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What do you do when the house power goes out? Look for flashlights! But if you're as sloppy as I am, you're going to see that they are out of batteries since the last time the power went out.
Since, in 90% of the times, the phone line is still working even when the whole city has no light. This instructable will show how to make a flashlight that uses the phone line power. (Yes, the phone LINE delivers a small amount of current to your house)
Before I start, I'd like to say that I did not find anything forbidding me to plug this into my phone line, but you should check whether it's legal in your country and if using the phone line current is prohibited by the phone company's contract. (and take it easy on the comments. English is not my first language and this is my first instructable)
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Signing UpStep 1What you need
The materials to make the flashlight are:
1x Phone wire
1x Box to put everything inside
12x White LEDs (3.0V / High Brightness)
1x LM317L or LM317T (Voltage Regulator)
4x IN4007 (Diode)
1x 6.8K ohm resistor
1x 270 ohm resistor
(the 2 resistors values may change depending on your phone line - See step 4)
Sorry for the picture, I've made this project a couple of years ago (way before I found the Instructables website) so everything is already put together.
1x Phone wire
1x Box to put everything inside
12x White LEDs (3.0V / High Brightness)
1x LM317L or LM317T (Voltage Regulator)
4x IN4007 (Diode)
1x 6.8K ohm resistor
1x 270 ohm resistor
(the 2 resistors values may change depending on your phone line - See step 4)
Sorry for the picture, I've made this project a couple of years ago (way before I found the Instructables website) so everything is already put together.
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Thanks! :)
lm317 is a voltage regulator and u can get it from college road in rawalpindi near commetiee chowk.
for further information on lm317 read its datasheet u can download one from alldatasheet.com
My blog is here.
danialjose(at)gmail(.)com
It's the FCC part 68 that governs this in the US. Do not put devices like this on the phone lines for many reasons covered below by responsible people.
And here is a great compliance article on the subject that will be a great education for anyone interested in connecting things to the pots (Plain Old Telephone Service) lines that are coming into their house.
http://www.ce-mag.com/99ARG/Gubish233.html
Cheers, and with that I'll sign off!
I think that anyone that puts something together like this and ties it into a POTS line is silly, and inviting disaster on multiple fronts..
I work on the mobile backhaul and transport side of telco, and don't have the local loop experience in troubleshooting problems to the CPE so thanks for proving the point.
I'm not doubting the electronic engineering - built many circuits myself over the years - yes, it does 'work' - but if not done properly (UL Listed devices) it's asking for trouble.
@everyone else (including mainly LaserDave) -
1. it's great to learn how to 'build things correctly.
2. It's never correct to hook home made projects up to the utilities (including our pots -48 vdc)
Cheers!
This is literally a 50 year old discussion (yep, it's been around longer then that) ..
After the posts last night . .I thought more about it, and could you imagine if multiple people did this in developing countries where the infrastructure is not as robust and they were using old switches ...
Again, worst case scenario - but the main idea is there's other ways to get power then draining the -48 from the batteries in your local hut.
Cheers, mate - gonna write this one off!
@Colin55 -- I don't know what has blown your skirt up, but the LM317 IS required to keep the current on the LEDs constant. The circuit in this 'ible needs to be changed slightly as mentioned in my earlier post, but it will allow the LEDs to operate properly even when the phone rings.
NO, the LM317 will NOT be damaged when the phone rings because it's in SERIES with the LEDs with no reference to ground. This is called "FLOATING", and the regulator will see less than 6v once it goes through the loop. You DO remember series circuits, don't you? This is how Christmas "mini" lights used to work - a group of them in series allowed 6v lamps to work on 120v. In this situation (once the schematic is slightly altered) the regulator sits on the line and varies the current based on the voltage drop across the main resistor. It NEEDS to be there, and so does the bridge to protect the circuit from the 96vac RING voltage. Do you not like the LM317 or bridges? Are they hard to get where you are??
This circuit isn't "absolute madness" and to "avoid it like the plague" - where are such comments coming from and why so bitter?? Nobody asked you to include this circuit into your eBook, in fact advertising your stuff in someone else's instructable is pretty lame.
And finally - it is NOT illegal to put something on the phone line that draws a small amount of power, so long as it isn't loaded down to the point of tripping the "off-hook" sensing. Novelty phone items have been powering their circuitry off the line for YEARS - this is no different!! Would you agree that a short-circuit would be the most extreme condition for a phone line? Would you think such a thing would be permissible? Well, this very thing occurs and HAS occurred for decades - rotary-dial phones short the line multiple times for each dialed number (quantity of pulses equal the digit being dialed - ie: #6 = six pulses).
I've sent the author (art.z) a schematic that WILL work off the phone line. He will put it up because this site won't seem to let me upload an image with my comment. Since different phone company's sensing current varies, this circuit will work with most systems. The bridge (or 4 diodes) will rectify the incoming voltage and change the ring-voltage AC into DC, then limits the current going into the string of LEDs to 12mA, so high-brightness LEDs will be quite bright. This circuit works with any number of LEDs and any voltage input of any polarity. (Of course the input voltage must be enough to satisfy the number of LEDs you choose. ie: 4 LEDs = minimum voltage of (4 x 3.4volts = 13.6v) or 12 LEDs need a minimum voltage of (12 x 3.4volts = 40.8v) which is straightforward).
*** Note: I have this exact circuit operating on my own phone line, and it has been running since this article came out. It works PERFECTLY. When the phone rings, the LEDs do a nice gentle flickering - PERFECT for the hearing impaired. ***
I agree with you completely - which is why I provided a schematic (via art.z) that shows the proper values to use in order to preserve the functionality of the telco line. I wouldn't want anyone to trip their "off-hook" and then have an emergency where they couldn't use their phone.
While I would personally RATHER that people don't even bother with the line and use solar or some other alternative, I will still fight for people's rights to learn how to do it correctly. My point of view is that the topic has come up, people are guessing about how to do it with many variations. Since I am an engineer, I felt that it was best to show how to do it correctly and to avoid creating problems for themselves. In other words, if they are going to do it anyway, at least do it right.
One thing I'm not clear on, is how a personal phone line (residential assumed) being compromised has anything to do with "homeland security"?? A residential POTS line is always at risk for short circuits, rain, crushed cable, bad equipment (this would apply here) - but it never has any effect on the Central Office since each line is separate and won't affect another. In fact, no matter what torture you can bring onto your line, there will be no effect on any other in the trunk system whatsoever. While I am really sick to death of hearing how everything affects "homeland security" in one way or another, I am curious to learn if there is something to this and maybe you are aware of something I'm not.
Thanks for your comments. Have a good one.
~ Dave
But I still want to get a perfboard and paint it white to make it look better!
Please, post some pictures here.. I bet it looks awesome!
I like the Slow changing RGB with UV in the center idea!!
I'll make one for sure!!
It sounds cool though.. Can you post pictures?