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Ultimately you can just use a 9v Battery and a resistor....
I did know about the LM317 as a constant current source but I did not happen to have any laying around and wanted an instant solution, no waiting for shipping.....I do agree that that would make a good led tester but if you only have basic parts then I think this is the closest you can get.
IoT Pill Bottle
Battery Hand Warmer In Sweet Box
IoT Development With Mobile Directly
Tea light cup warmer
I tried measuring the current but accidentally blew my 200ma multimeter fuse.....I did not have proper resistors and so I played around until I got something decent. The current changes a bit with voltage it goes from 10-20mA.If you want a more accurate current then you can calculate a resistor value and use a slightly modified circuit...
You cant see it in the photos but my power supply amp meter keeps switching to 0.001A to 0.002A in the video
Yeah had some fun dancing
Luv the dancing!
Best mini audio amplifier with TDA2822
TimeFrame - A time portal to put on your desk.
Golf Ball Puzzle
LED Tester (20ma Constant C...View Instructable »
I pluged in my led and it went POP!
Working Sonic Screwdriver - Version 3.0
Sonic Screwdriver 2.0
I just had an idea....You could add a 2nd jack connected straight to the buzzer...Then you play the sonic sounds on your mp3/laptop and it sounds it....I guess it would not be portable anymore..... (facepalm)
how to make a simple sonic screwdriver
Cool!Mini Sonic Screwdriver!Might give ti a try if i find charged batteries.....
Lego Mini Sonic Screwdriver
Doctor Who TARDIS Laser Cut Money Box
Doctor Who Tardis Sneakers
Doctor Who Gallifreyan Clock
DIY functional Sonic Screwdriver
Metal Doctor Who Sonic Screwdriver with Arduino
PasswordKeeper on Aruino Pro Micro or why keep it simple when elaborate way exists!
LM386 tube amp [homage]
Small solar rechargeable led flash light with no solar panel/cell. (uses the led to charge!)
Make a Professional OTG Cable From Scratch!
Mini Speaker Tester using Cheap Chip (Unique sound!)
Neon Goofy Lite
LOL. I tried your apple script prank on one of my friends, he had no idea was was going on...
Making a Multiboot USB drive (All-In-One).
Cool!I looked at the thumbnail and thought it was necklace sized, with SMD leds, XD
DIY Parts and Crafts Infinity Mirror
Electromagnetic levitation device
Simple Tesla Coil
Bar-graph display Digital Clock
Do you absolutely need the 22nF capacitor?, it looks just like a smoothing capacitor.
Build a World's Smallest Electronic Shocker! version 2.5
Tiny Wood Computer Case
Mr. Octopus Nightlight
Cool! This is the first transistor audio amplifier that i build that has decent quality!
Make a Ring from a Nut
LED Cork Light
Yeah media players end to have these motors, the one I used was from an old DVD burner.
USB Flash Capacitor
Pocket Survival Fishing Kit
SIMPLE Polarity Reversing switch
A Shutter Release That Will Outlive Your Camera
Build a mechanical Lego Binary Calculator
Smallest Binary Clock
LED Binary Calculator
4 Bit Binary Calculator
Low cost WIFI temperature (DS18B20) data logger based on ESP8266 with connectivity to thingspeak.com
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