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I am looking for a low current optocoupler. I am using 50-80mA optoisolators and would love to find something that can switch on 1-10 mA. I am trying to put together a very low current controller for cameras.

Thanks
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I don't think you connected the grounds, Dave.
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That seems an awful lot of current - is that for multiple channels in a single package?
I use MOC3020 opto-triacs to fire flashguns (one per channel), they're around 15mA per channel, but I think there are variants that go under 5mA.
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I am just setting them up as per the spec sheet. I found a suggestion on another forum to use a 4n33 darlington OK. They have a 500% CTR so they can be used with low input current and will switch higher loads. I am just switching cameras so I don't care as long as I can get the max signal to the camera down a 25ft extension cable. I am going to try this today and see if I can drive them on 1mA.
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I am just setting them up as per the spec sheet.

You may want to share with us the device number and a link to the spec sheet, so we might actually be able to help?

Lefty
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The 2 OKs I am using at spec are NTE3086 (40-50mA) and PS2501-4 (50mA). These are close to the max current for the led. The electrical characteristics lists a lot lower current rating.

Here are the datasheets
NTE3086
http://www.datasheetcatalog.org/datasheet/nte/NTE3086.pdf

PS2501-4
http://www.cel.com/pdf/datasheets/ps2501.pdf
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The 2 OKs I am using at spec are NTE3086 (40-50mA) and PS2501-4 (50mA). These are close to the max current for the led. The electrical characteristics lists a lot lower current rating.

Here are the datasheets
NTE3086
http://www.datasheetcatalog.org/datasheet/nte/NTE3086.pdf

PS2501-4
http://www.cel.com/pdf/datasheets/ps2501.pdf

One would never operate those optos at their max led current rating (that's a safety rating). Both fully saturate the output transistor at 20ma or less. Perhaps it's the transistor output interfacing that is your problem?

Lefty
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Ok so I was told by another guy that using that level of current was the proper way to go about this but I guess that is wrong as that is the max current. I guess that using the test current would be close to reality as far as current needed to saturate the transistor. I'll build up a test board and do some experimenting.

Thanks, any other ideas or pointers?
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And if you haven't gathered I am a newby at this sort of thing. Learning electrical design on a project by project basis.

Thanks
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@Robert quick question: what’s the reason you are trying to use an opto-coupler? Is it because you’re worried about false triggering your flash or because you are worried about vibrations or G-forces? No wrong answer here. I just remember always hearing a relay snap just before being blinded. I know you need to stay away from reed relays because on high currents they will wield themselves closed, but Omron makes a 5 volt relay that will not act like a transformer (sending noise back into your control logic- though you might still want your opto-coupler to control your relay through a Darlington transistor and a diode across the relay pointing to the positive side of the power) and they are rated for 2 amps at 110 V. It might be a good plan B. Sorry, I don’t have my Omron data book anymore.
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The optoisolators are controlling cameras not flashes.
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I just remember always hearing a relay snap just before being blinded.
That will be the sound of the tube discharging not a relay triggering it.

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I know you need to stay away from reed relays because on high currents they will wield themselves closed
That will happen with any relay if you exceed the current rating of the contacts.

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Omron makes a 5 volt relay that will not act like a transformer
That will happen wit any relay.
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Well i figured all that out but at this moment all of my camera controllers use optoisolators not relays. I had one prototype with a relay but I am using OKs to keep current down and size small. Just trying to figure the current thing out at the moment. I picked up a couple of 4N33 (OKs with Darlington transistors) yesterday to test and see if I can use them with 1-5mA if so that may be the ticket. I am also going to futz with my current crop of controllers and see if I can reduce the OK current to around 20mA. I have about a dozen at the moment I am using for shooting the space shuttle launch. I also have 4 arduino's I am using as well. I may use more in the future. I really like the fact I can program them for a week or more of launches, the launch time changes every day, so it makes life a bit easier.
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I'm guessing that you have a two wire connection to each camera.  You should measure voltage and current on those two wires and you're going to need to know the polarity.  The camera supplies a loop current and you supply the switch.

You might want to consider using power MOSFETs that are designed to be switched at five volts.  A fifty amp transistor with an on-state resistance of about .03 ohms can be had for around fifty cents each.  It takes next to no current to switch them on and as long as you respect polarity and current you can treat them like a relay.  The on-state resistance of an optocoupler might be too high to trigger the camera. 

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Transistors and Mosfets don't provide enough isolation. I am running 1 to 4 cameras per controller and focus as well as shutter lines for each camera. Each camera has to be isolated from the other cameras or you get strange interactions and possible feedback of voltage for any of the cameras connected. I have tried it with transistors and not had great results. I have heard lots of good stories about frying of cameras when not properly isolated. Anyway any ideas on low current optoisolators? I have a few more things to try this week.
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Mouser (www.mouser.com) has a good search function for the characteristics of optoisolators.  I have no idea what the cameras require for remote focusing.  Obviously you have to have their specs.  If you can provide a power supply at the camera you can amplify the output of the optocouplers.  I have a project right now where I'm using optocouplers and MOSFETs, both for isolation and level shifting.  I run a resistor from the positive power supply to the optocoupler, ground the other side, and control the MOSFET from that.  This needs no current amplification on the optocoupler. 

You can treat a MOSFET by itself like relay contacts by connecting the drain and source to the device that you are controlling.  You can feed the signal from the controller to the MOSFET through two resistors.  The source is connected to signal ground through one resistor and the gate is connected to the signal through the other.  Those can provide an arbitrarily high degree of isolation, so any currents that might cross-couple would be very small.  The resistors can add up to ten megohms or more if you want.  A little bit less makes the circuit less sensitive to interfering signals.
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