Jasen Betts wrote:> On 2013-03-03, Michael Black <et472@ncf.ca> wrote: > >>On Sat, 2 Mar 2013, Michael A. Terrell wrote: >> >> >>>ehsjr wrote: >>> >>>>On 2/28/2013 2:22 PM, steve wrote: >>>> >>>>>I tested and built the following circuit. >>>>> >>>>>http://www.circuitstoday.com/telephone-in-use-indicator >>>>> >>>>>It all worked fine untill I tried to test it by calling into my phone. >>>>>(the one test I didnt do before I soldered it all together) >>>>> >>>>>What happens is taht the phone rings for a about 1/2 a ring then stops ringing. >>>>>To my surprise when I life the phone up the line is alive eg. Its like the device has answered the phone. >>>>> >>>>>I think that the circuit must be drawing too much power and then telling the phone that it has been answered, because the voltage has gone down. >>>>> >>>>>I have had to replace the Transistors with NTE199, which according to the book are the same. I have also used a rectifier that is a 2 amp 400v SIP 2KBP04M-1. >>>>>Im wondering if I used a different rectifier if that would change the results? >>>>> >>>>>I recognize that your not suppse to take power from the phone co. but I would like to get this circuit working. Can anyone tell me why its not working. >>>>>thanks. >>>>> >>>> >>>>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. >>> >>> Old 400E KTU cards (1A2 key phone systems) are floating around >>>surplus and are made for the phone companies. >>> >> >>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. > > > 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. > > >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
Phone in use circuit not working
Started by ●February 28, 2013
Reply by ●March 3, 20132013-03-03
Reply by ●March 3, 20132013-03-03
"P E Schoen" <paul@peschoen.com> wrote in message news:kguke2$94j$1@dont-email.me...> "Ian Field" wrote in message news:%VtYs.393090$5F3.188588@fx21.fr7... > >> The ones I often find in phones are the MPSA42 & 92 - ones PNP & the >> other NPN. > > You can also scrounge some HV transistors in CFL bulbs.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> capacitors and a transformer,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> relaxation oscillator to blink an LED without overloading the phone line.I suggested that yesterday - do try to keep up at the back!
Reply by ●March 3, 20132013-03-03
"Jon Kirwan" <jonk@infinitefactors.org> wrote in message news:3g65j8p5fcrfcn03jtqf57rr1ain4e04tn@4ax.com...> On Sat, 2 Mar 2013 21:22:37 -0000, "Ian Field" > <gangprobing.alien@ntlworld.com> wrote: > >> >> >>"Jon Kirwan" <jonk@infinitefactors.org> wrote in message >>news:7sm4j81hs4ep7gti49mukuolcvv68unerc@4ax.com... >>> On Thu, 28 Feb 2013 11:22:00 -0800 (PST), steve >>> <stevesemple@lycos.com> wrote: >>> >>>>I tested and built the following circuit. >>>> >>>>http://www.circuitstoday.com/telephone-in-use-indicator >>>> >>>> It all worked fine untill I tried to test it by calling into >>>> my phone. (the one test I didnt do before I soldered it all >>>> together) >>>> >>>> What happens is taht the phone rings for a about 1/2 a ring >>>> then stops ringing. To my surprise when I life the phone up >>>> the line is alive eg. Its like the device has answered the >>>> phone. >>>> >>>> I think that the circuit must be drawing too much power and >>>> then telling the phone that it has been answered, because >>>> the voltage has gone down. >>>> >>>> I have had to replace the Transistors with NTE199, which >>>> according to the book are the same. I have also used a >>>> rectifier that is a 2 amp 400v SIP 2KBP04M-1. >>>> >>>> Im wondering if I used a different rectifier if that would >>>> change the results? >>>> >>>> I recognize that your not suppse to take power from the >>>> phone co. but I would like to get this circuit working. Can >>>> anyone tell me why its not working. >>>> >>>>thanks. >>> >>> There is quite a long specification for telephone lines in >>> the US. I have a copy, thanks to Don Bowey, when he dropped a >>> copy over at my home back around 2003 or so. It represents an >>> industry composite of various systems and includes envelopes >>> of operation. The gist of it is, as Don wrote before coming >>> over back then, >>> >>> "The FCC R&R require a minimum of 5M of customer premises >>> equipment loop resistance in the on-hook state. Also. >>> at 220uA some Central Offices will declare a line fault >>> and remove the line from service." >>> >>> The basic idea of presenting 5MOhm total customer premises >>> load (that is the TOTAL of all phones and connected >>> equipment) when on-hook is incredibly hard to meet with an >>> unpowered attachment that shows "in use" and "not in use" led >>> lights. >>> >>> I've also read that, "if you are in USA or canada Bellcore >>> specs allow a max of 5micro amps at 48VDC in an on-hook >>> state." That's 10MOhm, in effect, though I believe the 5MOhm >>> for the entire premises still fits the spec. >>> >>> The upshot here is that you aren't going to be seeing an LED >>> lit continuously and still meet on-hook specifications. You >>> can design a system to blink periodically, >> >>If you can use that 48V to charge a capacitor above 32V without violating >>the on hook current spec; you can make an LED flash very brightly >>periodically by dumping the cap into it with a DB3 diac. >> >>You'd have to trial & error for how many uF to make the flash bright >>enough >>without blowing the LED. > > Yeah, that is true enough I suppose. So examine: > > http://www.infinitefactors.org/misc/spice/Pulser%202.pngSeems rather elaborate when 1 resistor, 1 capacitor, 1 diac & 1 LED would do the same job just as well.
