[Milsurplus] Parallel Zeners

[Jim Whartenby]

Just about unlimited power dissipation in a simple Zener shunt regulator circuit is achieved by adding your favorite NPN power transistor.   Again see: https://makingcircuits.com/blog/how-to-increase-power-rating-of-zener-diodes/

Since all reversed PN junctions seem to be decent noise sources, a third (or fourth) component should be bypass capacitors, one for DC and another for RF.

I assume that David is looking at high voltage applications since he could have used a TO-220 style series pass regulator IC for anything below 125 volts and get much better regulation, 0.3% is advertised for the TL783.
Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.  Murphy

-----Original Message-----
From: Kenneth G. Gordon <kgordon2006 at frontier.com>
To: milsurplus at mailman <milsurplus at mailman.qth.net>; David Stinson <arc5 at ix.netcom.com>
Sent: Wed, Jul 27, 2022 12:12 pm
Subject: Re: [Milsurplus] Parallel Zeners

On 27 Jul 2022 at 6:56, David Stinson wrote:

> If one carefully matches forward conduction impedance,
> can one parallel zeners to achieve higher dissipation?

Although, in my opinion, it MAY be possible, I would not attempt it.

Although Zeners may be viewed as solid-state versions of VR tubes to a certain extent, they 
are far better voltage regulators than VR tubes.

One can parallel VR tubes by using small-value resistors at each tube...which, of course, 
makes the regulation percentage a bit worse, but I doubt that this method would work with 
Zeners.

Even so, I much prefer VR tubes to Zeners for most applications, mainly due to the pretty 
colors. :-)

And their regulation is good enough for most purposes.

Ken W7EKB
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