Thursday, May 8, 2008

Modifying GWS voltage indicator to show voltage in bar mode

The OBI-02-5 is a 6V battery level indicator made up of 10 SMD LEDs driven by a LN3914N indicator driver. I wanted to use one of these on my RN-1 robot, not necessarily for the indicator but because all humanoid robots need cool looking LEDs :-).

GWS make various versions for 4, 5 and 6 cell NiMH/Nicad cells(4.8V, 6V and 7.2V) specifically for RC applications. GWS ships the indicators configured to only light up one LED at a time. I wanted all indicator to light up like a BAR indicator rather than a dot/point indicator.

The datasheet for the LM3914N shows that it is capable of displaying in bar mode. The mode selection pin (pin 9) needs to be hooked up to the V+ pin (pin 3).


The indicator board from the front

The indicator board from the back

The back of the board after modification

RN-1 proudly displaying his lights


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