Beginner Electronics Math and circuitry - Page 1
Forum section: electronics / beginners

author: MWhite1961
author_rank: Newbie
timestamp: February 20, 2015, 06:12:06 am
content: I had an idea the other day for a way to place LED lights inside of a bowling ball.This would look interesting when bowling in the dark.My thought was 6 LEDs (at the end of each orthogonal axis) placed just below the surface, with a "Slow Vibration Sensor" installed at the center of the ball. A battery pack will also be installed into the ball.I work in a bowling pro shop, so drilling, and filling the ball with resin is in my skill set, electronics however is currently not.My question revolves around how likely am I to either burn out an LED, or use up the battery in a short amount of time.The Sensor that I found is located athttp://www.adafruit.com/products/1767I realize that some resisters are required to keep the LEDs from burning out, but how much I don't have a clue.How many (and how large) of a battery would be required to achieve at least 3 hours of usage.Thank You

author: Falcon69
author_rank: Super Contributor
timestamp: February 20, 2015, 06:24:07 am
content: You need to read data sheets, But as long as the circuitry is designed properly, LED's will light for 100,000 plus hours before reaching the end of its life and burning out.But, designing a circuit to go over the LED's Forward Voltage or current rating will limit it's life exponentially. Why do people design circuits in this way? To get a more intense (brighter) light from the LED.My question is, How will you recharge this battery once it is inside the resin?I was reading briefly on a Perpetual Motion recharging system. Might do some research on that. Not sure if it will work. I didn't read much on it. But, with the ball rolling down the lane, it could recharge the battery using this method.But, maybe not, like I said, I didn't read much into it.Most LED's only operate at a max of 20mA, and most circuits will usually only run them at 10mA. On a single AA battery that will light for longer than 6 hours, (maybe twice that?) given that a standard AA battery puts out as much as 1200mhA.

author: Amra
author_rank: Contributor
timestamp: February 20, 2015, 08:24:09 am
content: Just a couple questions, do you intend to use a clear resin, or would it be frosted on the outside?Reason I ask, is that if its not completely transparent, you could have a cap that unscrews at the base of the thumb hole and contains a few button cell batteries that you could replace when necessary, that would eliminate the need for a complicated charging system altogether.That said, if you are intent on a complicated charging system, you could use some kind of wireless charging system (inductive charging). For example:http://www.adafruit.com/product/1407For something such as that, the charging ring could likewise be mounted near the top of one of the finger holes, which you could use to align the charging ring. i.e. embed the ring atop a plastic tube which slides into the finger hole and thusly mates the rings near the top of the hole.Sounds like a fun project, and if you do it, I would love to see the finished product!

author: Rerouter
author_rank: Super Contributor
timestamp: February 20, 2015, 11:32:27 am
content: For a circuit, the simplest way would be your sensor, a battery a dropping resistor and the LED's,The more correct way would be to use a constant current boost converter after the sensor, most LED light strips have a little module that can be pinched, as this will get you more consistant brightness and a bit more time for the same capacity batteries,as for your battery life, that comes down to how much power you are putting through the LED's, as a rule of thumb to make more sense to you, if you are pushing 20mA through your LEDs in series, for a basic alkaline battery your looking at about 2000mAH (you will need enough to make its voltage exceed the LED's for the simple circuit), thus for that you can expect about 100 Hours before it goes flat,If you used cheap rechargables (~700mAH) you would expect about 35 hours before its flat, but the perk would be you could expose a metal pad in 2 of the finger holes to charge it back up,

author: cosmicray
author_rank: Frequent Contributor
timestamp: February 20, 2015, 03:02:08 pm
content: A similar implementation to what you are attempting is the light-up heels in certain fashion shoes. These were popular around 2004-2006. They had a long life circuit with a small watch battery and were, in many cases, sealed in acrylic. Check thrift stores, there may be a few pair (or odd shoe) still plugging along on the same battery after 10 years.

author: MWhite1961
author_rank: Newbie
timestamp: February 23, 2015, 08:50:00 pm
content: Thanks for the info, this has the little wheels in my head spinning in terms of other options.I picked up the book "Practical Electronics for Inventors". The next step is actually reading it.