lm3886 as driver + mjw21195/6

[kinser]

djk,
ok! I will test it!
Thanks alot for all of your help!
will also post the results + pics!
Thanks,
Kinser

 

[kinser]

Hi gusy,
After fixing the circuit and chanching components (adding, removing)
Every time i power the amp up the fuses on the secodary rails blow( a big blue light show) I dont know what to do anymore
Pleaaasssse help me!!!
Thanks,
Kinser

 

[xplod1236]

check to make sure that you have the diodes put in the right way

 

[boholm]

Your diagram does not show anything from the power supply. No capacitors - no diodes - no transformers. Can you please draw that into your diagram as well, please? And also add the placement of the fuses, please. And please also state what type of fuses you use.

As a test you can place a 10 ohms resistor (as many watts as possible) instead of the fuses and try and make some current and voltage measurements.

If you are using fastblow fuses and they are placed just before the power supply capacitors, the fuses may blow because of the inrush current to the power supply capacitors during startup.

 

[kinser]

ok i made the power supply its 35+/- dc the fuses blow when i power up, and if i power up without the amp conected, then power down and connect + and groud of the amp to the power supply its ok, then i connect the - and there is a spark between the - of the power supply and the - of the amp.
also if i connect the + of the power supply to the + of the amp and then connnect the - of the power supply to the - of the amp there is a spark(without havig the ground connected)

 

[Upupa Epops]

Use in start up proces variac ( regulation transformer ) or regulated symetrical laboratory power supply and slowly rise supply voltage from zero.

 

[kinser]

AMM...i dont have a lab power supply so that is not possible at the moment!
I also have another circuit added to the lm3886 its not conected to the + and - of the power supply but to the + and - of the lm3886
its a circuit with 15v zener diodes to reduce voltage from 35v to 15v for the filter that i whant to use with it also to power a fan(12 volt fan)
Thanks,
Kinser

 

[Upupa Epops]

It is not solution - you must " catch " voltage, by which current consuption rise " jumply " and in this point you can easy find out where is problem - only variable voltage can to help you. Do you understand now ?

 

[kinser]

I do unserstand that that is the only way to find out... but i cant test it like that at the monemt... maby i should take out the zener part of the circuit and use some lm7x12 regulators?
Thanks
Kinser

 

[Upupa Epops]

I understand you very well - you are horny for it - but sometime is better take an beer and let it for tomorrow.

 

[kinser]

ya you could say that but you see im going tmrw to build my subwoofer box and the amp is going into the box... and tmrw is the only day i can build the box and i cant do it another day because i need the sub for a friend in three days... thats why i want to make it work!
heheh
Kinser

 

[kinser]

i thaught of 1!
could i maby quickly bridge 2 op541/ 549(which two will give more power?)
at 35vdc for an 8 ohm load?
and i know that you could use the same parts of the lm3886 but what about the current sense? what resistor?
Kinser

 

[Upupa Epops]

With two OPA's or LM's connected in bridge you can to get cca 120 W into eight ohms ( by +/- 35 V ) and it will be easy way if you need it quickly .

 

[kinser]

ok I think i will use two opa541 since the opa549 only takes +/- 30vdc
Thanks
Kinser

 

[kinser]

1 more question
can the opa541 drive 4 ohm load at 35vdc?
because its an 8 ohm driver and each chip would have to drive 4 ohms!
is it ok?
Thanks,
Kinser

 

[Upupa Epops]

In bridge only eight ohm speaker, four ohm is in this case too low load. 120 W is not enough ?

 

[kinser]

120 is good
do you have a schematic? because i cant seem to find one.... its 1:35AM amp and im a bit...
i gotta wake up at 9AM to make the subwoofer...
Thanks,
Kinser

 

[Upupa Epops]

For both chips use some normal noninverting connection from datasheet and on front of one of them give an invertor with opamp ( gain - 1 ). Load must be connected between both outputs. Good luck, my bed calling .