SmaTrig 2.1

DIY wired remote control for Canon EOS cameras

EOS 400D

The EOS series of cameras from Canon offer a nice feature which is of particular interest for DIYers and technically oriented photographers. It is possible to trigger these cameras externally using an electrical signal. To the hobbyist's delight Canon used no special protocol to trigger the camera - you just have to short-circuit two wires.
Knowing this, building a homebrew Canon RS-60E3 wired remote control clone is a snap! Or maybe an interval trigger, or a microcontroller based...

Pinout 350D, 400D, 450D, 500D, 550D, 600D, 650D, 700D, 60D, 70D

The external trigger can be accessed with a stereo (3 pole) 2.5 mm jack plug. It is not the standard plug used in mp3-players etc. which has a diameter of 3.5 mm! But don't worry, you can buy the smaller plug in any bigger electronics store. The pinout is shown in the picture below.

Pinout wired remote control

Connecting the focus-wire (ring) with ground (sleeve) corresponds to pressing the shutter button halfway down and results in focusing the camera. Accordingly, connecting the shutter-wire (tip) to ground (sleeve) corresponds to pressing the shutter button all the way down. In this case the camera is first focused and then triggered if the focusing was successful. In manual-focus mode the camera is triggered instantly.

Pinout 20D, 30D, 40D, 50D, 1D, 5D, 6D, 7D,...

The double and single digit Canon cameras have a different connector (for whatever reason). Canon calls it the N3-connector. The only way to get the connector is to cannibalise a cheap wired remote control. The electrical circuit behind the connector equivalent to the xxxD types.

Pinout Canon N3 connector

Electrical characteristics

I measured the electrical characteristics of the wired remote control connector on a Canon EOS 400D and 40D. The values are equal for both models. They are listed in the following table

Voltage (no load)3.3 V
Threshold voltage1.8 V
Short circuit current68 µA
Current at threshold voltage30 µA

The shutter and focus inputs have the same electrical characteristics and work independently. The remote control port and the shutter button seem to share the same wires. Pushing the shutter button results in a voltage drop to 0 V at the external shutter or focus wire. A possible equivalent circuit for the trigger circuitry might look like this

Equivalent circuit

If the camera is in stand-by mode, there is a voltage present at the focus wire. The camera can be waken up from stand-by by connecting the focus wire to ground.
The trigger inputs can serve as power supply for circuits with a supply current of less than 30 µA like the HDR-Jack.

Comments (33)

Sekunden Tick und IR
falls es ein Update (oder den Source) geben sollte:
(1) Ich würde mir wünschen, daß bei der Bulb Einstellung bzw. allen Langzeitfunktionen beim Ablauf ein SekundenTick zu hören wäre. Dann bräuchte man keine extra Stoppuhr.
(2) Weiter wäre es toll statt der IR Sendediode eine IR Empfangsdiode zur Auslösung eingebaut werden könnte (klar kann man auch stecken), dann kann man mit jeder IR Fernbedienung auslösen (kein Code, nur "kommt was"). Ich brauche die IR Sendung nicht und so verliere ich meinen extra IR Adapter nicht.
Viele Grüße Sige
#33 - Sige - 03/03/2022 - 12:00
fertig bestückte Platine oder fertiges SmaTrig? Sony A7RIII
Hallo Luk,

hast Du noch eine fertig bestückte Platine oder ein fertiges SmaTrig zum Verkauf? Ich hätte gerne ein SmaTrig.

