power/adjustable resistor/index.org

   1 #+TITLE: Adjustable resistor / indicator
   2 #+AUTHOR: Svjatoslav Agejenko
   3 #+LANGUAGE: en
   4
   5 * (document settings) :noexport:
   6 ** use dark style for TWBS-HTML exporter
   7 #+HTML_HEAD: <link href="https://bootswatch.com/3/darkly/bootstrap.min.css" rel="stylesheet">
   8 #+HTML_HEAD: <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
   9 #+HTML_HEAD: <script src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.5/js/bootstrap.min.js"></script>
  10 #+HTML_HEAD: <style type="text/css">
  11 #+HTML_HEAD:   footer {background-color: #111 !important;}
  12 #+HTML_HEAD:   pre {background-color: #111; color: #ccc;}
  13 #+HTML_HEAD: </style>
  14
  15 * General
  16 + DISCLAIMER: I DO ELECTRONICS AND 3D DESIGN SOLELY AS A HOBBY. THERE
  17   COULD BE ERRORS THAT CAN RESULT IN ALL KINDS OF DAMAGE. USE THESE
  18   DESIGNS AT YOUR OWN RISK.
  19
  20 + This design is released under Creative Commons Zero (CC0) license.
  21
  22 + Author:
  23   - Svjatoslav Agejenko
  24     - Homepage: https://svjatoslav.eu
  25     - Email: [[mailto://svjatoslav@svjatoslav.eu][svjatoslav@svjatoslav.eu]]
  26
  27 + See also:
  28   - [[../../index.html][Other physical projects in this repository]]
  29   - [[https://www.svjatoslav.eu/projects/][Other projects hosted at svjatoslav.eu]]
  30
  31 * Project description
  32 I needed a way to experimentally find resistance that works best in
  33 certain circuits. Usual potentiometers could not handle required power
  34 dissipation and were not precise enough.
  35
  36 Solution is to build adjustable resistor:
  37
  38 [[file:make.png]]
  39
  40 Logically there is series of resistors that increase in resistance in
  41 the power of 2: 0.5, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512. Each
  42 resistor can be enabled or disabled by a switch. This makes entire
  43 range of 0 -- 1023.5 ohms available with the 0.5 ohms precision.
  44
  45 Schematic:
  46 [[file:schematic.png]]
  47
  48 Here is front panel for switches:
  49 [[file:front%20panel.png]]
  50
  51 Download:
  52 + [[file:front%20panel.FCStd][FreeCAD project]]
  53 + [[file:front%20panel.stl][STL file]]
  54
  55 Sometimes I would like to use lightbulbs with various parameters as
  56 test load/indicator. Current device has 4 of them included.
  57
  58 Here is front panel for light bulbs:
  59 [[file:indicator%20panel.png]]
  60
  61 Download:
  62 + [[file:indicator%20panel.FCStd][FreeCAD project]]
  63 + [[file:indicator%20panel.stl][STL file]]
  64
  65
  66 After assembly using prototype PCB:
  67 [[file:make,%202.png]]
  68
  69
  70 Following body is used as a case and PCB support:
  71 [[file:body.png]]
  72
  73 Download:
  74 + [[file:body%20and%20back%20cover.FCStd][FreeCAD project (body + back cover)]]
  75 + [[file:body.stl][STL file for body]]
  76
  77 Result:
  78 [[file:make,%203.png]]
  79
  80 Cover on the back:
  81 [[file:back%20cover.png]]
  82
  83 Download: [[file:back%20cover.stl][STL file]]
  84
  85 Button covers:
  86 [[file:button.png]]
  87
  88 Download:
  89 + [[file:button.FCStd][FreeCAD project]]
  90 + [[file:button.stl][STL file]]