Velleman-projects K8097 Assembly instructions Manual de usuario descargar pdf (Pagina 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)

eries resistor

Leds feature a speciﬁ c 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

1 2 3 4 5 6 7 8 9 ... 19 20

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Velleman-projects K8097 Assembly instructions Manual de usuario Pagina 4