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G8MNY > TECH 25.05.07 09:03l 128 Lines 5194 Bytes #999 (0) @ WW
BID : 15857_GB7CIP
Read: DK5SG GUEST OE7FMI
Subj: A Simple Telephone Tester
Path: DB0FHN<DB0NOE<DB0GAP<DB0FSG<DB0MRW<OK0PKL<OK0PPL<DB0RES<ON0BEL<F4BWT<
I0TVL<LA1SFS<GB7CIP
Sent: 070524/2340Z @:GB7CIP.#32.GBR.EU #:15857 [Caterham] $:15857_GB7CIP
From: G8MNY@GB7CIP.#32.GBR.EU
To : TECH@WW
By G8MNY (new Mar 07)
Ever needed to test the functions of a pair of Phones, Answering machine, FAX,
Modem etc. without 2 telephone lines? This is a simple tester I knocked up in a
duel phone socket, plus a plug top PSU, to mimic most telephone line functions.
FEATURES
PHONE 1 "off hook" can listen to dial tone
Manual ringing of PHONE 2
PHONE 2 "off hook" removes dial tone from PHONE 1
PHONE 1 "on hook" causes line reversal to PHONE 2 (release the call test)
Variable line loss
Line status LED indicators
PLUG TOP PSU
ÚÄÄÄÄÄÄÄÄ2k2ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ>Ringing drive
³
LÄ¿ ÚÄÄÄÄÂÁÄ´>ÃÄÂÄÄÄÄÂÄÄÄÄÄÄÄÂÄÄÄÄÄ¿
)||( ³ ³ ³ 1K ³/
)||( À´<ÃÄÄÄ)Ä¿ ³ ÃÄÄÄ´ T1
)||( 36V ³ ³ === _³_ ³\e
)||( Ú´>ÃÄÄÄÙ ³ ³470u /_\' ÀÄÄÄ>+50V (@ 40-80mA)
)||( ³ ³ ³100V ³50V
NÄÙ ÀÄÄÄÄÁÂÄ´<ÃÄÄÄÁÄÄÁÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄ>0V
heat fused ³
Transformer ÀÄÄÄÄÄÄÄÄ´ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ>Dial Tone
u1
100V
The 50V 1W zener is actually series of zeners, T1 is any 200mA 100V 2W NPN.
The transformer's AC voltage in not high enough to ringing a phone directly, so
it is used to drive a line reversing relay to make the ringing.
A small capacitor takes off some of higher harmonics of the AC to mimic dial
tone.
TEST CIRCUIT
+50V>ÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄ¿
_³_ ³ ³ _³_
LED 1=\_/ ³ ³ \_/=LED 2
³ 1K5 1K5 ³
Ringing>ÄÄÄÄÄo o 1W 1W ³
drive RING / SW ³ ³ ___³___
___³___ ³ ³ ³RELAY 2³
³RELAY 1³ ³ ³ ~~~³~~~
~~~³~~~ ³ ³ ³
RING \ SW ³ ÃÄÄ2k2ÄÙ
o oÄÄÄÄ2k2ÄÄÄ´ u47 ³
³ ³ 100V 4K7 ³ relay 1
2ÄÄÄÄÄ)ÄÄÄÄÄÄÄÄÄÄÄÄÁÄ\ oÄ´ÃÄÄVARIABLEÄÁÄÂÄÄo o¿
³ relay 2 o line loss ³ \ ³
Calling ³ ³ ³ ÀÄ)ÄÄÄÄ>2 Answering
PHONE 1 ³ Dial tone>ÄÄÄÙ ³ ÚÄÄÄÄÙ PHONE 2
Socket ³ ³ ³ ÚÄÄÄÄÄÄ>5 Socket
5ÄÄÄÂÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ)ÄÁo/ o
³ ÀÄÄÄÄÄÙ
0V>ÄÄÄÄÄÄÄÙ relay 1
Both relays are double changeover (only 1 needs to be) 28V 7mA DIL type, with
4K coil resistance, note some types may have internal diodes so polarity may
matter! During ringing RELAY 1 has to operate & release 50 time a seconds to
deliver +/- 50V to PHONE 2 to look similar to the 75V AC (17-25Hz) + 50V DC of
real ringing.
The manual RING SWitch is a non locking double pole changeover.
Line loss & matching is all approximate, like the real world nothing is 600ohm!
But using 600 ohm test gear & blocking the DC etc. actual line losses could be
calibrated on the variable resistor scale (eg, 10-30dB Max). A more realistic
dummy line could be used as the middle secion if it was important (eg. for a
high speed modem).
REAR VIEW LAYOUT
ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
³ ()LED LED() ³
³ ÚÄ¿ 2 1 ÚÄ¿ ³ The PCB is removed from the case by heating the
³ ³R³ 1k5 1k5 ³R³ ³ melted spigots (with a soldering iron).
³ ³L³ ³L³ ³ PCB needs links cutting to isolate the 2 lines if
³ ³1³ 4k7 u47 ³2³ ³ it is for a shared phone. The PCB at the switch
³ ÀÄÙ_____ _____ÀÄÙ ³ location is cut away & it is mounted in drilled
³o) ³_____³ ³_____³ (o³ front case hole. Tight holes in the case are also
³ PHONE 2 PHONE 1 ³ made for the LEDs who's wires poke new PCB holes.
³ ³ After testing reassemble & reheat anything left
³ ³ of the spigots or use some glue.
³ ÚÄ¿RING [] ³
³ ³ ³SW [] ³
³ ÀÄÙ [] ³
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
In UK jack pins 2 & 5 are the 2 wire line, & a 3rd wire may be used for the
phones ringer path via a master socket capacitor. See your local telecomms Co.
(POTS) arrangements if different.
PHONE CALL SIMULATION
1/ Connect 2 PHONE devices.
2/ Lift PHONE 1, LED 1 lights up, listen to buzzing dial tone & U have "Blow".
3/ Intermittently operate ringing switch (cocadance ringing).
4/ Does PHONE 2 ring? (LED 2 lights dimly to ringing) Can it answer the call?
5/ On answer, LED 2 lights, PHONE 2 has "Blow", & PHONE 1 dial tone disappears
& a transmission path to PHONE 2 is made.
6/ Can you talk or send data both ways over transmission paths, is loss OK?
7/ Clear down PHONE 2, LED 2 goes out, & dial tone is returned to PHONE 1.
8/ If you cleared down PHONE 1 first instead, then PHONE 2 gets a line
polarity reversals, which should cause automatic kit to hang up & clear the
line for the next call. I found some kit just times out instead!
Why Don't U send an Interesting Bul?
73 de John G8MNY @ GB7CIP
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