Help with reading/understanding schematic

Miscellaneous
1

Hi

Hoping someone might be able to help me

I have attempted to design a .brd file for the preamp schematic donated by synapsys in the direct injection thread (a couple of topics below)

http://synapsysllc.com/guitarpreamp.htm

I have a couple of main questions they are pretty basic so dont be too mean…

  1. Does the IC pinout shown apply to all 4 IC’s?

  2. The upsidedown triangle symbol’s are earth’s right???

  3. Is anyone prepared to check my design? If so let me know in this thread and i’ll email you the brd file (no webspace!).

Any help appreciated

cheers

LO

2

Hi,

I’ll try to answer:

  1. Yes, but there are only 2 IC’s. Both of those are Dual OPAMPs, check markings inside opamp symbols and you’ll see.

  2. In THIS case, yes. (In some schematics it refers to negative power supply.. What, Standards, eh?! (But usually it’s marked somewhere))

  3. I wouldn’t trust myself on this :smiley: (and I’m also a bit “Eagle restricted”)

I hope this helped, Moebius

3

Thanks Moebius

thats a big help,

there are 4 IC’s total but yes only 2 different types  :)

If no-one is keen to check it I guess i will just have to try it!

If it works??? and anyone wants the .brd file just let me know and I can send it to you.

..pEaCe..

4

no webspace? What about the portal?

I’m not sure if the portal is designed for these things though…anyone know?

5

mmmm try this

http://avishowtech.com/midibox//home/avishowt/www/midibox/photos/preamp_v2.brd

um no that didnt work?

6

mail the file to smash :wink:

By the way there are 2 op amp in a NE5532 package :wink:

7

Try:http://avishowtech.com/midibox/photos/preamp_v2.brd

That one works  ;)

hopefully one of these days I can build a better upload script, that does not give the wrong URL to the uploader!  

Best

SmashTV

8

cool Thanks!   ;D

I have a feeling that I may have the IC’s “flipped”?

But I guess I could always mirror the board…

Thanks

[tt]LO[/tt]

9

Ok, let’s see..

Yeah, IC’s are flipped.. anyway: DO IT AGAIN!!

Ever wondered, WHY you have 2 same type of opamps, but signals are wired to differend pins (besides of power)?! :o OPA2604 and NE5532 are DUAL OPAMPs, so there are 2 separate OPAMP circuits inside. Those OPAMP symbols marked U1 are build around one IC and same goes to U2.

You better believe me  ::slight_smile: and do the next version with only 2 IC’s, ok :wink:

(Yeah, sorry.. It’s good to exercise some schematic reading.. sometimes it get’s really cryptic, when some logic chip is marked somewhere in the schematic, but its gate symbols are spread around)

Also, I’d like to add that in my board creation process, I usually break circuit in smaller subsets in my mind, then place IC’s first, and then rest of the components.

And when routing, power goes first, and then “troublesome” signals (long traces/ with crossings).

Bye, Moebius

(<opinion> p.s. Autorouters just give you a looong coffee break, before you can start working</opinion>

10

oh shite I understand… I really do have to do it again; dont I! there is only one 5532 & one 2604…der…

mmmmmm this is fun??? 8)

Thanks :smiley: i’ll post again soon as I get some time to redesign the circuit

11

OK OK, would be real nice if someone could cast there eye over this…

http://avishowtech.com/midibox/photos/preamp_v3.brd

I think I have got it this time???

My main concern is I have got pin 5 of the IC’s to earth but in the schematic http://synapsysllc.com/guitarpreamp.htm it has a “+” next to pin 5 although they run to earth…

harder than it looks this circuit design.

12

Ok, back to OPAMP basics:

OPAMPs have 2 inputs: inverting and non-inverting.

Those OPAMP stages, with signal connected to minus (input) and plus (input) grounded are configured as inverting amplifiers. So, there’s nothing to worry about. If you want to dig deeper in theory check:

http://www.williamson-labs.com/480_opam.htm

By, Moebius

13

Ok,

I had a quick peek at your V3 design, and didn’t see any errors. I think that you could get rid off jumper wires  altogether, with some modifications. Like rotating cap C2 90 degrees, and running trace (C-D) under it and manipulating orientation of battery connections.

:wink: Moebius

14

hey thanks very much!!!

thanks to all who helped me ;D ;D

I’ll try and make it now :o