Caller id without hydro ?

[roddy]

I have a crazy idea of taking the phone line voltage and dropping it down to power caller id up at camp. There is no hydro there, we only have power when running the generator. Does anyone know if this would be possible or not(and why)? My electronic skills are somewhat limited so any ideas will be very helpfull. Thanks everyone!

roddy

[Chris Smith]

Phone line voltages and currents are very limited.

Also Your description of what you are actually trying to achieve, is also limited?

Expand on your thoughts?

[Robert Reed]

Phone line DC is typically set at 48VDC on hook. The length of any particular twisted pair will determine line resistance. This could easily run a few thousand ohms. This series resistance will greatly reduce voltage at the "business end" with any useful amount of current flow.Even 10 ma thru a high impedance line could drop 20VDC or more. Without regulation, your end would be all over the place. If you are near a central office, your success will be better. This would be a hit or miss situation and the phone company would certainly frown upon it. Also remember that this is a floated line (no ground).

<small>[ January 04, 2006, 09:20 PM: Message edited by: ROBERT REED ]</small>

[dyarker]

Current flow is how the telephone switch recognizes that you've gone "off-hook". The nominal value is 20mA, most actually trigger on 8 to 10mA to allow for long lines. To allow for leakage (like a wet junction box) you may be able to use 5mA.

Better yet if the Caller ID unit can power up before the end of the first ring, you won't have to have any continuous current. Full wave rectified ringing voltage can be used to "quick start" the power supply section. The limit on ringing current is 40mA; use some for normal telephone's bell, some for Caller ID unit.

Cheers,

[rshayes]

The simplest solution may be to get a phone with caller ID built in. The one that I have uses 4 "AA" cells. They last several months at a time. This will avoid having to build something that meets a failry complex set of requirements, suaah as minimum on hook resistance, maximum off hook resistance, etc.

In a camp environment, you are likely to have frequent transients from nearby lightning strikes and other incidents. A reasonably well made telephone instrument will probably be more reliable than a home built unit.

[roddy]

Although it sounds like this may be possible, and at the same time a fairly rewarding challenge. I think i'll look at the simpler solution as suggested by stephen. This task sounds a little more advanced than i had first anticipated. Thanks to all of you,

roddy

[Will]

When I signed up for caller i/d (Which is now a robber/exorbitant level of close to $10.00 /month) I got a free unit which is powered from the phone line - It remembers about fifty phone numbers

[roddy]

Originally posted by Will:
I got a free unit which is powered from the phone line - It remembers about fifty phone numbers

Will, can you tell me what make/model the phone is? I seem to be having trouble finding one. Thanks,

roddy

[jimandy]

I'm not sure I've seen an external CID unit that didn't have a receptacle for a battery, although there may be some. Those with memory however need a battery to hold stored calls if for no other reason than to let you temporarily disconnect or relocate the unit. I pulled one out of storage the other day that had been there for over two years and still had the last 50 calls on file.

Try eBay for bunches of units at almost nothing but shipping.

<small>[ January 09, 2006, 12:09 PM: Message edited by: jimandy ]</small>

[Will]

Roddy,
It was made by CIDCO International - Cidco Model # JA 60A 18 - Made in Thailand - It holds four x AAA cels (Presumably to fold up the 50 stored phone numbers in memory) and is kind of a small model - about 3.1/2 x 3 x 1.1/2 inches . I got it free from South Western Bell (Now Southern Bell Co) for signing up for the Caller i/d/ service - I think about ten years ago or more. Good Luck! B

[Will]

Roddy,
Sorry ! - on re-reading your message I see that you referred to the 'phone' - This isn't a phone with a caller i/d/ feature - it's a small, self contained, separate unit from the phone B

[roddy]

I found a Casio Phonemate Model TI-360 on ebay for ninty nine cents plus nine buck shipping. The seller told me the caller id function is powered through the phoneline. It's even located in Canada Thanks everyone,

roddy

[jollyrgr]

I missed out on this one when the thread first started. You CAN power things using a phone line. The uses are usually limited but it CAN be done.

To power your caller ID I suggest the following. Obtain a bridge rectifier (or build one) that can withstand 200V or more. (Ring voltage is about 90V to 130V 20Hz AC.) Also get a couple 3.3K resistors in the one watt range. (Yes, this way overkill on size.) Place a resistor on each leg of the AC input to the bridge rectifier. Put a zener diode (5.1V or 9V range???) across the output of the bridge to clip or regulate the voltage, especially during ringing. If you connect the free resistor legs to the phone line, the output of the bridge should give you minimal current. (Consider putting an electrolytic capacitor across the output.) Possibly just enough to trickle charge the batteries (suggest NiCads or NiMH) in the caller ID box. Certainly more than the consumption of a caller ID box. If the circuit makes the phone go off hook, increase the value of the resistors.

There is another way but it is much less reliable. Forget putting the resistors on the bridge rectifier input and put the input IN SERIES with the phone line. When phone goes offhook current will flow through the bridge rectifier and anything connected to it. You might even need a load resistor in order for the phones to work properly.

Here is another link to consider. BE SURE TO READ THE ENTIRE PAGE, INCLUDING THE TERMS AT THE BOTTOM, IF YOU DECIDE TO ORDER ANY OF THESE DEVICES!!!!! This is a site that has numerous phone powered devices. I especially like the newer items he plans on releasing; namely devices powered by depleted uranium 238, due out later this year. Possibly if you wait long enough you can get a caller ID powered by his invention. Go here:
http://www.sandman.com/telco.html

I can hardly wait until I can buy depleted uranium batteries as I get tired of replacing them in my smoke detectors, clocks, and thermostats once a year. (I don't know why they didn't think of this for pace makers.) I'd really like a depleted uraninum car battery so I wouldn't have to worry about dead car batteries. (Heck, I'd like to make a car that ran on these.)

<small>[ January 10, 2006, 06:04 PM: Message edited by: Jolly Roger ]</small>

[roddy]

Originally posted by roddy:
The seller told me the caller id function is powered through the phoneline.roddy

At least i got burnt in Canada.. I got the phone nice and quick. It came with the manual that clearly states it needs an AC adapter to power the caller id function.

To add insult to injury the phone does not work (the seller had tested it!?! I bet!!) and did not come with the AC adapter.

I'll look for one of the external box's like you have Will.

roddy

BTW very interesting read Jolly Roger. TY

[Will]

Roddy - Remember I told you my caller ID was made by CIDCO ( Model JA 60A 18) ? I entered 'CIDCO' in Google and got 463,000 + replies - The first few I looked at clearly refer to the same outfit - take a look - good luck !