Thought for the day.
I have some places in my home where I want to install LED strip lighting, which requires 12 volt transformers. One place is in a bathroom, where I also want to install an in-wall Bluetooth amplifier. So I got to thinking: would it make sense to install a central 12 volt supply in the home and wire it out to the locations where it is needed?
Is this a thing? Cars, boats, and RVs have 12 volt distribution, so why not a house?
Mm. I don't know the answer, but doesn't low voltage have difficulty traveling very far unless the wire is extremely thick? I'd think that resistance would eat up the low voltage.
Again, I'm very knowledgeable about electricity. I only know that in the house I'm building, the power company wants to step down its high voltage near my house, not hundreds of feet away at the street even though that would be a lot less expensive.
Correction: Again, I'm ***NOT*** very knowledgeable about electricity.
POE level 3 (I think that is what it is called or something like that), puts out a maximum of 13 volts. So you could just run cat 6 everwhere, and hook up POE injectors and run it that way. Then if you need to later you can use them as regular network, or what have you.
I spent a lot of my childhood around boats, where there was always a 120 volt system and a 12 volt system. The 12 volt system did use thick wires.
Remember that watts = volts * amps, so for the same amount of power, if the volts are lower the amps are higher. It becomes a question of what's going to cost you more, the loss from a transformer being less than 100% efficient or the thicker cables.
Telecom equipment runs on -48 volts. It's the standard for their stuff.
Their racks are always fitted with a -48 volt power supply (usually a few of them). The "UPS" is just a four-pack of batteries. It actually works really well, which is why equipment that can be used within a telecom facility is often available with your choice of power supplies: 100-240VAC or -48VDC. Some number of years ago there was a big push to move computer equipment to -48VDC so that the power supplies that are in servers etc. don't have to deal with as much loss. This push was killed by the fact that data centers would have to install giant copper conductors everywhere, and that was right around the time the price of copper started climbing again.
Subject: Nostalgia day!
I found this old photo of my computer-filled basement from 2003-2004 or thereabouts.
[ http://photos.citadel.org/spaghettisburg/spaghettisburg0019.jpeg ]
There's all sorts of wonderful stuff in there. Top left: a cheap wireless router (used only as an access point) and my DSL modem. The machine beneath it, between the stack of tapes and the UPS, is that era's iteration of uncensored.citadel.org. My phone system is there too, along with a dumb terminal I still have. My actual desk with the main screen is off to the left and just out of the shot. In the center are my printers and a thin client I used from time to time. Under that desk you can see stuff that was useless even then: a CB radio, a dot matrix printer, and a Mac.
I'm still a server hugger, but everything now fits into a single 2U rack server thanks to virtual machines. I know people who still maintain home labs but I don't know why. This was a lot of fun but I don't exactly miss it.
Subject: Re: Nostalgia day!
Dang. That brings back a lot of memories. Though the phone (wired including handset) hanging there amuses me too.
Subject: Re: Nostalgia day!
The ONT which terminates my home's fiber connection from Verizon has a built-in UPS, with a 12 volt battery inside. Over the past weekend I spliced into that battery connection and ran it outside the enclosure as a 12 volt power take-off to be used for "various things". I added a 1 amp fuse just in case something ever gets shorted out, so it doesn't destroy the battery. Right now it's just powering a bluetooth amplifier for the in-wall speakers I installed in my bathroom, but in the future I might add a small distribution board for other loads.
When you say heavy use do you mean digital data stuff or phone calls?
I think if you did nothing but talk on the phone all day it should keep up.
I'd gladly have a phone double in depth if it extended its battery life.
External batteries sell for a reason. Lot's of people kill their phones fast.
That shouldn't be a thing in this day and age.
In the back of my head I've been tossing around an idea for "the perfect digital clock". Some of it is just sentiment for the way playing around with LED's made me feel when I was a kid. (Yes, I was a nerd then too.) Some of it would just be coolness factor, having a display piece with perfboard and discrete components visible from the outside.
The requirements for The Perfect Digital Clock are as follows:
1. 7-segment LED display (bare components visible from the outside)
2. No alarm. Seriously ... everyone under 60 uses their phone as an alarm clock.
3. Cannot be set manually. Until it gets a fix from an external time source, no time is displayed.
4. No oscillator. 60 Hz derived from mains power shall be used as the timing source.
About 25 years ago I built a four-digit LED display that was driven by a desktop computer. It used four 7-segment display drivers, four latches, and eight input lines: four bits of BCD and one latch input per digit. Today's hobbyist designs seem to rely on microcontrollers. I'm not opposed to using a microcontroller, especially if it will lower the component count (and the number of connections that can go wrong).
This guy [ https://tinyurl.com/y6qb23lk ] built something close, prototyping it on an Arduino and then removing the ATMEGA328P from the prototyping board and installing it directly into his circuit. I like the way it looks but there are a couple of things I'd do differently.
He uses a 74HC595 shift register to address all seven segments of the LED without consuming seven I/O pins on the microcontroller. I've come to understand this is a common practice when you need more outputs than your microcontroller has available, but I don't like this. He's going four lines in to seven lines out. If I have to consume four I/O lines, I'm just going to throw a 7447 BCD-to-7-segment decoder chip on the board and let the gates do the work.
The time source can be WWVB or NTP. For a microcontroller project I would imagine it's going to be WWVB, because you can buy ready-made receiver chips and then interface them to the main circuit using I2C or some other simple protocol. NTP would require protocol decoding, a TCP/IP stack, etc. and at that point you might as well just slap a 7-segment display onto a Raspberry Pi and call it a day. I have an old Pi sitting around, and maybe I'll do that as a proto-proto-type.
Thu Jul 04 2019 03:56:03 PM EDT from IGnatius T Foobar @ Uncensored2. No alarm. Seriously ... everyone under 60 uses their phone as an alarm clock.
I don't use my phone as an alarm clock, I know others that don't. Not everyone has to check their facebook page at 3am. I keep my cell phone on my desk most of the time, that is where it charges. I have no reason to keep the phone by the bed. People that need to sleep next to their phone are either on call for work or fans of Windows and Zuckerberg. No other person should keep a phone next to their bed.
I wake up between 5am-5:30am on my own, if not I have a fur alarm as a backup.
My CPAP machine has a clock and an alarm, rarely use it. Newer CPAP machines have eliminated the alarm clock.
I do happen to be on-call 24/7/365, even though I don't get many calls anymore because my primary role isn't in production support. I did start putting my phone near the bed years ago when calls came in all the time. I like using my phone as an alarm clock. It's convenient and it's right there. My WWVB clock is on the far side of the room. Occasionally I will use it as a backup alarm clock when I *must* be out of bed and there's no room for error, like when I have to be at the airport in time for an early flight.
Aside from that, I might listen to a podcast if I'm not tired enough to go right to sleep. But anything even approaching social media ... not until I'm awake and usually only at the computer.
In any case, my "perfect clock" probably isn't going to be put in the bedroom anyway.
Has anyone here done anything with Arduino? It looks like a pretty easy way to get into microcontrollers. In particular I'm interested in knowing whether it's possible to use something like an Arduino Uno as a prototyping/programming rig, and then just keep replacing the microcontrollers as they go into finished projects. Is that a thing?
I am under 60.
Here is an ardunino clock kit, but it has alarms.
Did big clive demo a clock kit a while back?