Techyman

Hi
I need a 3 input LDR circuit with 3 LEDs as outputs for my GCSE project.

Torben

Hi Techyman! Welcome to the forum.

Can you post what you have so far and what problem you're having so we can check it out and try to give you a hand? Without that we don't really have a place to start.

We could just make one for you but that would defeat the purpose of the project.


Torben

Techyman

the idea was to have a childs toy abit like a jigsaw -when you added the shapes,which would cover an ldr an led would then light up -image of type of toy can be seen here-http://www.elc.co.uk/category-536 -the blossom farm puzzle-thanks for helping-

Torben

OK, so how far have you gotten? What does your current schematic look like? Have you tried it out on a breadboard yet?

Also, what course is this for, and have you covered transistors yet?


Torben

Techyman

This is for a GCSE Technology and Design course in Northern Ireland exam board being CEA - I have covered night light circuits using ldrs and variable resistors with a tip 121 transistor

Torben

Wouldn't you then just need three of those? Or do you need to use a microcontroller or something?


Torben

Techyman

hi
i need an all in one circuit that includes an IC

KMoffett

LM339 quad comparator with open collector output.

http://cache.national.com/ds/LM/LM139.pdf

1 LM339
1 potentiometer
3 LDRs
6 resistors
3 LEDs
1 battery
1 switch

If you need help with this, ask specific questions?

Ken

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Hero999

You also need to consider the lighting conditions when designing this. If it's used in a dimly lit room then all the LEDs could turn on.

Here's some more information regarding omparators.
http://home.cogeco.ca/~rpaisley4/Comparators.html

Also, please remember to sight your resources so you don't get accused of cheating. Inclued links to this website and to the datasheet and link I've provided with your project.

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Techyman

where would i find a circuit digram/component values for this so i can draw it using crocodile technology and then convert it using the pcb wizard software?

1 LM339
1 potentiometer
3 LDRs
6 resistors
3 LEDs
1 battery
1 switch

cdstahl

you can fix this in some ways by using IR parts as well to ensure light hits the LDRs, even if its not visible light.

no idea what crocodile tech is.

the data sheet should have the information required.

Hero999

Have you checked the link I provided in my previous post?

Have you checked the datasheet for the LM339 (this can be found using Google)?

Have you read Crocadile Technology's help file?

Have you showed this forum to your teacher?

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Techyman

would this be a good starting point?- see attachment

Attached Images

LM 339.jpg (44.4 KB, 11 views)

Hero999

Yes, that's the sort of thing you're looking for.

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