[Possum]

Here is a really really really nice implementation of a preamp utilizing PGA2310's:

http://www.mhennessy.f9.co.uk/preamp/

The designer has yet to do the listening tests (as stated on the bottom of the first page), but it's still a great site with plenty of detail on the design.

EDIT: BTW, the rest of the main site has a lot of useful information, too.

 

[[so]hai(R)]

hi trespasser_guy, good to heard from u too....

Thanks guys 4 the links, i can verify that i'm on the right path to success...

Actually the schemetic from both links seem similer to mine... the first link uses slightly different but same family of microcontroller, oh yes, i'm using PIC16F84(A) with the chip. For LCD displays, i'll need to use the bigger and more powerful MC 'cos there r not enuff pins on PIC16F84 to integrate the LCD as well....

so i'll leave that out 4 a while...

ok, back to PGA2311, it actually can configure as complete CMOY with digital volume control!!! If u read the datasheet and look at the internal construction of the chip, it's 2-op amps with adjustable gain!!! The PGA2311 can boost a signal to 31.5dB, which is about gain of 37!

Therefore, the chip can be used as headphone amp with DVC or just DVC... the connection of the circuit can be maintained, only the firmware need to change between each type...

also i'll my best to try to fit the serial programming port onboard so that everyone can easily update the firmware through PC...

p/s: anyone who is kind enuff to offer me to post the schemetic?

I got no website to upload them... yet.......
Also i think i should better switch back to headwise to continue the "unfinished" thread so that everyone can get everything on one thread, ok?

 

[Noesis]

I have an LCD display in my computer which is made my Crystal Fontz. They make a myriad of LCDs, I bet they make one that would suit your needs.

While mine is used on my computer, you might still find my review of interest. It is located at: http://www.digitalnoesis.com/diy/crystalfontz.shtml (The picture is not being displayed, I'll fix that later).

Here is Crystal Fontz's website:
http://www.crystalfontz.com/

Regards,
-Chad

 

[yejun]

Quote:

Originally posted by Possum Here is a really really really nice implementation of a preamp utilizing PGA2310's: http://www.mhennessy.f9.co.uk/preamp/ The designer has yet to do the listening tests (as stated on the bottom of the first page), but it's still a great site with plenty of detail on the design. EDIT: BTW, the rest of the main site has a lot of useful information, too.

Where I can get this kind buttons?

 

[DCameronMauch]

What would be involved in making a discrete
digitally controlled attentuator. I am guessing
like a ladder of resistors with a bunch of jfets
acting as switches to select which point in the
ladder to use for output. And a mux to simplify
the selection. Say six bits for 64 points. You
could set the dB per step to whatever you wanted.
Or use that linear variable plus a fixed to yeild a
psuedo log curve thing. Does anyone know any
source of information on this kind of attenuator?
It looks like it has become more popular with the
likes of Pass Labs and Ayre in their newer products.

 

[aos]

What's even better when using uC, you can add IR remote control functionality too.

 

[yejun]

If using a serial interface LCD, probably only need two I/O ports.
Can I use PIC16F877A's ADC to serve as a VU meter?

 

[[so]hai(R)]

hi... of course u can.... but u need at least 3 i/o lines 4 LCD interface... However, there r plenty of i/o lines available in PIC16F877A, so no worry...

 

[yejun]

which compiler is good?

 

[[so]hai(R)]

For those who interested, u can d/l the MPLAB IDE compiler from Microchip Website, here is the link:
http://www.microchip.com/1010/pline/...lab6/index.htm

For the flash programmer, there r plenty of them on the web, just google 4 it... however, yejun if u use PIC16F877, then u probably need to build more complicated or expensive flash programmer... i'm not very sure about it 'cos i didn't use them b4...

For me, i'm using IDE as compiler, com84 and ponyprog as programmer...

p/s:com84 won't work with laptop serial port... they just can't get enuff voltage to programme the chip.

 

[yejun]

I found some programmers are pretty cheap.
http://www.electronics123.com/amazon...gue/c3-3-7.htm
http://www.kitsrus.com/upuc.html#k149