Velleman projects K8018B Assembly instructions - Manual (Page 4)

Supply voltage (V) - led voltage (V)
required current (A)
= series resistance (ohms)
required current (A)
= series resistance (ohms)
Required resistor power handling=
voltage over resistor x current passed trough resistor
9V - 1.7V
0.005A
= 1460 ohm
9V - (3 x1.7V)
0.005A
= 780 ohm
(9V - 1.7V) x 0.005A = 0.036W
closest value :
use a 1k5 resistor
use an
820 ohm resistor
a standard 1/4W resistor
will do the job
Supply voltage (V) - (number of leds x led voltage (V))
How to Calculate the series resistor:
Example: operate a red led (1.7V) on a 9Vdc source.
Required led current for full brightness: 5mA (this can be found in the datasheet of the led)
LEDs in series:
Example: 3 x red led (1.7V) on 9V battery
Required led current for full brightness: 5mA
(this can be found in the datasheet of the led)
Leds feature a specific voltage
drop, depending on type and
colour. Check the datasheet for
exact voltage drop and rated
current !
Never connect leds in parallel
Leds and how to use them
An open collector output can be compared to a switch which switches to
ground when operated
Example: How to switch an LED by means of an open collector output
open collector outputs
Build your 3D led cube and created unlimited 3D effects. The unit
comes standard loaded with effects. Connect to your computer
(USB) and create your own!