AVR-Chat

carl


I have built quite a large installation for the venice biennale using 
100 pieces of el paper driven by 1 small microcontroller.

The way i did it is by using a triac based optocoupler (MOC 32020) to 
switch every panel on and off. These were connected in groups of 20
to 5 STM M5450 acting as a power shift register. It's an LED driver so 
it drives the optocouplers with no additional resistors.

you need two pins for each m5450 (1 clock, 1 data)... i guess that you 
could also use MAX7300 parts and use only 2 pins because they
are driven by I2C

the el side of the circuit was powered by a single inverter.

be warned that in certain conditions an rc network was needed on the 
triac side in order for it to switch off properly.


have fun


massimo





On 29/nov/04, at 23:36, Henry Carl Ott wrote:

>
>   I don't know, my life is pretty simple already :-)
>
>   I just checked out their site.
>   Unless I missed something obvious,  coolneon.com sells el wire and 
> some
> el wire sequencers. Not quite what I'm trying to do.
>
>    I want to use about 96 EL segments to display data, not look phat 
> at a
> rave or burning man.
>
>   But thanks,
>
> -carl
>
> At 03:55 PM 11/29/2004, you wrote:
>
>
>> 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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