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Diomedian 22nd May 2009 06:29 PM

Sulzer Regulator for B1
Hi all,

I've been building a B1, and I've decided to add a discrete voltage regulator in order to learn a bit. I've got enough space on my board for a Sulzer regulator like the one pictured here:

The only problems I'm having is which pass transistor to use. The 2n3053 is no longer produced, and even when it was, it was in a to-39 package which isn't so easy to use on my board. The d44h11 as used in newer regulators of this type (like the Jung super-regulator) has a minimum hfe of 60, but the B1 is said to only draw 20mA or so. I'm a bit of a newb... does this mean the B1 doesn't draw enough current to allow a d44h11 to operate?

If this is the case, can anyone suggest an appropriate pass transistor?

thanks in advance,

DougL 22nd May 2009 06:47 PM

If I understand your question, hfe used to be called beta, the transistor current gain. Ic = Beta * Ib
I do not see where this regulator has a min current requirement.
It may have a minimum requirement for hfe.

Diomedian 23rd May 2009 02:06 AM

Oh, I see. The Collector Cutoff Current of the d44h11 is 10uA, which is very small indeed. Am I correct in thinking the Collector Cutoff Current is the minimum current which can flow through the transistor when it is "on"? With a min hfe (or Beta as you said) of 60, this would mean that the base current could be as low as 0.17uA for this circuit to work (which should be the case)?

I guess I need to read more about how this circuit works. :-)


analog_sa 23rd May 2009 07:20 AM

These types of regulators work well at even very small load currents. Still, would not hurt to preload it with a resistor - i always do it in the belief that this improves transient performance.

It's a great idea to use a proper regulator with such a simple circuit. Will be interesting to know your assessment of the sound.

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