AVR-Chat

I assume you're familiar with the folks at Cool Neon  (coolneon.com).
Your life will be simplified by about a factor of 10.

Ken


>
> Hi Folks,
> A little off topic (but we'll still have one of our favorite MCUs driving
> the mess)
>   I want to drive a rather large array of electro-luminescent segments. 4
> to 8 "chars" with about 16 segments each "char".
>   EL displays need to be driven by a high voltage ac signal in the 100-200
> volt 100hz-8khz range, current is very low.
>   Trying for the simplest, cheapest, and  preferably smd approach (I doubt
> these will be achievable).
>   I'm not real experienced with the hv ac design of the problem, and just
> want to bounce a couple of schemes off the list.
>
> I can see a couple of ways right off the line. (after some googling)
>
>   First,
>    I make an hv ac power supply swinging +/- 100 volts around ground, use
> triacs to select segments, and I THINK I can also use triacs to select
> digits. I believe triacs would drive okay from the avr, should not need
> isolation.  But, I can't find triacs in packages smaller then to-92. Would
> like sot-23 package. Suppose I could mount the to-92 as smd.
>    Power supply would have to be true ac to be sure triacs would turn off
> by themselves.
>
>   Second,
>   Make a DC hv power supply about 100vdc. Use a couple of mosfets to
> switch
> segments between hv, ground, or hi-z. Ditto for digit select. Reversing
> drive will supply the ac signal requuired at about 200 volts potential to
> selected segment. Something like an  h-bridge. I like this better because
> I
> can adjust the drive freq. / dutycycle in firmware and get brightness
> control. But, I have no idea how to configure  / interface the fets to
> avr.  Seems like more parts, but more control over the parts.
>    Power supply design would be simpler.
>
> Whatever happens I'll probably be using shift registers to expand the avr
> output pins.
>
>   Anybody hit this one before?
>   Thanks
>   -carl
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> Yahoo! Groups Links
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