Led circuit problem

customPC

Hi guys,

Hope ye can help? I am a complete noob in terms of circuits so any advice is greatly appreciated. I wired a single led with push to make switch a while ago but need help on this one.

I have 3 different colour LED's and 3 push to make switches that i want to connect to a 9V battery inside a small box. Two of the LED's have a 3.4V forward drop and the other is 2.4V with a Max current of 20mA. Should i wire them in series or parallel? Only one LED will be active at any one time so wondering which way is better.

Also how does one calculate resistance for this circuit?

If i have left anything out i apologize, but any help is appreciated. Thank you.

Bejubby

I think its best to wire in paralell
Use ohms law for calculations:v is voltage,I is current,r is resistance

V
--
I*r

Cover the letter your looking for and work out the formula.

Forget that its for series


Paralell you need to wire up the circuit
Then get your mrasurments and we'll use a different formula

customPC

Wouldn't it be better to have all the values and understand it before actually wiring

Chet T16

Are you sure all the LED's have the same forward drop? Different colours normally have different drops

customPC

Just double checked there Chet and you are correct sorry. 2 of them have 3.4V drop and the other has 2.4V drop

Chet T16

Connect them like this



You need to calculate the value for each resistor individually taking the voltage as (Battery Voltage - Diode Drop) and 20mA as your current

customPC

Thanks Chet. Thats a great help. Now to put my soldering to the test:-)