Recent content by Lagerhead

If your purpose is to "know" specifically which smoke detector has alarmed, this does not necessarily mean that you need separate power lines to each one. It seems to me that you would need only one power run, one EOL relay at the end and one reversing relay at the front. Meanwhile you wire...

If you have an attached automation controller, you can use the M1 ASCII Protocol function "IC" to signal a code entry, and then signal back to the M1 to perform the function that you want. It's a bit of an odd use of the function but I can explain if you are interested.

You can power the optoisolators from the same power supply as your controller board. This makes sense as they will have ground in common with your controller anyway. Voltage doesn't really matter -- currrent is everything with LEDs, and the trick is to use suitable dropping resistors once you...

Consider skipping the relays. You can get four optoisolators in a 16-pin DIP package for $1-3 per chip. Total under $15 including sockets for sixteen channels, and every output is individually isolated. One example is the Liteon LTV-847, 79c at Jameco, but there are many other options. Check...

FWIW -- There is a Wikipedia article specifically on "open collector" (duh) -- /wiki/Open_collector You can make a quick-and-dirty optoisolator with an IR LED and a compatible phototransistor pointed at one another inside a short length of opaque tube. This can sometimes be easier than working...

Yes, and optoisloators are also good in these situations. Can be superior to relays -- no moving parts. compact, and no back EMF to deal with.

What you are discussing here is a very common use of a transistor as a switch. "Open collector" refers to the transistor terminal, the COLLECTOR, that connects to the load to be switched. It is "open" because it is not connected to anything -- it is deliberately left open for your use. The...

A thread just a few weeks ago on the Proliphix support group (proliphixgroups on Yahoo Groups) has this: Q: "I was just advised by Proliphix that the IMT family's API will not be available? Has anyone else confirmed this, or is anyone using the IMT family and programming via an API?" A...

Actually this is exactly how I have wired mine (!). Putting the EOL resistor across the NO and NC contacts is a convenience, because it lets you avoid a flying splice connection. The relay when deactivated (non-alarm) has the resistor in series with the zone (because COM=NC) exactly as if ir...

How did you connect them to the panel, and where (at what point) are you taking the voltage measurements?

The point of the EOLR (end-of-line relay) is to monitor the power supplied across the length of the smoke detector string, and indicate trouble in the event the power run should be broken (open or shorted at any point) for some reason.. It should be installed at the end of the line, which is to...

Ditto. Grid monitoring and the management of generation and transmission are macro-level functions that are quite well done today by the various ISOs, cooperatives, etc. Knowing in isolation that 512 Main Street has a 10% usage increase is not going to lead to spinning another generator. And if...

LOL -- I agree wtih you Well yes but I am both and believe that good engineering necessarily has a healthy respect for economics. Reminds me of a lengthy article on EMP (electomagnetic pulse) warfare and the corresponding vulnerability of the electric transmission and distribution...

In MBA school we call this "paving the cowpaths."

Interesting discussion, along with a "best-practice" story from davidfay. For me, It begs the question -- what is the purpose of the growing, government-funded "smart grid"? How many "lesser-tech-savvy-than-Coontech-types" regular people will really care to use -- or be competent to use -- the...