Finally built something :)

[wintermute]

Well It's not a speaker but will be used for testing speakers (assuming it works, haven't tested yet).

Its Eric Walin's preamp2 mic preamp. built on a ic experimenter board from jaycar. When you look at it, it looks pretty simple, but It took me ages..... had to work out the layout from scratch, (first time on this sort of board, have only used the board with no copper in the past), add to that I'm very rusty and well it took ages.

I could definitely be a little less generous with the solder, but...... At least IMO it's a bit better than some of the stuff I posted in the ugly prototypes thread will be going in a nice diecast metal box, once I make sure it all works ok.

Tony.

[Vikash]

Looks good Tony

[wintermute]

Thanks Vikash

I'm off to buy a battery to test it out.... Allways forget something

Tony.

[wintermute]

not working some debugging comming up....... virtually no gain only barely hear it with 20X gain. clipping indicator seems to work though

Tony.

[JOE DIRT®]

you know where help is

[usekgb]

I like your new web layout Vikosh. Very nicely done.

Cheers,
Zach

[wintermute]

Originally posted by JOE DIRT®
you know where help is

yep probably a track I forgot to jumper or one I did and shouldn't have......

I'm having a rest, probably look at it tomorrow.

Tony.

[wintermute]

Turns out I hadn't done anything wrong at all (except trusted the original schematic). Turns out that Eric's schematic has a critical resistor missing, the one that feeds the voltage to the voltage reference, doh.....

I kept looking at the schematic originally and thinking it was strange, but never having used a voltage reference before thought it was right. On looking at his pcb schematic (and another circuit diagram from Jason Neal) determined the problem was a missing 100K resistor from +9V to the +ve of the voltage reference. Had to solder it to the back of the board, due to no room to put on top, but it all works now

Couldn't wait till tomorrow, had to fix it now.......

Tony.

[Vikash]

I'm having a rest, probably look at it tomorrow...
Couldn't wait till tomorrow, had to fix it now.......

What made you think you had the will power to walk away in the first place. Lol.

Why would Eric not bother to correct it? This is a little dauting as the most complicated electronics I have attempted before this is the Jig v2. Which schematic would you recommend using?

Cheers Zach

[wintermute]

I've emailed eric so hopefully he will update the schematic... Only one resistor missing, although his version is different to jason's (in values of resistors)... I just added a 100K resistor from +ve input on the opamp (in the voltage ref section) to +9V..... If you look at the schematic for preamp 1, it's there, the only difference is that the voltage reference replaces the diodes, and there is an additional 15K resistor.... (preamp 1 has the missing 100K resistor).

Tony.