Another LM1875 question

[soundNERD]

OK, about the website, I am setting it up at the site below:

www.diyaudio.ssxh.net

I am just waiting for activation, then hopefully it will work.



About the amp,
I got the samples of the chip yesterday. I cant believe that ONSemi gives this many free samples... 25 of each (50 total) and they aren't small little things.

Is the heatsink I used big enough for the transistor, or do i need more?



Also, if you could post that schematic u were taling about that would be great.

-Mike

 

[soundNERD]

another pic...

 

[jez]

I have taken up Static's offer to post this diagram but nothing seems to have happened, maybe he's to busy.
Anyway, if any one wants it please let me know and I'll e-mail it to them, file is about 1M. It turns out that after I retrieved this diagram it is quite a bit differant to what I described but it does have some unusual features.

Jez.

 

[soundNERD]

This file is for the boosted 3886, right?

If so, i would like it. my address is in my profile. Is there a way you could winzip it or compress it in any way?

Also, is the heatsink big enough?

Thanks, Mike

 

[jez]

Soundnerd,
No, this file is for the parallel bridged LM1875 amp.All attempts to send the file by any means have failed hence my offer to e-mail it.

Jez.

 

[soundNERD]

OK, i would still like it.

Thanks!

 

[soundNERD]

Actually, does anybody have the schematic foir the boosted 3886?

Thanks, Mike

 

[soundNERD]

any ideas on the heatsink?

I would really like that schematic e-mailed to me


also, somebody has to have a schematic for the 3886. Please post it.

Thanks!

 

[jez]

Just thought I would point out to members and to moderator that two members of this group have offered to post a diagram on my behalf (see above) and were duly e-mailed the ciruit diagram, niether of these people has done anything about this,maybe I was wrong to share my work with others in this forum....or am I being cynical?. I will certainly think twice about shareing specific details in future.
Jez.

 

[goering]

hi jez,
sorry to hear about your previous experience but if it's ok, you can email me the files and I'll give it a go to post it here. hope you're not once bitten, twice shy

my email: goering_h@yahoo.com

thanks

 

[mrskinny]

I would be interested in a copy of the schematic also, if it is still available. E-mail address is- mrskinny@3web.net Thank you!

 

[li_gangyi]

in ur last schematic (which I saw) on http://www.diyaudio.com/forums/attachment.php?s=&postid=295126
you forgot the gain setting resistos from the output to the negative input of the opamp...put that in place and I believe it should work...test the opamp section and make sure it's working BEFORE sticking the transistors in...

 

[Adi_007]

hi, which is the recommended power supply for LM1875 in bridge mode?....is +/-21Vcc enough or is to much......this amplifier will be used with 8ohm speakers

 

[johnr66]

hi, which is the recommended power supply for LM1875 in bridge mode?....is +/-21Vcc enough or is to much......this amplifier will be used with 8ohm speakers

I'd go +/- 18 volts or so (under load). Mount the chips direct on the heatsink as well as they'll need to dissipate a lot of heat for that package style. The tab insulator adds thermal resistance. If you must have an isolated heatsink, use a heat spreader that is electrically isolated from the main heat sink. Consider the TDA2050 as it is rated at 5 amp max current.