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	<title>Betsie Lawnbott &#187; electronics</title>
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	<description>This robot loves grass</description>
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		<title>I&#8217;m a Mechanical Engineer, but I delve into electronics now and then</title>
		<link>http://betsielawnbott.com/2008/10/01/im-a-mechanical-engineer-but-i-delve-into-electronics-now-and-then/</link>
		<comments>http://betsielawnbott.com/2008/10/01/im-a-mechanical-engineer-but-i-delve-into-electronics-now-and-then/#comments</comments>
		<pubDate>Wed, 01 Oct 2008 22:35:35 +0000</pubDate>
		<dc:creator>sara (betsie's mom)</dc:creator>
				<category><![CDATA[electronics]]></category>

		<guid isPermaLink="false">http://betsielawnbott.com/?p=149</guid>
		<description><![CDATA[The type of voltage regulator that I used for the first Lawnbott Live camera was only rated for 8V, so I needed to get a 12V one.  I bought the only one I found at Radio Shack.  However, it didn&#8217;t seem to work for the new camera setup (I&#8217;ll write about what the [...]]]></description>
			<content:encoded><![CDATA[<p>The type of voltage regulator that I used for the first Lawnbott Live camera was only rated for 8V, so I needed to get a 12V one.  I bought the only one I found at Radio Shack.  However, it didn&#8217;t seem to work for the new camera setup (I&#8217;ll write about what the setup is once it is working).  I suspected the 1 amp limit on the regulator might be the problem.  I only paid for one AC adapter with the new camera so I had to scrounge around the house looking for two more in order to test things out without Betsie&#8217;s battery.  Luckily 12V adapters are very common (got one from the old Linksys router and another from &#8230; something&#8230;).  I plugged everything into the wall and lo-and-behold it worked perfectly.  Nice picture!  I went back to using battery power and the transmitter barely made it to the receiver over a 3 foot distance.  Hmmm&#8230;. The transmitter needs more power.</p>
<p>I realized that my scrounged adapters came in different two different amperage values, one 500mA and one 1A. I knew my voltage regulator was rated for 1A, and had thought that might be the problem (if you can&#8217;t get enough current then you can&#8217;t get enough power as Power = Voltage * Current).  I switched the transmitter to the 1A AC adapter and powered the camera from Betsie and everything worked great again.</p>
<p>This is when I started researching voltage regulators and came across switching regulators.  Similar concept, looks about the same from outside the IC, but inside it&#8217;s all different.  How it&#8217;s different goes beyond this Mech. E&#8217;s interest/experience level, but the end result is that it&#8217;s a lot more efficient.  In a linear voltage regulator the voltage dropped is lost as heat.  This really only works when you&#8217;re at low powers or small voltage drops.  No, I didn&#8217;t do the calculation to figure out how much I&#8217;m wasting, but I did burn my fingers last time so I know there&#8217;s a lot of heat being wasted.  The switching regulator is rated for 80% efficiency.  Since I know I need more power, it seemed like a good way to go.</p>
<p>Here&#8217;s the part I ordered:  http://octopart.com/info/Diodes+Inc./AP1512A-12K5L-13</p>
<p>It arrived today, so I might get a chance to put things together.</p>
<p>I&#8217;m still operating without a soldering iron and without my own voltmeter so I probably won&#8217;t get anything finished tonight.  I need to fix this!</p>
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