Using inductors in BOSOZ PSU question.

[audionut]

I have built a BOSOZ power supply. It is going to power two BOSOZ's in a Bi-Amped system. For higher capacity I used larger 60 volt transformers and used two 1000uf capacitors on each rail.

When I put a .5amp load on the power supply rails, the voltages are + and - 84.5 volts, and a/c ripple peak to peak is one volt. I gather that the regulators down stream will take care of this ripple.

I experimented by putting in 500 mh inductors (40 ohms) between the two capacitors on each rail. a/c ripple went to 20 mv.
the rail voltage went to + and - 74 volts.

Is it beneficial to leave these inductors in? Do I care about the 40 ohms of dc resistance? Is it better to have cleaned up the dc before the regulators?

 

[paulb]

Yes. Maybe. Yes.
See this thread for a great simulator. You'll play with it for hours, I'm sure:
http://www.diyaudio.com/forums/showthread.php?threadid=3934&highlight=Duncan+AND+PSU

 

[audionut]

I had downloaded the program. I saw that inductors would reduce the ripple, but I am wondering about the added 40 ohms of dc resistance. I have read that you want to have low impedence power supplies. Seems to me that these inductors might be adding impendence. Problem is, I don't know much about power supplies.

 

[paulb]

The preamp is running Class-A, so there is a constant current drawn from the power supply. In this case, the additional resistance (assuming the inductor can handle the power) does not cause any harm, and is actually a good thing from a ripple reduction standpoint.
Make sure the inductors are rated for a high enough current to handle the total current draw.
Good choice for preamp, I want to build one someday too.

Paul

 

[NickC]

if you are worried that the addition resistance might cause harm,
lower the 500mh choke, while increase the current it can handle
for higher current capability, the wire must be thicker hence smaller resistance
i am affraid that at 0.5 amp the 500mh,40 ohm will get very hot
P(loss)=0.5*0.5*40=10 watts
any with such high resistance there would be a big voltage drop
v=IR
v=(0.5)*40
a drop of 20 volts
i used 5 amp chokes,15mh,0.15 resistance
doesn't get hot,while running 2.5 amp,