I could post some (easy) schematics (but only next week) if anyone is interested.
 
Eva

Eva

Member
Joined 2003
Some time ago, somebody did quite extensive LED and Zener noise and impedance measurements and published the results in some forgotten thread. The author was quite shy at making conclusions, but his measurements clearly showed the zeners below 8v2 or 10V (I don't remember exactly) to be the noisy ones, and the zeners above 8v2 or 10V to perform much better than the equivalent string of leds both in terms of noise and impedance.

The results also suggested that some colours and sizes of LEDs are noisier than others.
 
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