{"id":1058,"date":"2013-09-09T10:33:33","date_gmt":"2013-09-09T17:33:33","guid":{"rendered":"https:\/\/logicalelegance.com\/journey\/?p=1058"},"modified":"2013-09-09T10:33:33","modified_gmt":"2013-09-09T17:33:33","slug":"mosfets-games-and-a-demonstration-of-shiny-object-syndrome","status":"publish","type":"post","link":"https:\/\/logicalelegance.com\/journey\/2013\/09\/mosfets-games-and-a-demonstration-of-shiny-object-syndrome\/","title":{"rendered":"MOSFETs, games, and a demonstration of shiny object syndrome"},"content":{"rendered":"<p>Conversation this morning:<\/p>\n<pre>Me: You named one of your gadgets MOSFET...\u00a0\r\nHim: Yes...\r\nMe: Why? Is it something to do with Star Wars? Boba Fett?\r\nHim: (Uncomfortable silence.) No. They are used in music amplifiers.<\/pre>\n<p>I keep coming back to MOSFETs. I keep seeing them in different contexts where they end up being the &#8220;oh you just put a MOSFET in there and it will work the way you want&#8221; component.<\/p>\n<p>Maybe it is time I learned what this magical component does.<\/p>\n<p>As a pretest, though, I&#8217;ll splat out everything I can think of.<\/p>\n<ul>\n<li>When I wanted to connect a IO to a motor, the IO pin didn&#8217;t have enough current. So the EE (Phil) put in a MOSFET so I could toggle the IO line to get the motor to turn on and off without pulling current through the processor.<\/li>\n<li>When I asked Phil about my resistor divider sucking too much power, he said I should put in \u00a0a MOSFET so the divider was only on when I needed to measure the battery. I didn&#8217;t carefully read the ensuing EEspeak because I don&#8217;t have an extra IO pin.<\/li>\n<li>A FET is a form of MOSFET. Probably one with less moss&#8230; Actually, it is probably that a MOSFET is a form of FET. Probably with more moss. Really though, there is probably no moss, it tends to be damp and that&#8217;s bad for electronics.<\/li>\n<li>It seems to be a switch that is controlled electronically.<\/li>\n<li>They come in n and p varieties. I don&#8217;t know the difference.<\/li>\n<li>(And this just in!) They are used in musical amplifiers.<\/li>\n<\/ul>\n<p>So, let&#8217;s be clear: I&#8217;ve used MOSFETs before. But as I try to design my own hardware, I keep getting smacked upside the head with them, like getting hit with a fish tail as the fish escapes the boat and swims away. That&#8217;s always been ok with me: I never really wanted the fish. But now I want to understand MOSFETs. And not just for a few minutes until some shiny other thought comes along.<\/p>\n<p>Let&#8217;s go back to what Phil said in my resistor divider email exchange.<\/p>\n<blockquote><p><em>To prevent that leakage current you could just put a FET to turn off that voltage divider when you&#8217;re not checking the battery voltage. You could use a high-side P-Channel FET, (between VBat and R1) but turning it off solidly would require a voltage equal to (or higher than) the battery, or you could use a low-side N-Channel FET, but then you&#8217;d still have the leakage current through the ADC. \u00a0Although that 50KOhm is probably only while it is sampling, not when it is not in use. \u00a0So that is what I would try for a minimal-part, minimal cost solution, if you have a spare digital I\/O to turn that FET on and off&#8230;<\/em><\/p><\/blockquote>\n<p>Ok. Well, I guess I retained enough of that though I suspect Phil copied the paragraph from the last five times I asked him something that required a MOSFET. I suppose what I need to do is use MOSFET in a circuit I design myself.<\/p>\n<p>First, a little more information, courtesy of <a title=\"MOSFET on Wikipedia\" href=\"http:\/\/en.wikipedia.org\/wiki\/Mosfet\" target=\"_blank\">Wikipedia<\/a>. Wow, that article is long. Let&#8217;s just come back to it, ok?<\/p>\n<p>And since my attention span is tiny this morning, let me tell you about this game I&#8217;ve been playing. It is <a title=\"Circuit Coder in iTunes\" href=\"https:\/\/itunes.apple.com\/us\/app\/circuit-coder\/id492180472?mt=8\" target=\"_blank\">Circuit Coder<\/a> for the ipad. It gives me little challenges, like build a NAND gate using only NOR gates, then I build what it wants, trying to think through the problem. Here is my half-adder.<br \/>\n<a href=\"https:\/\/logicalelegance.com\/journey\/wp-content\/uploads\/2013\/09\/photo.png\"><img loading=\"lazy\" decoding=\"async\" alt=\"Circuit Coder Half Adder solution\" src=\"https:\/\/logicalelegance.com\/journey\/wp-content\/uploads\/2013\/09\/photo-1024x768.png\" width=\"490\" height=\"367\" \/><\/a><\/p>\n<p>I had a decent amount of logic in college, in the CS courses, so this NAND and NOR gates are buried deep in my brain but have a solid foundation. I like the puzzle aspect. I&#8217;m a little stuck on SR latches but I have a plan to go read about them and I suspect they&#8217;ll fall pretty quickly.