AVR-Chat

Bernd Felsche wrote:
> 
> On Thursday 12 August 2004 11:00, Dave VanHorn wrote:
> > At 09:57 PM 8/11/2004, kc9dag wrote:
> > >> I think the problem is there are not enough current to
> > >> drive the relay.
> > >
> > >oops, posted the wrong schematic... mine was still wrong, but I did
> > >have the transistor...  The one I ment to post is
> > >http://www.dpicts.com/Tiny15L-LaserDetector-2.jpg  which has the
> > >NPN, but I hooked up the transistor the way it is shown on page 3-2
> > >of the STK500 manual...
> > >so after everyones advice I have changed the schematic to
> > >http://www.dpicts.com/Tiny15L-LaserDetector-fixed.jpg    I didn't
> > >add the diode as someone suggested b/c I am actually using a solid-
> > >state relay (an Laa110)...
> >
> > An SSR may still have a coil, with a small relay activating a large
> > triac.
> 
> Yikes! That's an interesting concept of "Solid State Relay" :-)
> 
> > Also, I'd still reccomend the 10k pulldown on the tiny's output pin,
> > Otherwise, you have an excellent RF detector connected to your relay,
> > whenever the uP is in reset.
> 

Just for interest, SSR's have been around for 25 years or so. (Think of them as
opto-isolators with industrial strength AC or DC outputs.) A real SSR uses an
LED to drive a photo transistor or diode on the output side. This opto link
provides the input/output isolation. (If the thing uses a mechanical relay on the 
input, it should not be called a Solid State Relay.)

All of the SSRs I've ever used have a resistor, internally, in series with the
LED and the input is rated by voltage or voltage range, i.e. 3-28V. Daniel, what 
is the input voltage and current requirements for the SSR you are using? 

Bruce