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Wave JT - Larson Scanner with Joule Thief

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Picture of Wave JT - Larson Scanner with Joule Thief

 
I love LED chasers. A bunch of LEDs neatly turning on and off on a precise timing - lights running one way, then the other way… It's relaxing, soothing, and hypnotic.
There are so many LED chaser/scanner/sequencer circuits out there, some are made with discreet transistors, some based on logic ICs, and more and more others are using microcontrollers.

There is one thing in common with all of the LED chaser circuits you find on the net - none of them can operate with just one alkaline battery!

Most of us know that LEDs need at least 2.2V or so to light. Blue and white LEDs require even higher, typically 3.2V. So obviously you can't use just one AA battery to operate an LED chaser. But we all know that there is Joule Thief that boosts voltage high enough to light any LEDs. Why not use that to operate an LED chaser?


Missing Link
Joule Thief is a nickname for this simple voltage boost circuit, predominantly used to light LEDs with one battery cell. However Joule Thief can be used to power more than just LEDs. I decided to power a microcontroller circuit with Joule Thief. (Although I ended up still lighting LEDs.)
 
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Step 1: Features

Picture of Features
Wave JT is not only powered by a single AA battery, but it's feature rich. Here are the highlights of the Wave JT.
  • Compact & streamlined design.
  • Uses only one AA battery (or any 1.5V battery you can hook up to).
  • Works well with rechargeables (NiMH or NiCd) too. 
  • Eight LEDs, each with its own 256 level brightness control.
  • Energy efficient - works even with a run-down battery, down to 0.6V (0.8V to startup).
  • Versatile PIC microcontroller based LED chaser/scanner/sequencer.
  • Many light animation patterns to choose from.
  • Speed control via multiple taps of a button (double/triple taps to speed up/down).
  • Start up "Quick-select" mode to choose from top 8 of over 16 patterns.




atwas91110 months ago
What does it do? What function does it serve? What action is this device completing that those leds are indicating?
ledartist (author)  atwas91110 months ago
Wave JT creates beautiful movements of light that you can look at forever, while being compact and energy efficient.
It's therapeutic and enchanting. But if that's not enough, you can find practical uses such as bike light or Xmas ornament.
It's up to your imagination.
Ah ok, thats what I was wondering. It seemed like somewhat of an over complex design to just blink led's. I love the design. Defiantly the most attractive battery discharger I've seen in a long time.
Ploopy1 year ago
Coolest thing ever!!!!!!!!!
Ploopy1 year ago
Would it work if instead of using the Joule Thief system (for more power) to just use a USB (5V)?
jtjones731 year ago
Would it be possible to get the un-compiled code for the pic? I would like to see how you are ramping up and down the brightness, and I would like to use a different pic controller since I have an over abundance of several others, just not the 1824 or 1823.
ledartist (author)  jtjones731 year ago
I've uploaded the source file.
mrmerino1 year ago
Damn that's impressive. How do you figure out how to program these?
robwasab1 year ago
I'm just learning about joule thief's and I want to power a microcontroller with one. Does your circuit self oscillate because of C1 charging in series(which I don't think is the case)? what does that transistor network exactly do?

But my biggest question is, if you are starting and stopping the current through the inductor with the uC pwd, what waveform are you using? PWM, clear timer on compare?
ledartist (author)  robwasab1 year ago
The voltage booster circuit oscillates by itself when SW1 is closed or enough voltage is applied to PWR pin. This circuit is a variation of popular Joule Thief circuit, which uses one transistor and a two winding inductor (much like a transformer) to do the job. My circuit uses two transistors to make use of an easy to find single winding inductor. (The exact workings of the circuit takes way too long to explain - please google Joule Thief...)

The microcontroller simply turn the PWR pin on and off to keep the voltage within target. No PWM. I'm using the A/D converter to read the supply voltage of the microcontroller, and turning the PWR pin accordingly.

jenov1 year ago
Can I know which exact model number of the Schottky Diode is being used for this project? Thank you.
ledartist (author)  jenov1 year ago
It's BAT85 or SD103 type. Sorry I forgot to post that information - now it's added to the instructable.

Aki
J-Five1 year ago
SWEET
ledartist (author)  acmefixer1 year ago
This is one of the exciting aspect of microcontroller projects. You can simplify the circuit and let the microcontroller take over some of the analog functions.

With this project, the Zener diode only comes in to play when the switch SW1 is closed. Microcontroller turns of the base current to Q2 when the voltage is high enough, but lower than 5.1V. This effectively regulates the output voltage of the Joule Thief without letting the Zener to conduct. (Explained in the above chapter.)

This method not only saves a few parts, but is also more energy efficient - since there's no current wasted by Joule Thief when there's enough voltage.
Thank you for posting your circuit though. Other people looking to use Joule Thief as a standalone DC power supply will benefit from your circuit.

Aki
pfriedel1 year ago
I'm not clear on the electrolytic and the inductor - are those just ranges of acceptable values? I suspect the cap is, but I'm not familiar enough with inductors to be certain.
ledartist (author)  pfriedel1 year ago
Yes the values are the range that should work.
For inductor I recommend to stay within 47 to 100 uH, but higher values would work ok. Capacitor C2 also can be larger, but larger ones are also physically larger - not good for this project...

Aki
iceng1 year ago
Cool work..
Referred you to a Question and voted ;-)
ledartist (author)  iceng1 year ago
Thanks!
What question?
Here you are

A
grunff1 year ago
Your work is, as always, beautiful
ledartist (author)  grunff1 year ago
Thanks!
sagaura1 year ago
Where download the HEX file?
ledartist (author)  sagaura1 year ago
Oops. Will be uploaded shortly.

This look great!!! I will love one (or many) of this, did you sell this? where?, thanks I love all this led thingies too!!!
ledartist (author)  di-multimedia(r)1 year ago
Thanks!
You can purchase the kits and PCBs at theLEDart.com. 

http://www.theledart.com/blog/wave-jt-kit


duggerpato1 year ago
As usual, absolutely awesome. Video is fun, and the instructable is precise and educational. Thanks for being a great electronic/microcontroller engineer
jeff-o1 year ago
Another home run. Very nice work.
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