Digital dash

[Matt Cramer]

	Thanks for that chip number.  It'd be a lot easier to use that than trying
to build a flash converor out of op amps to drive a LED bargraph readout,
which was the idea I had before..  But while a bargraph readout would
certainly look pretty spectacular, I've been wondering about getting some
kind of numerical readout too.  Could you elaborate on what these "74LS"
circuits are?  Thanks a lot!

Matt Cramer

At 11:14 AM 4/25/2000 -0400, Frederic Breitwieser wrote:
>A digital dash is not that difficult to do, both digitally controlled and
>analog controlled.
>
>For analog in, nat semi has a chip, the LM3914 which takes a 0-1V input and
>spread it across 10 LEDs.  Two of these chips could make a 0-1V 20 LED scale
>for more resolution, or a 0-2V scale if you perfer.  Most of the aftermarket
>$100 oxygen sensor digital readouts are based on this premise. (Most o2
>sensors produce 0-1V).  You can use op-amps to change the scale accordingly.
>
>>From a digital perspective, its a matter of taking a certain number of bits
>and making a readout in bargraph format.  I designed and started assembling
>a dash for my mid-engine car, each graph having 16 rectangular LEDs.  16
>LEDs translates into 4-bits... $0 to $F in hex.  So, the digital dash has a
>single 8-bit input - the high order 4 bits (nybble) represent the gauge
>address, and the lower 4-bits indicate the value.  Using simple 74LS154's
>for the gauge display drivers for the bar graphs, and 74LS47's for the seven
>segment displays, it was pretty easy to build.  Then, whatever I drive this
>with, could be something as simple as a parallel port off a PC, any 8-bit
>microprocessor, etc.
----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org