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Topic: Schematic Check Needed Please. (Read 5449 times) previous topic - next topic


yeah.. I was planning on following the schematic of the WaveShield..and that link I sent:

(although one uses a smd potentiometer ..and the waveShield does not)

Im fine with static caps/resistors.. as long as we get a decent range.. (if thats what the pot was used for?)

but I woud like to use a 100uF tant cap.. ON-BOARD.. but the speaker pads..  (I was looking and I think if we rotate some caps over there... there might be room.. not sure what else is needed? (component wise)

surface mount 100uF tantalum capacitor.. Im not familiar with the package names?  package size D is it?


Thinking also to change LM386 circuit. Right now has 2 resistors as a voltage divider. If we take the resistor that goes to DAC output, connnect that end to +5 instead, can have the LM386 input sitting at 2.5V. Then take the filtered DAC output and run it thru a cap to AC couple it into the LM386, so the '386 output sits at 2.5V and can swing from 0-5, then the 100uF output cap will AC couple it to the speaker to sit at 0V and swing -2.5/+2.5V.
The pot might have been to do the same thing.

I'll send you the pad sizes, you can review cap sizes against that & see what fits.
Maybe we can do holes, one on each side of the uSD side mount tab.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.


I'll have to defer that amp stuff to you...(its making my head spin already)..LOL

How does the WaveShield schemaic do it? I know they 'do not' use a pot... but that alt image/diagram I sent does.

Im open to either/whatever..  Im hoping for quality at least as good as the WaveShield. =)

Lost me here:
Maybe we can do holes, one on each side of the uSD side mount tab.

holes where?  if you mean speaker & power pads...   

I wouldnt bother.. possible short on uSD perhaps if goes through?? I dont mind the pads themselves..  size, placement..etc.

as a matter of fact Im super happy with the whole board/project.. outside of the fixes/change of DAC we need to do in order to get it to work/play audio!  LOL

but layout, footprint/size..  I really like it!  you did good work!


ok.. getting this thread back on track a bit here!  lol..

the SMDuino_w/uSD socket: schematic & pcb layout.

First I wanna say thanks to everyone.. for looking and the feedback.  Im learning alot in Eagle, which was the focus/goal  (thanks Crossroads)


here is my latest attempt that is targeting the fixes outlined prior: (hope I did them all correctly)

*ICSP connector are not correct:

I think I went through and re-labled things and have the correct pinout/labels/connections now for ICSP

*Update using DIODE part for pads to real pad symbol/component:

I used the Sparkfun lib as instructed.. and I used a different one.. should be ok..yes? elongated one..  (kinda separates the battery/power pads from the rest. ;)

*U2/5v vRegulator GND fixed

*Connected the enabled pins to VIN on BOHT 3.3v & 5v vRegulators  (per datasheet and your old schematic) :)  :)

*changed caps C6,C8, from 10nF to 100nF value

*checked ERC tool in both schematic & pcb (no errors)

*Used polygon tool to draw a polygon (rectangle) over the board (same size as pcb dimensions).. on BOTH top and bottom layers... and named them both GND.

(never done that before.. nor ran across it any tutorials yet..  whats it for? do?  a ground plane for something?)

So if tings are looking all in order... I can/should start on the routing aspect of things?


1.) before I go into the PCB stuff (again)... and start fooling around..

should I maybe find a bunch of 'SINGLE' through hole symbols/components.. and replace these 'header strips' I am currently using?  (ie:  take my serial 'pin set'... which consists of a row/header of 5 pins, and add 5 separate/individual through hole symbols..  so its easier to place the I/O's along the side?... sorta allowing me to mix-n-match whre the go?..and help correct all the spaghetti strings I have going on a bit?...................OR.............. should I just leave things as they are.. and get to cracking on manual placement of traces on any left over errors, using vias and traces on both sides?)


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