Keantoken's CFP cap multiplier

[KlipschKid]

I'll try the BD139-16, and have a better look at the datasheets from On, Fairchild, ST and Multicomp to see if any seems better in any regard.

Thanks very much for your help !

[keantoken]

Unfortunately the datasheets aren't very helpful. IIRC ST has the good ones, but I'm not sure.

[danielwritesbac]

Originally Posted by keantoken

BC639/640 from NXP/Phillips are a good bet if you can get them anymore.

There's both bad news and good news and here it is:
BCP53; BCX53; BC53PA 80 V, 1 A
BCP56; BCX56; BC56PA 80 V, 1 A
BCP52; BCX52; BC52PA 60 V, 1 A
BCP55; BCX55; BC55PA 60 V, 1 A
BCP51; BCX51; BC51PA 45 V, 1 A
BCP54; BCX54; BC54PA 45 V, 1 A
BCP69, BC869, BC69PA 20 V, 2 A
BCP68; BC868; BC68PA 20 V, 2 A
The bad news is that the packages are so tiny and the good news is that they are available.
The BCP can be soldered with an ordinary soldering iron, the BCX is impossible and I haven't tried the new flat pack. I just wish they came in TO126 or Dpak sizes.

[KlipschKid]

Thanks again !

I can use the the BUP41 for the 5V 50mA positive rails that supply the DAC ICs. I also have two (L/R) ~15mA +/-15V supplies for the op amps so maybe I'll try all BC327/337 for them and see if they pop, and if they do, ST BD139-16/140-16.

I have another quick question - if I want to set the voltage drop / output using a potential divider, would this work ? My input voltage would be 21V, and output between 12V and 9V, @40mA, R2 and R3 are created using a 10K potentiometer. The 2SA would be a BUP41 with a heatsink. C1 might need to be smaller so the RC delay isn't too long, say 47uF.



Thanks !

[KlipschKid]

Hello again,

I just realised it might be far easier and more effective to replace the string of diodes with a 12V zener, so this would drop about 12.7V ? So 21V in and 8.3V out. This would be fine for my application. Would the higher voltage drop cause any issues, except of course the need for a heatsink on Q2 ?



BTW, if you don't like me using your images in this way, please let me know. I just thought it's the easiest way to describe the changes.

[AndrewT]

Originally Posted by keantoken

...............If BC550C is the NPN part then that's what it should be. I mix them up all the time! Must fix that...

N comes before the P means you select the lower numbers before the higher numbers.

Only works for this series. Other makes country codes are all over the place, except 2sa/c.

[AndrewT]

Originally Posted by merlin el mago

I don't know the input ripple: ...........

use psud2

[merlin el mago]

Originally Posted by keantoken

So if I understand correctly 240VAC->340VDC. 30mA*220R=6.6V. So I have 13.4V to work with.

Merlin, what do you think about this? The 220R/220u RC is from your supply. It took some determination to make it safe from overvoltage and inrush current, but I like how it turned out.

Don't put more than 330uF between the Kmultiplier and the HV2. Capacitance after the HV2 is okay because it will be limited to 30mA inrush.

Thanks Keantoken, before to make it I will measure with the scope real ripple between the PSU & SSHV2.

[merlin el mago]

Originally Posted by AndrewT

use psud2

Thanks to remember Andrewt, I will measure with the scope.

[merlin el mago]

@keantoken
Scope ripple measurement done at the last CRC, scope set 0.5mV/cm so it's Ok to use. Where have I to connect the cap multiplier: in the PSU box or in the lineamp box togheter the SSHV2? I guess in the lineamp box, right?