I knew you were going to ask that...  :)
Basically I want to build:

http://www.elwire.com/faq/seq/seq5/index.html

But I don't have a schematic nor the thing itself to examine.  EL wire
glows then you put a 120v current thru it; 4-8khz is the brightest, but
60hz will produce some light.  What you normally do it get a "driver"
(battery to 120vac / someKhz, they vary) and connect the EL wire to it.
  The aforementioned circuit uses a little PIC to switch the connected
driver's output to one of five EL wires using triacs.

I looked up the triac specs ("L201E3" into google) and it seems more or
less identical to the one I'm using.  It looks like the triacs are being
driven directly by the PIC pins thru 470 ohm resistors.  So I wired up
what I think is the equivalent circuit (I have EL wire and a driver, not
the same as theirs, but its 120vac at 1Khz) and a triac and no go.

In their circuit I don't understand what the diode is for (polarity
protection for the DC to power the pic?).

It looks so simple yet I can't get the equivalent to work at all and I'm
running out of time and getting kind of frantic about it (10 days before
an art exhibition happens) ...

Anyone?  Anyone?

Should I just order a bunch of optoisolator triac drivers (MC3010) and
be done with it?

All I want is for when the PIC output line is low, triac off.  When
high, triac on.  Seems simple enuf and clearly the aforementioned
circuit works this way.  I need to be able to switch rapidly, and I'd
like to have dimming based on PWM (which I have working with LEDs) so
relays are out.

Help...help....  :(
Jesse



Spehro Pefhany wrote:
> At 05:00 PM 4/12/02 -0400, you wrote:
>
>> Hi - I'm trying to do something similar - 16f877 pic turning on/off a
>> triac that switches a bit of an unusual AC waveform - AC, but not a sine
>> wave, 4Khz / 120V approximately.  Very low power - a few milliamps at
>> most.
>>
>> I haven't used triacs before and I'm getting nothing but grief.  I have
>> a bag (100 of) MAC228A8 - motorola "sensitive gate" triacs, but what is
>> happening is that the triac switches on when the gate is positive or
>> negative - its only off when the gate is floating.
>
>
> Issues:
>
> 1)      Commutation time  (the triac doesn't have time to turn off
>        completely)
>
> 2)      Holding current (if you are using pulse drive)- at only a few
>         mA the triac may or may not stay on until the next pulse.
>
> I will be building many of these, as in 24 triac switches on one board
>
>> with the PIC, and keeping the component count to a minimum for both cost
>> and space savings is desirable...
>
>
> Can you say a little more about the load you are using and the
> AC waveform? Possibly some other kind of switching device might be more
> appropriate (probably).
>
> Best regards,
>
> Spehro Pefhany --"it's the network..."            "The Journey is the
> reward"
> speff@interlog.com             Info for manufacturers:
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> Embedded software/hardware/analog  Info for designers:
> http://www.speff.com
> 9/11 United we Stand
>
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>


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