![\"317t](\"http:\/\/killernat.com\/wp-content\/uploads\/2013\/11\/317t-final-300x203.png\")
<\/a><\/p>\n(please note that the pin numbers are wrong out is pin 2 and adj is 3)<\/p>\n
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<\/p>\n","protected":false},"excerpt":{"rendered":"
Since most people don’t own a backup generator (including myself though I would like one). I have been in this situation a few times in the last year\u00a0 due to a new building going up in my area or fires\u00a0 or wind between the power generation facility and the city and have lost power for more than a few hours. In the longest lasting one I found that my phones battery was pretty close to dead so I pulled out the bread board to remedy that problem my first reaction was to use a lm7805 (datasheet) a 5V regulator\u00a0 that would have been nice but I didn’t have any at the time (the closest electronics store is a 20 min bike ride away (and there POS terminals would probably be dead anyway) so I couldn’t be bothered but I had a few dozen lm317t’s (datasheet)\u00a0 a variable regulator With the last of my phones battery I\u00a0 looked up the data sheet (if I had room I would probably keep a print out of all the components data sheets\u00a0 I own )\u00a0 and built the circuit with the light from the camera flash The equation for the voltage regulator\u00a0 is\u00a0 Vout = 1.25v*(1+r2\/r1) I used a 240 ohm resistor for my r1 so 1.25(r2\/240)\u00a0 and I want a near 5v out put. So 5v=\u00a0 ((5\/1.25) -1) *240=720 and the nearest resistor I have is 750. So 1.25(1+(720\/240)) =5.156 close enough! the devices internal regulator can handle an extra 160 mV. In any case its a CMOS logic device so its all 3.3V anyway. I ended up using 2 in parallel to dissipate excess heat (I didn’t have any TO-92 sized heat sinks). As for a final product I added some low value caps (.1 uf on the input and a 10 uf on the out put) along with some protection diodes (see final schematic) . I now have it soldered on a perf-board and in an Altoids tin\u00a0 for use in the future. In fact the last time I went camping I brought it with me\u00a0 and it came in handy. The first night there\u00a0 pretty much killed the battery due to the cold night granted the only use I have for my phone was emergency communication and as a time piece (not an issue any more with my pebble). (please note that the pin numbers are wrong out is pin […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[18],"tags":[],"_links":{"self":[{"href":"http:\/\/killernat.com\/index.php?rest_route=\/wp\/v2\/posts\/196"}],"collection":[{"href":"http:\/\/killernat.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/killernat.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/killernat.com\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/killernat.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=196"}],"version-history":[{"count":12,"href":"http:\/\/killernat.com\/index.php?rest_route=\/wp\/v2\/posts\/196\/revisions"}],"predecessor-version":[{"id":243,"href":"http:\/\/killernat.com\/index.php?rest_route=\/wp\/v2\/posts\/196\/revisions\/243"}],"wp:attachment":[{"href":"http:\/\/killernat.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=196"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/killernat.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=196"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/killernat.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=196"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
![\"lm317](\"http:\/\/killernat.com\/wp-content\/uploads\/2013\/11\/lm317-basic-300x177.png\")
<\/a><\/p>\n![\"7805usb\"](\"http:\/\/killernat.com\/wp-content\/uploads\/2013\/11\/7805usb-300x153.png\")
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