A circuit that outputs 3V when there was a pulse input

[Mr. Man-wai Chang]

Is there a simple circuit that does that?



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[George Herold]

On Friday, August 12, 2016 at 9:11:22 AM UTC-4, Mr. Man-wai Chang wrote:

On 12/08/16 21:09, Randy Day wrote:
In article <nokeak$d2e$3@dont-email.me>, toylet.toylet@gmail.com says....

Is there a simple circuit that does that?

How long a pulse? 3v at how much current?
Does there need to be a reset feature to
turn off the 3v?

We need more detail.

I want to flash an LED when there is an incoming phone call.

Well a one-shot or something like that. 74HC123
or a 555 thing.

George H.

--
@~@ Remain silent! Drink, Blink, Stretch! Live long and prosper!!
/ v \ Simplicity is Beauty!
/( _ )\ May the Force and farces be with you!
^ ^ (x86_64 Ubuntu 9.10) Linux 2.6.39.3
不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA):
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[Randy Day]

In article <nokeak$d2e$3@dont-email.me>, toylet.toylet@gmail.com says...

Is there a simple circuit that does that?

How long a pulse? 3v at how much current?
Does there need to be a reset feature to
turn off the 3v?

We need more detail.

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[Mr. Man-wai Chang]

On 12/08/16 21:09, Randy Day wrote:

In article <nokeak$d2e$3@dont-email.me>, toylet.toylet@gmail.com says...

Is there a simple circuit that does that?

How long a pulse? 3v at how much current?
Does there need to be a reset feature to
turn off the 3v?

We need more detail.

I want to flash an LED when there is an incoming phone call.


--
@~@ Remain silent! Drink, Blink, Stretch! Live long and prosper!!
/ v \ Simplicity is Beauty!
/( _ )\ May the Force and farces be with you!
^ ^ (x86_64 Ubuntu 9.10) Linux 2.6.39.3
不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA):
http://www.swd.gov.hk/tc/index/site_pubsvc/page_socsecu/sub_addressesa

 

[Mr. Man-wai Chang]

On 12/08/16 21:35, George Herold wrote:

I want to flash an LED when there is an incoming phone call.

Well a one-shot or something like that. 74HC123
or a 555 thing.

Thank you for the tip!

--
@~@ Remain silent! Drink, Blink, Stretch! Live long and prosper!!
/ v \ Simplicity is Beauty!
/( _ )\ May the Force and farces be with you!
^ ^ (x86_64 Ubuntu 9.10) Linux 2.6.39.3
不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA):
http://www.swd.gov.hk/tc/index/site_pubsvc/page_socsecu/sub_addressesa

 

[default]

On Fri, 12 Aug 2016 21:11:21 +0800, "Mr. Man-wai Chang"
<toylet.toylet@gmail.com> wrote:

On 12/08/16 21:09, Randy Day wrote:
In article <nokeak$d2e$3@dont-email.me>, toylet.toylet@gmail.com says...

Is there a simple circuit that does that?

How long a pulse? 3v at how much current?
Does there need to be a reset feature to
turn off the 3v?

We need more detail.

I want to flash an LED when there is an incoming phone call.

A land line telephone has a 20 HZ 90 volt ring signal imposed on the
line. It should be a piece of cake to run a led on that. I'd use a
cap to isolate the AC and dropping resistor and clamps to protect the
led.

Bound to be something on line already.

Google: telephone light flashing circuit

About 418,000 results

 

[Jasen Betts]

On 2016-08-12, Mr. Man-wai Chang <toylet.toylet@gmail.com> wrote:

On 12/08/16 21:09, Randy Day wrote:
In article <nokeak$d2e$3@dont-email.me>, toylet.toylet@gmail.com says...

Is there a simple circuit that does that?

How long a pulse? 3v at how much current?
Does there need to be a reset feature to
turn off the 3v?

We need more detail.

I want to flash an LED when there is an incoming phone call.

Does it have to be an LED?

eg: wire a NE2 neon indicator and a 100K resistor in series across the
phone line.



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This email has not been checked by half-arsed antivirus software

 

[Mr. Man-wai Chang]

On 13/08/16 08:00, Jasen Betts wrote:

eg: wire a NE2 neon indicator and a 100K resistor in series across the
phone line.

There is indeed a neon bulb in the handset of the telephone I wanna
modified. It flashes when there is an incoming call. And that's what I
want to replace with a modern, brighter LED.

