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+<h1><span class="title">Thor&#39;s Hammer</span></h1>
+
+<h2 class="date">2018/05/03</h2>
+<p class="terms">
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+<p>In case you were having an inferiority complex because your friends' IBM Model M keyboards are so much louder than the
+shitty rubber dome freebie you got with your pc... Here's the solution: Thor's Hammer, a simple typing cadence enhancer
+for <a class="reference external" href="https://en.wikipedia.org/wiki/PS/2_port">PS/2</a> keyboards.</p>
+<figure>
+    <video controls loop>
+        <source src="video/thors_hammer.mov" type="video/h264">
+        <source src="video/thors_hammer.webm" type="video/webm">
+        Your browser does not support the HTML5 video tag.
+    </video>
+    <figcaption>A demonstration of the completed project.
+
+        <a href="video/thors_hammer.mov">h264 download</a> /
+        <a href="video/thors_hammer.webm">webm download</a>
+    </figcaption>
+</figure><p>The connects to the keyboard's PS/2 clock line and briefly actuates a large solenoid on each key press. An interesting
+fact about PS/2 is that the clock line is only active as long as either the host computer or the input device actually
+want to send data. In case of a keyboard that's the case when a key is pressed or when the host changes the keyboard's
+LED state, otherwise the clock line is silent. We ignore the LED activity for now as it's generally coupled to key
+presses. By just triggering an NE555 configured as astable flipflop we can stretch each train of clock pulses to a
+pulse a few tens of milliseconds long that is enough to actuate the solenoid.</p>
+<figure>
+    <img src="images/thors_hammer_schematic.jpg" alt="The schematic of the PS2 driver">
+    <figcaption>The schematic of the driver stretching the PS/2 clock pulses to drive the solenoid.</figcaption>
+</figure><p>Since PS/2 sends each key press and key release separately this circuit will pulse twice per keystroke. It would be
+possible to ignore one of them but I figure the added noise just adds to the experience.</p>
+<p>Built on a breadboard, the circuit looks like this.</p>
+<figure>
+    <img src="images/thors_hammer_breadboard.jpg" alt="The circuit built on a breadboard">
+    <figcaption>The completed circuit built up on a breadboard and attached to a keyboard.</figcaption>
+</figure><p>Since my solenoid did not have a tensioning spring I used a rubber band and some vinyl tape to make an adjustable
+tensioner. The small orange USB hub serves as an end-stop because I had nothing else of the right shape. The sound and
+resonance of the thing can be adjusted to taste by moving the end stop, adjusting the tensioning rubber and tuning the
+excitation duration using the potentiometer. My particular solenoid was a bit slow so I added some pieces of circuit
+board as shims between the plunger and the case to limit the plunger's travel inside the solenoid core.</p>
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