<\/p>\n<p>Since some of the puzzles are tricky, there is a <a title=\"Circuit Coder official walkthrough\" href=\"http:\/\/sweyla.com\/circuit-coder\/walkthrough\/\" target=\"_blank\">walkthrough<\/a>. I was afraid to look at it for fear of taking away the puzzle aspect. However, the walkthrough is only for the first 3.5 minutes of the game so I am more likely to cheat using a computer engineering text book. And a game that can get me to look up how components work and demonstrate logic gates so effectively&#8230; this is more what I want from learning. Sneaky learning. Though, I wish the game had a little more help and could be a little more competitive (what is the minimum component solution for each?). But completing puzzles is very satisfactory.<\/p>\n<p>I was hoping one of the components I need to make is a MOSFET. But looking around now, I don&#8217;t see that in Circuit Coder. (Though I do see a <a title=\"Reviews of educational games\" href=\"https:\/\/www.appolearning.com\/categories\/120-computer-science-technology\" target=\"_blank\">review<\/a>\u00a0that rates this game highly and suggests <a title=\"Codea in iTunes\" href=\"https:\/\/itunes.apple.com\/us\/app\/codea\/id439571171?mt=8\" target=\"_blank\">Codea<\/a>\u00a0as a good learn-to-code game. Whew, expensive though! And then my appolearning &#8220;trial&#8221; expired and I am considering whether to buy their (too expensive) app so I could learn about other instructional apps.)<\/p>\n<p>And this is why my quest for MOSFET intuition has, to date, been for naught. I keep looking at the Wikipedia article and then finding something else to do. It is too theoretical and not tactical enough: what should I use a MOSFET for and why?<\/p>\n<p>Getting away from the shiny distractions available in Wiki, I switched to looking at Charles Platt&#8217;s <a title=\"Components\" href=\"http:\/\/my.safaribooksonline.com\/book\/electrical-engineering\/9781449333881\" target=\"_blank\">Encyclopedia of Components<\/a> in Safari. (If you write an O&#8217;Reilly book, you get a free lifetime subscription to Safari online. Happy perk!)<\/p>\n<p>There was nothing about MOSFETs in the table of contents. That seemed so unlikely for a book titled thusly. I searched for MOSFET, found some entries under\u00a0<em>Chapter 29. field effect transistor<\/em>.<\/p>\n<p>I bet &#8220;field effect transistor&#8221; has been used to sound very sci-fi. If I had a band (made up entirely of light theramin), it would be called &#8220;field effect transistor&#8221;.<\/p>\n<p>And apparently, I should read chapters 26-28 before proceeding so I understand diodes and transistors because those are related.<\/p>\n<p>I had hoped to share my new-found understanding with you in this post. Instead, I feel like I&#8217;ve wandered around in circles until exhausted. I&#8217;m going to go sit in a corner with this book and see what I can learn.<\/p>\n<p>Or maybe I&#8217;ll do some paying work.<\/p>\n<p>Naw, I think I&#8217;ll go run errands.<\/p>\n<p>Or maybe push reload on twitter.<\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Conversation this morning: Me: You named one of your gadgets MOSFET&#8230;\u00a0 Him: Yes&#8230; Me: Why? Is it something to do with Star Wars? Boba Fett? Him: (Uncomfortable silence.) No. They are used in music amplifiers. I keep coming back to MOSFETs. I keep seeing them in different contexts where they end up being the &#8220;oh [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[1],"tags":[16,8,40,34],"class_list":["post-1058","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-books","tag-learning","tag-reviews","tag-tech"],"_links":{"self":[{"href":"https:\/\/logicalelegance.com\/journey\/wp-json\/wp\/v2\/posts\/1058","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/logicalelegance.com\/journey\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/logicalelegance.com\/journey\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/logicalelegance.com\/journey\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/logicalelegance.com\/journey\/wp-json\/wp\/v2\/comments?post=1058"}],"version-history":[{"count":2,"href":"https:\/\/logicalelegance.com\/journey\/wp-json\/wp\/v2\/posts\/1058\/revisions"}],"predecessor-version":[{"id":1061,"href":"https:\/\/logicalelegance.com\/journey\/wp-json\/wp\/v2\/posts\/1058\/revisions\/1061"}],"wp:attachment":[{"href":"https:\/\/logicalelegance.com\/journey\/wp-json\/wp\/v2\/media?parent=1058"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/logicalelegance.com\/journey\/wp-json\/wp\/v2\/categories?post=1058"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/logicalelegance.com\/journey\/wp-json\/wp\/v2\/tags?post=1058"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}