trigger for digital camera

I've got a digital camera that I am trying to connect to a motion
sensor. I've disassembled it and have the wires available to wire into
a circuit. I have three relays. I need a circuit to trigger the camera
in this fashion:

1. Receive signal, activate Relay A and hold for 10 seconds
2. Same signal, after a couple of seconds, activates Relay B for 5
seconds
3. Same signal, after a couple of seconds, activates Relay C for 2
seconds
4. Then reset all relays for next event

These steps simulate Power, Focus and Shutter.

It's been awhile since I've worked with 555 timers, but I think tying
them together in a circuit might be the simplest way to make this
happen. I believe a 555 timer configured as a monostable one-shot
could be used for Relay A. What I'm not sure about is steps 2 and 3,
maybe a 556 timer that has some sort of startup delay?

Or would this project be easier with some sort of PIC?

Open to ideas.

Thanks

 

Hey JF, thanks for the reply. Yes, the shutter should be activated
after the focus. I think your diagram is correct.

So, Relay A (pwr) is on for the entire event, Relay B (focus) comes on
a couple of seconds later and stays on for 5 seconds, Relay C
(shutter) comes on a couple of seconds after Relay B is activated.
Then everything times out for next event.

I suppose something could be done to keep activating Relay C when an
event from the motion sensor is received during the 10 seconds, but I
wanted to keep it as simple as I could.

 

It might be easiest for you to use two 555's (or a 556) and
a 4017. The first 555 (set for 10 seconds) and activates
relay A. The second 555 (set for 1 second) pulses continuously
whenever relay A is energized.

The 4017 counts from 0 to 9, advancing one count each time the
1 second 555 pulses. Each count has its own output pin on the
4017. Tie the needed 4017 outputs together with diodes to get
the needed duration and delay. For example, you wanted a 2
second delay before relay B energizes, and you want it to stay
energized for 5 seconds. To do that, use counts 2,3,4,5, and 6
tied together through diodes to turn on an NPN transistor which
in turn energizes relay B. In the same manner, energize relay C.
(I'm not sure when you want C to turn energize - at count 8?)

Here is a representative partial schematic:
+ Vcc ----+
----- |
{ } [Relay]
|4017 |-2--->|----+ |
| |-3--->|----+ /c
| |-4--->|----+--[1K]---| NPN
| |-5--->|----+ \e
| |-6--->|----+ |
{ } |
----- |
|
Gnd ------+

You need to add a diode across the relay with anode tied to
the collector side. The numbers 2 through 6 are the count
numbers (not the pin numbers) of the 4017. Each count is
connected to t6he anode of a diode - all diode cathodes
are toed togehter and connected to the base of the NPN
through a 1 K resistor.

You can find an example 4017 circuit here:
http://www.doctronics.co.uk/4017.htm
You would connect the output of the 1 second 555 to the
clock input (pin 14) of the 4017 and would not use the
4093 circuit. The outputs would be wired as indicated
above.

Ed

 

Correct.

I don't have a data sheet on the PIR as it's something I picked up
couple of years ago a closeouts place. It's actually a wireless PIR
that, when motion is sensed, makes a receiver play some sort of
recorded message ("intruder", "quit picking my flowers", "get off my
lawn"). I think it has adequate range between pir and receiver, maybe
50'.

I'm planning on hacking the receiver and finding some kind of output
and pushing that to the circuit.

I've been having great conversation on another forum about using a PIC
(picaxe) which seems like it would be loads easier due to the timing
issues. Pretty cheap too.

 

Here's the thread. The 8 pin PICs are less then $4.00 each. It's cool
stuff. Check it out.

http://groups.google.com/group/sci.electronics.design/browse_thread/thread/83e2614681dc7b5a