Simplistic MosFET HV Shunt Regs

[merlin el mago]

Could you post schematic? pics?

 

[rickmcinnis]

Merlin, are you speaking to me?

There is not useful schematic for the PCB. Plenty of schematics for the circuit, itself.

Here is a link to the manual at Broskie's site. http://tubecad.com/2008/07/13/PH-1 Phono preamp.pdf

Look on page 11.

One can easily use the resistor positions on the B+ rail for the regulators but the grounds ....

Thanks for your interest.

 

[king4joy]

OK, we cross posted. Those numbers SSLV1.1 can do with IRF9530 at CCS position also as it has on output already. And its better spec than the the BJT special one for 1.5V-2.5V I designed for disco once. You set it at 1.5A and Bob's your uncle.

Salas.......For Q101, have you changed to use IRF9530 as well?? better??

What is CCS current setting and CCS-LoadCurrent?? The filament is burning at 1.25-1.50A....will there be lots of heat at Q106??

Could I use 9V-0V-9V 3.3A transformer per channel??

Cheers,

King

 

[merlin el mago]

There is not useful schematic for the PCB. Plenty of schematics for the circuit, itself.

Here is a link to the manual at Broskie's site. http://tubecad.com/2008/07/13/PH-1 Phono preamp.pdf

Look on page 11.

One can easily use the resistor positions on the B+ rail for the regulators but the grounds ....

Thanks for your interest.

What's the problem with the grounds? Or do you use two regulators with different B+ for each channel?

 

[rickmcinnis]

Reply to merlin

That all of the regs will be the same is my intention.

I know this would not be a concern with four passive supplies but the sensing connection of the SALAS regulator had me concerned that there could be some kind of unwanted interaction.

 

[merlin el mago]

I never tried, but why do you want to do four regs? what's the total consumption of your Aikido?

 

[Salas]

I am building four of the regulators to power a Broskie Aikido phono board using TEA BAGS pcbs (thanks again, TB)

It is basically four of the AIKIDO circuits on one board.

I am using four since I have ECC99's in the cathode follower position and these seem to require more than average current so I figured why not use four?

It is simple to connect the positives to the individual "modules" and they are isolated but PCB surgery (not that I am afraid of this) is required to isolate the individual grounds. The question is: is it necessary?

My instinct is that it is but I thought I would ask before starting the procedure.

Help is appreciated and my apologies for not knowing the answer to this myself.

THANKS!

Yes, it is necessary if you want the Kelvin sense system to work best, and its audible when it does so.

 

[Salas]

Salas.......For Q101, have you changed to use IRF9530 as well?? better??

What is CCS current setting and CCS-LoadCurrent?? The filament is burning at 1.25-1.50A....will there be lots of heat at Q106??

Could I use 9V-0V-9V 3.3A transformer per channel??

Cheers,

King

In SSLV1.1 builds thread for the LV questions. Thanks.

 

[Salas]

hmm... 2N5457?

No, dangerous for coming up with a high Vgs(off) sample relative to the purpose here even at low IDSS.

 

[Milos P.]

OK, thank you.

 

[rickmcinnis]

Thanks for the assurance

Yes, it is necessary if you want the Kelvin sense system to work best, and its audible when it does so.

I went ahead and did the board surgery yesterday.

I feel much better now.

THANKS very much for the advice!

 

[rickmcinnis]

How good does the 10uF capacitor need to be?

Are there gains made with higher quality caps?

Looking at the OBBLIGATO Gold or the JANTZEN Z Superior - the OBBLIGATO certainly a better value.

Any opinions on how far to go?

Thanks,

 

[Salas]

Whatever your subjective knowledge and preference is, may it be right or wrong from your favorite capacitors in signal use, applies in that position too.

 

[roger57]

C1 Position, Capacitor Value

Salas,

Is a 0.47uF Ok in the C1 position, or will it put the network too far out of spec?
I happen to have some good MKP caps at that value...

Gary

 

[Salas]

Will work.

 

[roger57]

Hi Salas...

I've built a second SSHV2 regulator, but for some reason, this one's not producing. I'm shooting for 350V output at 60mA across the load. For a test load, I have a 5800 ohm power resistor,
which works out to 60mA at 350V.

With both R4 (current) and R11 (voltage) wide open, the best I can get is 730mV (73mA) and 340V with 400V at the input. The bench supply is capable of about 400mA at 450V, so no problem at the supply side.

I should mention I'd like to get 80-85mA, so this should be well within spec.

Suggestions?

Thanks,
Gary

 

[Salas]

Your test load should be 20mA less than CCS setting. Give it 370V input to see if the input Mosfets will produce 80mA. Else if they aren't particularly mighty for IDSS and VR4 at max, make the 10 Ohm TP resistor (R5) to 1 Ohm and translate mV for mA 1:1. That will detract less from top IDSS.

 

[Salas]

If Vo is still not reaching, put a higher IDSS 2SK117.

 

[roger57]

If Vo is still not reaching, put a higher IDSS 2SK117.

My input MOSFET, as discussed previously, is the IXTP08N50D2. It's rated at 500V and 800mA, and had no issues getting 350V at 80mA in my other board.

I'll try replacing the 2SK117 and will test one for a different Idss. What's the minimum Idss required to achieve the spec output of the regulator of 380V at 100mA? Is higher, or as high as possible, better?



Thanks again,
Gary

 

[Salas]

Yep it may, but the Supertex one underneath does the current. The IXTP shields HV.

(68Kx2)*K117 max in circuit current=Vo max.