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Mounting Motorfader


Pearl

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Hi ...

on my faders i got between 13 - 15 Ohm at the end.

With 10-bit resolution we have 10.000 Ohm/1024 makes 9,765625 Ohm for every step. So we have to subtract one or two bits(steps) to get the right result.

Is this calculation right and is it possible to do this by the firmware?

Pearl

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if you use only 9 or 8 bit, you will have only 512 or 256 step...

I think, a mod could be to take 5V and -1V and a pot in serial with the fader for ADC... Thorsten? am I right??? to get 0V when the fader when it is at its the end

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Hi Pilo,

the PIC could be damaged with a negative voltage at an analog inputs, so it would maybe be better to add a shottky diode to all Vss pins of the PIC in order to shift the negative reference voltage by ca. 0.3V - but I'm not sure which side effect can occur thereafter. :-/

Best Regards, Thorsten.

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as a very rough workaround, I have added resistors like this.....

________________ +5v rail

 |

[]   470ohms

 |

 |

 |

| |

| |<--------- 10kohm fader wiper pin to ADC

| |

 |

_|______________ 0v rail

this has the effect offsetting the positioning of the fader, but a side effect is that you can only reach a midi value of 123 at top of travel, not 127.

 TK, if you put shottky diode between 0v and pins of PIC, I wonder if pic is getting enough voltage? I guess you could hand pick a 7805, as these seem to vary up to 5.3v anyway.

 I am setting Logic to work only with bit values of 7 bit anyway, so as to avoid jitter, and occasionally the fader will only go down to 1, and not 0, but this is not really a hassle!

BTW TK, I hope you had a great holiday!! I think you should schedule regular breaks from this forum, as you do so much for us already! But then again, I'm not going to complain if someone helps me so much like this!! ;D

bye, from Steve

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