telephone" tip & ring capacitance"

[sokrat]

telephone capacitance

Hi all


i want to ask about the capacitance between the tip & ring. or what standerd value for this capacitor and how I can modifay this value of the capacitor.


NOT:
When I sent my telephone to the central offece type (5ESS USA DTMF TYPE)
He send this result
1- measurements for normal set
0.0 VDC A-ETH
0.0 VDC B-ETH
0.0 VDC CALC. A-B
.079 VAC A_ETH
.099 VAC B_ETH
.020 VAC CALC. A_B
>10 MOHMS A-BAT
>10 MOHMS A_ETH
>10 MOHMS B_BAT
> 10 MOHMS B_ETH
>10 MOHMS A-B
0.0MADC LOOP
TEARM ? A-B-------------------------------------->?
.145 Uf CAP B-ETH
.145 UF CAP A-ETH
<-30 DBM PWR INF
7.97 DBRNP CCT NOISE
< -40 DBM LVL
29.8 DB CCT BAL
37.7 DBRNP GND NOISE
and tell me to change the capacitor between tip &ring

thanks

yours

SOKRAT

 

[pool_77]

dbrnp

You need to know in which state it is:

on hook:

The complex impedance is mainly represented with a ringer circuit.
There can be used capacitors from 470nF up to 1uF (20-50kohm up to 2-10kohm).

Ask them for a graph from measuring to be all more clearly...

Impedance are measured from 25Hzto 1kHz.

Search web for some schematic of phones...

pool_77

 

[sokrat]

capacitance

Hi pool_77

if you have any good links for this measure send it


thanks
yours
s 8O krat

 

[pool_77]

tbr21 complex impedance schematic

The proces depend on the country, where you want to approve the phone. Contact test laboratory for description of measure procedure and required parameters.

If will not be succesful, I can send you some info for EU.

pool_77

 

[sokrat]

capacitance telephone testing

OK pool_7

Send any info for EU

THANKS

yours

S 8O KRAT

 

[kudjung]

You can download several spec. from www.etsi.org

For EU, we normally follow TBR21 spec. with some deviation on specific country on EG 201 121.

OK pool_7

Send any info for EU

THANKS

yours

S 8O KRAT

 

[pool_77]

measuring methode