electrical nerds needed D:

[kinkywink]

hey guys.. i was wondering if i could get a little insight and learn a few things for my future..
im currently wiring up LEDs in my room, and i was wondering...

would it be okay for me to use a power supply that outputs 12 volts and 250mA or 0.25 amps for say 20 LEDs, (2 sets in series of 10 in parallel)

 

also.. im creating a.. you could say "color-organ" for a different set of LEDs to pulse with the music.. does it matter what type of NPN transistor? i gather that say if i was using a TIP31a the LEDS would flash in a more "sensitive" way compared to a TIP31c..

 

 

any feed back is appreciated :D

[Maskot]

I personally don't know, but if you don't get your answer here, http://www.electronicspoint.com, go there, they'll be able to easily answer your electronic question, they answer all of mine.

[João Severino]

The power supply you use depends on the LEDs you choose

The things you should look for are

• voltage drop of each LED (meaning the voltage at the LEDs terminals)
• current drawn by each LED (meaning how much current the LED draws when in use)

After knowing this you add all the voltages and currents and you have the values for the power supply you need

A regular LED has a 2V voltage drop and a 20mA of current which means if you add 2 sets in series of 10 LEDs in parallel like you want you would get

• 4V of voltage drop
• 200mA of current

However I advise you to do 2 sets in parallel of 10 LEDs in series and for this configuration you would get

• 10V of voltage drop
• 20mA of current

 

On the transistor side I advise you to get MOSFETs as they are more suited to handle bigger loads than a regular transistor

[Tigerbomb8]

http://makezine.com/2010/10/18/circuit-skills-led-color-organ-spon/

 

have a look at this.

[kinkywink]

The power supply you use depends on the LEDs you choose

The things you should look for are

• voltage drop of each LED (meaning the voltage at the LEDs terminals)
• current drawn by each LED (meaning how much current the LED draws when in use)

After knowing this you add all the voltages and currents and you have the values for the power supply you need

A regular LED has a 2V voltage drop and a 20mA of current which means if you add 2 sets in series of 10 LEDs in parallel like you want you would get

• 4V of voltage drop
• 200mA of current

However I advise you to do 2 sets in parallel of 10 LEDs in series and for this configuration you would get

• 10V of voltage drop
• 20mA of current

 

On the transistor side I advise you to get MOSFETs as they are more suited to handle bigger loads than a regular transistor

so far, what i have done is 7 leds all in parallel but also in series with another 6 leds that are in parallel, there running off of 3 volts and 400mA they arent running to hot and a fairly bright at the moment, using an old stereo volume to give them a little bit of resistance as well..