Reply by ●March 3, 20132013-03-03
"Jamie" <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in message news:KNIYs.36533$dz5.7008@newsfe07.iad...> Jasen Betts wrote: > >> On 2013-03-03, Michael Black <et472@ncf.ca> wrote: >> >>>On Sat, 2 Mar 2013, Michael A. Terrell wrote: >>> >>> >>>>ehsjr wrote: >>>> >>>>>On 2/28/2013 2:22 PM, steve wrote: >>>>> >>>>>>I tested and built the following circuit. >>>>>> >>>>>>http://www.circuitstoday.com/telephone-in-use-indicator >>>>>> >>>>>>It all worked fine untill I tried to test it by calling into my phone. >>>>>>(the one test I didnt do before I soldered it all together) >>>>>> >>>>>>What happens is taht the phone rings for a about 1/2 a ring then stops >>>>>>ringing. >>>>>>To my surprise when I life the phone up the line is alive eg. Its like >>>>>>the device has answered the phone. >>>>>> >>>>>>I think that the circuit must be drawing too much power and then >>>>>>telling the phone that it has been answered, because the voltage has >>>>>>gone down. >>>>>> >>>>>>I have had to replace the Transistors with NTE199, which according to >>>>>>the book are the same. I have also used a rectifier that is a 2 amp >>>>>>400v SIP 2KBP04M-1. >>>>>>Im wondering if I used a different rectifier if that would change the >>>>>>results? >>>>>> >>>>>>I recognize that your not suppse to take power from the phone co. but >>>>>>I would like to get this circuit working. Can anyone tell me why its >>>>>>not working. >>>>>>thanks. >>>>>> >>>>> >>>>>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. >>>> >>>> Old 400E KTU cards (1A2 key phone systems) are floating around >>>>surplus and are made for the phone companies. >>>> >>> >>>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. >> >> >> 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. >> >> >> > 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. > > JamieThere 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 by ●March 3, 20132013-03-03
"tuinkabouter" <dachthetniet@net.invalid> wrote in message news:kgvktk$8ok$1@dont-email.me...> On 2/28/2013 8:22 PM, steve wrote: >> I tested and built the following circuit. >> >> http://www.circuitstoday.com/telephone-in-use-indicator >> >> It all worked fine untill I tried to test it by calling into my phone. >> (the one test I didnt do before I soldered it all together) >> >> What happens is taht the phone rings for a about 1/2 a ring then stops >> ringing. >> To my surprise when I life the phone up the line is alive eg. Its like >> the device has answered the phone. >> >> I think that the circuit must be drawing too much power and then telling >> the phone that it has been answered, because the voltage has gone down. >> >> I have had to replace the Transistors with NTE199, which according to the >> book are the same. I have also used a rectifier that is a 2 amp 400v SIP >> 2KBP04M-1. >> Im wondering if I used a different rectifier if that would change the >> results? >> >> I recognize that your not suppse to take power from the phone co. but I >> would like to get this circuit working. Can anyone tell me why its not >> working. >> thanks. > > For off hook indication you can put a led in series with the telephone > line. Across tte led a diode.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 by ●March 3, 20132013-03-03
On Sun, 3 Mar 2013 16:30:33 -0000, "Ian Field" <gangprobing.alien@ntlworld.com> wrote:> > >"Jon Kirwan" <jonk@infinitefactors.org> wrote in message >news:3g65j8p5fcrfcn03jtqf57rr1ain4e04tn@4ax.com... >> On Sat, 2 Mar 2013 21:22:37 -0000, "Ian Field" >> <gangprobing.alien@ntlworld.com> wrote: >> >>> >>> >>>"Jon Kirwan" <jonk@infinitefactors.org> wrote in message >>>news:7sm4j81hs4ep7gti49mukuolcvv68unerc@4ax.com... >>>> On Thu, 28 Feb 2013 11:22:00 -0800 (PST), steve >>>> <stevesemple@lycos.com> wrote: >>>> >>>>>I tested and built the following circuit. >>>>> >>>>>http://www.circuitstoday.com/telephone-in-use-indicator >>>>> >>>>> It all worked fine untill I tried to test it by calling into >>>>> my phone. (the one test I didnt do before I soldered it all >>>>> together) >>>>> >>>>> What happens is taht the phone rings for a about 1/2 a ring >>>>> then stops ringing. To my surprise when I life the phone up >>>>> the line is alive eg. Its like the device has answered the >>>>> phone. >>>>> >>>>> I think that the circuit must be drawing too much power and >>>>> then telling the phone that it has been answered, because >>>>> the voltage has gone down. >>>>> >>>>> I have had to replace the Transistors with NTE199, which >>>>> according to the book are the same. I have also used a >>>>> rectifier that is a 2 amp 400v SIP 2KBP04M-1. >>>>> >>>>> Im wondering if I used a different rectifier if that would >>>>> change the results? >>>>> >>>>> I recognize that your not suppse to take power from the >>>>> phone co. but I would like to get this circuit working. Can >>>>> anyone tell me why its not working. >>>>> >>>>>thanks. >>>> >>>> There is quite a long specification for telephone lines in >>>> the US. I have a copy, thanks to Don Bowey, when he dropped a >>>> copy over at my home back around 2003 or so. It represents an >>>> industry composite of various systems and includes envelopes >>>> of operation. The gist of it is, as Don wrote before coming >>>> over back then, >>>> >>>> "The FCC R&R require a minimum of 5M of customer premises >>>> equipment loop resistance in the on-hook state. Also. >>>> at 220uA some Central Offices will declare a line fault >>>> and remove the line from service." >>>> >>>> The basic idea of presenting 5MOhm total customer premises >>>> load (that is the TOTAL of all phones and connected >>>> equipment) when on-hook is incredibly hard to meet with an >>>> unpowered attachment that shows "in use" and "not in use" led >>>> lights. >>>> >>>> I've also read that, "if you are in USA or canada Bellcore >>>> specs allow a max of 5micro amps at 48VDC in an on-hook >>>> state." That's 10MOhm, in effect, though I believe the 5MOhm >>>> for the entire premises still fits the spec. >>>> >>>> The upshot here is that you aren't going to be seeing an LED >>>> lit continuously and still meet on-hook specifications. You >>>> can design a system to blink periodically, >>> >>>If you can use that 48V to charge a capacitor above 32V without violating >>>the on hook current spec; you can make an LED flash very brightly >>>periodically by dumping the cap into it with a DB3 diac. >>> >>>You'd have to trial & error for how many uF to make the flash bright >>>enough >>>without blowing the LED. >> >> Yeah, that is true enough I suppose. So examine: >> >> http://www.infinitefactors.org/misc/spice/Pulser%202.png > >Seems rather elaborate when 1 resistor, 1 capacitor, 1 diac & 1 LED would do >the same job just as well.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 by ●March 3, 20132013-03-03
On Thu, 28 Feb 2013 18:42:53 -0500, Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:>steve wrote: >> I tested and built the following circuit. >> >> http://www.circuitstoday.com/telephone-in-use-indicator >> >> It all worked fine untill I tried to test it by calling into my phone. >> (the one test I didnt do before I soldered it all together) >> >> What happens is taht the phone rings for a about 1/2 a ring then stops ringing. >> To my surprise when I life the phone up the line is alive eg. Its like the device has answered the phone. >> >> I think that the circuit must be drawing too much power and then telling the phone that it has been answered, because the voltage has gone down. >> >> I have had to replace the Transistors with NTE199, which according to the book are the same. I have also used a rectifier that is a 2 amp 400v SIP 2KBP04M-1. >> Im wondering if I used a different rectifier if that would change the results? >> >> I recognize that your not suppse to take power from the phone co. but I would like to get this circuit working. Can anyone tell me why its not working. >> thanks. > > > I think some one gave you some bad transistor numbers.. > > THe phone system in the US rings at around 100 Volts AC and on hook >is around 50Volts. Off hook may give you around 10 volts and it depends >on how many phones you have at one time off hook. > > The 2N3392 can only handle 25Volts and it may work if you can insure >that the unit will switch on in time to load it down. Further more, the >other transistor will be sitting there with this 50v (on hook), leaking >through the collector. > > The NTE199 replacement isn't much better, it has a 70V limit at best >and most likely will work find when on hook, but when it rings, you can >expect some leaking to be taking place. > > You first need to get HV transistors. > > Try getting some 2N5550 transistors, or the 2N5551 which is a little >higher.. > Mouser.com has 2N5551 for 0.78 ech and they have over 3k in stock. > > >JamieHow 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 Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Reply by ●March 3, 20132013-03-03
