Octave switcher layout question

isak · Posted: Sun Sep 23, 2012 7:20 am Post subject: Octave switcher layout question

Hi guys

i did a pcb design to a scheme i found hear in forum and i'm working on my pcb designing skills.
could you please let me know if i did a mistake? only by looking of course.

i thank you in advance.
Isak E.

EDIT:
i just found that i did a mistake by putting the 1k resistors in parallel when i needed to put them in series.
the attachment is updated.

voltage_switch_165.jpg

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octave switch - comp + layout new.png

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isak · Posted: Sun Sep 23, 2012 9:14 am Post subject:

found another mistake and update the above attached.

emdot_ambient · Joined: Nov 22, 2009 Posts: 669 Location: Frederick, MD

I haven't been on this forum in a while...

Nice one! Have you made it yet? And if so how well does it work?

What would the calibration procedure be? I'd not be sure how to use the Scale and Octive trimmers to set it up.

And...what would have to be done to convert it to 15V power supply?

Osal · Joined: Aug 16, 2011 Posts: 108 Location: Here

Hello Isak,

To avoid voltage drops when splitting the signal, the resistor at the output should be before the feedback, and 1K is the appropriate value.

You could solder the voltage divider's resistors in the rotary switch to simplify the PCB and the wiring to the front panel

You could save the trimmer resistor in the op-amp feedback matching the resistors to 0.1%. This would give you a worst case deviation gain of 0.002. For 5V at the input it would be -5.01V at the output that it is worst case error of about 1/17 tone.

It is recommendable to use a voltage reference instead of use the power rail directly.

isak · Posted: Tue Oct 09, 2012 4:16 am Post subject:

thank you Osal.

i'm making few changes with your suggestions.
will post new layout soon!