So, I purchased a camera trigger that moves the camera and then triggers the shutter. I wanted to change when the camera shutter was triggered so I purchased a cheap eBay delay timer relay. I knew the camera trigger was basically a switch, so I intended to use it to trigger the delay timer, and then have the relay switch the camera shutter signal on the other end. The camera side is working as intended, but I am having issue with the trigger side.

It appears that the camera switch is not just an on/off switch, but resists a portion of the electricity normally open, but is fully switched normally closed. The trigger signal output is 4.5v, with the switch NO (measuring from trigger to ground) I show about 0.5v, and NC I should 0 volts.

EDIT: I have since measured the resistance as 460ohm NO, 100ohm NC; I have updated the schematics to represent this

Unfortunately, this change is not enough to actually trigger the timer. Using a different camera trigger I was showing 1.5v NO, but that still was not enough to trigger the timer. When grounding the trigger directly the timer would trigger. So, what I gather from this is that the timer needs a greater change than the 0.5v or 1.2v to ground that my camera triggers are putting out. Current Configuration My idea was to add a transistor to switch the trigger signal to ground, using the camera switch as the base and pulling power for this operation directly from my 5.3v source.

I have never used a transistor before, so I do not know if this would actually achieve my intended desire, nor what sort of transistor I would need to purchase. I would also like to limit the current from my battery going through the switch as it's just a trigger signal, but I am unsure of how to do that.

I have attached 2 schematics to show where I am currently and what I was intending. My experience in this field is rather limited, so please let me know if there are any glaring issues with the schematics (besides my disconnected relay).

With transistor

  • \$\begingroup\$ Your transistor is destroyed as soon you flip the switch, you need a base resistor in any case. \$\endgroup\$
    – Janka
    Dec 14, 2017 at 5:03
  • \$\begingroup\$ I have since measured the resistance as 460ohm NO, 100ohm NC; I have updated the schematics to represent this. Do you think that would be enough resistance to not fry the transistor given a 5.3v source? \$\endgroup\$
    – Greg W
    Dec 14, 2017 at 9:39

1 Answer 1


Well, I managed to scare up a P2N2222A transistor from an Arduino kit my girlfriend has, along with a couple of 10k resistors. I wired those into a +3.3v header I found on the board, through the switch, and into the base of the transistor. After all that, it seems to be working fine.

It was also working with when I tried a 220 ohm resistor, and also while running off 5v. I decided that 2 10k resistors and 3.3v was probably safer in the long term as long as it worked.

Here is the schematic for my completed circuit:

enter image description here


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