SCHEMATICS AND ILLUSTRATION UPDATED.
COMPONENTS WITH MISSING VALUES WILL BE FIXED SHORTLY. PLEASE COMMENT ON DESIGN AND OPERATION
~ TAKE 2 ~
This is my project to upgrade an A/V alarm at my workplace. My knowledge of electronics is still full of holes so your advice and help would be appreciated.
The design presently in use is simply a mutable piezo alarm. The new design will incorporate some features which have been suggested by my colleagues.
The port triggers a transistor to activate the alarm.
Explanation of intended operation:
The unit is essentially a video black/ audio silent warning.
The computer in the plant room detects those conditions and closes the circuit between pin 1 and 2 of a DB9 cable.
A ring illuminated push on/ push off switch acts as a mute button. An internal flasher LED provides the flashing effect in series with the ring LED on the mute switch.
No alarm. Ring = OFF
Alarm. Ring = FLASHING
Mute position (alarm or no) = SOLID ON
In the mute position, a selectable duration timer activates and provides a 250ms approx. chirp sound at the end of each duration. This is a reminder that the system is muted. It should be active wether the DB9 port is closed or not.
The mode switch acts as an emergency bypass of the complex circuits. The operator would be able to quickly bypass failed components as a stop gap measure until repairs could be made.
The piezo is a DC 12V with built in driver cct. The different inputs to the piezo provide a few selectable sounds to differentiate from other alarms in the same room.
* A 555 generating a DC square wave
* A 555 generating a DC triangle wave
* Straight connection to 12v provides a constant tone
I have not added the rotary switch for selecting the timing interval yet but will do soon.
RENDERED ILLUSTRATION OF THE 1RU PANEL MOUNT:
SCHEMATIC:
COMPONENTS WITH MISSING VALUES WILL BE FIXED SHORTLY. PLEASE COMMENT ON DESIGN AND OPERATION
~ TAKE 2 ~
This is my project to upgrade an A/V alarm at my workplace. My knowledge of electronics is still full of holes so your advice and help would be appreciated.
The design presently in use is simply a mutable piezo alarm. The new design will incorporate some features which have been suggested by my colleagues.
The port triggers a transistor to activate the alarm.
Explanation of intended operation:
The unit is essentially a video black/ audio silent warning.
The computer in the plant room detects those conditions and closes the circuit between pin 1 and 2 of a DB9 cable.
A ring illuminated push on/ push off switch acts as a mute button. An internal flasher LED provides the flashing effect in series with the ring LED on the mute switch.
No alarm. Ring = OFF
Alarm. Ring = FLASHING
Mute position (alarm or no) = SOLID ON
In the mute position, a selectable duration timer activates and provides a 250ms approx. chirp sound at the end of each duration. This is a reminder that the system is muted. It should be active wether the DB9 port is closed or not.
The mode switch acts as an emergency bypass of the complex circuits. The operator would be able to quickly bypass failed components as a stop gap measure until repairs could be made.
The piezo is a DC 12V with built in driver cct. The different inputs to the piezo provide a few selectable sounds to differentiate from other alarms in the same room.
* A 555 generating a DC square wave
* A 555 generating a DC triangle wave
* Straight connection to 12v provides a constant tone
I have not added the rotary switch for selecting the timing interval yet but will do soon.
RENDERED ILLUSTRATION OF THE 1RU PANEL MOUNT:
SCHEMATIC:
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