Circuitry of Alarm Panel Outputs and Inputs

[Eugene's DIY Den]

Ok, so I'm a bit confused about how the internal circuitry works for zone o/ps,  switched negative o/ps and tamper o/ps. Terminology and o/p descriptions vary a bit on different panels and sounders, so I'm trying to get my head around it.

 

1) Bell/strobe switched negative - Is this o/p on a panel just an open collector transistor whose collector is pulled low when the base is driven, providing a ground for the strobe and sounder?

 

2) Zone inputs - Is one leg of the input connected high via a pull up resistor to the 5v supply, and the other leg tied to ground? When contacts are closed, voltage i/p is pulled low, then goes high when a contact opens

 

3) SCB0 and tamper return - Is SCB0 a permanent, nonn-switched  0 volt supply for powering a sounder? On some panels this is hard wired to tamper feed which is sort of a misnomer because it's a feed of 0 volts, rather than positive voltage.. Is tamper return a 5 volt o/p pulled high by  a resistor internally or a fixed 5 volt supply?

 

I'm trying to wire up an old A1 security and Electrical Advantage SX6 panel to a new HKC SABB sounder. This is the way I think the connections should be made.

Edited August 9, 2017 by Eugene's DIY Den

[sixwheeledbeast]

I'd say all looks correct but the SCB return should be in TR not NC (which I assume from the diagram to mean "No Connection" and not "Normally Closed")

As for the electronics behind the panel I have never seen the panel so difficult to comment. What you have said seems right for panels of that era tho.

[al-yeti]

23 minutes ago, Eugene's DIY Den said:

Ok, so I'm a bit confused about how the internal circuitry works for zone o/ps,  switched negative o/ps and tamper o/ps. Terminology and o/p descriptions vary a bit on different panels and sounders, so I'm trying to get my head around it.

 

1) Bell/strobe switched negative - Is this o/p on a panel just an open collector transistor whose collector is pulled low when the base is driven, providing a ground for the strobe and sounder?

 

2) Zone inputs - Is one leg of the input connected high via a pull up resistor to the 5v supply, and the other leg tied to ground? When contacts are closed, voltage i/p is pulled low, then goes high when a contact opens

 

3) SCB0 and tamper return - Is SCB0 a permanent, nonn-switched  0 volt supply for powering a sounder? On some panels this is hard wired to tamper feed which is sort of a misnomer because it's a feed of 0 volts, rather than positive voltage.. Is tamper return a 5 volt o/p pulled high by  a resistor internally or a fixed 5 volt supply?

 

I'm trying to wire up an old A1 security and Electrical Advantage SX6 panel to a new HKC SABB sounder. This is the way I think the connections should be made.

Swb must be talking in general as each manufacturer can make there outputs different 

[Eugene's DIY Den]

Can't seem to edit original post (is this not possible once a period of time has elapsed?). Panel is a ZX6, not an SX6.

[al-yeti]

27 minutes ago, Eugene's DIY Den said:

Ok, so I'm a bit confused about how the internal circuitry works for zone o/ps,  switched negative o/ps and tamper o/ps. Terminology and o/p descriptions vary a bit on different panels and sounders, so I'm trying to get my head around it.

 

1) Bell/strobe switched negative - Is this o/p on a panel just an open collector transistor whose collector is pulled low when the base is driven, providing a ground for the strobe and sounder?

 

2) Zone inputs - Is one leg of the input connected high via a pull up resistor to the 5v supply, and the other leg tied to ground? When contacts are closed, voltage i/p is pulled low, then goes high when a contact opens

 

3) SCB0 and tamper return - Is SCB0 a permanent, nonn-switched  0 volt supply for powering a sounder? On some panels this is hard wired to tamper feed which is sort of a misnomer because it's a feed of 0 volts, rather than positive voltage.. Is tamper return a 5 volt o/p pulled high by  a resistor internally or a fixed 5 volt supply?

 

I'm trying to wire up an old A1 security and Electrical Advantage SX6 panel to a new HKC SABB sounder. This is the way I think the connections should be made.

Have you done it and what's the issue ?

[Eugene's DIY Den]

25 minutes ago, sixwheeledbeast said:

I'd say all looks correct but the SCB return should be in TR not NC (which I assume from the diagram to mean "No Connection" and not "Normally Closed")

As for the electronics behind the panel I have never seen the panel so difficult to comment. What you have said seems right for panels of that era tho.

Yes, I would have thought that and pull up to 5v is at the point where NC is marked on the sounder. Then tamper return monitors voltage on the collector of the transistor which goes high or low depending on how the logic is setup.

 

This photo (sorry about the quality) shows how they recommend connecting another panel. It seems to show tamper return connecting to the top screw terminal in the block, rather than the next one down. Maybe it's an error. I'll contact them tomorrow

Edited August 9, 2017 by Eugene's DIY Den

[Eugene's DIY Den]

15 minutes ago, al-yeti said:

Have you done it and what's the issue ?

No, not yet, don't want to damage the sounder and/or panel if the connections are incorrect. Probably damage is unlikely because voltage supplies are produced by 7812 and 7805 regs which are short circuited protected, but just want to be sure.

[james.wilson]

as already mentioned you only use the nc connection if using the sol resistor. In this case connect to tr (tamper return)

[sixwheeledbeast]

18 minutes ago, Eugene's DIY Den said:

Yes, I would have thought that and pull up to 5v is at the point where NC is marked on the sounder.

 

 

This isn't a pull up resistor, some of the more modern panels have a tamper resistor that the panel monitors for a value you would install this at the end of line for security (hence SEOL resistor).

You could fit a staple (dead short) across the SCB terminals for example and not damage the panel (this would link the tamper detection out).

[Eugene's DIY Den]

9 hours ago, james.wilson said:

as already mentioned you only use the nc connection if using the sol resistor. In this case connect to tr (tamper return)

Ok, so the resistor value  allows the panel to identify which device generated a tamper?
My panel has two pairs of tamper terminals: '24 hr' and 'SCB'. Are these typically looped in series within the panel on the PCB? So the SCB terminals are just for convenience so that the  tamper loop for sensors doesn't have to be broken to add in the SCB tamper circuit.