Gcse project NEED HELP

[Chabs]

I have to do a dt project for gcse please can someone help. Im using 10 white ultra bright leds and 3 AA batterys, what resistor should i use and should i be using a different power source. All the info is circled in the picture i appreciate any help. Also using a push switch aswell so can somebody explain how i should wire my circuit.

 

[kellys_eye]

Check out the forward voltage of the LEDs - the 'typical' value is relevant.

Your three batteries can only deliver a maximum of 4.5V. What does this mean about connecting an LED (or string of LEDs) to the battery?

Will you be wiring them in parallel or series?

You will need to limit the current flowing through the LEDs too. This is achieved using a series dropper resistor the value of which can be determined by the voltage to be dropped by the resistor (the difference between the supply and the LEDs requirement) and the current that is to flow through the LED (from the datasheet).

From the above 'hints' you should be able to figure out how to connect them and what parts are needed.

I'd give all the figures for you but you state this is for a GCSE project therefore some input from yourself will be beneficial to understanding - rather than having it handed to you on a plate.

Under which circumstances this thread should really be in the 'homework' section.....

 

[Audioguru]

We do not have GCSE in North America but since this project is extremely simple then it must be for little kids who are only 10 years old or younger, or you were taught nothing about electronics.

it should be obvious that the resistor value is simply calculated with Ohm's Law and a little bit of common sense.

 

[kellys_eye]

Whilst I agree that the OP's project is 'simple' there's no need to be so dismissive of the effort - it may be part of an introduction to components for all we know.

 

[(*steve*)]

I have to do a dt project for gcse please can someone help.

Take a look at this. It may answer some of your questions. If you can't understand something then please ask us for clarification.

 

[Audioguru]

It seems that this student has a teacher who is paid to teach the basics but didn't.
Why can't the student ask the teacher to explain the basics?
Does the teacher expect the student to find out things on the internet?

 

[(*steve*)]

It seems the are only 4 people who have posted on this thread so far. Let's Play a game.

Can you spot the poster who:

1. Could have their posts removed with no loss of information to the person who posted the question?
2. Has spent their effort almost totally in disparaging the op and their teacher, justifying this on the basis that the question is too simple.
3. Could be reasonably assumed to believe that belittling beginners is the best way to encourage them.

In the words of Sesame Street, one of these posters is not like the others.

And as much as the grubby green guy who lived in the bin could make some pithy observations, and was usually well informed, he was shocking when it came to his personal interactions.

 

[Audioguru]

The OP said he has to do a "dt" project for GCSE and I found out that GCSE in the UK is equivalent to grade 11 high school in Canada where grade 12 is the final high school year. But what is "dt"?

Is "dt" a Design and Technology course? Then he selects a project himself? The university project is called "A Thesis" in North America.

I am sorry I was wrong and the student was taught nothing about LEDs or electronics and selected this LED project himself, knowing that somebody on the internet would do it for him. When I was in grade 11 my science teacher said nothing about electronics and there was no internet. Also LEDs were not invented yet.

 

[(*steve*)]

My understanding is that a GSCE is taken over 2 years by students aged 14 to 16. I also understand that they are currently in the first half of their school year.

It is entirely possible that this person who is probably need well and truly scared off is 14 or 15 years of age and has just started their GCSE.

And, even if that's not true, what is the harm in pointing them at a source of information?

In this case, the question was not something you could simply type verbatim into Google.

 

[FuZZ1L0G1C]

I=V/R >> R=V/I
So add all forward voltages for total LED's in a series leg (multiply if all Vf equal).
Subtract this total Vf from supply Vs.
As current is equal throughout the leg, the minimum series resistance can now be calculated.

 

[Alec_t]

When doing the maths for this project, bear in mind that LEDs will have a longer life if run at a current less than their rated maximum current. Reduced current will also give a longer battery life.

 

[Audioguru]

I=V/R >> R=V/I
So add all forward voltages for total LED's in a series leg (multiply if all Vf equal).
Subtract this total Vf from supply Vs.
As current is equal throughout the leg, the minimum series resistance can now be calculated.

Since the supply is only 3V to 4.5V (three AA batteries) then there will not be any LEDs in series.

 

[kellys_eye]

I suspect the OP has been well and truly scared off from returning.

Shame.

 

[AnalogKid]

I suspect the OP has been well and truly scared off from returning.

Agree, but not surprised. It fits the pattern.

ak

 

[FuZZ1L0G1C]

Since the supply is only 3V to 4.5V (three AA batteries) then there will not be any LEDs in series.

Good catch AG.
I overlooked the U/B Vf of 3V....

 

[bushtech]

Sadly in this age of instant gratification perseverance seems to be a dying trait