how do i make this work

175

05:11:12

help

published 4 years ago

Robert_Kidd

4 years ago

Intentionally or not ?? - you have adjusted the default values of the LEDs. Was it what you meant to do? If you make the characteristics of all the LEDs the same, then connect a matching supply voltage then it will work.

JayC1

4 years ago

it was intentional, i want to learn how to control different individual segments of LED

Robert_Kidd

4 years ago

It’s important to keep component values real - in other words, only use values that real components have.

Robert_Kidd

4 years ago

In the top row 2nd LED from left is 20mA rather than 120mA like all the others in that row. I wouldn’t think that’s intentional?

Robert_Kidd

4 years ago

You’ve set the lower ones all at 3.8V, 500mA working. They don’t illuminate because the supply is set too low for these - it needs to be 3.8V - but this will burn out top LEDs that only require 2.15V.

Robert_Kidd

4 years ago

Put a 1.5 Ohm resistor between the supply and the top resistors to limit current to 120mA so they don’t burn out.

Robert_Kidd

4 years ago

This will get your circuit working but be aware it is not good practice to put LEDs in parallel.

dB7

4 years ago

@robert_kidd .. why is it not good to put LED in parallel assuming each led has its own resistor?

Robert_Kidd

4 years ago

That’s the point. With individual series resistor it’s fine. Circuit above doesn’t have a single resistor - at the moment.

mlira

4 years ago

The reasons I've heard you shouldn't put LED's in parallel are that components can differ slightly so won't all be perfectly equally loaded and if one dies the current is then shared across the rest. So if one LED has a slightly lower resistance an is overloaded compare to the rest it will fail increasing the current causing another to be overloaded and then a cascade failure. However if they're in series and one goes the circuit is broken for all of them.

mlira

4 years ago

I much prefer the redundancy you get from running them in parallel (would you prefer an emergency light to die immediatly from a surge or slowly over time). In reality most LED arrays I've seen are small strings of ~3 LEDs in parallel. What I would reccomend is running them slightly under the rated current, that way if one dies the rest are unlikely to be overloaded.

Redstone_guy

4 years ago

What @Robert_Kidd said

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