Hi Guys,
Just set up an external horn for my ness system through the "siren" output.
Every time my dialler reports - you can hear the dialler through the siren as if it was connected thorough the listen pins?!
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Hi,
Make sure the type of siren your using obviously is the corect rated type, from my experiance it sometimes payes to stick with the same manufactured brand for that type of alarm system.
Noise certainly can be an issue using & eol resistor may filter this out, but might drop the siren output volume down.
If all fails maybe try wiring the siren directly into the panel to rule out any other issues.
From memory the NESS panels have a "listen in" feature. Look through the book
That's an interesting username.
And you are? :-)
Hound-Dog is spot on - the outputs on the D8 use open-collector drivers, rather than relays (which provide clean "make" and "break" switching). So sometimes there is a small leakage current, which needs to be shunted with a resistor.
Shouldn't matter what brand of horn speaker you use, as long it is 8 ohm and its power rating is within the manufacturers' specifications. (unless you work for the panel manufacturer, of course).
Are you sure about this? Put a 1k or 3k3 resistor in series with a horn speaker and hear how much sound you get out of it. The shunting resistor, by definition, always goes in parallel.
What is that supposed to mean?
Hound-Dog is spot on - the outputs on the D8 use open-collector drivers, rather than relays (which provide clean "make" and "break" switching). So sometimes there is a small leakage current, which needs to be shunted with a resistor.
Alarmman - If you have leakage at an open collector output then it is stuffed. It is OPEN collector not LEAKY collector. You may be thinking of the supervision current that is there by design.
There are plenty of explanations on the internet about how an open-collector output works. Here is just one of them:
On an alarm panel, with an audio load (say a horn speaker, screamer etc) connected between the positive supply and the open-collector output, in theory when the output is off, there is no sound. However, sometimes there is a small voltage present on the output due to leakage currents in the internal circuitry controlling the output. This voltage is sometimes enough to cause a soft sound to be emitted from the sounding device. I've had this happen many times when connecting screamers to open-collector outputs on the Solution panels. A 1k to 3k3 resistor between the output and COM+ always fixes the problem. In fact, in this situation I now fit a resistor across the output as standard.
Last edited by alarmman; 02-05-12 at 07:14 AM.
Great reference , a blog for builders. Get a load of this bit of rubbish they state -
"Here’s an example…when the transistor is off, and you have one lead of a resistor on the collector and the other lead tied to 12 VDC"
It doesn't seem to be important that they tell you the resistor they mention is in fact your switched load.
Maybe you should check electronic texts references.
I will say once again - if you have un designed leakage current at the collector then you have a fault condition or shithouse design
If you continue to put peizos on outputs that are not designed for them , you will continue to have that problem
Last edited by watchdog; 02-05-12 at 08:39 AM.
Not interested in arguing the point with you. I know and understand the theory, and am only stating what I experience in the "real world". Next time you have ANY type of load connected to an open-collector output, measure the voltage across the output whilst it is switched off, and see what reading you get.
If you can't connect devices such as piezos directly to open-collector alarm outputs, then what do you suggest I do? (I know the answer, just seeing if you do).
bla bla bla too much politics.... I say replace the board and be done with it!
I need to ask what output do you connect your screamer to. Bosch designate O/P 4 (relay) as the screamer o/p & as you have found out , they probably do that for a reason. Why not try using it ?
Here's a project for you. Grab yourdelf a switching transistor (BC547 etc) Put your multimeter (on ohms) across the emitter & base & measure. Reverse the leads & measure again. Divide 12 by the answer you got in ohms & you end up with the leakage current. If it has been designed as a switching circuit then the biasing will be set up to drive it into saturation. With proper design techniques, in the "off" state there will be no collector/emmitter leakage
Hi
- This is the Ness brand Horn
- This is connected directly with the fry leads of the siren to the "siren" output
- Yes, the listen PINS are at the top of the PCB ... seperate.
I will try some resistors later in the week and report back.
Thanks Guys.
This may be of some help to you.
P89E 3E - Listen In To Dialler.
This is a diagnostic feature to allow the installer to hear the dialler message and other
telephone tones through a horn speaker.
There are 2 methods of listening to the dialler.
Method 1: Temporarily connect a horn speaker to the LISTEN pins on the main
board. This method required no programming options to be set - the LISTEN pins are
always active.
Method 2: This method requires option P89E 3E to be turned on. Listen-In is enabled
for a minimum of 4 minutes after exiting Program Mode.
During Method 2 Listen-In, the dialler message and other telephone tones can be
heard through the Siren output (at low volume) while the dialler is sending reports. The
4 minute period is restarted whenever any key on the keypad is pressed.
To turn Listen-In off, go back into Installer Program mode and toggle the option OFF.
Thanks Dean , I mentioned that in post #4
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