Part identification help

[Danich_ivanov]

Hello there. Found a old telephone, took it apart as i usually do with old stuff, and it seem to have some kind of a transformer, i am a complete nub when it comes to transformers, typing "6779 u3 fr" in google did not help much. What interestests me the most is, is it an audio transformer at all? Can i use it for audio?

Thanks.

[tonyharker]

Google 'Telephone isolation transformer' instead.

[thermionix]

A little bit funny that there's a resistor that starts with 911 in a telephone.

[Danich_ivanov]

A little bit funny that there's a resistor that starts with 911 in a telephone.

Hah, true! and such an enormous one.

Google 'Telephone isolation transformer' instead.

Have you ever had experience with such transformers?

[ElectricDruid]

A little bit funny that there's a resistor that starts with 911 in a telephone.

Lol! Well spotted!

[PRR]

It is "audio", but rated 300Hz-3KHz. Speech Band, not Guitar Band.

And it is carbon-mike impedance which is WAY lower than guitar pickup impedance.

The maybe-fine use is with an opamp buffer as a ground isolator. Driven from extra low impedance the bass may extend well below 300Hz. (The treble is usually better than claimed.) However the performance varies with different parts, and nobody put good transformers in 'phones. There are several low-price transformers sold and *known* be good in ground buffers. Probably better than old salvage.

[Danich_ivanov]

It is "audio", but rated 300Hz-3KHz. Speech Band, not Guitar Band.

And it is carbon-mike impedance which is WAY lower than guitar pickup impedance.

The maybe-fine use is with an opamp buffer as a ground isolator. Driven from extra low impedance the bass may extend well below 300Hz. (The treble is usually better than claimed.) However the performance varies with different parts, and nobody put good transformers in 'phones. There are several low-price transformers sold and *known* be good in ground buffers. Probably better than old salvage.

Gotcha. I started thinking about turning this phone into a "marshall ms-2" type thing with 3,5 - 4 inch speaker, using phone's circuit as a power amp basically, in this scenario lack of low end shouldn't be a huge issue.