Problems designing an PSU for an gainclone.

[samsagaz]

Hi guys, hope someone can help me, i want to drive 1 or 2 LM3886 so im designing the PSU.

My transformer are Primary 220v/50Hz, and secundaries 28-0-28 (with CT).

i cant figure how are the current that this PSU need to handle!, i dont know which diodes i need to use.

Hope someone can help me, Regards.

[Akita]

Actually it depand on your amplifier. So for your transformer, Make it 3A will be good if you use it for both channel. or in other word maybe >168VA. For easy job, you can buy a bridge rectifier with rated 6A, 200v will work fine.

[samsagaz]

Akita

i see some schematics that the LM3886 use +40 -40 for an single CHIP.

If i drive just one channel with this values. how i calculate the current, i know that each chip is capable to give 68W into 4Ohms. and 50W into 8Ohms.

i want to know how do the calculations to all diferent configurations.

Thanks

[seventenths]

http://www.national.com/appinfo/audi...gn_Guide15.xls

Try this. I hope you find it useful


7/10

[Akita]

Ok, let's use simple calculation, P= VI, P=IxIxR,
When

P=68,R=4, then; sqrt(68/4) = 4.1A
P=50,R=8, then; sqrt(50/8) = 2.5A

**The Actual Iq(A) is a bit bigger the the value above.

[samsagaz]

Originally posted by seventenths
http://www.national.com/appinfo/audi...gn_Guide15.xls

Try this. I hope you find it useful


7/10

Thanks, after use the xls file i found that use 4.73A.

if i use 2 Mono Parts still need the same Current? or its the double?

and is not possible to calculate it using an math formula? i want to know how its calculated to do my own calcs

btw, that help me a lot, now i know that i need to use at least 8A diodes for an 8Ohms load and like 15A Diodes for an 4Ohms one :S

[samsagaz]

Originally posted by Akita
Ok, let's use simple calculation, P= VI, P=IxIxR,
When

P=68,R=4, then; sqrt(68/4) = 4.1A
P=50,R=8, then; sqrt(50/8) = 2.5A

**The Actual Iq(A) is a bit bigger the the value above.

ok, so i need to know the output power of the amp. and if i connect it to an 8ohms, 6ohms or 4ohms speakers, to know the current.

Thanks too much!.

[Praudio]

Originally posted by samsagaz


My transformer are Primary 220v/50Hz, and secundaries 28-0-28 (with CT).

.

28-0-28 :way to much!,

[samsagaz]

Originally posted by Praudio


28-0-28 :way to much!,

Yeah i know will try to lower it a bit with something is the only Transformer that have at home now, i will use an 26-0-26 later i think.

[AndrewT]

Hi,
is this a transformer/rectifier/smoothing cap PSU?
Or
is it a regulated PSU?

The maximum current for two 3886 could be between 14Apk and 23Apk. Check the datasheet.

Where is that going to come from?