Table of Contents
Advertisement
English
Computation of the series resistors for the front light LEDs
In order to spare the accumulator batteries it is recommended to
restrict the input of the LEDs for the front lighting to approx. 10 mA.
This guarantees as well a sufficient brightness. In this case you can
determine the series resistor from the following formula:
R = (U
- U
B
R: necessary series resistor [Ohm]
U
: voltage at the voltage output of the circuit [V]
B
U
: forward voltage of the LED [V]
F
I: Current through the LED [A]
Example for a LED with U
R = (4,8 – 4,0) / 0,01 = 80 Ohm
As the calculated value in this example does not correspond to a
commercial resistor we choose the next lower value, that means a
resistor of 68 Ohm. The input of the LED then is ca. 12 mA.
FAQ
§
Parts are getting very hot and/or start to smoke.
!
Disconnect the system from the mains immediately!
Possible cause: The connections to the power supply are connected
the wrong round. à Check the connection. In this case the module
is probably damaged irreparably.
§
The LEDs do not light / flash.
Possible cause: The LEDs are connected the wrong round. à Check
the connections.
Possible cause: The power supply is interrupted. à Check the
connections.
§
The siren does not work.
Possible cause: The connections of the transistor are reversed.
à Check the connections.
Possible cause: The power supply is interrupted. à Check the
connections.
Page 30
) / I = (4,8 - U
F
= 4 V:
F
) / 0,01
F
FCS-4
Advertisement
Table of Contents
