Power distribution schemes / tips
Does anyone have any tips for power distribution?· If I put two leds in a row, it seems like the first one is brighter.·· Is it any different for combining numbers of circuits?
It is the same thing which happens in my car.· I'm stopped at the Red light and when I touch the power windows, the headlights dim.
If I want to go from two leds to a whole board with projects, what would you suggest?· Just use a parallel wiring scheme?· Something else?
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It is the same thing which happens in my car.· I'm stopped at the Red light and when I touch the power windows, the headlights dim.
If I want to go from two leds to a whole board with projects, what would you suggest?· Just use a parallel wiring scheme?· Something else?
·
Comments
with the LEDs I guess one of them is less bright or the supplyng voltage is not high enough.
What happens if you change the order of the LEDs ?
Whenever you have multiple loads that are REALLY THE SAME, you can connect them in serial and you have to increase the supplyvoltage
Example light-bulbs: let's assume they have 6V 1A
If you put three of them in sequence you need to supply them by 18V 1A
If you put three of them parallel you need to supply them by 6V 3A
Whenever you want to supply DIFFERENT loads with the same voltage the only way to go is to supply them parallel
example:
one light-bulb 6V 1A
one light-bulb 6V 0.3A
three light-bulbs 6V 1.5A
the only way you can supply them is to connect them parallel to a 6V powersupply which can deliver 1A + 0.3 + 3*1.5A = 5.8A
best regards
Stefan
@Chukz:
How big is the difference? In case it is big you might have mixed LEDs of different type. There are low currency (~3mA)·types and the normal types (~10mA).
Do you mix LEDs from different manufacturers? Even if they have the same nominal currency the light they emit can be different.
Do you mix LEDs that have a different color? They emit a different 'amount' of light. You can see that in the specs of the LEDs, where it says how many mcd the LED emits.
Is the difference small? That's normal deviation of the nominal brightness. Each electronic component has a deviation of·it's given value (resistance, capacity ...). If you need the LEDs to be really equal in brightness, you can test several LEDs and find those that match best or drive each LED with it's own current.·
MagicIO2 said..."Just out of curiosity ... what do you expect? Parasite flow of currency in the PCB?"
In the context here it seems like a good question to me. Even if only to get Chckz thinking about what is going on here.
I can imagine that two LEDs in series are quite likely to have different brightnesses depending on the variation between the LEDs. But the statement was "...it seems like the first one is brighter.". Well which is the first one? The one nearest the negative supply or the one nearest the positive. How would each LED possibly know what position it is in such that it would get dimmer or brighter?
A challenge: Is there any such serially connected circuit where swapping the components around cause the components to behave differently?
Chukz: Pick up a beginners electronics book or two or have a search around the net. A million years ago I found exactly playing around with 6v bulbs, motors, wires, and batteries to be most informative about such things. Even before I knew what voltage, current and resistance were. Stay away from LEDS at the start, they confuse the issues.
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For me, the past is not over yet.
See, for example, the section in the following guide that deals with Loop Equations. (I'm sure other forum members can direct you to better links, too.)
hss.energy.gov/nuclearsafety/ns/techstds/standard/hdbk1011/h1011v1.pdf
en.wikipedia.org/wiki/Voltage_divider
en.wikipedia.org/wiki/Current_divider
hope that helps,
Mark
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Watching the world pass me by, one photon at a time.