"Jon Kirwan" <jonk@infinitefactors.org> wrote in message news:7l37j89pon3c6c35lbhgds841uta9eb4fs@4ax.com...> On Sun, 3 Mar 2013 16:30:33 -0000, "Ian Field" > <gangprobing.alien@ntlworld.com> wrote: > >> >> >>"Jon Kirwan" <jonk@infinitefactors.org> wrote in message >>news:3g65j8p5fcrfcn03jtqf57rr1ain4e04tn@4ax.com... >>> On Sat, 2 Mar 2013 21:22:37 -0000, "Ian Field" >>> <gangprobing.alien@ntlworld.com> wrote: >>> >>>> >>>> >>>>"Jon Kirwan" <jonk@infinitefactors.org> wrote in message >>>>news:7sm4j81hs4ep7gti49mukuolcvv68unerc@4ax.com... >>>>> On Thu, 28 Feb 2013 11:22:00 -0800 (PST), steve >>>>> <stevesemple@lycos.com> wrote: >>>>> >>>>>>I tested and built the following circuit. >>>>>> >>>>>>http://www.circuitstoday.com/telephone-in-use-indicator >>>>>> >>>>>> It all worked fine untill I tried to test it by calling into >>>>>> my phone. (the one test I didnt do before I soldered it all >>>>>> together) >>>>>> >>>>>> What happens is taht the phone rings for a about 1/2 a ring >>>>>> then stops ringing. To my surprise when I life the phone up >>>>>> the line is alive eg. Its like the device has answered the >>>>>> phone. >>>>>> >>>>>> I think that the circuit must be drawing too much power and >>>>>> then telling the phone that it has been answered, because >>>>>> the voltage has gone down. >>>>>> >>>>>> I have had to replace the Transistors with NTE199, which >>>>>> according to the book are the same. I have also used a >>>>>> rectifier that is a 2 amp 400v SIP 2KBP04M-1. >>>>>> >>>>>> Im wondering if I used a different rectifier if that would >>>>>> change the results? >>>>>> >>>>>> I recognize that your not suppse to take power from the >>>>>> phone co. but I would like to get this circuit working. Can >>>>>> anyone tell me why its not working. >>>>>> >>>>>>thanks. >>>>> >>>>> There is quite a long specification for telephone lines in >>>>> the US. I have a copy, thanks to Don Bowey, when he dropped a >>>>> copy over at my home back around 2003 or so. It represents an >>>>> industry composite of various systems and includes envelopes >>>>> of operation. The gist of it is, as Don wrote before coming >>>>> over back then, >>>>> >>>>> "The FCC R&R require a minimum of 5M of customer premises >>>>> equipment loop resistance in the on-hook state. Also. >>>>> at 220uA some Central Offices will declare a line fault >>>>> and remove the line from service." >>>>> >>>>> The basic idea of presenting 5MOhm total customer premises >>>>> load (that is the TOTAL of all phones and connected >>>>> equipment) when on-hook is incredibly hard to meet with an >>>>> unpowered attachment that shows "in use" and "not in use" led >>>>> lights. >>>>> >>>>> I've also read that, "if you are in USA or canada Bellcore >>>>> specs allow a max of 5micro amps at 48VDC in an on-hook >>>>> state." That's 10MOhm, in effect, though I believe the 5MOhm >>>>> for the entire premises still fits the spec. >>>>> >>>>> The upshot here is that you aren't going to be seeing an LED >>>>> lit continuously and still meet on-hook specifications. You >>>>> can design a system to blink periodically, >>>> >>>>If you can use that 48V to charge a capacitor above 32V without >>>>violating >>>>the on hook current spec; you can make an LED flash very brightly >>>>periodically by dumping the cap into it with a DB3 diac. >>>> >>>>You'd have to trial & error for how many uF to make the flash bright >>>>enough >>>>without blowing the LED. >>> >>> Yeah, that is true enough I suppose. So examine: >>> >>> http://www.infinitefactors.org/misc/spice/Pulser%202.png >> >>Seems rather elaborate when 1 resistor, 1 capacitor, 1 diac & 1 LED would >>do >>the same job just as well. > > 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?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 by ●March 3, 20132013-03-03
