03-01-2013, 03:16 PM
BIKE WHEEL POV DISPLAY
[attachment=46337]
Persistence of vision
You probably don’t realise it, but you use POV every
day – when you watch TV. Movies also take advantage of
this phenomenon.
The TV and movie picture is not continuous, – rather
(in the case of TV), 25 individual pictures are displayed
every second. But your eyes and brain cannot follow the
25 individual frames of picture per second – instead, they
If you slowed down those frames to, say, 10 per second,
then you would be able to see the period between each
movies where the hero moves like a Thunderbirds puppet.
Let’s take this one step further. Say you had a moving light
– we’ll make it an LED because they can be turned on and
wheel, so they follow a circular path as the wheel rotates.
By using some clever circuitry to switch the LEDs on
and off at particular moments, a pattern or picture can be
created – in fact, the display is almost unlimited. It can be
anything from geometric shapes to text, cartoon characters
and even very high contrast pictures (see examples below).
In a nutshell
The display consists of three PC boards, each with a
row of 32 LEDs on each side (a total of 64 LEDs). These
boards are mounted radially in/on the spokes of a pushbike
wheel and each has a battery pack mounted near
the wheel’s hub.
Soldering the LEDs
You have probably noticed that we have left the
LEDs until last. That’s because there are a lot of them
and they can also be a bit tricky to solder. There are
32 LEDs to be soldered to each side of the PC board.
the LED next to the cathode (labelled ‘K’ on the circuit
diagram). Also, the anode (A) lead is usually longer.
On the top (component side) of the PC board, the
LEDs are arranged with their cathodes (K) oriented
towards CON1 (the 4-pin connector) while on the
bottom side, the reverse is true – see Fig.2.
The LEDs are controlled in pairs, one for each side
of the board. This ensures that your chosen POV
image can be viewed from both sides of the bike.
The LED pairs are connected in series with small
jumper wires (red dots on the component layout
diagram) through the PC board that serve the same
purpose as a PC board ‘via’ – they connect together
the copper tracks on both sides of the PC board
where required.
Wheel mounting
The accompanying photo shows the
position of the PC boards on the bike
wheel. It’s important to note that the
inner edge of the PC board sits right
up on the axle and that the whole
thing is centred between the spokes,
so that the board is right in the centre
of the wheel.
[attachment=46337]
Persistence of vision
You probably don’t realise it, but you use POV every
day – when you watch TV. Movies also take advantage of
this phenomenon.
The TV and movie picture is not continuous, – rather
(in the case of TV), 25 individual pictures are displayed
every second. But your eyes and brain cannot follow the
25 individual frames of picture per second – instead, they
If you slowed down those frames to, say, 10 per second,
then you would be able to see the period between each
movies where the hero moves like a Thunderbirds puppet.
Let’s take this one step further. Say you had a moving light
– we’ll make it an LED because they can be turned on and
wheel, so they follow a circular path as the wheel rotates.
By using some clever circuitry to switch the LEDs on
and off at particular moments, a pattern or picture can be
created – in fact, the display is almost unlimited. It can be
anything from geometric shapes to text, cartoon characters
and even very high contrast pictures (see examples below).
In a nutshell
The display consists of three PC boards, each with a
row of 32 LEDs on each side (a total of 64 LEDs). These
boards are mounted radially in/on the spokes of a pushbike
wheel and each has a battery pack mounted near
the wheel’s hub.
Soldering the LEDs
You have probably noticed that we have left the
LEDs until last. That’s because there are a lot of them
and they can also be a bit tricky to solder. There are
32 LEDs to be soldered to each side of the PC board.
the LED next to the cathode (labelled ‘K’ on the circuit
diagram). Also, the anode (A) lead is usually longer.
On the top (component side) of the PC board, the
LEDs are arranged with their cathodes (K) oriented
towards CON1 (the 4-pin connector) while on the
bottom side, the reverse is true – see Fig.2.
The LEDs are controlled in pairs, one for each side
of the board. This ensures that your chosen POV
image can be viewed from both sides of the bike.
The LED pairs are connected in series with small
jumper wires (red dots on the component layout
diagram) through the PC board that serve the same
purpose as a PC board ‘via’ – they connect together
the copper tracks on both sides of the PC board
where required.
Wheel mounting
The accompanying photo shows the
position of the PC boards on the bike
wheel. It’s important to note that the
inner edge of the PC board sits right
up on the axle and that the whole
thing is centred between the spokes,
so that the board is right in the centre
of the wheel.