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how do I rig a row LEDs to come on and stay on in response to an outside stimuli? Answered

I want to make a wedding card box that has a row of LEDs in hearts (like the life bar from Zelda that is a row of hearts that light up as you get more life)

So as more and more cards are put into the box, the hearts will light up.

I picture that after, say, 3 cards are put in, that half of the first heart lights up. Then after 3 more cards are put in, the whole heart lights up. Then after another 3 cards are put in, the 1st half of the next heart will light up.

Originally I thought that I could make it pressure sensitive. That after so much pressure was put on the sensor it would make the LEDs light up. But looking through this site, I see you can rig things up to a darkness indicator. So as more cards are put in and the cards block out more and more light to the sensor, more and more LEDs will light up.

Or a motion sensor. But a motion sensor, senses motion-lights up the LED-shuts off the LED after the motion has stopped. I need a few of the LEDs to light up in response to the motion of the cards entering the box, then stay on. Then more LEDs light up as more cards fall in.

I am not sure what way would be the easiest.

I am a noob when it comes to electronic projects. I have bought an Arduino starter kit and some LEDs to pay around with. I have made it through some online tutorials and I am catching on.

If anyone has any suggestions or advice, it would be greatly appreciated. 


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6 years ago

You could possibly use a photo interrupter at the slot to count the cards. I found this example of someone using one with an arduino: http://www.martyncurrey.com/?p=262

You then need to keep count of cards in the arduino, and light up the leds based on whatever formula you like.

I do not think just using a light intensitivity detector will work because it only takes one card to block it completely. It also sounds like what you call a "motion detector" is actually just a "photo interruptor" - you can have the arduino increase a counter and blink leds whenever it is interrupted and keep the "health bar" running in parallel

Basically ;-)