Trying to run a SSR

Hi,

I am currently using a EasyVR shield and arduino Duemilanove to try and turn on some 120v light bulbs. In order to do this, I am using a solid state rely (http://www.sharpsme.com/download/pr3bmf51nsz-epdf). I have an arduino pin connected to a 270 ohm resistor which runs into pin 2 of the SSR, but I am seeing a voltage drop of around 4 volts from my pin to the end of the resistor, so I am not getting the voltage or current I need to turn on the SSR which would turn on my light. I have made sure to set the pin mode as an output, and it does work when I connect the SSR's diode to the 5v pin, but I am not sure what is causing this voltage drop. It seems like the arduino is getting loaded down, but it says the pins should be good for 40ma so I am not sure exactly what is going on. If it does matter, I do have a couple of other LEDs being run off two other pins, but I cant imagine this would load down the arduino.

Any thoughts?

Well the SSR's LED has a typical forward voltage drop of 1.2 volts, so seeing around 3.8vdc or so across the series resistor is nominally ok. What current do you read going through the LED?

Lefty

Interesting package, <= 1a
[<= 100w lamp].

retrolefty:
Well the SSR's LED has a typical forward voltage drop of 1.2 volts, so seeing around 3.8vdc or so across the series resistor is nominally ok. What current do you read going through the LED?

Lefty

The 3.8 volt drop is not across the resistor. It happens from the pin to the resistor

azbacnik:

retrolefty:
Well the SSR's LED has a typical forward voltage drop of 1.2 volts, so seeing around 3.8vdc or so across the series resistor is nominally ok. What current do you read going through the LED?

Lefty

The 3.8 volt drop is not across the resistor. It happens from the pin to the resistor

??? from the pin to which end of the resistor? A drawing is a much better method for discussing such issues, it is the universal language of electronics. :wink:

Drawing attached. Sorry for cruddy quality. All I currently have to work with on my computer is paint, but its a pretty basic circuit, just not sure why I am getting the voltage drop from the pin to the resistor

Edit: if not obvious, I drew the inside of the SSR I linked above. Input pin is pin 2, ground pin is pin 4. The pins the triac is on is pins 6 and 8 (gate pin is not used).

That is rather bizarre. On the surface it would appear to have to be a bad connection somewhere, break inside the wire, something weird like that.

Lefty

I tried measuring the voltage straight out of the jumper wire from my pin and I get 5 volts. I have the thing breadbaorded and I have tried multiple wires, but it seems like as soon as I connect it the voltage drops. I even tried using different holes in the breadboard but that didn't do anything.

It looks like you haven't got it wired as you think. It is not possible to wire it up as in the diagram and get the results you see. How about a photo of your setup.

I will upload it as soon as I can, unfortunately, I am away from my project for the time being. I should be able to get it uploaded tomorrow.