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momentary latching circuit for video camera

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edmatney

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i need help designing a simple circuit to add to my Panasonic HDCAM. i want to use the camera's record switch (14 vdc signal) to create a momentary pulse each time the camera recorder turns on or off. The pulse should last at least 100-200 ms since i want to use that pulse to momentarily close a relay to control a MP3 recorder. All this needs to fit inside the camera battery plate; the available space is about 1"x 1" x3/8" high. The camera is powered by a 16 v battery.

thanks for any advice/diagrams you may have.

ed
 

dougy83

Well-Known Member
So what's the deal? You get a 14vdc pulse when you press the record button and you want to send a 100-200ms pulse to the MP3 player?
 

edmatney

New Member
The camera does not produce a pulse, but rather a steady state condition, either on or off. i need a pulse output to control the MP3 player.
 

dougy83

Well-Known Member
The attached cct should work. There will be a small (~330ms) delay before switch on or off. If this is a problem, and if you can guarantee that the record input will only change state slowly (> 150ms before changing), then R2 may be reduced and the delay will reduce accordingly. Otherwise, just leave as is.

The output relay could be replaced by an optofet (with current-limiting resistor) if you need to reduce space consumption. If you can only find relays, often the reed-relays are very small.
 

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