Nick,

The phototriac is intended to switch high voltage AC currents from a low
voltage DC source and to provide dielectric isolation (7,500V insulation)
between the DC and AC sources.
As per the pin out that you provided:
Pin 3 is the anode of the phototriac's internal LED.
A DC current (+) of 10mA to 25 mA  should be applied to pin 3 to illuminate
the internal LED and to turn on the triac.
Pin 4 is the cathode of the phototriac's internal LED and is frequently
connected to the DC power supply's common (-).
Pin 1 is typically connected to the AC load. The other end of the AC load
is connected directly to the AC power source (excluding fuses/circuit
breakers).
Pin 2 is connected to the AC common.
A true test of the triac's performance requires an AC power source, an AC
load and a low voltage DC power source. However, a crude basic functional
test may be performed using DC.
While not intended, nor conventional, the triac may be used for certain DC
applications, however, generally there are more appropriate DC devices.

Vasile,

A triac will turn off or interrupt DC current, if the DC current is pulsed
energy and decreases in amplitude to near zero volts. As an example, a
triac will effectively control a half wave or full wave rectified DC signal.
However, an SCR would be a more appropriate control device.

Good Luck!
Sincerely,
Ned Seith
Nedtronics
59 3rd Street
Gilroy, CA 95020
(408) 842-0858




At 09:22 AM 8/2/01 +0300, you wrote:
>It seems you don't know how a thyristor or a triac works.
>If you supply A-K ( thyristor ) or A1-A2 ( triac ) ( A = anode, K =
>cathode ) in DC the AK or A1-A2 junction will stay on after a gate or opto
>command until the currrent through this junction will go to zero ( in fact
>must be less than sustain current) and this will never hapened in DC .
>Use a bulb for test and supply it in AC. Will works.
>Cheers, Vasile
>
>
>On Thu, 2 Aug 2001, Nick Veys wrote:
>
> > Hi all, I'm using an Omron G3MB-202P solid state relay, 5V flavor.  It's
> > a phototriac.  It's not behaving how I would expect though, hopefully
> > someone can clear this up..
> >
> > Pin definitions:
> >
> > 1 - load
> > 2 - load
> > 3 - (+) input
> > 4 - (-) input
> >
> > Here's what I am seeing:
> >
> > Connections:  to test this I just want to light an LED...
> >
> > 5V to Anode of 5V LED
> > pin 1 - cathode of LED
> > pin 2 - ground
> > pin 3 - ground
> > pin 4 - ground
> >
> > This is how I start it up.
> >
> > Now when I apply power to this, of course nothing happens as I expect.
> > I then switch over the pin 3 to +5V, the LED lights, as expected, I then
> > switch the pin 3 back to ground, the led stays lit.  In fact, no
> > arrangement of the input pins (3,4) will make the damn LED shut off, I
> > can't break the circuit once it's made...  Doesn't sound too useful of a
> > relay!
> >
> > Hopefully I'm doing something obviously wrong!!
> >
> > I've tried this with 3 different relays so I doubt they are defective...
> >
> > Someone please smack me and tell me the simple solution! :)
> >
> > Thanks all!
> >
> > -- Nick
> >
> > nick@veys.com | www.veys.com/nick
> >
> > --
> > http://www.piclist.com hint: The PICList is archived three different
> > ways.  See http://www.piclist.com/#archives for details.
> >
> >
>
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