[time-nuts] uC ADC resolution (was: Poor man's oven)

Chris Albertson albertson.chris at gmail.com
Sat Jun 10 16:10:39 EDT 2017

On Sat, Jun 10, 2017 at 12:59 PM, Poul-Henning Kamp <phk at phk.freebsd.dk>

> --------
> Delta-Sigma strategies for spreading the noise-spectrum are
> interesting, but will not save you if the required heater power
> ends up being a small rational fraction (1/2, 1/3, 1/4 ...) of the
> full scale.

How many output bits are required?  Most uPs have quite a few digital
output pins.  Each pin could drive a heater resister.  Values of the
resisters organized by power of two.   Again note the title (poor mans...)
 resisters cost almost zero.  Even of driver transistors are needed you'd
get change back from a dollar bill.

The reason I ask "how many bits" is because the above is reasonable with 4
to 6 effective bits but not reasonable with 24

I say "effective" because we can dither the low order bits to gain maybe 6
effective bits form 4 real bits (we can filter the switching noise from a
low frequency dither)


Chris Albertson
Redondo Beach, California

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