I am finally starting sales on my lighted tail boards
how it began can be read here
each generation adds more features
Generation 1
simple 2x3 LED with balance resistors optional trimmer
each LED has its own balance resistor so different LEDs can be combined
2 channels can be dimmed with optional trimmer
it is advised to use LEDs with similar forward voltage (CW, WW, blue, ice blue, pink or red, orange, yellow)
if different colors used the LEDs with higher forward voltage dim out with lower battery voltage, this can be used as battery indicator
Generation 2
2x4 or rainbow added voltage stabilisation
2.8V 18uA LDO used to keep brightness stable down to about 3V battery voltage
trimmer optional
Generation 3
2x3 +1 LED added low battery warning and LVP
inner ring lights up with constant brightness
low battery: inner ring gets switched off and one red LED turns on to indicate low battery
LVP: all LEDs are switched off 2.8V LDO and IC standby current of 21uA remain
low battery and LVP can be set to custom voltages
The tail boards run with an 1kOhm resistor as bleeder this works with relative low current drawn from LEDs
Note the more current the LEDs draw the more voltage drops on the bleeder so battery voltage is higher than the calculated values
With standard hysteresis there is a fade between both LED groups and LVP shut down
this is PWM because when the comparator switches the LED off, then the voltage drop on the bleeder is gone,
so it switches on again just to notice that with the voltage drop again it is too low, aso
with battery voltage dropping the PWM cycle gets shorter and fades out
OD 17, 20, 22mm Omten 1288 (6.5mm hole)
Gen 1-3 available
OD 17, 20 9.5mm switch hole for bigger switches
Gen 2 8 LEDs or Rainbow no trimmers
OD 20mm Convoy L6
Gen 2 Rainbow or 2x4
22mm Omten 1288 (6.5mm hole)
Gen 2 rainbow
[LED colors] (top are most efficient, bottom inefficient)
LED color and each single LED current based on my “0.5mA” brightness level
green 14.1uA
blue 21.2uA
ice blue 25.2uA
pink 37.7uA
WW 40.2uA
red 50.9uA
CW 66.7uA
orange 124uA
yellow 206uA
emerald green 349uA
my LED brightness scale is based on my Rainbow+WW boards total current while LEDs seem same brightness
basically I have 4 levels “1mA”, “0.75mA”, “0.5mA”, “0.3mA”
this does only reflect on rainbow boards with WW the total current drawn
on 2x3 or 2x4 boards the total current depends on used colors and brightness level (“0.3-1mA”)
for example you order a “0.5mA” pink/green 2x4
18uA LDO + 151uA pink + 57uA green
total current 225uA
now we add 20k trimmers for brightness adjustment
total current at min trimmer level 95uA
It is possible to define a total current consumtion with trimmers on max position
I got a very complex table to calculate the needed resistances