power supply filter choke current rating.

[tubo]

hey folks,

i have a 10henry 200ma filter choke. im breadboarding a power supply which requires a 10h 100ma choke. im using the 10h 200ma choke instead of the specified choke and im getting a higher voltage. do i need to stick with the 10h 100ma to get the correct voltage?

the power supply is poinz's 6v6 music machine.
http://www.diyaudio.com/forums/attac...lp-bog6gk5.gif


thanks

ivan

[astouffer]

The 200ma choke probably has a lower dc resistance, thats the reason for the voltage increase. You could use choke rated for less current but the simplest solution is to add a resistor in series.

[BZed]

How much higher is the voltage? If its within 5 - 10% it's not going to be a problem. The AC line will change more than that causing the voltage to change with it.

Are you testing the PS with a load on it? If not the voltage will be much higher than the loaded voltage.

Good luck BZ

[tubo]

im breadboarding all of the amp itself. i do have a higher incoming AC which is 125v and is causing the secondary to have a much higer voltage. the scheme of the amp is on the first post.

i replaced the first cap on the power supply which is 1uf with a .22uf which brought the voltage down to the correct voltage which is 340v from 390v.


will the lowish .22uf first cap create some problems?

thanks

[tubo]

Originally Posted by astouffer

The 200ma choke probably has a lower dc resistance, thats the reason for the voltage increase. You could use choke rated for less current but the simplest solution is to add a resistor in series.

do i need to put the resistor before the first filter cap or after and in series with the choke?

[tubo]

Originally Posted by BZed

How much higher is the voltage? If its within 5 - 10% it's not going to be a problem. The AC line will change more than that causing the voltage to change with it.

Are you testing the PS with a load on it? If not the voltage will be much higher than the loaded voltage.

Good luck BZ

the PS supply is loaded.

thank you

[andRookie]

Originally Posted by tubo

do i need to put the resistor before the first filter cap or after and in series with the choke?

In series with the choke, between the caps is ok. Remember to calculate the dissipation and use a resistor with about 3x wattage rating.

[BZed]

With that much extra voltage its a good opening to build a regulator. A good regulator makes an amp work so much better it's always worth it in my opinon

[tubo]

im having a different problem with the power supply again. now im reading 250vdc coming from pin 8 of the 5y3gt loaded. that is with the exact power supply values on the scheme and still with 10h 200ma choke.

im reading 400-0-400 volts on pin 4 and 6 of the 5y3 unloaded. and 530vdc on pin 8 unloaded.what is happening?

thanks

ivan

[Bandersnatch]

Originally Posted by tubo

im having a different problem with the power supply again. now im reading 250vdc coming from pin 8 of the 5y3gt loaded. that is with the exact power supply values on the scheme and still with 10h 200ma choke.

im reading 400-0-400 volts on pin 4 and 6 of the 5y3 unloaded. and 530vdc on pin 8 unloaded.what is happening?

thanks

ivan

Research the term 'critical current'. The properly loaded L-C filter will deliver .9x the rms input voltage( minus rectifier losses, and they're significant with type 5Y3 ).
cheers,
Douglas