Door Release from in-house Monitor

[MrTechnology]

Hi,
I have purchased a Home Monitor that consists of;
- A LED Screen with buttons on it (the inside monitor eg: Near your Living area)
- A 'Doorbell' for the front door that has a Mic, Speaker, and a Camera (and infrared lights etc)
You use this to see who is at your front door, and talk with them, through the monitor (perfect if you have a double story house).

See the unit here: [url]http://www.ebay.com.au/itm/Night-Vision-Touch-Key-9-Video-Door-Phone-Doorbell-Intercom-CCTV-Camera-Monitor-/261155824031?pt=AU_Home_Personal_Security&hash=item3cce19a19f&_uhb=1#ht_8487wt_1139[/url]

You can also extend the Doorbell part with two wires to a Door RELEASE... A Door strike that opens, which in turn - allows the door's lock to pass through, allowing the door to open (letting them in).

The high-level picture of this arrangement looks like the following;
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I have purchased a Door Strike the same as this one [url]http://www.ebay.com.au/itm/DOSS-RECESSED-LATCH-LOCK-STRIKE-12VAC-DC-ELECTRIC-DOOR-RELEASE-LOK110NC-/310433557307?pt=AU_Building_Materials&hash=item4847482b3b&_uhb=1#ht_5540wt_1202[/url] - that has the following main properties
- Operates on, 12v DC, or 12-16v AC, Current draw 350mA.

The problem is that the Front Doorbell sends 12v DC to the Door Strike, but only for a few hundred milliseconds!.... and this is not enough to OPEN the lock/door most of the time.

If I keep PRESSING the door release, then the lock can open every so often (build up of repeat/voltage)

[b][u]Two questions;[/u][/b]
1) Any ideas on amplifying the Voltage a bit and 'holding it' for say at least a few seconds? (The Doorbell section has 12V that I can use as a VCC / Voltage source)
2) I would prefer NOT rely on the 2 wires only (coming from the Doorbell), being the ONLY thing needed to activate the Door Strike... Since if someone rips the Doorbell/Camera off the wall and puts a battery across the two wires - bingo - the door strike would OPEN! and they are in.

Note: I can run additional wires to the Doorbell and/or strike at the moment since the house is being built and the Plaster is not yet installed.

Thanks for any ideas you have!

[JMACgyver]

Hello,

I would look up "12V off delay relay"

Incorporating this device into your system should allow the milliseconds pulse from the doorbell to trigger the TDR to activate, and pass the current to the strike for the length of time needed to open.

As far as the security of those two wires -any type of remote entry can be compromised, whether it be to house or car, or by IR, RF, or wired.
The only thing I can think of is to run the wires that power the 'lock strike' voltage back to the 'door release' switch, as part of an AND circuit (using one-half of a DPDT switch) so that only when the DR switch is pressed, does the current flow physically to the LS wires, which at that point are being run back to the lock strike, totally separate from the dorrbell/camera assembly.

I hope this helps, and makes sense.
Post back with any questions

--Electro--
aka The Other David

[sheldons]

Heres a circuit to play with.....you can adjust the timing components to suit.....

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