Grüße von Michael
#32 - Michael Graf - 02/17/2021 - 15:34
Smartrig 2.1 Sony Alpha 7 III
Hi. Ich habe vor einigen Jahren einen Smatrig 2.1 bei dir bestellt und zusammengebaut. Hat bei meiner Olympus leider nie funktioniert. Hab jetzt eine Sony und bin dann draufgekommen dass bei dem Bild in der Bauanleitung die IR Diode verdreht eingebaut ist. Hab sie jetzt nach dem Schaltplan umgepolt, geht jedoch trotzdem nicht. Die IR Diode leuchtet nicht (mit handykamera geprüft). Und die lötpads der IR Diode haben sich auch schon abgelöst. Ebenso funktionieren die Piepstöne nach der Konfiguration nicht. (doppelton zu Anzeige was eingestellt ist) Pipst nur in einzeltöne.
Hast du noch eine Platine mit SMD bestückt bzw. eine fertige Version?
Mit freundlichen Grüßen
Ing. Peter Waltner
#31 - Peter Waltner - 12/20/2020 - 22:21
hast du vielleicht noch ein fertig aufgebaut zu bekommen, und zu welchen Preis?
Für ein sony alpha 7rii
oder sony alpha 99
#30 - stathi - 09/10/2020 - 08:54
Which votlage
Thanks for your great reverse engineering.
I'm a bit surprise by the 3.3V reading as input.
Should it be something a bit higher than that?
The camera power is 7.4V, so I'm surprise they have such low logic input.
#29 - - 06/28/2020 - 11:35
I bought an EOS 1000D body to only do macro photography with a Nikon bellows, therefore I just need to control the shutter.
I used a 2.5mm stereo jack plug and a redundant reset switch and cable from an old computer - works well and only cost me the price of the plug, about 3 pounds.
#28 - Ashley - 06/09/2020 - 17:48
Ja, ein paar habe ich tatsächlich noch da. Schreibe mir einfach die Email ganz unten.

Grüße, Luk
#27 - Luk - 04/08/2020 - 15:30
Hallo, ich habe Interesse an einem Trigger. Gibt es noch welche und ja zu welchem Preis?
#26 - chris - 04/08/2020 - 11:49
Smatrig 2.1
Hi Ulli,

I have a a couple of ready assembled Smatrigs here. I'll contact you per email.

Regards, Luk
#25 - Luk - 02/18/2020 - 17:12
Smatrig 2.1 für Canon EOS 5D
Interressant Geschichte dieser Smatrig 2.1.
Wäre es möglich, diesen auch fertig aufgebaut zu bekommen und wenn ja,zu welchem Preis?
Gruß aus Gladbeck,
Ulli Magasin
#24 - Ulli Magasin - 02/18/2020 - 15:08
Made one with a 60 foot cable
Works fine. I'm able to tripod my camera at my yard's popular bird-perching spot, or where the hummingbirds feed, and I can sit on my back porch and shoot whenever I want.
#23 - David R Weesner - 02/06/2020 - 17:53
End of exposure confirmation
You can get the end of exposure confirmation by monitoring the trigger singal in the flesh hot shoe of the camera. If you set your camera to 2nd curtain flash sync, it will try to fire the flash just before ending the exposure.
The other method would be to control the camera using the bulb mode. In this case you know how long the exposure time is. The problem is, that you have a stiff exposure time not adjusting to the scene.

#22 - Luk - 08/12/2017 - 05:17
7D freezes
I guess the focus or the shutter is accidently connected to ground permanently. Check the cables for short circuits.
#21 - Luk - 07/01/2017 - 19:05
Thank you very much
I used the scheme and it's working great.
#20 - Sharon - 09/20/2016 - 12:05
Lock up after long remote time
GEO, I have the same issue, after using a home made shutter ONLY remote after say 15 minutes the camera freezes and no more pics unless i turn it off and back on again.
#19 - Mike - 04/04/2016 - 08:08
I wouldn't try it
It seems easy to damage expensive cameras with a home grown remote, so I won't be trying it on my canon 40d.
#18 - David - 08/03/2014 - 17:16
I use cheaps remote control for car centrall door lock for car , wich has 4 channel , with key chain remote,,,1 cahnnel for focus 2nd cahnnel for shutter ,,, spare 2 channel mya be for zoom in or out later
#17 - K2L - 08/19/2013 - 00:15
Succesfully made a remote control for my EOS 1000D
Hello, thanks for sharing this info about how remote controls for EOS cameras work.
I have a EOS 1000D, whose remote is identical to 500D's one. So I decided to build one from an old small radio. I recycled its buttons and its case, and added another switch. This is what came out:
The first button (starting from the left) is the focus button; the second one is the shutter. The switch is for the shutter too, and it is useful with BULB mode.
#16 - Davide Depau - 08/12/2013 - 17:31
re. Schematic incorrect for 'some' models using N3 connector
My 10d has the same voltages. I got a $11 timer for a 40d from oeverstock thinking I could just make an adapter but no luck. The focus pin reads -3.3 till it is pressed than it goes to 0 v and than it stays that way until the stutter is released (as long as you keep pressing it). I think I need to add some sort of latch circuit because the cheap switch I cut the plug from is a reed switch which makes the focus first and holds it where this one puts out one quick pulse.
#15 - karl - 03/13/2013 - 16:20
Remote wiring and homebrew connectors
Going to wire up a 2.5mm jack to fit the plug. I have a relay output from a controller that I plan to interface to. SHould be a simple wire of the shutter to ground and hopeully do not need to wire in focus. I plan to have it setup in manual mode and never sleep mode. That way if the trigger activates I will capture what in a consistent way. For a starting line of a race so I need consistent firing.

