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Electronics Answered

http://www.taskled.com/techbflex.htmlI wonder if anyone can help

I want to make a bike light using CREE leds (*4) and have spotted the bflex (see here - http://www.taskled.com/techbflex.html - I was going to go for the UIB2 version) as it has battery monitoring facilities built into it.

You set two voltage values v(low) and v(med). There's a connection on the board V(stat). S is the voltage from the battery.

V(stat) = 0 if S is higher than v(med) => State 1
V(stat) = 3.3V if S is between V(low) and V(med) => State 2
V(stat) = alternates 0 and 3.3V between 0V and V(low) => State 3

So I was thinking (of displaying this via 2 LEDs (green and amber))

State 1 - green on, amber off
State 2 - green off, amber on
State 3 - alternating between green and amber.

I was hoping to combine the LEDs into one bicolour LED.

If anyone has any cunning plans or improvements they'd be appreciated.. whatever it end up with though it mustnt use up too much battery power.

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LasVegas (author)2007-10-16

If your V(stat) truly switches to 0V as opposed to open cathode (open line), then you could simply run the cathode of LED1 and the anode of LED2 to the V(stat) line. The other ends would go through any necessary current limiting resistor to +3.3v (the anode of LED1) and ground (the cathode of LED2). Now when V(stat) goes high, LED2 lights and low, LED1 lights.

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