Phone in use circuit not working

ringing.

device has answered the phone.

phone that it has been answered, because the voltage has gone down.

are the same. I have also used a rectifier that is a 2 amp 400v SIP 2KBP04M-1.

like to get this circuit working. Can anyone tell me why its not working.

There's a lot wrong with that circuit, but as an experiment add a small (10uf or less) electrolytic from the base of Q2 to ground, then ring your phone to see if it works.

Then, when you've got it working or not, remove it from the phone line and use the parts for something else. It is not "phone company friendly" nor are the parts properly V rated.

Ed

Reply to
ehsjr
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Yeah, that is true enough I suppose. So examine:

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That should keep the draw under 1 microamp, while pulsing an LED for about 10 microsecond pulses. I didn't include a resistor limiter in series with the LED, as that is something for the end user to insert as appropriate. I also didn't add a bridge rectifier, either. Again... up to the user. I don't think that circuit will do much at 10-12V or less for the off hook voltages. But if it does, it will blink ... very slowly, I think.

Jon

Reply to
Jon Kirwan

ringing.

device has answered the phone.

phone that it has been answered, because the voltage has gone down.

book are the same. I have also used a rectifier that is a 2 amp 400v SIP

2KBP04M-1.

results?

would like to get this circuit working. Can anyone tell me why its not working.

Old 400E KTU cards (1A2 key phone systems) are floating around surplus and are made for the phone companies.

Reply to
Michael A. Terrell

ringing.

device has answered the phone.

phone that it has been answered, because the voltage has gone down.

book are the same. I have also used a rectifier that is a 2 amp 400v SIP

2KBP04M-1.

results?

would like to get this circuit working. Can anyone tell me why its not working.

Or surely a modem, just uinsg the "DAA" part. Even the "winmodems". THere has to be an off-hook indicator to tell the modem the line's not available.

I recall back when this sort of circuit seemed to come up here over a decade ago, John whatshisname suggested something so that when his modem went online, it disconnected the other phones in the house. Obviously he had to arrange things right he could control the rest of the phone wiring in the house.

Michael

Reply to
Michael Black

You can also scrounge some HV transistors in CFL bulbs. And some fairly good capacitors and a transformer, and a diac, which can be used to make a relaxation oscillator to blink an LED without overloading the phone line.

I have wondered how much power can be drawn from the phone line without causing an error notification to the TELCO. The maximum power is probably the point at which the line voltage drops to 1/2 the 48 VDC, which may be in the order of 10 mA, so at 24 VDC it's about 1/4W. You might get away with it if you go off-hook every 10 seconds or so.

A lot more power could be extracted if you could cause an incoming ring signal, which is about 100 VAC at 25 Hz and possibly 25-100 mA, maybe

40% duty cycle, so perhaps a couple of watts.

Paul

Reply to
P E Schoen

That was easy. Connect the real phone line to the second pair. Connect the modem's line jack to that line, and the phone jack back to the regular line.

Reply to
Michael A. Terrell

You draw 10mA and they'll think your phone lines ahva a fault (perhaps wet)

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Reply to
Jasen Betts

ringing.

device has answered the phone.

the phone that it has been answered, because the voltage has gone down.

book are the same. I have also used a rectifier that is a 2 amp 400v SIP

2KBP04M-1.

results?

would like to get this circuit working. Can anyone tell me why its not working.

some modems had a switched socket that would be disconnected from the line when the modem went off-hook, some had the pads but just had wire links in place of the relay.

A second relay was needed as the main relay was also used for pulse dialing.

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Reply to
Jasen Betts

ringing.

device has answered the phone.

phone that it has been answered, because the voltage has gone down.

are the same. I have also used a rectifier that is a 2 amp 400v SIP 2KBP04M-1.

like to get this circuit working. Can anyone tell me why its not working.

For off hook indication you can put a led in series with the telephone line. Across tte led a diode.

Instead of the diode you can use an optocouple and then control whatever you like.

Old fashion method, a 12 V relais in series.

Reply to
tuinkabouter

which is why they made modems with a line in and phone out...

Jamie

Reply to
Jamie

ringing.

device has answered the phone.

the phone that it has been answered, because the voltage has gone down.

book are the same. I have also used a rectifier that is a 2 amp 400v SIP

2KBP04M-1.

results?

would like to get this circuit working. Can anyone tell me why its not working.

Seems like in my distance past I used a low voltage low current Reed relay in series with the phone line with a by pass zener pair to protect it from higher voltages.

Jamie

Reply to
Jamie

Usually of a type similar to MJE13007 - pretty low gain - the base current alone would probably be more than you can get away with "on hook".

And some fairly good

The 220V UK ones have a HF ballast driven by a half-bridge - maybe the 110V US ones have a transformer.

and a diac, which can be used to make a

I suggested that yesterday - do try to keep up at the back!

Reply to
Ian Field

Seems rather elaborate when 1 resistor, 1 capacitor, 1 diac & 1 LED would do the same job just as well.

Reply to
Ian Field

There was an interesting reed relay project published some years ago to thwart premium rate rogue diallers.

A coil wound around a standard reed, pulls it in while off hook current flows to complete the connection - you have to hold down a pushbutton while the modem initiates the call.

Once the connection is established, the rogue dialler has to drop the line to dial the premium rate number - without anyone holding down the pushbutton, this operation fails.

Reply to
Ian Field

If it turns out that any current pulses at any time can blow the LED - put 3 silicon diodes in series to make a Vf clamp, you do of course still need the inverse parallel diode to clamp Vr.

Reply to
Ian Field

It's a reliable design, as I've built a couple, at least.

I've not used diacs, yet. Just a hobbyist. But yes, I can see how that should work. Breakover voltage is higher, which has its advantages in this application.

Any particular diac you'd consider trying?

Jon

Reply to
Jon Kirwan

ringing.

device has answered the phone.

phone that it has been answered, because the voltage has gone down.

book are the same. I have also used a rectifier that is a 2 amp 400v SIP

2KBP04M-1.

results?

like to get this circuit working. Can anyone tell me why its not working.

How about a pair of back-to-back paralleled LEDs in series with the line? Rings would be bright, off-hook less bright. Might look cool, especially with different color LEDs.

--
John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    
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Reply to
John Larkin

I already suggested the DB3 in the post I sent yesterday.

They're fairly common in UK CFLs, although Philips don't use them in types less than 18W.

Reply to
Ian Field

ringing.

device has answered the phone.

phone that it has been answered, because the voltage has gone down.

book are the same. I have also used a rectifier that is a 2 amp 400v SIP

2KBP04M-1.

results?

like to get this circuit working. Can anyone tell me why its not working.

Rings

Not sure how the audio would sound going through diodes.

Jamie

Reply to
Jamie

Like about 1 3/4V of crossover distortion on a 48V signal.

Reply to
Ian Field

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