Persistence of vision is a fun feature of the human visual system, which allows us to blink a bunch of spinning LEDs at the right time to spell out messages that appear to hang in the air. [TN_Inventor] took a stab at his own POV build, using an old desk fan as a base.
The initial build relied on a rotor made of MDF and some very old-school LEDs. The rotor was heavy and unbalanced, causing issues for the motor, and the dim LEDs weren’t visible in normal daytime conditions. Like any good maker, [TN_Inventor] persevered and iterated the design.
The next revision instead relied on protoboard itself for the rotor, greatly reducing the weight and making it easier to balance. The problem of getting power to a rotating mechanism was sidestepped entirely, with a small lipo battery being mounted on the rotor itself. High-brightness white LEDs were employed, making the effect much more visible. This was helped further thanks to the use of transistors to run the LEDs directly from battery voltage, rather than obeying the current limits of the Arduino Nano’s output pins.
The build presents well, with the final POV board being built into the chassis of an old desk fan. Rather than use the original motor, instead a smaller 12 volt geared device was used, powered separately from the main board. The familiar form factor of the desk fan is a great way to finish the project off, and gives it an interesting industrial aesthetic.
POV builds can go a long way – we’ve even seen volumetric displays built in this way. Video after the break.
An easy way to get power to the rotor would be to use some little DC motors and props like the ones on toy helicopters as generators.
Or use a slip ring.
I’ve always wondered why someone hasn’t just wired up a coil on the rotor, to pass by stationary magnets. Power the LEDs off the induced current, and get a sync pulse for free. A rectifier+small capacitor+regulator should store ample energy for a revolution or two of light.
I should just get off my ass and do it.
Was thinking the same thing. Leave a gap in the magnets somewhere and you even know where the top is…
You might need multiple coils though. Thinking about the way the magnetic flux lines go.
Gonna build this one day.
“Persistence” is not spelled like that!!!
Indeed. Thanks! Fixed.
I need that on all my fans that says “keep you fingers out”
my kids LOVE sticking their fingers in the fan –
Nope wont work they cant read yet :(
Im suprised he didnt use the existing fan blades and attach the LEDs directly to them. Just drill holes for the LED’s and poke ’em through.