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New project + automatic power source selection? |
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bwilbee 
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Joined: 29 October 2007 Location: Isle of Wight Status: Offline Points: 141 |
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 Topic: New project + automatic power source selection?Posted: 09 February 2012 at 12:32pm |
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Been puting together another 12volt powered speaker, it's based around a TA2024 amp, i changed the input caps for a 0.1uf cap to give a high pass at 80hz and added a volume pot.
It has 2 audax 3" full range drivers and is powered by a 2ah liPo pack.  I've added an input for an ac adaptor and would like the amp to start using this instead of the internal battery when an adaptor or external battery is plugged in. Any ideas on how i can do this automaticaly? Edited by bwilbee - 09 February 2012 at 12:33pm |
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login4
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Joined: 03 April 2006 Location: Wales Status: Online Points: 1277 |
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Posted: 09 February 2012 at 12:44pm |
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thats a great little thing you've made there
 why not just have a little rocker switch or something, allot easier?
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bwilbee
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Joined: 29 October 2007 Location: Isle of Wight Status: Offline Points: 141 |
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Posted: 09 February 2012 at 12:54pm |
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yeah it's lots of fun, tbh i'm enjoying getting into the electronics side of things and want the challenge.
I think i solved my own problem tho http://www.maplin.co.uk/6-and-12v-8a-miniature-relays-2525 |
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odc04r
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Joined: 12 July 2006 Location: Sarfampton Status: Offline Points: 1959 |
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Posted: 09 February 2012 at 1:33pm |
Normally closed SPST relay that connects batteries to 12V then opens to connect adaptor 12V to circuits when it is applied? Aka adaptor connection energises the relay coil and then connects itself. Capacitor storage on the output of relay to avoid drastic change in voltage during relay switch and click/pops? I'm sure you could make it more elegant with a couple of transistors, bring down the relay coil current etc but the general idea should work. |
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davey t
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Joined: 11 March 2004 Location: Bristol UK Status: Offline Points: 1239 |
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Posted: 09 February 2012 at 3:34pm |
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u need a power supply with a higher voltage than the battery. eq 14V for 3-cell lipo. Then just use two diodes and it will switch automatically.
Even easier is use a 8-cell Nimah AA pack and a 12V power supply. Using two diodes and a 8R2 5W resistor you can charge the pack and power the speaker from the 12V power supply. This was the battery and charging method of the Minirig 0.1
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www.minirigs.com
Quality portable travel speakers Davey T: Electronics and audio engineering, PASCE Ltd |
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Lyndon A
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Joined: 15 November 2004 Location: Bristol Status: Offline Points: 517 |
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Posted: 09 February 2012 at 6:47pm |
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Or use FETs and forget about looses in the diodes!
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bwilbee wrote: