Simple 8-bit D-A / load meter?
Gordon JC Pearce
gordonjcp at gjcp.net
Thu Dec 1 12:15:01 CST 2005
Ethan Dicks wrote:
> I've dug around a bunch, even here
> ... where I thought things were, but I appear to have lost an old file
> that described how to make a simple D-A that one could hang off of an
> 8-bit I/O port to generate a voltage from approx 0 VDC to +5VDC. Does
Off the top of my head, look in the top left bit of a TB303 circuit
diagram where the 7-bit converter to generate the VCO control voltage
is. Googling for "tb303.gif" should bring it up.
Quick description looking at my printed out copy is:
100k resistors from each data line
100k resistor to ground from the "open" end of the D0 resistor
50k (two 100k in parallel) from the junction of the two 100k resistors
connected to D0 to the open end of D1's resistor, another from there to
D2's resistor, and so on up to D7
output voltage off the top of D7's resistor/50k resistor junction.
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