Using a zener diode as voltage reference with variable voltage regulators

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ginetto61

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Joined 2009
Hi,
I am looking for schematics of regulated power supply where the voltage reference is a zener diode.:eek:
More in particular I would like to build a +60V power supply using the TL783.
Is this an insane idea ? will I get low residual ripple ?:confused:
Thanks to everyone and kind regards,

ginetto :D
 
jan.didden

jan.didden

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Joined 2002
linearaudio.net
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ginetto61 said:
Hi,
I am looking for schematics of regulated power supply where the voltage reference is a zener diode.:eek:
More in particular I would like to build a +60V power supply using the TL783.
Is this an insane idea ? will I get low residual ripple ?:confused:
Thanks to everyone and kind regards,

ginetto :D
Click to expand...

Confusing. What is your priority: using a zener, or using the 783, or low ripple (or maybe low impedance?)

jd
 
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ginetto61

Member
Joined 2009
Actually I am thinking at a solution like that one attached with the TL783 in place of the tip29:confused:
In this way I could go without the RC filters
Is it feasible ?:rolleyes:
thanks and regards,
ginetto:D
 

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Elvee

Elvee

Member
Joined 2006
If you want something simple and effective, the TL783 is certainly the way to go: you just need two additional resistors, and it will amply outclass any simple zener-based regulator.
The ripple rejection will be close to 80dB, meaning that a 6V input ripple will translate into ~1mV at the output.
If you find this insufficient, you may try to bypass the adjustment terminal, although it is not recommended, and requires some precautions.
Alternatively, you may add a gyrator at the input, or use other similar ripple-reduction techniques.
 
jan.didden

jan.didden

AX tech editor
Joined 2002
linearaudio.net
Paid Member
ginetto61 said:
Actually I am thinking at a solution like that one attached with the TL783 in place of the tip29:confused:
In this way I could go without the RC filters
Is it feasible ?:rolleyes:
thanks and regards,
ginetto:D
Click to expand...

This is not a regulator but just an emitter follower, it has no active regulation. It will always have higher ripple and higher Zout that a real regulator like the 783. There are app examples in the 783 data sheet, that would be your best bet.

jd
 
G

ginetto61

Member
Joined 2009
Elvee said:
If you want something simple and effective, the TL783 is certainly the way to go: you just need two additional resistors, and it will amply outclass any simple zener-based regulator.
The ripple rejection will be close to 80dB, meaning that a 6V input ripple will translate into ~1mV at the output.
If you find this insufficient, you may try to bypass the adjustment terminal, although it is not recommended, and requires some precautions.
Alternatively, you may add a gyrator at the input, or use other similar ripple-reduction techniques.
Click to expand...

Thank you so much !
I think that a ripple rejection be close to 80dB is so much more than what I hoped.
Kind regards,
ginetto
 
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ginetto61

Member
Joined 2009
Salas said:
I would not chain 6 Zeners, the normal non compensated parts available to us are very noisy.
Use a 6mA Idss Jfet and a 10k 1W resistor for a 60V Vref instead.
Will do much, much better.
Click to expand...

Thanks a lot for your suggestion.
As I am a very beginner I will try one of the schematic on the tl783 data sheet
I am afraid to complicate the schema for now
Actually I did the Pass power supply, but for some reason it did not convince me completely
Kind regards,
ginetto
 
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Gordy

Disabled Account
Joined 2006
ginetto61 said:
Actually I was thinking about replacing the tip29 with a tl783 in the following schema
http://cygnus.ipal.org/mirror/www.passlabs.com/images/zenbrde2.jpg
could it work ?
suggestions are very welcome and appreciated
regards
ginetto
Click to expand...

If you have little experience, then start with that open-loop voltage stabiliser and do not change anything. Use it as it is drawn. It is not perfect, but will work fine. Get it working before thinking about any changes.

However if you want better performance (lower noise, etc.) then use the TL783 as per the datasheet. Read the entire datasheet before using the part! I recommend using it according to Figure 17 on page 10.

Here is the datasheet: http://www.datasheetcatalog.org/datasheet/texasinstruments/tl783.pdf

You might need a heatsink.

...
 
Last edited:
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ginetto61

Member
Joined 2009
Gordy said:
If you have little experience, then start with that open-loop voltage stabiliser and do not change anything. Use it as it is drawn.
It is not perfect, but will work fine.
Get it working before thinking about any changes....
Click to expand...

Thank you very much for your kind suggestion
I would like to explain better
actually I did the power supply as per Mr. Pass schematic.
Not bad but ...
Then I tried a kit based on a LM317 modified to get 60V at the output
My modification was bad, and after let's say 10 minutes the regulator broke.
But for those few minutes I heard a much better sound from a Bride of Zen line preamp

However if you want better performance (lower noise, etc.) then use the TL783 as per the datasheet.
Read the entire datasheet before using the part! I recommend using it according to Figure 17 on page 10.
Here is the datasheet: http://www.datasheetcatalog.org/datasheet/texasinstruments/tl783.pdf
You might need a heatsink. ...
Click to expand...

Thanks again for your directions.
To be perfectly honest I have not abandoned the idea of using (in the right way of course) a LM317 to do the same job.
But I understand that this task is not that easy as I hoped.
The LM317 is so much common in the shops.
I went today to RS but the tl783 is available only on order.
Are you saying that it would be much better to leave the 317 for low voltages and to direct me without any other rambling to the TL783 ?
Just to give a clear view I was not able to build the BOZ.
A friend made it for me.
I made only the power supply following the original schematic.

Just a last question: if I buy the 783 also the protection diodes IN4001 used normally with the 317 are needed ? in the same arrangement as here ?
http://www.elecfree.com/electronic/...power-supply-regulator-15v3v45v5v6v9v_15a.jpg

thank you very much indeed and best regards,
ginetto
 
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