Please Help. How to build this circuit?

[kiefer]

Please Help
I need help with my project. I have the circuit which I can control with the main switch. I need another circuit which automatically should switch ON when the main circuit goes OFF. ON position has to be IMPULSE ONLY and has to have delay too, but not more than 2-3sec.
I'm using DC 12V and current is 250mA.
How to build this circuit?
Thanks for any help

 

[BobK]

From your description, I have no idea what you are talking about.

Bob

 

[kiefer]

HI Bob,
Sorry to confusing You.
Attached is schematic drawing of my project. I hope this will help.
Thanks
Kiefer

 

[(*steve*)]

Is there any other source of power?

If not, what is going to power "Y"? Another question is what is "Y" (and what is "X"). Knowing this can be important. The difference between a LED and an electric traction motor is significant.

 

[kiefer]

There is only one source of the power and this is 12V DC. The X is small DC motor (300mA),
and Y is small digital camera.

 

[(*steve*)]

If you are powering the camera after the power goes off, then this is likely to be a no-go unless there is a battery placed within the ??? box.

If all you're doing is releasing the shutter (and you'll have to tell us how you plan to do that (closed contacts, or voltage pulse, or something else???) then it should be possible to store enough charge in capacitors to achieve this.

 

[kiefer]

Basically, the timer switch has to power two items (Always only closed contacts) . Once, the timer switch is on - the DC motor is on.
When the timer switch becomes OFF - it has to power (close the contacts for shutter) the camera shutter. But with the delay of 2-3sec! In this case it has to work only as a switch( closed contacts ), but only as an impulse switch (not permanently closed contacts). Additionally to this, there has to be a short delay before the camera shutter is ON ( 2-3sec)

 

[(*steve*)]

Yep, that's fine. Does the switch in your diagram completely remove power to the ??? box? Or is there an option to have it continuously powered?

 

[donkey]

ok here is something that I have worked with before and it works I have just never put a good circuit to it.
ok use the mains power to charge the battery, run everything off the battery.
so if power goes off then battery drains. if power is on battery is charged.
so if you need pulses or anything that is after the battery.
a few notes to consider, a 12volt battery is never 12volts:its usually higher when full and lower when depleted.
a charger never gives 12volts (especially sla) they usually charge at above that.
and last but not least is the battery will only ever be charged if the charger outputs mores amps then the circuit uses, so for example if the circuit uses 1 amp and the charger only does 0.5 then the circuit will fail. however if the charger outputs 2amps then the battery will charge at 1 amp per hour. if they are both 1amp then the battery will never recharge.

 

[kiefer]

I set the ??? box as a questioning point, something what is missing.
The main problem is: The timer switch has to power two items. First item will be powered with closed contacts in ON position, and the second item should be powered with closed contacts in OFF position ( but this one with delay and only short impulse).

 

[(*steve*)]

Yep, that's fine. Does the switch in your diagram completely remove power to the ??? box? Or is there an option to have it continuously powered?

(hint: the answer to both of these questions is Yes, or No)

 

[kiefer]

The switch doesn't remove the power.

 

[CDRIVE]

and the second item should be powered with closed contacts in OFF position .

Maybe I'm being picky but this is a contradiction of terms.

Chris