Hello again. So, I need somebody who has experience to check over the trouble circuit in this schematic I made:
I have been trying to do this over PM, but it’s very hard to do.
(BTW the EOL resistors will be 2K ohms.)
The reset button would have no functionality since it would deactivate when the pull station was reset. To get this functionality you would need to wire the zone the NO contacts on the relay so that it would keep itself activated. Also, just a suggestion, wouldn’t it be easier to have the reset switch break the circuit itself instead of being wired to a relay?
This schematic is not done. If you see my old topic, Building a FACP, you can see a finished one. I’m only interested in the trouble circuit. Also, the reset button cannot handle much current, so I put in a relay.
I apologize. I misinterpreted the diagram and thought that the relay was designed to activate an alarm condition, not a trouble.
Oops, forgot to label that…
Do you know if it would work?
I think that the relay would activate once the pull station was pulled. That’s why I assumed that it was the alarm relay. I think that you would have difficulty getting this circuit working the way it is, and I am not sure exactly what resistor value you would need to limit the current below the pressure value of the transistor switch. Also, just a suggestion to add to your design, you could move the disable switch to the other side of the reset switch and use a latching relay circuit, so that a Zone disable could be cleared by the reset button.
Well, the trouble relay would trip when going into alarm, as well as when a resistor is in place. The op amp is what compares it, and if it only sees the resistor and no closed circuit, it won’t trip.
Yeah, I actually do have to do that with the disable button because of how it’s not latching.
Your OP amp will not work because it does not have a seperate source of electrical power.
Here we go. Any other issues you see? Will this work correctly?
From what I can see it will, theoretically, work. However, there are many variables, such as transistor type and resistance values, that you will have to get correct in order for this to operate as intended, so be careful and pay attention to the specification on your parts.
What transistor values do you recommend? I already have resistors for the LEDs.
It really depends on the specifications of the relays you are using, including the voltage, current draw, etc. If your circuit runs on 5VDC, a 2N306 PNP Transistor should work (Intelligent Power and Sensing Technologies | onsemi). However, if your circuit runs on a higher voltage (I think most 714 OP amps operate at around 12 volts), then you will need to research to find a more suitable transistor. This website should be able to help you: How to Use A Transistor as a Switch | Teach Me To Make
Can I reduce the 24V to 5V with a voltage regulator?
You would need a heavier duty version of a standard 7805 regulator, such as this: http://www.dx.com/p/dc-6-5-24v-to-5v-mini-buck-converter-power-supply-module-for-diy-156969#.Uz9uPyG9LCQ
So for supervisory, is there an EOL resistor? How is it wired? Like init. devices? Don’t know if that would short it though…
Or would I use an EOL relay?
What do you mean? Are you talking about supervisory as in monitoring a zone for troubles or a seperate zone for a supervisory output, as in a lower priority alarm?
No, monitoring the NAC circuits.
I made a schematic of a reversed polarity NAC at one time and a test found it successful. I’ll dig through my flash drives’ files and see if I can find it for you.
OK. I have figured out how to reverse it with relays already, but I want to know how that would be monitored. Because alarms get positive and ground, while init. devices only get positive going back to positive. Wouldn’t a resistor start burning? So I would need to use a relay instead?
My design used a resistor at the end of the circuit and a relay wired in series to the rest of the circuit before it went back to the negative return of the panel.