How do I make LEDs pressure sensitive?
I'm trying to hook up some LEDs to the soles of some shoes, so when I step down, LEDs light up, but stop glowing when I'm not stepping down.
I was thinking something with a piezo transducer, but I'm not entirely sure how they work, or how I would hook it up efficiently.
If anyone could explain it, or link to a site that explains it clearly, I'd be very thankful.
Answers & Comments
Verified answer
Think it simple. Just use a spring to the voltage source. When the step is down the foot will exert pressure on the spring to make the contact close to the voltage source and the LED will lit.
Possibly you can get some manufacturer reject LEDs, and a few of them will behave like they have a built in pressure switch = pull or push on one of leads and the LED will light or stop lighting. This will require a 2 volt or a bit more battery for each shoe.
The piezo shoes, the piezo unit is the power source, so the LEDs light only when the pressure is increasing or decreasing.Each LED can have a reversed LED in parallel as one will light for increasing pressure and the other for decreasing pressure. Possibly the manufacture prevents destruction of the LEDs if the shoe wearer stamps their feet (as the voltage, current and power increase with the amount of pressure) by using a constant current integrating circuit for each shoe. Possibly the the increasing pressure LEDs have higher current rating and only light brightly if the feet are stomped. Likely all the LED pairs are in series for each foot and one piezo device lights all of them on each foot. Neil
It is probably not possible to make LEDs pressure sensitive byt themselves. Piezo transducers are crystals that produce electricity when pressure is applied to them. What you are describing can be easily achieved with simple contact switches placed on the soles of the shoes. Switch, proper voltage source and LEDs are all you'd need.