Simple Logic Inversion Circuit?

[archie1234]

Hello,

I need to make a simple circuit to remotely trigger this camera.

http://s1183.photobucket.com/user/mneme ... 3.jpg.html

Based on what I observed with my multimeter, the button on the camera is connected to "KEY" and "GND". A multimeter reading across the GND and KEY tabs pulls the signal from KEY from 3.3v to ground. I want to expose the ground and signal tabs from the button, and use an external signal to trigger the button press.

My problem is that the external signal goes HIGH instead of pulling low. It's a 3.3v output from my microcontroller.

How can I create a simple circuit which, when my microcontroller output pin goes to high, it pulls the KEY signal on the button to ground? (Ideally, in a simple and size efficient manner-- so not using a mechanical relay).

[KMoffett]

A logic level MOSFET (RFD14N05L of equiv.). Drain pin to KEY, Gate pin the the microcontroller output, and Source pin to the camera's and microcontroller's grounds.
Or an NPN transistor (2N3904 or equiv.) and a resistor (~10KΩ). Collector pin to KEY. The resistor between Base pin and the microcontroller's output. The Emitter to the camera's and microcontroller's grounds.

Ken

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