Digital Velvet Vernier. Any Suggestions?

Discussion in 'Programmer's Corner' started by Rory Starkweather, Jan 30, 2015.

  1. Rory Starkweather

    Thread Starter Member

    Jan 27, 2015
    41
    4
    I bought a pair of DIY HAM band receivers several years ago, from Ramsey. Nice kits, but tuning was/is iffy. They both use potentiometers to control tuning and my hands shake so much that I can't lock on to a target frequency, especially since they only have about 300 degrees of a circle to cover the whole tuning range. Kind of frustrating so I'm tryiing to think of a 'workaround'.

    I love Velvet Verniers, but they haven't been made for years, and I can't afford $50 per tuning knob on kits that originally cost less than $25.

    One thing that came to mind was some kind of digital tumer. (Up button, down button and an LCD readout, of . . . something.) Now I know there are are a lot of things like this in use, but I don't even know what to Google.

    I'm thinking of replacing the tuners with some more expensive versions, but, before I go there, I'm wondering if there is a cheaper solution already out there.

    The bottom line is that I would like to replace a pair of variable resistors with something with more accuracy, and selectivity.

    Does anyone have any suggestions?
     
  2. DNA Robotics

    Member

    Jun 13, 2014
    122
    26
    Maybe a more mechanical method with pulleys and a belt. Salvage parts from an old cassette player? If you put a large knob on the motor shaft, you would have a lot of control.

    pulley system.jpg
     
  3. joeyd999

    AAC Fanatic!

    Jun 6, 2011
    2,674
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    I am radio illiterate.

    But, why not two tuners: course and fine?
     
  4. MikeML

    AAC Fanatic!

    Oct 2, 2009
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  5. Rory Starkweather

    Thread Starter Member

    Jan 27, 2015
    41
    4
    I'm not saying "No" but the whole thing is like 6" by 5". (The whole receiver.) I've thought about breaking it out, but I haven't gone there yet.

    Your idea is a very good one, but I would have to buy something like the ten turn pot, mentioned below, and then there's the problem with limit switches. I don't want the motor trying to tear off either end of the potentiometer.

    Almost forgot. I suk at salvaging. :) I can't salvage a pebble from a rock.
     
  6. Rory Starkweather

    Thread Starter Member

    Jan 27, 2015
    41
    4
    You have been a constant source of really good suggestions. HOWEVER, this time, I don't have any idea how to build either one, let alone, both. I believe in success through successive approximations.

    As usual, your idea is a great one, but I'm not advanced enough for that yet.
     
  7. Rory Starkweather

    Thread Starter Member

    Jan 27, 2015
    41
    4
    You know. That's a really good suggestion. I think I'm having the 'forest for the trees' problem. A ten turn pot would be cheaper than any of the alternatives, and it would be a step forward. Something I could build on if necessary. TYVM.
     
  8. Rory Starkweather

    Thread Starter Member

    Jan 27, 2015
    41
    4
    I messed up on this one. Wrong forum. If there is a person available to move this, it should be in projects.
     
  9. DNA Robotics

    Member

    Jun 13, 2014
    122
    26
    I guess I confused things by using a motor as an axle mount.

    When I said If you put a large knob on the motor shaft, you would have a lot of control, I meant to turn it manually with a 50:1 or so gear reduction.
    If you turn the knob a lot, it turns your tuner a little bit.
     
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