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Old 9th November 2013, 11:12 AM   #11
JMFahey is offline JMFahey  Argentina
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1) you could probably work with no more than 25/30mA.
Even if many Leds are lit, they can be wired in series, so current consumption does not add up.

2) in such tight spaces, SMPS is your friend, but even so, you may salvage some proper sized conventional transformer, from stuff such as, say, an old clock radio.
Or pull the SMPS from a dead DVD player or something.

3) you could make a passive VuMeter, where rectified audio voltage which already feeds the speaker, can be rectified and used to directly light Leds.
No need for a PSU.
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Old 9th November 2013, 12:11 PM   #12
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Andersonix just beat me to it. Yes, a walmart plugtop may well have the tiny board that you are looking for.
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Old 10th November 2013, 02:39 AM   #13
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it sounds good idea to strip off a casing...I have to find a very small one. Thanks for suggestions guys!
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Old 10th November 2013, 02:47 AM   #14
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Originally Posted by sofaspud View Post
You should have a better idea of the supply requirements to obtain a helpful response. A LM3915 and 10 LEDs shouldn't require half an amp. Less than 250mA seems more sensible; if all the LEDs stay lit at once you should redesign the meter!
Having said that, there may be a ready-made encapsulated module that you could use. Something like this VSK series from CUI found in Digikey's catalog
Very nice sofaspud . I am going to put it on my list of candidate for sure! Thanks!
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Old 10th November 2013, 03:55 AM   #15
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I tore down one of the white plug-in iPod/iPhone cube style chargers a while back,cause I was curious. They really pack it in that little cube! The only downside is that it's 5V output,not 12V.
Something similar could probably be found with some searching around the local thrift-store,or such.
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Old 15th November 2013, 05:07 PM   #16
AndrewT is offline AndrewT  Scotland
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A regulated 12Vdc at a continuous 1A requires a 12Vac 2Aac transformer.
Unregulated needs 9Vac 2Aac for continuous duty. For cool running double the AC current ratings.

For an intermittent 1Apk and around 150mAdc continuous, then the current rating could be reduced to around 500mAac.
regards Andrew T.
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