Hi all,
I am an of a Silent Knight IFP-50 addressable system (running Hochiki protocol devices) and I noticed that the panel is lacking the ability to code the NAC’s to do 120 beats per minute March time. Is there any way I can build a relay-based closer to have my system do this coding? By the way, this panel is not installed in a commercial building. Thanks.
I suppose you could jury-rig some relays to do that, or you could even attempt to find an old adjustable code wheel like Andrew had in one of his videos.
Of course, even if it isn’t in a commercial building I’d still advice against either because, you know, safety. Plus the IFP-50 wasn’t really designed for that.
Anyway, what you’d have to do is install whatever device you want to pulse your horns with in line with the NAC output, but make sure that NAC is set to continuous.
But, I digress. Please use good judgment, and please don’t burn your house down!
Your best bet would be to reprogram one of your NACs as a constant AUX power circuit, then run that power feed through one of the Form C relays set to close during an alarm condition. With that setup, you’d able to wire in whatever sort of coding device you’d like onto the circuit without having to worry about interrupting the supervision of a standard NAC. Plus, you’d still have the other NAC for running strobes.
Instead of going through all that… Why not just set the NAC output to continuous and get a Wheelock MT or two and System-Sensor SpectrAlert Classic that can do that can do March Time built in?
Can be purchased on EBay pretty inexpensively…
That’s actually a really good idea. Instead of using a 555 or a microprocessor to pulse the circuit, couldn’t someone disassemble an MT and wire a relay to the horn output on the PCB? That way, you could select between continuous, march time, and temporal using the DIP switches.
It might be slightly excessive though.
I’m looking to use this on many different alarms including mechanical horns. It’d get a little boring having the same devices up, not to mention, I already have both those alarms.
The actual output to the horn is not going to be able to energize and hold the relay coil. The “horn” itself is just a strong piezoelectric speaker, and it receives the frequencies from the board to produce the alarm’s different sounds from the PCB.
I have a broken Wheelock Telhorn (which is based on an EHS horn, similar to the MT in some ways) I could try some experiments on. Conveniently enough, everything works except the piezo horn itself. With a few transistors it may be able to drive something like a small magnetic reed switch.
Thank you all for the suggestions. If there’s anything I can build like an exnternal NAC coder that I could easily hook up to one of my panels NAC’s, please feel free to share it.
Do you have access to microcontrollers like the Basic Stamp or Picaxe? That would be the easiest way to make your own coder.
Even Easier… Why not just get a Arduino I think someone probably has a program that will work for his purposes.
Any device that can utilize BASIC would be decent. Remember, you’re not building a panel, just a coder card. What you’d have to do is write a program that would pulse 25ms ON, 25ms OFF, and loop.
The basic argument (but not necessarily program) would be something to this effect:
10 'IF argument to determine whether or not to power the horns
20 'Code to sound horns for 25ms
30 'Code to silence horns for 25ms
40 'IF argument to check whether or not to stop the cycle
50 GOTO 20
That would be 250 ms on and 250 ms off. 250 ms = 1/4 second = 2 on/off cycles per second. 25 ms would be a very, very fast march time.
OOPS! :oops:
I totally meant 250ms or .25s, but I had a total brain fart.
Here’s an example of the PBASIC programming I created in 2012 when I used to make homemade panels. This shows the entire sequence for a zone one alarm condition, and the coding itself is divided into its own section. In this case pin 12 on the chip was used to control the output of the NAC circuit.
I used 200ms in my program to make up for the delay caused by the transistor circuit and relay used to connect the chip to the NAC, but 250ms is technically the correct value as Robert and Retired-STR-SG mentioned.
This can also be done in hardware. I borrowed a section from Andrew’s 5001-DC with march time drawing. I added a supervision blocking diode and a shunt diode across the regulator. I also went with 1N4004 diodes just because I like the higher voltage units. I changed the resting relay contact from N/O to N/C to pass the supervision voltage to the rest of the circuit. I did not verify any of the existing 555 timer circuit. I figured Andrew had already done that.
If you would rather not have the circuit powered by the NAC it can also be powered externally through an alarm relay.
So if I were to build what this drawing below, this would sufficiently create a coding card?
Yes, the LM555 in this circuit is running in astable mode, aka free running multivibrator. I calculated the timing with the values shown and it comes within a few thousandths of a second of 1/4 sec. on and 1/4 sec. off.
Alright thanks for your help! Now it’s on to figuring out this diagram, I’m not real experienced with this kinda stuff 
If you have questions post them here or send a PM.