I've just had a brainwave, thanks guys should give me an excuse to get out some wood, plexi, leds & my soldering iron and work on a little circuitry You gonna love what I got planned
impressed by the original coaster, but bards table is gonna be awesome! need to do something with my desk a bit like this...
i cant seem to get led's to light up when connected together like the pic on page 1 of this thread. im testing with a batery till i get it to work but no light is there a basic 101 to led's?
LED's have a value called a foward voltage, this value has to be met before the LED's will turn on. For Reds, greens its about 2V for blues its 3-3.5V. What colour are yours and how are you trying to connect them ?
Just saw this thread. That coaster looks really good. And now because of looking at that pic, I have to go get myself a coffee.
mine are green i have solderd the legs together ( tried diode to anode and diode to diode but nothing worked)
If you have three connected in series you will need about 6 volts to light them properly... try only 2 or use a higher voltage.
Series = negative leg connected to positive leg, 2nd led drawing power from first, etc. Parallel = positive wire connected directly to all of the positive legs, each led connected to the power source directly. (I think)
Just try dabbing the LED leads on the terminals of that battery it should light brightly (dont do this for longer than a split second, you will fry the LED). Since you are working from a 3V battery then you will need to connect your LED's in parallel, ie so each LED has the full 3V. You will then need to insert a resistor in series with each LED to limit the current and drop some voltage. According to this you will need a 56 Ohm resistor for each LED @ 20mA
im only testing on a 3v they will be attached to ether the 12 v or 5v line in my pc. so what is best parralell or series? series i cant get to light up with the test 3v parralell i can light , but i beleive the pic on the first page is in series. im so
If running in parallel, if the voltage is ok then leds are bright but more current is drawn. Series is ok if say you're running 4 3v leds off a 12v line. I doubt there is a better or worse way of doing things, just depends on your voltage and current. I assume you haven't got the led's the wrong way round?
Since you are using green LED's which usually have a forward voltage of 2V then I would put them in series connected to the 12V line with a current limiting resistor. Neither Series or Parallel is best, use either or a mix of both depending on the application, voltage etc
Since it's now the holidays, I finally found time to make myself one of these coasters: I made it from one disc of 7mm polycarbonate. There are 3 LED's in the middle, one red, one green and one blue, controlled by a tiny PIC which you can just see as a black dot to the side of the green and red LED's. There's also 3 UV LED's shining out round the edge. Here's some more pictures in action:
Very nice work Stevey!! I'm hoping to have some extra time over the Xmas period to get some modding done.... and eagerly waiting for some more modding tools from Santa!? LOL
Of course, but you'll kick yourself when you see how simple it is... Since I used PWM control of the LED's, only 1 resistor is required, as only one LED is lit at the same time (although it appears to the eye that more than one LED is illuminated). This made the component count minimal, and it all fitted within the 7mm polycarbonate coaster - A round hollow was made into the disc with a router, and then I filled the hollow with epoxy, so all the electronics are sealed. I used a surface mount PIC since they are much smaller.