To make a long story short I have a Nikon D70 and I need it to trigger a 120v power source. My idea is, hook a flash cable up to the shoe, wire the flash cabe to a relay and the other side of the relay to the power source. So here’s where I need help. First, does anyone know how many volts the shoe puts out. I’m thinking it would be a good idea to put a fuse in between the camera and the relay just in case the relay has a problem and sends 120v backwards, I’d hate to fry the camera. Second, the big question, what relay do I buy? I assume I look for one that’s rated to handle 120v on one side and whatever the camera voltage is on the other. Also, is there somesort something I can put on this attachment that will allow it to stay on longer. Not alot longer, like instead of instant (well however long the camera voltage stays up) about 1/100, 1/50…1/2 second. That would be really helpful, but I’m not sure what I’d be looking for, other then electronics, but I’m not looking to spend a ton of money. Any ideas? Am I making any sense?
The camera “shoe” doesn’t output any voltage at all. It’s simply a switch that makes contact at the correct time to trigger the flash. The flash unit generates the voltage.
So to trigger your 120V source, you might not need a relay at all. How much current are we looking at here? Many digital cameras are rated to handle voltages up to 500V, but at a low amperage of course. A circuit consisting of a battery in series with the relay’s coil would work, as long as the relay didn’t require too much current to pull in.
Most modern flashes trigger on very low voltages. Like 6 volts. Old flashes used to use very high trigger voltages on the order of 200-400 volts, but some digital cameras can’t take the voltage and can be damaged.
I’m a little confused as to what you want to control with the camera, but a relay may not be fast enough if you want whatever it is to appear in the picture. You may also have to worry about pre-flash triggering, depending on the camera.
A fuse is not going to help – it’s too high current. If that kind of current goes through your triggering circuit, kiss it goodbye. You’re going to want a rock-solid design that isolates your camera from the circuit being triggered. A relay should do that, though.
OoooKaaaaay.
Now just what do you want to accomplish?
Presumably to take a photograph. Right?
What are you going to trigger with the high voltage?
Perhaps you will need fast response solid state components.
Is the on time critical or can it be on a little longer that to on time of the camera shutter?
More information will yield more helpful answers.
Okay, here is what I’m doing (that’s my picture by the way). It’s a 9000v transformer I’m using to create an arc and then taking a picture of the arc. The problem is, if I leave the transformer on for more then a very very short time (about as fast as you can flick a switch on and off) there’s a sort of plasma cloud that get’s in the way and ruins the shot. Right now, I set the camera for 1 sec and while the shutter is open I flick the switch on and off just about as fast as I can. What I want to do is get the camera to control this. Now, for the protection of the camera I’ve decided against wiring anything directly to it, but I do have a wireless slave adapter. It uses the onboard flash to trigger another flash. I’m thinking of hooking the wireless adapter up to a relay with a battery in series with it, then the other side of the relay up to a 120v power source which will switch on and off the transformer. The shutter can be set to stay open for as long as I need it to, so if the whole setup takes a little bit longer to get going it’s okay. What I’m really looking for is the duration of the spark to be very short and I’m hoping this will work. I’m mostly worried it will be to short and the transformer won’t have a chance to make the spark. So does this idea seem like it should work, or should I keep doing it by hand. (Which by the way yeilds more interesting pictures as I can’t control the timing all that well, but it might be nice to have control over the timing as well.)