Using a zener diode as voltage reference with variable voltage regulators

[ginetto61]

Hi,
I am looking for schematics of regulated power supply where the voltage reference is a zener diode.
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 ?
Thanks to everyone and kind regards,

ginetto

[janneman]

Originally Posted by ginetto61

Hi,
I am looking for schematics of regulated power supply where the voltage reference is a zener diode.
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 ?
Thanks to everyone and kind regards,

ginetto

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

jd

[ginetto61]

Originally Posted by janneman

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

Thanks for the very kind reply.
Actually my aim is to get low ripple 60V PS with a simple schema because I am a beginner.
it will feed a line preamp eventually
Kind regards,
ginetto

[ginetto61]

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

[ginetto61]

Actually I was thinking about replacing the tip29 with a tl783 in the following schema
http://cygnus.ipal.org/mirror/www.pa...s/zenbrde2.jpg
could it work ?
suggestions are very welcome and appreciated
regards
ginetto

[Elvee]

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.

[janneman]

Originally Posted by ginetto61

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

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

[Salas]

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.

[ginetto61]

Originally Posted by Elvee

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.

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

[ginetto61]

Originally Posted by janneman

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

Thank you very much
I will follow your suggestion.
Kind regards,
ginetto