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okelk
Joined: May 08, 2014 Posts: 71 Location: Vienna
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Posted: Sat Oct 04, 2014 11:31 am Post subject:
Estimating Power consumption |
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Hi! I hope there isn't another thread asking the same question out there already, but I couldn't find any....
Do you have something like a rule of thump for estimating the power consumption on a cmos synth?
something like X 4000 series chips + X leds = X mA ...
I assume in many cases the leds need more power than the chips? |
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synaesthesia
Joined: May 27, 2014 Posts: 291 Location: Germany
Audio files: 85
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Posted: Sun Oct 05, 2014 12:44 am Post subject:
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CMOS chips vary, but most can drive between 0.5 and 2 mA per output, which depends on the supply voltage you use. The input pins consume next to nothing. A modern LED needs only between 5 and 10 mA. As a rough estimate for the total current you can start with (LEDs + CHIPs) x 5mA. You probably will have other chips as well in a synth, so also consider the amplifier, filter etc.
As always, it depends, check the datasheets. For an overview for the CMOS family see http://www.nxp.com/documents/data_sheet_addendum/familyhef4000specification.pdf |
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PHOBoS
Joined: Jan 14, 2010 Posts: 5591 Location: Moon Base
Audio files: 705
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Posted: Sun Oct 05, 2014 2:51 am Post subject:
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synaesthesia wrote: | A modern LED needs only between 5 and 10 mA. |
I'd say it can be even less then that. I personally use 4K7 resistors in series on a 12V supply for standard diffuse LEDs.
That's about 2mA per LED and they still are pretty bright. So if you have very bright LEDs you can decrease the current even more.
I've used >100K for blue and white LEDs.
Quote: | As a rough estimate for the total current you can start with (LEDs + CHIPs) x 5mA. |
yeah that should work, keep in mind to count only the number of LEDs that are on at the same time.
For example if you use something like a decimal counter you might have 10 LEDs connected to it,
but there will only be 1 on at the same time. _________________ "My perf, it's full of holes!"
http://phobos.000space.com/
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