IR Remote and Intervalometer for S100fs

A DIY Project

Standard disclaimers apply....   if you would be worried about killing your camera, don't read the following.

RR-80 with added Phototransistor
    You will see how to convert a FujiFilm RR-80 Remote Release into a simple IR Remote.

    We add a $2 Radio Shack IR Phototransistor ( PN 276-0146 ) to allow the RR-80 to be triggered by the IR burst from an IR intervalometer, like a GentLEDS AUTO.   The phototransistor also allows the remote to be triggered by ambient light.   For example, if you want to set up a time lapse series to start when the sun comes up, you can set the camera for continuous shooting and when light hits the sensor, it will trigger the camera to shoot continuously.   Interrupting the light stops and starts the camera.  Its that easy.

    Its not a perfect solution in that when the phototransistor sees less light it triggers the "half press" response.   But the IR also works in conjunction with the button... we merely use it to bridge the full-press switch.   Also when you DON'T want the phototransistor to fire you need to cover or plug the hole we create in the body of the RR-80.   This is a small price to pay, however, for the cool stuff you can do with the modified RR-80.

    Parts needed:

    - FujiFilm RR-80  ( you can build your own from parts, however )
    - RadioShack 276-0146 NPN Silicon IR Phototransistor
    - Salvaged connector from a PC speaker ( any type will do )

    Time:  30 minutes
    Difficulty: Easy if you know how to solder.

Unmodified RR-80 Remote Release

The RR-80 is a remote release cable for certain Fuji Cameras including the S100fs.   It connects to the cameras mini-USB port.   Mini-USB uses 5 pins, only 4 are used to carry standard USB signals and power.   Pin 4 is normally not used or not connected.   The RR-80 uses pin 4 to feed an analog signal back to the camera.   A simple network of resistors and switches signal the camera to tell it that (A) the RR-80 is connected; (B) the half-press button is depressed, and (C) the half press and full press button are depressed.  The camera just detects the resistance between the USB GND ( Pin 5 ) and the normally unused Pin 4.   Its not sending a USB data stream.

Your mission, should you decide to accept it, is to pop your RR-80 apart and add a phototransistor across the switch that signals the full-press position of the shutter.

The RR-80 disassembled.   Oh my God, what have you done!!!

Removing the two long screws using a small phillips screw driver you expose the greatest mystery of the 20th century.

Disassembly complete.

After removing the single short screw holding the PCB and cable assembly in place.

The component side of the PCB

So here is whats happening.   The trace marked A is connected to the USB GND pin, and trace B is connected to PIN 4.   R1 is connected between the two, telling the camera something is connected to the USB port.    R2 is connected to the half press switch.   R3 is connected to the full press switch.     So for normal operation, there is an 82K resistance.   Half press places a 39K in parallel with the 82K, and full press places an additional 12K in parallel with these.     

So the big queston... can we simply use the full-press switch withouth the half-press?    If we have to transition between the unpressed to half-pressed to full-press state, that complicates matters tremendously.    So orienting the RR-80 as shown below, I shorted the pins on either side of the switch ( which I then attached the red and black wires to ).   On shorting these, the camera focused and took a shot.   Meaning that the half press is not necessary and the exact resistance ( approximately 9K ) is not necessary and the 12K provided by shorting across the full-press switch is good enough.   Very good news.   But this was tested with a S100fs, so testing would be necessary with another camera.   This is easy to do without destruction of your RR-80.

Attaching the connector

So  I wanted a way to attach the phototransistor across the terminals.   So I found a 2 pin connector in my junk heap.   You can buy something, or salvage one from a junk PC, or just forget the connector an attach leads to the phototransistor.    I used the connector so I could remove the phorotransistor and replace with a dry contact ( like a relay or solid state relay ) if I wanted to or rework the remote withouth further soldering.   The switch is surface mounted, so reworking it will eventually damage the PCB board.   Uh, and no, this is NOT my finest soldering job.   

Connector salvaged from a trashed PC speaker attached

OK, so this looks a lot better all dressed up!   Note the capacious case of the RR-80 gives us plenty or room for this modification.    Now I'm a, well, to put it politely, reubinesque guy... so I was getting sort of insulted by seeing the word "abs" for 30 minutes.   It did inspire me to to think about that lapsed gym subscription.   Note that the red vs black is not arbitrary...   Black is connected to the USB GND pin via  trace A on the PCB.    So with an NPN phototransistor its installed as shown.

