ELM307
Camera Control
Description
The ELM307 is a retriggerable one-shot circuit
that has been designed for electronically controlling
the shutter of a film or digital still camera. The circuit
provides a variable pulse width timer, a variable
delay reset timer, power control, and an LED status
drive all in an 8 pin package.
In operation, a monitored signal (alarm contact,
audio signal, oscillator signal, etc.) is applied to the
circuit’s Trigger input. A low level at this input
immediately causes an output at the Camera pin
(controlling the shutter) that lasts for the duration set
by PW. Further triggering is inhibited until an
additional period (set by Delay) passes, allowing
time for the film to advance or for the digital image to
be stored.
To help with setup, the circuit has a test mode in
which the Camera output is blocked, and the LED is
instead energized. Toggling between the test mode
and the run mode is accomplished with the single
pushbutton input, as is the power on and off.
Features
• Low power CMOS design - typically 1mA at 5V
• No external timing elements required
• Test mode assists with setup
• Single pushbutton control
• Auto power off saves batteries
• LED output shows status
• High current drive outputs - up to 25mA
Connection Diagram
PDIP and SOIC
(top view)
V
DD
Delay
1
2
3
4
8
7
6
5
V
SS
Camera
LED
Trigger
Applications
• Security camera control
• Candid shots of animals or people
• Time lapse photography
• Remote triggering of cameras
PW
PB
Block Diagram
Delay
2
PW
Delay
Timer
3
Trigger
5
Pulse
Generator
V
DD
Control
Logic
LED
Logic
7
Camera
6
LED
PB
4
ELM307DSA
Elm Electronics – Circuits for the Hobbyist
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