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	<title>Sound Garage Tales &#187; tuning indicator</title>
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	<link>http://www.soundgaragetales.com</link>
	<description>Adventures in thermionic home brewed guitar tone</description>
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		<title>The Magic Eye Wink</title>
		<link>http://www.soundgaragetales.com/amp-mods/the-magic-eye</link>
		<comments>http://www.soundgaragetales.com/amp-mods/the-magic-eye#comments</comments>
		<pubDate>Thu, 30 Apr 2009 17:53:58 +0000</pubDate>
		<dc:creator>Gabi</dc:creator>
				<category><![CDATA[Amp Mods]]></category>
		<category><![CDATA[amplifiers]]></category>
		<category><![CDATA[EM80]]></category>
		<category><![CDATA[EM84]]></category>
		<category><![CDATA[guitar]]></category>
		<category><![CDATA[Guitar amps]]></category>
		<category><![CDATA[magic eye tube]]></category>
		<category><![CDATA[magick eye]]></category>
		<category><![CDATA[tuning indicator]]></category>

		<guid isPermaLink="false">http://www.soundgaragetales.com/?p=107</guid>
		<description><![CDATA[A simple video demonstration of what's known as a Magick Eye tube, a tube commonly used as a tuning indicator in old radios. This time used in a guitar tube amp.]]></description>
			<content:encoded><![CDATA[<p><a class="tt-flickr tt-flickr-Small" href="http://www.soundgaragetales.com/gallery/photo/3477115362/magick-eye.html"><img class="alignright" src="http://farm4.static.flickr.com/3596/3477115362_38e4c6d1b5_m.jpg" alt="Magick Eye" width="240" height="180" /></a> I couldn&#8217;t control myself. After seeing these cool demos of the <strong>Magick Eye tube</strong>, (a tube commonly used as a tuning indicator in old radios) I had to try them out in my amps. So I plopped together a quick video to see the dramatic and cool visual effect. I will probably tweak some values but overall I am very happy with the visual effect.</p>
<p>The circuit is nothing complicated. All you need is one of the many <strong>Magick Eye tubes</strong> existent out there, with many different beam patterns, that might need a slightly different pin-out connection, but all of them work in a main common way &#8211; it taps in the path of the signal level of roughly 10 to 25 Volts (depends on the type of tube used), and a high DC voltage of something between 200 to 250 (B+).</p>
<p>I used a Russian <a title="EM80 Magick Eye Tube" href="http://www.akh.se/tubes/htm/em80.htm" target="_self">EM80/6BR5</a> I scored off Ebay. The EM80 tube has a &#8220;U&#8221; shaped fluorescent target and two rods connected to the anode, producing two angled shadows on the edge triggered by the control voltage (input signal).</p>
<p>The schematic I used is the one below, <a href="http://www.18watt.com/modules.php?name=Forums&#038;file=viewtopic&#038;t=12916">posted by Michael on the 18watt site</a>.</p>
<p><a href="http://www.soundgaragetales.com/wp-content/uploads/2009/04/em80_schematic.gif"><img class="aligncenter size-medium wp-image-109" title="em80_schematic" src="http://www.soundgaragetales.com/wp-content/uploads/2009/04/em80_schematic.gif" alt="" /></a></p>
<p>I tapped the control voltage (signal) off one of the plates of the EL 84 tubes, and got the high voltage of about 250v off one of the filter caps.</p>
<p>Check this video out of how cool this can be!</p>
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