I noticed my fellow group members in the Yahoo Group RegenRX are often using a 9V battery to power their projects.\u00a0 This blog is a way to save them a lot of money if they use a lot of 9V batteries.\u00a0 First, the 9V pro’s and con’s, then the DC-DC converter pro’s and con’s.<\/p>\n
For a source of 9V power, there is nothing cleaner\u00a0 than a 9V battery.\u00a0 It makes no RF interference (RFI), no electromagnetic interference (EMI), no hum and very little audio noise.\u00a0 The batteries are easy to obtain and found at most stores.<\/p>\n
The 9V alkaline batteries are ridiculously expensive (however the 9V ‘heavy duty’ batteries are a dollar at the dollar store).\u00a0 I went past a display at the Target store and saw that two name brand alkaline 9Vs were eight dollars.\u00a0 For that much, I can buy 16 to forty AA cells, or sometimes more at Fry’s<\/strong><\/a> or online.<\/p>\n The DC-DC converter circuit is simple and easy to build.\u00a0 It uses parts that can be bought mostly at Radio Shack.\u00a0 It can use a single AA cell if the load is low power, but for 9V power at over 20 milliamps it would be better to use two AAs in series for 3V, and the cells will last longer.<\/p>\n For RF receivers, the converter has one drawback that can be a problem if the builder doesn’t do due diligence: it can cause RF interference.\u00a0 I have used a converter on an AM \/ FM pocket radio and found that the FM works okay but the AM band has a lot of interference.\u00a0 I changed to 470 uF electrolytics for the filter capacitors and that reduced the noise a lot, but what it takes is some RF chokes and the ferrite sleeves that are found on keyboard USB cables and VGA cables.\u00a0 A few well placed EMI sleeves on the cords and power leads should help a lot.\u00a0 Remember that if you’re doing moon-bounce or deep space reception this may not be suitable.\u00a0 But even if you decide that it can’t be used in your project, it’s capable of powering any other of your 9V toys, etc or projects, such as a crystal checker, transistor tester,\u00a0 etc.<\/p>\n My DC-DC converters are not like the cheaper circuits you might see.\u00a0 These are just a voltage boost circuit commonly known as a Joule Thief that uses one transistor and a coil to boost the 1.5V up to 3.2V to light a LED.\u00a0 Except the LED has been replaced by a Zener diode, often 5.1V, that just wastes all of the power as heat while it acts as a shunt regulator.\u00a0 The load taps off the Zener’s current and uses what it needs.\u00a0 But the converter draws a steady load from the battery at its maximum current, and there is no change as the load varies.\u00a0 Instead, my converter feeds back the output voltage to the converter, and when there is low or no load, the converter shuts down and reduces its drain on the 1.5V cell, so that the converter only supplies the load’s demands and the battery life is extended.<\/p>\n Here is a link to the DC-DC converter I built for my cheapo DMM.\u00a0 It’s designed for only 8 or so mA maximum so that the battery will last a long time.\u00a0 L I N K<\/strong><\/a><\/p>\n Here is another link to a DC-DC converter that uses two transistors for the converter.\u00a0 The second schematic uses two transistors that switch in a square wave instead of a single transistor that sharply cuts off and makes a steep waveform with a lot of harmonics.\u00a0 This should reduce the amount of RF and electromagnetic interference.\u00a0 Also the ratio of the windings on the transformer determines the output voltage.\u00a0 The windings have just a dozen or so turns so they are not difficult to wind.\u00a0\u00a0\u00a0\u00a0 L I N K<\/strong><\/a><\/p>\n I have some schematics out there from my old watsonseblog that are accessible but I can’t changes or corrections or delete them.\u00a0 Some of the ones for DC-DC converters are in these links.\u00a0 L I N K<\/strong><\/a><\/p>\n <\/p>\n","protected":false},"excerpt":{"rendered":" I noticed my fellow group members in the Yahoo Group RegenRX are often using a 9V battery to power their projects.\u00a0 This blog is a way to save them a lot of money if they use a lot of 9V batteries.\u00a0 First, the 9V pro’s and con’s, then the DC-DC converter pro’s and con’s. For <\/p>\n (Read More…)<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4,7],"tags":[],"class_list":["post-8745","post","type-post","status-publish","format-standard","hentry","category-joule-thief-smps-dc-dc","category-radio-frequency"],"_links":{"self":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/8745","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=8745"}],"version-history":[{"count":17,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/8745\/revisions"}],"predecessor-version":[{"id":8747,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/8745\/revisions\/8747"}],"wp:attachment":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=8745"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=8745"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=8745"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}