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Special Assignment D3000

In this DIY tutorial Philip Schütz (see his Flickr account here) takes us through the process of making a wireless remote shutter release from a doorbell. NOTE: no responsibility for damage to you, your camera or doorbell will be taken by DPS: proceed with care.

Did you ever want to try wildlife shots, but the animals were scared by your presence? Did you ever want to do self portraits, but your IR remote couldn’t do the job? Real wireless remotes can help you, but they are an expensive piece of equipment. In this tutorial you will learn how to modify a wireless doorbell, that you can get in any home depot store or garage sale, to make your Canon EOS DSLR focus and release the shutter from a great distance.

Please note: I do not take any responsibility if your camera and/or you take any damage. Building the wireless control requires a bit of soldering, the soldering iron is hot and if you short?circuit parts you could destroy the doorbell. However, don’t worry if you never used a soldering iron before, if you follow the instructions carefully and handle the soldering iron with care any damage is very unlikely. You don’t have to worry about high voltages or currents, the bell and the camera use only batteries, you should avoid touching any parts anyway unless you have to.

1. What you need

  • A small soldering iron (15 – 25W)
  • Big tweezers or needle?nosed pliers
  • Two pieces of wire, you can cut almost any piece of old wire you have
  • A stereo cable with 2.5mm plug (Or a 2.5mm to 3.5mm adapter and old headphones)
  • A MOC 3020 or MOC 3040 chip, ask the local electronics store, they’ll help you out
  • A wireless doorbell, make sure it has an LED that is lit when the bell rings and a long melody

2. The Bell

At first you should test the bell, the LED has to light up when you press the button, and it is best if the LED stays lit for as long as you push the button on the remote. Open the bell and disconnect the speaker, you don’t want the animals be frightened by the sound, do you? Test the bell again, even if you disconnect the speaker, the LED should still light up.

Now disconnect the LED. If it has high legs, you can just cut if off near the LED, that’s the easiest way. If it is soldered directly to the board, you have to heat the solder spots on the other side of the board with your soldering iron and pull it out.

Take your MOC and look at the top, the legs facing down. There is a little marking, a small circle or a semi?circle imprinted in the case. In the photo below you can see the numbers of the pins I will refer to from now on. On the left side of the MOC between pins 1 and 2, there is a LED, similar to the one you just removed from the bell. The pins 4 and 6 on the right side of the MOC are only connected, if the LED in the left part is lit.

It gets a bit tricky now, so be careful. If you have soldered before, you can skip the following section.

Excursus: Soldering

Turn your soldering iron on and wait until it is hot. Meanwhile you take your piece of wire and remove the isolation on the one end. Now wrap the copper core of the wire around the part you want to connect it to. Put some solder on the tip of your soldering iron so it melts.

Now bring the solder onto the connection of the wire and the other part so it flows on the wire and the other part to get a good electrical connection. Repeat until the wire does not move anymore. Use the tweezers or pliers to hold the wire or the chip in place. Pull gently to test the connection.

You have to connect pins 1 and 2 to where the LED was before you cut it out. The anode must be connected to pin 1 and the cathode to pin 2, do not confuse them, it will not work the other way round. You should see which one is which from a small drawing on the board (see photo below). If there is no drawing, well then it is a bit of a guess. I suggest you only connect the wires without soldering until you know if you got it right. You can use two pieces of wire like I did, or you can connect the MOC directly to the board if you know what you are doing.

Be careful when soldering: Pins 1 and 2 and the wires on the board must not be connected in any way, don’t use too much solder.

3. The Camera

We will now work with the camera. Plug your 2.5mm cable into the cable release connector of the camera. Now cut the cable at the desired length (I suggest at least 4 inches) after the plug and remove the isolation. You should now see for separate wires, two of which are isolated again and two blank ones. Remove a piece of the second isolation as well. Make sure none of the wires are connected and turn your camera on.

One of the isolated wires connected to either of the blank ones will cause the camera to focus, the other isolated wire connected to a blank one will make the camera focus and shoot. This alone is an improvised cable release, should you ever need one. Now solder one of the blank wires to pin 6 of the MOC and the isolated wire that made the camera focus and shoot to pin *4*, or vice versa, it doesn’t matter here. You can now test it ? press the button of the remote and the camera should take a photo. If the camera focuses but does not shoot, try holding the button of the remote for some time until it does. Nothing happens? Most likely you switched anode and cathode of the LED ? fix that and it should work.

4. The Case

Put everything in the case of the doorbell, make sure nothing is connected to anything it should not be and cut a hole for the wire to the camera. I secured the cable with some tape for strain?relief.

Congratulations, you are done!

The basic answer to "why" is: because it doesn't matter in any practical way.

To put it into perspective, this is a 4.8% difference in sensor area. Or, linearly, it's 2.3% difference in crop factor.

This is not very much, and generally other measurement tolerances will be less precise. For example, if you measure the actual focal length of, say, a bunch of different models of 50mm lenses, they probably have a greater variation in field of view.

In general, newer sensor technology moves forward, and in this case there's no exception: the D3100's sensor is significantly better, particularly for controlling noise at high ISOs. From dpreview:

The D3100 offers little to complain about in terms of image quality, and its new 14Mp sensor delivers very good results. High ISO performance is substantially improved over the D3000 [...].

Basically, the small difference in sensor size is insignificant compared to the improvements in terms of image quality, and the small difference in framing is likewise a non-issue.