John Larkin wrote:> On Thu, 28 Feb 2013 18:42:53 -0500, Jamie > <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote: > > >>steve wrote: >> >>>I tested and built the following circuit. >>> >>>http://www.circuitstoday.com/telephone-in-use-indicator >>> >>>It all worked fine untill I tried to test it by calling into my phone. >>>(the one test I didnt do before I soldered it all together) >>> >>>What happens is taht the phone rings for a about 1/2 a ring then stops ringing. >>>To my surprise when I life the phone up the line is alive eg. Its like the device has answered the phone. >>> >>>I think that the circuit must be drawing too much power and then telling the phone that it has been answered, because the voltage has gone down. >>> >>>I have had to replace the Transistors with NTE199, which according to the book are the same. I have also used a rectifier that is a 2 amp 400v SIP 2KBP04M-1. >>>Im wondering if I used a different rectifier if that would change the results? >>> >>>I recognize that your not suppse to take power from the phone co. but I would like to get this circuit working. Can anyone tell me why its not working. >>>thanks. >> >> >> I think some one gave you some bad transistor numbers.. >> >> THe phone system in the US rings at around 100 Volts AC and on hook >>is around 50Volts. Off hook may give you around 10 volts and it depends >>on how many phones you have at one time off hook. >> >> The 2N3392 can only handle 25Volts and it may work if you can insure >>that the unit will switch on in time to load it down. Further more, the >>other transistor will be sitting there with this 50v (on hook), leaking >>through the collector. >> >> The NTE199 replacement isn't much better, it has a 70V limit at best >>and most likely will work find when on hook, but when it rings, you can >>expect some leaking to be taking place. >> >> You first need to get HV transistors. >> >> Try getting some 2N5550 transistors, or the 2N5551 which is a little >>higher.. >> Mouser.com has 2N5551 for 0.78 ech and they have over 3k in stock. >> >> >>Jamie > > > 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. > >Not sure how the audio would sound going through diodes. Jamie
Reply by ●March 3, 20132013-03-03
"Jamie" <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in message news:ISMYs.81579$KR.62297@newsfe27.iad...> John Larkin wrote: > >> On Thu, 28 Feb 2013 18:42:53 -0500, Jamie >> <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote: >> >> >>>steve wrote: >>> >>>>I tested and built the following circuit. >>>> >>>>http://www.circuitstoday.com/telephone-in-use-indicator >>>> >>>>It all worked fine untill I tried to test it by calling into my phone. >>>>(the one test I didnt do before I soldered it all together) >>>> >>>>What happens is taht the phone rings for a about 1/2 a ring then stops >>>>ringing. >>>>To my surprise when I life the phone up the line is alive eg. Its like >>>>the device has answered the phone. >>>> >>>>I think that the circuit must be drawing too much power and then telling >>>>the phone that it has been answered, because the voltage has gone down. >>>>I have had to replace the Transistors with NTE199, which according to >>>>the book are the same. I have also used a rectifier that is a 2 amp 400v >>>>SIP 2KBP04M-1. >>>>Im wondering if I used a different rectifier if that would change the >>>>results? >>>> >>>>I recognize that your not suppse to take power from the phone co. but I >>>>would like to get this circuit working. Can anyone tell me why its not >>>>working. >>>>thanks. >>> >>> >>> I think some one gave you some bad transistor numbers.. >>> >>> THe phone system in the US rings at around 100 Volts AC and on hook is >>> around 50Volts. Off hook may give you around 10 volts and it depends on >>> how many phones you have at one time off hook. >>> >>> The 2N3392 can only handle 25Volts and it may work if you can insure >>> that the unit will switch on in time to load it down. Further more, the >>> other transistor will be sitting there with this 50v (on hook), leaking >>>through the collector. >>> >>> The NTE199 replacement isn't much better, it has a 70V limit at best and >>> most likely will work find when on hook, but when it rings, you can >>>expect some leaking to be taking place. >>> >>> You first need to get HV transistors. >>> >>> Try getting some 2N5550 transistors, or the 2N5551 which is a little >>>higher.. >>> Mouser.com has 2N5551 for 0.78 ech and they have over 3k in stock. >>> >>> >>>Jamie >> >> >> 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. >> >> > > Not sure how the audio would sound going through diodes.Like about 1 3/4V of crossover distortion on a 48V signal.