Connector stuck down and phototransistor installed

So use some double sided foam tape or whatever... to stick down the connector and install the phototransistor as shown.   Note the notch drilled into the top half of the RR-80 case.   At first I drilled a single hole, but later did the same on the other half of the case to make an oval opening..   Screw the PCB board back in place with the short screw.   OK, so its basically done.

Ensure mods don't interfere with switch operation.

Make sure the wiring doesn't interfere with the operation of the switch!    Note how the slack is looped up over the PCB.   Using thinner wiring would have been better.   But given lemons...

Its all done...

And we are done!    Remember that you will need to find a way to cover this hole when you don't want the photodiode to trigger a shot.   I'll leave that as an exercise.   But would obviously have room for a small switch on the other side which could interrupt the photodiode.   I, on the other hand, used a small piece of black electrical tape.   No big deal either way.


Well, first make sure your RR-80 works as it normally did.  ( Well, duh! )  Cover or disable the phototransistor.   With the camera off, attach the RR-80.   Turn the camera on, and then half-press the RR-80 button.   This should trigger the camera AF and exposure lock.   Then try the full-press.   Its should snap off a picture.   If not, check your work..  

If everything checks out, see if the photodiode is working.   Cover the hole with your finger, point it in the direction of a bright incandescent light source or direct sunshine. Incandescent or sun is necessary as this is an IR device and certain flourescent lights will not produce enough IR to trigger the device.  

Elaboration and Caveats

We have no IR filter in place, so it will respond to visible light on the red end.   You can get an IR filter by salvaging a piece of IR filtering plastic from an old IR remote control or iRDA reciever.   This will reduce / eliminate accidental triggering.   Also the phototransistor varies its resistance at varying levels of light, so it will first trigger the cameras half-press response at a lower level of light, and then finally the full press response  under brighter light.   This can be fixed by placing a transistor in addition to the photo transistor so the response is much more on / off.


I have a GentLEDS AUTO intervalometer for another camera.   It has an on / off switch, potentiometer to set the interval, a red LED, and an IR LED.   The red LED tell us humans the intervalometer is operating, and the IR LED tals to the camera.    We have modified the RR-80 to signal full-press when IR shines on the phototransistor.   The GentLEDS AUTO emits a burst of IR periodically, so we can use it to trigger OUR modified RR-80, using it as an IR Remote.    So I can recycle my GentLEDS AUTO for my Canon HV-20 camcorder and use it to trigger my S100fs as well.  

GentLEDS Auto Intervalometer: Its SO Cool!

Here is a video of the GentLEDS AUTO firing my S100fs via the modified RR-80.  It also shows the initial testing of triggering the shutter by interrupting light to the phototransistor and the final assembled RR-80.

So we can easily affix the AUTO to the RR-80 using electrical tape.   But my favorite is to use a black latex balloon,  which mates the two together as a single unit and does not interfere with the function of either.   You could use large diameter black heat shrink tubing as well.

Its also possible to use the modified RR-80 is a light sensitive trigger.   For example, if you set your S100fs in long period continuous shooting mode, the camera will sit there until enough light shines on the phototransistor to trigger the full-press signal.   This will start your camera shooting.   When the light goes out, it will stop.   Rinse, repeat.

If you use an IR LED to shine a beam on the remote, when the beam is interrupted this releases the shutter... and when the beam is no longer interrupted, it will trigger the shutter to be depressed.   Essentially taking a picture when a beam is iinterrupted.   So possible applications include catching that cat that's eating the garbage, or your spouse opening the fridge, or similar.   Again, you can increase the sensitivity of the modification by adding an additional transistor to amplify the output from the photo transistor.   This would allow it to be triggered by even less light.   There is plenty of room in the RR-80 for these additions.

High Praise for GentLEDS

Frankly these folks are a pleasure to work with and know their stuff.   I had a Canon HV-20 and wanted an AUTO to trigger the Photo button - in a week they made one for me.   They have great products and seem to be able to take requests from customers and translate that into working devices very rapidly.   Simply put, they rock!   My hope is that if enough of us are interested in a USB attached intervalometer and IR Remote for the Fuji cameras, these folks would be able to create one for us.   God knows Fuji won't. 

I like that I can use the AUTO for my HV-20 in conjunction with my modified RR-80... but I'd rather be able to buy a dedicated unit rather than sharing one between the two cameras.   On the other hand.... you could see where the AUTO could be set up to have BOTH cameras running in tandem, synchronized.   Which would open up some interesting possibilities, perhaps.
Last Modified 07-05-2008
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