I will pay $50 for someone to write simple program

i have drawn a picture of my wiring on the transistor

That'll be a pretty small picture, won't it?

but i'm not to sure of how to upload it.

Below the reply box it says additional options, click the triangle.
The 10K goes from the collector to the camera's supply.

so just to be sure ( cause i dont want to fry something ) am i connecting the 10k resistor from the camera battery positive to the collector which is also connected to the camera pwr button?

Snapshot_20111103.jpg

am i connecting the 10k resistor from the camera battery positive to the collector which is also connected to the camera pwr button?

Yes, if you are a bit apprehensive leave it out. What voltage do you measure on this button when it is not pressed? You are connecting this wire to ground through the transistor to switch it on. When it is not being connected to ground it has to be at some voltage.

i made a video response

BFW,
You could get a reed relay from Radio Shack to do this, too.

Its coil is 250Ω, so it'd draw 20mA from the output pin, no problem.
I think you need a rectifier diode across its coil (get that, too.)
Then attach the contacts (NO and COM) between Ground and your wire 3, either way, that part of the relay is just a switch.

Advantage: This keeps the Arduino and the camera volts/circuits separated.

[Sorry for the interruption.]

I think that the reviews-complainers' applications were likely inappropriate, these work like a charm in situations they're suited to - like yours.

Thanks for that.

With only 82mV on that signal it is looking like a transistor won't work. Essentially from what you said before the camera's power signal line turns it on when it is connected to ground, is that right?
So a high out of the arduino into the transistor's base (through the resistor) will cause the transistor to turn on and connect that line to ground.
That switch also turns it off so it turn it on it needs a quick pulse HIGH and then back to LOW for about 30 seconds while it is on. Repeat that and the camera should turn off.

However, if there is really only 82mV on that line then that is not enough for a transistor to operate. In that case you might have to replace the transistor with a small logic level signal FET. A small relay would also be good.

yes, when i short the cam rec but line to ground it activates the button making it rec or stop rec.

could i take the HIGH output of 5 volts and put it into a voltage divider bringing it down to 2.5 or would that still be bad?

In this demo, the circuit is switching +9V through the relay's contacts to a lamp connected to the supply's GND...

http://s270.photobucket.com/albums/jj118/new_clear_days/circuits/?action=view&current=OSRRdemo.mp4

It's running a modified version of "Blink", it has two different ON periods.

As you can see in the attachments, you could just as easily switch your camera's wire 3 to camera Ground.

(There are two in the RS bins, make sure you get the 5V one, NOT the 12V.)

OSRRsch.jpg

IMG_1425.jpg

IMG_1424.jpg

IMG_1423.jpg

I see what your saying with that. It looks like positive and ground going in and then the same coming out, and then it looks like 1 more to the ground rail? and what do i do just put the correct resistor on the by doing ohms law? (it's all new to me)

i mayhave small level signal fets actually lemme check; i will need to use whichever is lighter in this proeject

"I see what your saying with that. It looks like positive and ground going in and then the same coming out, and then it looks like 1 more to the ground rail? and what do i do just put the correct resistor on the by doing ohms law? (it's all new to me)"

I'm switching a voltage to a lamp, that's just for show.

Look at the "schematic"/dwg, it shows the underside of the relay, hook it up like I show there. It shows all of the components required, nothing else is needed (except wires, clips, whatever you want to do that way.)
That's all you're doing, right, touching "wire 3" to camera ground? If that's a cool thing to do, the relay will do the same thing, only controlled by the arduino.
Or you can mess around with some FETs or something.

This drawing shows the switch that's inside the relay assembly, hopefully this will be more revealing --

There's a little switch inside that clicks on/off when its coil is energised/de-energised (pin HIGH, LOW).

--> You need that diode, it's not optional.

i now understand completely; i will definitely look into these, thank you

Even though you're convinced, I just got finished with another demo, just using the ohmmeter.
I insist that you indulge me by watching it. :slight_smile:

http://s270.photobucket.com/albums/jj118/new_clear_days/circuits/?action=view&current=OSRRdemo-1.mp4

i ordered 2 5 volt relays from amazon which i believe are similiar

That'll work, too, but only because of those switching transistors - it's a package deal. The coils on those relays may be 60-100?, that's where the transistors come in, but that'll still be a load on your 5V (both on, expect around 150mA).

Reed relays can be driven from a digital output because they require much less current, 20-25mA, and no other components are required other than those diodes. Their contact ratings are skimpy, but yours is a very low current app.

Keep us all abreast of your progress.

I only got the ones on amazon because radio shack doesnt accept paypal, but i'll probably take a ride down to RS tomorrow morning and check out the other ones; especially if they use less juice

int sensePin =A1;

void setup (){
  analogReference(DEFAULT); //isn't necessary
  
  Serial.begin(9600);
}

void loop() {
  Serial.println(analogRead(sensePin));
}

I'm wondering about how i could set a threshold on this so that if the sensor went below 300 for 20 seconds it would activate a digital out, i can do the "if" part (i think) but i was wondering if i could get a little help with millis? i think i want?