BMW K bikes (Bricks)


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robmack

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I've been working on re-designing the electronic circuits I built for aftermarket accessories, but I want to understand whether there is interest in the K-bike community for these trinkets. The first trinket is a fuel gauge.

I have prototyped a circuit that interfaces to the K-bike fuel level sender and displays current fuel level on a single 5mm LED. The circuit plugs directly into the Additional Instruments socket in the harness. It displays fuel level by changing the colour or display state of the LED. The only requirement is the need for a place on the dash to drill a 5mm hole to accommodate the LED. Cost is projected to be somewhere in the $20.00 to $25.00 range (I've not costed it out just yet).

Would members here be interested in such a gauge?

The downside to this circuit is that it does not interface to an aftermarket gauge that has a built-in indicator. This limitation might prove to be the undoing of this circuit. Elsewhere in this forum, I detailed how to convert the fuel level sensor to cooperate with modern aftermarket gauges and that doesn't require any purchase. Also, the circuit does not work with the fuel level sender in pre-85 models; only the variable resistor sender from the later models.

Thanks for feedback.



Last edited by robmack on Sun Mar 01, 2015 8:38 pm; edited 1 time in total


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Robert
1987 K75 @k75retro.blogspot.ca
2011 Moto Guzzi V7 Racer
http://k75retro.blogspot.ca/
    

Dai

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I assume from the description that it would be for the 4V model only?


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'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

robmack

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Compatible with the following:

Part 62161459565 (PETROL GAUGE) was found on the following vehicles:
89V1 K 1 (0525,0535)
89V1 K 100 RS (0523,0533)
89V2 K 1100 LT (0526, 0536)
K569 K 75 85 (0562,0571)
K569 K 75 C (0564,0574)
K569 K 75 RT (0565,0573)
K569 K 75 S (0563,0572)
K589 K 100 83 (0501,0511)
K589 K 100 LT 87 (0506,0516)
K589 K 100 RS 83 (0502,0503,0513)
K589 K 100 RT 84 (0504,0505,0514)

Not compatible with the following:

Part 61311459047 (PETROL GAUGE) was found on the following vehicles:
K589 K 100 83 (0501,0511)
K589 K 100 LT 87 (0506,0516)
K589 K 100 RS 83 (0502,0503,0513)
K589 K 100 RT 84 (0504,0505,0514)


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Robert
1987 K75 @k75retro.blogspot.ca
2011 Moto Guzzi V7 Racer
http://k75retro.blogspot.ca/
    

JR_K100RS

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G'day Rob ,
yeah I'm interested , any images of the prototype , also would it go inside the instrument cluster or perhaps one of the blank rocker switch positions on the dash pad ?

John R


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Diamond Grey ( 617 ) 1987 K100RS ( European Delivery ) Original owner
    

charlie99

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sounds interesting rob ....whats the theory ...a couple of comparators ...or a bit of a -d conversion ?


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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

robmack

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The heart of the gauge is an Atmel microprocessor, which being extremely small can be integrated into the connector that plugs into the harness. From there, a 90cm wire terminates in a Red-Green LED. The microprocessor reads the resistance of the sender (yes, A-D conversion Charlie) and determines the %full of the tank. At various levels, the characteristic of the LED changes:

  • Full tank gives steady GREEN
  • Half full tank gives slow pulsing GREEN
  • Quarter full tank gives steady RED
  • 12% full tank gives flashing RED

The programmability of the microprocessor means the limit of what can be done is up to the imagination (and enough memory). I've come as far as breadboarding the circuit and designing the circuit card:



The card above is 0.9" X 1.2" (23mm X 30mm). The small size of the LED means it can be placed anywhere including in a hole on one of the switch blanks. Integrating the LED into the instrument cluster may be possible but it would require routing the white wire from the Additional Instruments connector up to the cluster and modifying the case of the cluster to accept the wire. Otherwise, the circuit is so tiny it is no problem to find space in the OEM cluster case. All that's needed in addition would be +12V and ground, both of which are available inside the cluster.


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Robert
1987 K75 @k75retro.blogspot.ca
2011 Moto Guzzi V7 Racer
http://k75retro.blogspot.ca/
    

charlie99

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woohoo sounds good rob

we like atmel processors also


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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

Dai

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Sounds like another item to collect towards the k-trike... count me in Rob.


__________________________________________________
'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

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