PCB Only/BOM problem reports

[Altitude]

So I now that I've had mine for a couple of days, I have some observations:

Bouncy encoders:  I tried bourns and alps ones and both seem to be VERY jumpy and overly sensitve, maybe some aggressive debounce code could be implemented?

Noise when volume is maxed: This disappears when you dial it back a hair from max, its a mid frequency hum/hash. It sounds like there should be a low values resistor in there somewhere since its the kind of sound when you drive an amp too hard

Noise when powering via usb: Some additional filtering/part value adjustment? I'll play around with it but the noise floor comes up a ways when powering off USB.  Powered hubs usually have shitty cheapo switching supplies so its always going to be poor quality power

USB/DC power: This is going to get people where the accidentally have it powered from both DC and usb, some fail safe might be a good idea. This was a problem with midibox cores that would take power from USB or externally.  The way I dealt with it was to use a DPDT switch have that the jumper wired up opposite to each other so in one position it would turn on from USB power and the other postion, from DC

outstanding job though, great evolution

Maybe I missed something but are the schematics up in a non-kikad format? I'd like to see how your power supply is set up since I was fully expecting to go to war with the OLED noise and I really dont hear it.  Are the internal signal levels really high?

[flocked]

I received my black case from Pokono and it looks awesome, however it's missing two holes for holding the front plate. I checked the .svg and it's also missing on it. Now I can't attach it :/

[Xavier]

Bouncy encoders:  I tried bourns and alps ones and both seem to be VERY jumpy and overly sensitve, maybe some aggressive debounce code could be implemented?

Have you tried both '12' and '24' encoder drivers in the settings ?
If it still does not work with both values, could you tell me the exact reference of your encoders ?

Noise when volume is maxed: This disappears when you dial it back a hair from max, its a mid frequency hum/hash. It sounds like there should be a low values resistor in there somewhere since its the kind of sound when you drive an amp too hard

Interesting... I haven't noticed that. Will give a try.

Noise when powering via usb: Some additional filtering/part value adjustment? I'll play around with it but the noise floor comes up a ways when powering off USB.  Powered hubs usually have shitty cheapo switching supplies so its always going to be poor quality power

Yes powering it up from USB requires good USB power supply. They can be very bad.
That's why i added a DC in in the PreenFM2 ;-)
If you find anything that can improve it, let me know.

USB/DC power: This is going to get people where the accidentally have it powered from both DC and usb, some fail safe might be a good idea. This was a problem with midibox cores that would take power from USB or externally.  The way I dealt with it was to use a DPDT switch have that the jumper wired up opposite to each other so in one position it would turn on from USB power and the other postion, from DC

Thanks for the idea.
I tried to connect both my IPAD to USB and a power supply to the DC in. Yeah that's bad.... but that didn't break anything.

outstanding job though, great evolution

Thanks :-)

Maybe I missed something but are the schematics up in a non-kikad format? I'd like to see how your power supply is set up since I was fully expecting to go to war with the OLED noise and I really dont hear it.  Are the internal signal levels really high?

I just upload a Postscript file in the Download tab.
I'm glad it works well with the OLED. I still haven't soldered the Audio part on my PCB with the OLED display.


Xavier

[Xavier]

I received my black case from Pokono and it looks awesome, however it's missing two holes for holding the front plate. I checked the .svg and it's also missing on it. Now I can't attach it :/

I'm glad it looks good and I'm sorry for this error in the file. I've just fixed it.
Thanks for the report.
I can send for free a crystal clear part now, or a black one in a couple of week. I have to reorder something on formulor/ponoko this W.E.
Let me know,

Xavier

[Altitude]

The 12/24 thing fixed my encoder issues, sometimes I forget I am not above the RTFM rule

For the PSU noise, it looks like there is some real estate to play around with, I'll see what I can do.  Not a ton of power rail smoothing in this design so some good 'ol heavy handed linear PSU tactics may help.

 I'm still curious why the OLED doesnt introduce noise into signal, I'm not a electrical engineer but it's odd that this design doesnt have issues with it and something like the shruthi, it's right in your face despite having a super robust PSU design and this does is not terribly different.

Looking forward to some P2 header love down the road though..

[Xavier]

Good news you have the encoders working now.

I'm still curious why the OLED doesnt introduce noise into signal, I'm not a electrical engineer but it's odd that this design doesnt have issues with it and something like the shruthi, it's right in your face despite having a super robust PSU design and this does is not terribly different.

Really ?
I'm glad it works well 
If i remember correctly the shruthi use PWM from the microcontroller as audio signal... It's possible that makes it more sensitive to voltage fluctuation.
The voltage reference for the 4 external DACs (2 * mcp4922) of the PreenFM2 are well filtered by 2 x 220uF capacitors which may make a big difference.
That's just a guest.

Don't hold your breath for the P2 love


Xavier

[Altitude]

WRT: OLED

I'll bet that it is a level thing. This really came up with the Curtis part, I was an a unique situation where I could test 3 different filter boards with the same digi board and all the current designs were not that bad but the CEM part was a disaster, noise floor went up 10x.

[werazefu]

The BOM says: "Wall power suply 7 to 9v :"

I tried 7,5v / 350mA - it seems to be too weak. The LCD is flickering. 7,5v / 600mA works well!

[Xavier]

The BOM says: "Wall power suply 7 to 9v :"

I tried 7,5v / 350mA - it seems to be too weak. The LCD is flickering. 7,5v / 600mA works well!

The PreenFM actually consumes 120mA.
It's possible that draining 120mA out of your smaller transformer move down the voltage to much.
With the diode AND the 7805 regulator the voltage need to be at least 7V.

Anyway, i'll add a note on that in the doc.
Thanks a lot for the feedback.

Xavier

[martindunne]

so just to clarify, is it ok to use encoders with push switch

[Xavier]

It is OK.
I have a working PreenFM2 with switch encoders.
You'll have to bend the 2 switch pins and eventually cut them.

Xavier

[martindunne]

hi again can i use encoders with 20 dents instead of 24, will it cause any problems

[martindunne]

hello also i have somme 1n4004 diodes at home could i use one of these instead of the 1n4001 in the bom

[Xavier]

20 dents encoders should work if it uses the same quadrature output table as :
http://www.bourns.com/data/global/pdfs/pec11r.pdf
What model do you have ?

1n4004 can replace 1n4001.

Xavier

[martindunne]

hi these are the encoders on ebay
http://www.ebay.co.uk/itm/121195339728?var=420187086302&ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
any good?