Circuit design for phone strobe light alerting system

[Blair]

Hi,
I have a mom who is hard of hearing and I have seen all over the web
phone strobe light alerting devices. Essentailly these units are
powered by the phone line and a ligh bulb flashes every time the phone
rings alerting the person that the phone is ringing. Does anyone have a
cicruit design for this I can have/buy.
I would imagine these are not terribly hard to make...if only I had the
design
Any help would be greatly appreciated.
Thank you very much,

Blair

 

[D from BC]

Hi,
I have a mom who is hard of hearing and I have seen all over the web
phone strobe light alerting devices. Essentailly these units are
powered by the phone line and a ligh bulb flashes every time the phone
rings alerting the person that the phone is ringing. Does anyone have a
cicruit design for this I can have/buy.
I would imagine these are not terribly hard to make...if only I had the
design
Any help would be greatly appreciated.
Thank you very much,

Blair

I don't know everything..so hopefully other posters can fill in the
gaps...

I know a ring off a telephone line is a large voltage.
But I don't know the waveform or how much it can be loaded.
But I do know very bright LED's can substitute for a strobe....
But I don't know how many can be used...

D from BC

 

[default]

Hi,
I have a mom who is hard of hearing and I have seen all over the web
phone strobe light alerting devices. Essentailly these units are
powered by the phone line and a ligh bulb flashes every time the phone
rings alerting the person that the phone is ringing. Does anyone have a
cicruit design for this I can have/buy.
I would imagine these are not terribly hard to make...if only I had the
design
Any help would be greatly appreciated.
Thank you very much,

Blair

You are sitting on one of the great research tools around - did you
search for it? Lot of schematics on the net.

This is Usenet, not Google Groups, before you post, you look for the
information yourself, "Groper."

 

[[email protected]]

I've used neon bulbs attached directly across the incoming phone line.
Radio Shack or your local equivalent probably stocks them.

Bob

 

[mpm]

I would imagine these are not terribly hard to make...if only I had the
design

Not hard to make, but why do it?
It will probably end up costing you more money.
I would suggest buying one, take it apart, tinker with it, etc.. get
the education, and then gift-wrap it?

You will solve at least the following problem issues: --which you did
not mention.

1 - FCC Part-68 Registration issues (legal & technical requirement for
devices intended to be connected to the public switch telephone
network). I assume you are in the US, if not, other countries have
similar requirements.

2 - Safety. (Think lightning strike, here.) Ring voltage (US) can be
90-volts DC nominal, sometimes much higher.

3 - Reliability. OK, this one might be a reach depending on what you
might buy. I don't mean to imply your design would be inferior, but I
think we can all agree it would be re-inventing the wheel. A wheel
that has literally been beat to death....

That said, I don't know a single elect. hardware design engineer who
hasn't taken a phone apart at some point!! Enjoy!

 

[default]

I've used neon bulbs attached directly across the incoming phone line.
Radio Shack or your local equivalent probably stocks them.

Bob

Neon bulb would work if you are looking directly at it, not too useful
otherwise.

Ring voltage is something like 90 VAC 30 HZ. With a cap, rectifier,
zener, small filter it is easy to just put the limited DC into a solid
state relay or optical coupler.

Or buy one ready made phone line flasher at Electronic Goldmine for
$5. receptacle switches 120 VAC lamp

 

[Michael Black]

Neon bulb would work if you are looking directly at it, not too useful
otherwise.

But then you use the light from the neon bulb to turn on a photelectric
device, which controls the light flasher.

Or, you get a modem, and power it up (easiest if it's an external modem),
and then use the ring detector circuitry from there to control a flasher.

Michael

 

[default]

But then you use the light from the neon bulb to turn on a photelectric
device, which controls the light flasher.

That's doing things the hard way . . . build an optical isolator
around a neon bulb (LED, cds photocell, triac and some potting
resin. I used to do that before solid state relays came along) It
could be done, but why would you want to?

Or, you get a modem, and power it up (easiest if it's an external modem),
and then use the ring detector circuitry from there to control a flasher.

Modem? Let me guess, you really, really, like Rube Goldberg?

You'll love this: take a laser pointer and power it from the ring
voltage and use mirrors or optic fiber to send it around the house.
Or how about a mechanical gate that drops a ball into a tube, the ball
winds its way through the house tripping mechanical flags, and setting
several wind up mechanical toys into motion, . . . .

http://www.aaroncake.net/circuits/pflash.htm Has a simple schematic,
except U1 and everything West of it could be replaced with a single
solid state relay, and eliminate the transistor and DC supply. Still
cheaper to buy it ready made though . . .

 

[jasen]

I don't know everything..so hopefully other posters can fill in the
gaps...

I know a ring off a telephone line is a large voltage.

50-100V low frequency (no more than 20Hz).

But I don't know the waveform

sine with a 48V DC offset.

or how much it can be loaded.

not a whole lot, but then a xenon strobe doesn't use much power,

start with a mains strobe bulb add a few Cockroft-Walton stages to rectifier.

If low-visibilty is acceptable use an off-the shelf 110V rated neon indicator.

Bye.
Jasen

 

[jasen]

But then you use the light from the neon bulb to turn on a photelectric
device, which controls the light flasher.

Or, you get a modem, and power it up (easiest if it's an external modem),
and then use the ring detector circuitry from there to control a flasher.

yeah, pin 9 (or 22 for 25 pin ports) goes to -12Vish when the phone rings.

that could switch on a p-channel mosfet, pnp transistor, or optocoupler
but there's not quite enogh drive to operate a small relay.

Bye.
Jasen