I need to change a constant negative to a momentary negative.
I found a diagram on this site to change a constant positive to a momentary positive www.the12volt.com/relays/page5.asp
Is there a simpler way to do this other than adding another relay to the momentary positive output to switch it to negative?
I am also unsure whether this diagram shows a diode. It looks like one, but isn't noted in the description.
www.the12volt.com/relays/relays.asp describes why this might be necessary, but I'm not sure
I think, maybe I'm a dumbass. I just have to make 87 a ground to get a momentary ground output from 30.
Is your constant ground output the alarm's (-) armed output? If so, using the diagram here:
https://www.the12volt.com/relays/page5.asp#ctm (shows a dioded across the coil) , connect the ground shown going to the cap and resistor to your constant negative output, connect 86 to a constant 12V+ source, connect 87 to ground, and 30 will be your momentary ground output. If your constant ground output is from a different source, the above may not be applicable. Let us know what output you are working with and we can be of more help.
I installed a Clifford Avant Guard 4 alarm on my work van. It has the ability to autostart for low temp and/or low voltage. This option has to be remote activated each time I disarm and rearm. This is a hassle, for instance, in the summer every time I run out to the truck for a tool it's one button to arm two buttons to vent the windows and two buttons to activate voltage/temp.
So I got an external time temp controller thats a little more use friendly. The controls would be right on the dash, it's settings are more flexible, its back lit.
I've since realized that I have no way to connect this to the alarm. The time temp controller has a momentary negative trigger. The remote start trigger goes from the alarm unit to the remote start unit via a two wire bus line whether it's due to voltage, temp or remote control. How information is sent back and forth between the two is beyond me. It's certainly not a positive or negative pulse.
So I was about to give up when I got the bright idea to use the negative trigger on the time temp unit to energize a relay that would be hard wired to the auto start button on the companion remote I got with the alarm. I think the weak point in this setup is having to occasionaly change the battery in the remote
Now that I've convinced myself this might work I figure I could do the same with a voltage monitor
The output I'm dealing with is an internal relay on a low voltage alarm. I have N.O., N.C. and COM contacts. I can have a negative or positive output.
When voltage drops below 11.8 volts for 120 seconds, the relay is energized until the voltage rises above 12.8 volts.
I'm calling this a constant output. I guess its not really but its much longer than I need. I think it would take a minute or two for this internal relay to switch off.
I only need a momentary trigger and I'm relying on a small battery in the remote that I don't want connected for a minute or two.
So, I've got a constant output of my choice that needs to end up a momentary negative trigger.
Can I turn a constant negative into a momentary negative? I would rather do that than use a constant positve to get a momentary negative. Hopefully its as easy or easier.
thanks,
Jonathan
Jonathan, I described in my post above how to convert your 120 second negative ouput to a momentary ouput by rewiring the relay configured here: https://www.the12volt.com/relays/page5.asp#ctm , connect the ground shown going to the cap and resistor to your constant negative output, connect 86 to a constant 12V+ source, connect 87 to ground, and 30 will be your momentary ground output.
For this configuration, the constant 12V+ is needed only for the coil of the relay to energize. If you had a positive output, the constant 12V+ would not be needed to get the pulsed ground output you're after.
the12volt