Negative voltage regulator.

  • Thread starter Tesladude
  • Start date
  • #1
168
1

Main Question or Discussion Point

So for a power supply project I need a voltage regulator giving me a positive output at around 40v.
Obsessively you can not buy these, So i am useing a circuit which consists of a resistor, npn transistor, and zener diode. the positive input goes to the collector of the transistor and through the resistor to the base of the transistor, and a zener diode of 39v is on the base to ground. Then my output is the emitter. This works fine, but...

As some of you may know I do a lot in audio and need a negative voltage regulator for the split audio power supply, is there a modification I need to do to make this the same thing just as a negative voltage regulator?

Also what the heck does a negative voltage regulator do anyway? I understand a positive obsessively but am not sure about the negative.
 

Answers and Replies

  • #2
NascentOxygen
Staff Emeritus
Science Advisor
9,244
1,072
So for a power supply project I need a voltage regulator giving me a positive output at around 40v.
Obsessively you can not buy these
LM723, positive voltage regulator (linear)

Also what the heck does a negative voltage regulator do anyway?
If you have a negative voltage supply and it varies a bit, the regulator delivers you part of that, but fixed at a steady value. A handy circuit to have. :smile:

Not much different from how the positive voltage regulator works, really. :wink:
 
Last edited:
  • #3
meBigGuy
Gold Member
2,323
405
LM317 can be had for 57 volts

http://www.mouser.com/ProductDetail/Texas-Instruments/LM317HVT-NOPB/?qs=sGAEpiMZZMug9GoBKXZ75%252bmFNJYHX7LMu0gFc3QRd28%3d [Broken]

there are lots of high voltage regulators.

negative voltage regulators regulate a negative voltage relative to ground. -40V in, -12v Out, for example. You can't just hook -40V into a positive regulator. (can't take the input below ground without destroying it --- look at the absolute max specs for the input voltage range)
 
Last edited by a moderator:
  • #4
168
1
do you have a variable negative regulator? also will this give me 3a of current.

The info you guys have given me helps but my first question was never answered, do you guys know?
 
  • #5
meBigGuy
Gold Member
2,323
405
You didn't say 3 amps. Any other secret specifications?
Using a zener diode and emitter follower is sloppy. google "lm317 current booster" for a better controlled supply architecture. You can use any regulator. I'll let you figure out the negative supply stuff.
 
  • #6
168
1
that helped thanks
 
  • #7
77
4
Nagative Voltage Regulator

The Negative regulated power supply provides for the negative half cycle of a the audio sine wave. It is typical for audio amps to be powered by positive and negative supplies to produce high fidelity reproduction.
An LM723 is typically a 10 pin positive regulator with an output current of 150mA...it is used with lots of peripheral components to make fine precision power supplies.
If you have a solid dc source that provides +40V and -40V with respect to common you can use positive and negative 3 terminal regulators with some peripheral components to provide the voltage and current that you need.
 

Related Threads on Negative voltage regulator.

Replies
2
Views
12K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
3
Views
5K
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
23
Views
8K
  • Last Post
Replies
9
Views
3K
  • Last Post
Replies
3
Views
3K
  • Last Post
Replies
3
Views
1K
  • Last Post
Replies
11
Views
4K
  • Last Post
Replies
1
Views
4K
Top