ledpowerwireless
I am working with a friend to develop a spinning disk with LED lights on it.
The issue we are having is wrapping our minds around the idea of electronics on a surface that is spinning.
How do we interface with the LED lights without cords getting tangled around the spinning rod?
Is there a way to provide power to electronics on a spinning disk without having the battery directly on the disk?
Does this make sense?
Thanks.
Voltage required to operate an LED varies with colour and technology used but is typically around
As 1.5V is below the rated operating voltage at normal operating currents of any visible light LED, not seeing light when using 1.5V is very expected. If you use a red LED and apply 1.5V at correct polarity and look at it in total darkness you may see very low level light output. Turn it on and off and look for any change in output. I have found that White LEDs that are rated for operation at say 20 mA maximum will produce visible light "in the dark" at well under 0.1 mA.
[Infrared LEDs may operate at about 1.5V at rated current but unless you have IR vision or an IR sensor then not seeing light is also very expected :-). ]
If you had used 3V and a RED LED and no series resistor it is possible for it to die so fast that you see no light at all.
Operation without a resistor makes very little sense in almost all cases.
Here is a TLHE510 - a typical 5mm red LED
It has the advantage for comparison purposes of having Red, Green and Yellow versions with some parameters in common.Red & Yellow versions have apparently the same voltage-current curves, whicle green has a higher voltage drop at a given current. The green current curve has been extended to 1000 mA. As can be seen, operating any of these at 1.5V will not produce much light. If you'd used two batteries to try to get light out and not used a resistor the green LED would conduct about 90 mA and the red and yellow "rather more" (off the graph but fairly obviously excessive). Note that the green LED is rated to carry up to about 800 mA - BUT only for 10 us and only with a duty cycle of not more than 1:1000.
Absolute maximum forward current is 30 mA and recommended maximum operating current is 20 mA.
Applying reverse polarity above the rated reverse breakdown voltage will kill most LEDs very rapidly even at very low currents - <= 100 uA is often given as max allowed reverse current and many power LEDs simply say "not rated for reverse voltage operation." . You need to check the relevant data sheet, but reverse breakdown voltage is generally greater than the rated forward operating voltage in continuous operation. Typically in the 5V - 7V range BUT check for your LED.
Information only:
The tape you refer to is generally called "duct tape", not "duck tape" although "duck tape" is a legitimate name as it originally used "cotton-duck cloth". BUT there is a Duck Tape brand of duct tape :-). Duct tape was originally designed in 1942 for quick repair of miltary equipment (its reputation is deserved ! :-) ) . Wikipedia - duct tape. Since then it has been used for every imaginable purspose and a few unimaginable ones - even things as diverse as helping solve the lives of the crew of lunar missions. Incidentally it is NOT recommended by its makers for patching air leaks in air conditioning ducts.
Yee Ha!:
How to save a lunar mission:
Wikipedia - Apollo 13 & duct tape
The real thing - not quite how it looked in the movie :
You do need to have common grounds between the strip and the microcontroller module.
The WS2801 PWM driver reads 24 bits of data and passes the rest on to the next module in series. It latches when the signal is low for >500μs.
If you're getting only one pixel to light, then the time between each set of 24 bits is too long, and the first pixel is treating each set as its own.
Best Answer
The lowest tech, probably easiest method - Use brushes, just like for a motor. On the rotating part, you'd have the equivalent of slip rings, although the orientation would be flat rather than axial. The power thus obtained on the rotating part might have a bit of high frequency noise in it from the sliding contacts, so you'd want to be sure to get some filter caps on involved, probably near to where the power comes onto the board.