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VK2RQ > ALL 28.07.13 17:20l 16 Lines 673 Bytes #999 (0) @ WW
BID : 14048_VK2RQ
Read: GUEST
Subj: Re: LEDs in parallel
Path: IZ3LSV<IW0QNL<JH4XSY<F1OYP<VK4TUB<VK2RQ
Sent: 130728/1613Z @:VK2RQ.#SYD.NSW.AUS.OC #:14048 [Sydney] $:14048_VK2RQ
From: VK2RQ@VK2RQ.#SYD.NSW.AUS.OC
To : ALL@WW
I agree Phil -- if the LEDs in parallel do not have individual
current limiting resistors, them it is indeed poor design. In
order to see if the LEDs have current limiting resistors built-in,
you could try measuring the voltage drop across the leads of the
LED for different values of external current limiting resistor.
If you then plot the LED voltage vs current and measure the slope
of the graph, you should be able to estimate the value of an internal
current-limiting resistor (ie. assuming the voltage drop of the
diode junction is more or less constant across the range of current
values you chose).
73, Matt VK2RQ
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