high voltage lm3876

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paulb,

Then would adding 2 resistors as a voltage divider suffice to create the split rails?


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Leadbelly
Well somehow it would. Never tried it with a poweramp and I think it´s not the way to go.
Works "well" with a headphoneamp.
BTW:Where are the +-23V coming from?
I think you´d still get around 46.5V.

Regards
Jens
 
hi,
your half wave rectifier can work teoreticaly. You put 3ohm resistor and get huge current, biiiiiig ripple, and small, teoreticaly good DC voltage on output (18V).

Better (and I think only practical) solution with this transformer is using stabilizated power supply.

Regards
 
zx3chris,

Your simulations are way off. What you are simulating is the case where the load is overcoming the capacitance, and that's why your DC voltage is lower than VAC*2^0.5.

Simulate the "one way symmetric" example with big capacitors and ignoring one of the outside taps.
 
joensd said:

Well somehow it would. Never tried it with a poweramp and I think it´s not the way to go.
Works "well" with a headphoneamp.
BTW:Where are the +-23V coming from?
I think you´d still get around 46.5V.

Regards
Jens
A voltage divider approach would only work properly if the current from the ground terminal is much less than the current through the divider resistors.
You may be able to get away with it by using big caps across the divider resistors (as in the "Cmoy" headphone amp), but I still think you'd have to waste a lot of heat in the resistors for it to work properly.
 
zx3chris,

I can't say it many more times: ignore 1 of the transformer taps. And read how many other posters have said that too.

When you put on big caps, the supply behaves properly...so you approach 33VAC*(2^0.5) which is where your 46 is coming from.

By putting on small caps to intentionally drop the DC, you are creating a wickedly poor supply that will not do a good job because the DC voltage is jumping around like crazy if looked at on a small time scale.

If you use the "one way symmetric" example with big caps, you will get about 46 volts...but as 2 rails of +/- 23V.
 
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