Monitor Controller based on Igors CRM

[craigb]

I'm not sure why you need BCD unless the attenuators are coded that way, and I don't know why you'd code the attenuators that way ...

The attenuator is binary, 1/2/4/8/16/32dB steps, like this:

http://jos.vaneijndhoven.net/attenuator-calculator/index.html

That's the way I've always seen it done with relays, is there a simpler configuration?

You have a processor (Arduino). Use a rotary encoder.

That's certainly another option, although in this application the "feel" of the control is important. And I agree with Jakob's comment about the visual benefit of using a real pot. At any rate, I haven't really designed anything yet, just thinking about it and tossing a few ideas out there.

 

[Andy Peters]

I'm not sure why you need BCD unless the attenuators are coded that way, and I don't know why you'd code the attenuators that way ...

The attenuator is binary, 1/2/4/8/16/32dB steps, like this:

http://jos.vaneijndhoven.net/attenuator-calculator/index.html

BCD isn't binary.

That's the way I've always seen it done with relays, is there a simpler configuration?

Depends on your definition of "simpler." Assuming that the attenuator switches in different resistors, a bunch of relays is simple if brute-force and large. You could use the one of the various "analog switch" chips, and pick one whose on resistance is a small fraction (within the 1% or whatever tolerance) of the resistor you're switching.

You have a processor (Arduino). Use a rotary encoder.

That's certainly another option, although in this application the "feel" of the control is important. And I agree with Jakob's comment about the visual benefit of using a real pot. At any rate, I haven't really designed anything yet, just thinking about it and tossing a few ideas out there.

With a real pot, it's easy enough to translate linear to log in firmware. Have your micro's ADC sample the pot value at regular intervals (fast enough to catch a knob twist) and use a lookup table for the linear-to-log conversion.

-a

 

[sodderboy]

For the Arduino tweakers, mpja.com has a new selection of shields and accessories, like this jammy.
Mike
PS: I always liked Igor's controller.  Very elegantly executed.  I hope he gets healthy and strong again to do whatever he chooses in the future.