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hello, i am new here and i have just got my electrical engineering started.I want to make a Board about the size of keyboard with Leds arranged parallel and with 'welcome' written on this veroboard.Can you guide me a little? Please and thank you.
Only cheap Chinese flashlights that burn out in a few minutes connect LEDs in parallel.
LEDs each have a different voltage so the one with the lowest voltage is the brightest with the most current and is the one that burns out first when LEDs are in parallel. Then the remaining LEDs have higher current and they also burn out.
Use a fairly high DC supply voltage and connect strings of LEDs in series and each string in series with a current-limiting resistor that is calculated with Ohm's Law. Use high quality wide beam-angle LEDs not cheap E-Bay Chinese narrow beam-angle ones that can't be seen unless they shine directly at you.
I really dont see a problem with leds in parallel as long as each has a limiting resistor.
It do create a very power hungry circuit though as there is a lot of energy lost in each resistor.
The problem with series leds is if one burns out or fails for a reason then the whole string fails, but it is a much more energy efficent method to connect the leds.
You need to give more information and what leds you will be using (like colour, voltage and current ratings for the leds) and what will be used to supply the power and at what voltage.
How many leds in total to make up the word "welcome"
If you intend to mix colours than it can get a little tricky working out the wiring groups.
ok the colour of leds is blue.the leds are high quality.these work at 3.7V.I ll be using 100 leds to write WELCOME and the 220V supply is to be used from mains.
Hmmm? i dont like the idea of using 220 volt ac mains, especially when you need to ask how to wire a led to light a word.
To me you are asking for trouble and will likely hurt yourself or someone else if not kill someone.
Better approach........ use a transformer to lower the voltage to 24 volt and rectifie it to dc.
Then use 6 leds in a series string plus a resister per string.
That would make it about 17 series strings all paralleled together.
The leds might be rated to 3.7 volts but i would only work to 3.5 volt per led max.
What is the current rating at 3.7 volt per led (20 mA ??)
More information needed...........
Current?
how do you intend to mount all the leds to form the word?
Its your project, so you do the leg work on finding information and we can help you work with the information.
You don't want 220VAC directly feeding this circuit. The resistor needed would be large and defeat the purpose. I agree with SABorn suggesting the transformer for safety's sake. My 1988-model name-in-lights boards used a wallpack for a PSU, the first letter was in caps, and the display blinked. I haven't kept in touch with the recipients, so I don't know how many are still around to this day.
Have you considered solar-powered, rechargeable batteries for a PSU?
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