BTW - All you hackers who are sourcing power to these pin be careful. The logic is pulled up by resistors internally in the camera. By sourcing a high on the ground wire your shorting voltage to the ground and this is a good way to damage items. You can source a high to the gate of a NMOS transistor. The source would be hooked to ground and the drain side would be hooked to the focus or shutter output pins. When you drive a high voltage on the gate of the transistor it will turn on and essentially pull the focus or shutter pins low. Relays can be used as well but don't drive voltage directly as it could interfere with the internal pull resistors and the sense nodes internally.
#14 - JN - 09/05/2012 - 05:18
@Elijah Lucian:

You should use two transistor in emitter circuit or better two optical coupler.

The last solution is better cause it's hard to damage the camera. May you create an adapter which already includes the optical couplers - so you can't damage the IC in your camera.
#13 - joph - 03/21/2012 - 16:00
IR trigger
I manufacture an "Intervalometer" that can be triggered by sound/light or in fact anything that can be used to trigger the shutter - IR beam included.
#12 - Graham Gillett - 10/04/2011 - 09:16
Look at the post below yours. Using a light (or IR) sensor and a laser pointer (or IR LED) you can use the schematics presented there.
The same remote (as functions) but based on TouchShield Slide is presented here but this one is more expensive (see and you will understand why)
#11 - Grozea Ion - 05/30/2011 - 16:03
Other example of remote
Long time has passed since i came here. In the mean wile i started to learn about micro controllers and i made myself a remote control for my Canon EOS 450D. You can have a look at it here
#10 - Grozea Ion - 05/09/2011 - 19:06
I've had a quick scan on Ebay and could only see IR or wired remotes. The IR remote only work from the front of the camera are very limited in range and are of course single shot only. The wired remotes can do continous but you are limited by the length of cable.

You can make up a wired remote in a few mins using a switch and 2.5m stereo plug. Cost about £2.

#9 - Legendarydevils - 03/13/2011 - 17:49
I made a wired remote controller for my 400D with a motorola cable, but I added a 2 phase button, just like the shutter button: half way down for focus, all the way down for shutter. On One Shot takes one shot, on Continuous takes pictures until i let go of the button, and on Self-timer/Remote Control, the timer counts down.
The Bulb function works good as well.
The only problem is that i need to put it in a little box or something, and find a way to lock the button for Bulb.
#8 - Ovidiu - 12/06/2010 - 09:47
I think it's just a N3 version of the RS-80E3 trigger as used for the 400D and other three-digit EOS cams.
#7 - engraved dog tags - 10/14/2010 - 09:10
Really useful
Thanks for writing this, I've been looking for something like this for so long!
#6 - peter otoole - 09/03/2010 - 21:00
Motorola Handsfree
Used a Motorola Handsfree - the one with the 2.5mm socket, and it works like a charm.

Thanks so much for sharing.

BTW, have used it on a Canon 500D
#5 - Hrishikesh Deshpande - 04/09/2010 - 04:53
Wired remote control
Thank you for this interesting information about the EOS. I would be grateful to know whether other brands have it on any of their cameras.
Many thanks
Brian Wilkins
#4 - Brian Wilkins - 12/21/2009 - 02:35
Thanks for the post! It is sure to be very helpful, I was just looking for this info.
#3 - rapid4me - 11/16/2009 - 08:59
If you hold down the shutter-button only: The camera focuses first and than shoots if the focusing was successful. If the camera can't find the focus (too dark, object out of focal range...) no image will be taken. You have to hold down the button until the focus has been found, it may take a second for bad light conditions.

You can also focus first using the focus button and than additionally press the shutter button to release. This way you can control on what the cam has focused and refocus if necessary.

If you are in manual focus mode, the cam will trigger immediately when the shutter button is pressed.

#2 - luk - 11/27/2008 - 09:36
Both the 20D and 1D3 have an N3 connector. I guess the characteristics of both cameras are the same because both use the RS-80N3 trigger. I think it's just a N3 version of the RS-80E3 trigger as used for the 400D and other three-digit EOS cams.
#1 - luk - 11/10/2008 - 14:10
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