4 <title>Adjustable resistor / indicator</title>
5 <!-- 2020-08-22 L 15:39 -->
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198 <div class="row"><div class="col-md-9"><h1 class="title">Adjustable resistor / indicator</h1>
200 <div id="outline-container-sec-1" class="outline-2">
201 <h2 id="sec-1"><span class="section-number-2">1</span> General</h2>
202 <div class="outline-text-2" id="text-1">
204 <li>DISCLAIMER: I DO ELECTRONICS AND 3D DESIGN SOLELY AS A HOBBY. THERE
205 COULD BE ERRORS THAT CAN RESULT IN ALL KINDS OF DAMAGE. USE THESE
206 DESIGNS AT YOUR OWN RISK.
209 <li>This design is released under Creative Commons Zero (CC0) license.
214 <li>Svjatoslav Agejenko
216 <li>Homepage: <a href="https://svjatoslav.eu">https://svjatoslav.eu</a>
218 <li>Email: <a href="mailto://svjatoslav@svjatoslav.eu">svjatoslav@svjatoslav.eu</a>
227 <li><a href="../../index.html">Other physical projects in this repository</a>
229 <li><a href="https://www.svjatoslav.eu/projects/">Other projects hosted at svjatoslav.eu</a>
237 <div id="outline-container-sec-2" class="outline-2">
238 <h2 id="sec-2"><span class="section-number-2">2</span> Project description</h2>
239 <div class="outline-text-2" id="text-2">
241 I needed a way to experimentally find resistance that works best in
242 certain circuits. Usual potentiometers could not handle required power
243 dissipation and were not precise enough.
247 Solution is to build adjustable resistor:
252 <p><img src="make.png" class="img-responsive" alt="make.png">
257 Logically there is series of resistors that increase in resistance in
258 the power of 2: 0.5, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512. Each
259 resistor can be enabled or disabled by a switch. This makes entire
260 range of 0 – 1023.5 ohms available with the 0.5 ohms precision.
265 <img src="schematic.png" class="img-responsive" alt="schematic.png">
269 Here is front panel for switches:
270 <img src="front%20panel.png" class="img-responsive" alt="front%20panel.png">
277 <li><a href="front%20panel.FCStd">FreeCAD project</a>
279 <li><a href="front%20panel.stl">STL file</a>
284 Sometimes I would like to use lightbulbs with various parameters as
285 test load/indicator. Current device has 4 of them included.
289 Here is front panel for light bulbs:
290 <img src="indicator%20panel.png" class="img-responsive" alt="indicator%20panel.png">
297 <li><a href="indicator%20panel.FCStd">FreeCAD project</a>
299 <li><a href="indicator%20panel.stl">STL file</a>
305 After assembly using prototype PCB:
306 <img src="make,%202.png" class="img-responsive" alt="make,%202.png">
311 Following body is used as a case and PCB support:
312 <img src="body.png" class="img-responsive" alt="body.png">
319 <li><a href="body%20and%20back%20cover.FCStd">FreeCAD project (body + back cover)</a>
321 <li><a href="body.stl">STL file for body</a>
327 <img src="make,%203.png" class="img-responsive" alt="make,%203.png">
332 <img src="back%20cover.png" class="img-responsive" alt="back%20cover.png">
336 Download: <a href="back%20cover.stl">STL file</a>
341 <img src="button.png" class="img-responsive" alt="button.png">
348 <li><a href="button.FCStd">FreeCAD project</a>
350 <li><a href="button.stl">STL file</a>
355 </div><div class="col-md-3"><nav id="table-of-contents">
356 <div id="text-table-of-contents" class="bs-docs-sidebar">
358 <li><a href="#sec-1">1. General</a></li>
359 <li><a href="#sec-2">2. Project description</a></li>
364 <footer id="postamble" class="">
365 <div><p class="author">Author: Svjatoslav Agejenko</p>
366 <p class="date">Created: 2020-08-22 L 15:39</p>
367 <p class="creator"><a href="http://www.gnu.org/software/emacs/">Emacs</a> 26.1 (<a href="http://orgmode.org">Org-mode</a> 9.1.9)</p>