DPA HV Microphone (discrete) Power Supply

[bcarso]

[quote author="Handcrafted Tone"]Last opsticale in the way, I'm having trouble finding a substitute for Q2 (BF721)
Mouser gives me the FZTA92 as a cross reference, but it's surface mount. Can I use any high voltage PNP transistor here, like maybe a MJE350?

Thanks[/quote]

MPSA92 is a TO92 300V PNP.

 

[Gus]

Lets think what happens without r7,r8 and no load?

Now I would leave in r7, r8

What are D1 and D2 numbers or rated zener voltages?

Look at the nice Q1, R3, D2. Max surge current or limited current will be D2 zener voltage - Q1s base emitter voltage drop / R3

Then we have the constant current supply to the zener.


What IC does all of what this low parts count circuit does?


It is a Si transistor circuit, What do we need to know for the transistors?

Max current spec needed

That sets the min beta of Q1
But we kind of know that already because if we have the D1 zener voltage we know the current Q2 is supplying that getting divided up for the base of Q1 and D3.

I would check something like a TIP50 if it would work for Q1

Then work out the max base to emitter, emitter collector, collector base breakdown voltages needed

Then workout heat sink sizes needed.

 

[Sorr]

I think you need more CR filtering on the output to reduce the noise floor.

 

[Marik]

[quote author="Sorr"]I think you need more CR filtering on the output to reduce the noise floor.[/quote]

On the outputs I used 20uf/350v with no any hum problem.

 

[Guest]

[quote author="mediatechnology"]

[/quote]
Maybe it is not good solution for microphone powering.
Also schemo based on "DPA". hmmmm
Voltage regulator here is common collector - base. Its output
is hard voltage source.
Topology do not allowe adittional output filtering cap. (without
patches like that 100 Ohms resistors)
Why not to do something like current source with big output capacitor.
Try to look to the S*nnheiser T-power supply and make variant with high voltage transistors.

... Only for fun

xvlk

 

[xenakisin58]

Hey all,
Can someone fwd me the hma 4000/5000 schematic? Also curious if anyone owns or has attempted to build the PCC4000 (130v to 48V converter). Any help would be much appreciated. Dying to get these mics into use.