BMW K bikes (Bricks)


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Nent2

Nent2
New member
New member
I was able to replace the flasher with an LED.

Failer light bulb of the flasher valve is detected by U243B of TELEFUNKEN Semiconductors.
The current flowing through the front and rear flasher bulbs flows through the 30mohm resistor
 between pin6 and pin7 of the U243B, causing pin7 to generate a voltage according to the current.
If the voltage is less than 81 mV, disconnection is detected and the blinking speed becomes faster.
Replace that 30mΩ with a register suitable for the LED current.

The current consumption of the flasher relay, flasher indicator lamp and flasher relay unit was 0.21A.
(I am replacing the flasher indicator lamp with a 20mA BA9S type LED.)

The current consumption of the LED bulb made in China purchased from Amazon Japan was 0.2A/1pcs.

So, the current with 1pcs LED is 0.21A + 0.2A = 0.41A.
And the current with 2pcs LED is 0.21A + 0.2A + 0.2A = 0.61A.

Assuming that 0.45A, which is between 0.41A and 0.61A, is the disconnection detection current.
(Since the LED that I bought is driven by a constant current, the current changes from 0.2A to 0.16A
 when the voltage rises from 12V to 14V, so the disconnection detection current was set to 0.45A.)

The resistance value at which 81mV is generated when a current of 0.45A flows is calculated.

R = 81mV / 0.45A = 0.18Ω ( I make 0.18Ω with 0.2Ω and 1.8Ω parallel connection.)

Note: LEDs are not standardized, so you need to measure the current consumption of your LED
         to determine the parameters.
         And inexpensive Chinese LEDs can get hot, so it is safer to add an overcurrent protection fuse
         to flasher bulb circuit (or inside of LED bulb that you bought).

Disable the 30mΩ resistor.
Cut the 30mΩ resistor and remove the vertical metal rod.
LED Flasher with light bulb break detection. 111

Install a 0.18Ω register here.
LED Flasher with light bulb break detection. 211

best regards.

    

Dai

Dai
Life time member
Life time member
Nice! Another solution to an old problem - the more solutions we have, the better it is.


__________________________________________________
1983 K100 naked upgraded to K100LT spec after spending time as an RS and an RT
1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500
    

Arlina

Arlina
Moderator
Moderator
Ehm... My english is not very good....
Register = resistor?  LED Flasher with light bulb break detection. 1f62c


__________________________________________________
LED Flasher with light bulb break detection. Eu-log10  K1100RS/LT - R1200RT - R1100RS - Cagiva SST 350 Ala Verde - K75LT project - K75 Schurgers - K75S - K1100RS - K75RT - K75C
    

Dai

Dai
Life time member
Life time member
Yup. Have a close squinty.


__________________________________________________
1983 K100 naked upgraded to K100LT spec after spending time as an RS and an RT
1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500
    

Arlina

Arlina
Moderator
Moderator
LED Flasher with light bulb break detection. Ab5f177ae141037d6d4b22f2724585a1

It is Michelle.....


__________________________________________________
LED Flasher with light bulb break detection. Eu-log10  K1100RS/LT - R1200RT - R1100RS - Cagiva SST 350 Ala Verde - K75LT project - K75 Schurgers - K75S - K1100RS - K75RT - K75C
    

robmack

robmack
Life time member
Life time member
Arlina wrote:Ehm... My english is not very good....
Register = resistor?  LED Flasher with light bulb break detection. 1f62c
His spelling corrector is not very good either.   register ≠ resistor

Joking asside, the solution was very innovative.


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

Nent2

Nent2
New member
New member
I'm not good at English.
This time I asked Google Translate.

It is necessary to use a resistor of 0.5W or more.
1W would be good.

    

td5

td5
Life time member
Life time member
Arlina,
Excellent post, takes me back to the 80's


__________________________________________________
LED Flasher with light bulb break detection. K_engi10
1988 / K100RS
2013 / R1200GS
2015 / K1300R
2002 / R1100S BCR
    

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