Nava Last Update: Accent improvement

Discuss Nava construction and related issues
  • It also looks like the new sample&hold circuits use much smaller capacitors (from 470nF to 470pF). I've noticed that the settling time of the previous circuit is quite long; I ended up adding sleep statements in the firmware of about 100us.

    More conjecture: It looks like the TL074 (used in the new sample&hold) has a much higher input resistance than the M5218 (the standard 909 op-amps used in most cases in the old sample&hold): 1000000 MOhm for the TL074 vs 5 MOhm for the M5218. Maybe the low input resistance of the sample&hold opamps in the previous design forced the use of the large 470nF s&h capacitors, which made the required sampling time of the previous s&h longer than you'd want.

    So apart from making the s&h circuits symmetrical across all accent inputs, the new s&h boards should also be faster because they smaller s&h capacitors.
  • superb explanation, thanks jvq!
  • Added name to sheet! Cheers!
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  • Added my name to the list also.
  • I received my PCB's today. Thanks Vincent!

    I have a question about the BOM. It lists this part: https://nl.mouser.com/Search/ProductDet ... 602-404HLF Mouser 649-68602-404HLF

    This is a 2x2 block of pins. But the header this is supposed to be soldered on is 2x3. So I think this part on the BOM is wrong.

    This looks like the right part https://nl.mouser.com/ProductDetail/FCI ... S9UA%3d%3d 649-68602-406HLF

    Something else: if you put the original multiplexer in an IC socket like I did you might want to use these headers to connect the new boards to the existing sockets: https://www.digikey.nl/products/en?keyw ... TS-108-T-A

    They have thinner legs than the pins on the BOM.
  • jvq wrote: I have a question about the BOM. It lists this part: https://nl.mouser.com/Search/ProductDet ... 602-404HLF Mouser 649-68602-404HLF

    This is a 2x2 block of pins. But the header this is supposed to be soldered on is 2x3. So I think this part on the BOM is wrong.
    Nava BOM updated with the right 2x3 pin header.
    Thank you jvq
    Best regards,
    e-licktronic
  • Just added my name...
  • just added my name to the list