--
@~@ Remain silent! Drink, Blink, Stretch! Live long and prosper!!
/ v \ Simplicity is Beauty!
/( _ )\ May the Force and farces be with you!
^ ^ (x86_64 Ubuntu 9.10) Linux 2.6.39.3
不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA):
http://www.swd.gov.hk/tc/index/site_pubsvc/page_socsecu/sub_addressesa

 

[default]

On Sat, 13 Aug 2016 21:41:12 +0800, "Mr. Man-wai Chang"
<toylet.toylet@gmail.com> wrote:

On 13/08/16 08:00, Jasen Betts wrote:

eg: wire a NE2 neon indicator and a 100K resistor in series across the
phone line.


There is indeed a neon bulb in the handset of the telephone I wanna
modified. It flashes when there is an incoming call. And that's what I
want to replace with a modern, brighter LED.

Tell us more.

are you hard of hearing? telephone in a noisy location? etc..

My old man already added a led to his telephone so he can "see" a call
when he's watching TV. Dad's in his 90's and not very lucid or I'd
ask him how he did it.

I had LED's working 24/7 on the phone line's "on hook" current (you
can steal about 5 milliamps at 48 VDC without affecting the line) just
to make a night light and battery charger that wasn't affected by
power outages.

But there's already so much on line that you don't have to understand
electronics to make something that works.

 

[Tim Wescott]

On Fri, 12 Aug 2016 21:11:21 +0800, Mr. Man-wai Chang wrote:

On 12/08/16 21:09, Randy Day wrote:
In article <nokeak$d2e$3@dont-email.me>, toylet.toylet@gmail.com
says...

Is there a simple circuit that does that?

How long a pulse? 3v at how much current?
Does there need to be a reset feature to turn off the 3v?

We need more detail.

I want to flash an LED when there is an incoming phone call.

If you're on a telephone line that works like a North American POTS line
then the ring signal is a 100V, 20Hz sinusoid. Think capacitor,
resistor, and a string of LEDs. You probably want two strings in
opposite directions, because LEDs don't like being reverse-biased by
much. Or a bridge rectifier feeding the LEDs.

You're limited in the current you can use (check your local
specifications for a ringer load equivalent), but you have lots of
voltage to play with. So more LEDs in series = more light. With modern
LEDs you can probably have people screaming and covering their eyes when
the phone rings.

--
Tim Wescott
Control systems, embedded software and circuit design
I'm looking for work! See my website if you're interested
http://www.wescottdesign.com

 

[Ian Field]

"Mr. Man-wai Chang" <toylet.toylet@gmail.com> wrote in message
news:nokqdo$n4h$2@dont-email.me...

On 12/08/16 21:35, George Herold wrote:

I want to flash an LED when there is an incoming phone call.

Well a one-shot or something like that. 74HC123
or a 555 thing.

Thank you for the tip!

There's phone line active circuits online and in dozens of beginner books.

The Vf of a white LED is nearer 3.4V - don't try to regulate the voltage,
its supply must be current limited.

 

Mr. Man-wai Chang <toylet...@gmail.com> wrote:

Isn't it silly in the very beginning?
Using software to prevent battery problems

Only if the phone is plugged-in.
For battery-run phones, I've heard that NOT plugging a Samsung Galaxy phone/tablet into the wall while using its features causes battery problems. Using it with the USB wall-charger plugged-in helps to ease battery problems.
(I don't know about capacitors).

 

[rickman]

Tim Wescott wrote on 8/13/2016 12:12 PM:

On Fri, 12 Aug 2016 21:11:21 +0800, Mr. Man-wai Chang wrote:

On 12/08/16 21:09, Randy Day wrote:
In article <nokeak$d2e$3@dont-email.me>, toylet.toylet@gmail.com
says...

Is there a simple circuit that does that?

How long a pulse? 3v at how much current?
Does there need to be a reset feature to turn off the 3v?

We need more detail.

I want to flash an LED when there is an incoming phone call.

If you're on a telephone line that works like a North American POTS line
then the ring signal is a 100V, 20Hz sinusoid. Think capacitor,
resistor, and a string of LEDs. You probably want two strings in
opposite directions, because LEDs don't like being reverse-biased by
much. Or a bridge rectifier feeding the LEDs.

You're limited in the current you can use (check your local
specifications for a ringer load equivalent), but you have lots of
voltage to play with. So more LEDs in series = more light. With modern
LEDs you can probably have people screaming and covering their eyes when
the phone rings.

I think this circuit can be very simple indeed. A suitable resistor will
limit the current during the ring signal, around 4.7 kohms or larger. No
point in the capacitor really. There is a DC voltage on the phone line of
around 48 volts which you don't want to light the LED, so wire it up with a
polarity that reverse biases the LED from the DC. Then only the AC will
make it light up. If your home was not wired professionally the installer
may not have preserved tip and ring polarity when installed. In that case
you might need the capacitor.

--

Rick C

Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998