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telehpone call magnification circuit

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New Member
I found this circuit in old book about electronics and this circuit related to PHILIPS company.
this circuit is used to magnificate the telehpone call when it put beside the telephone.
I want to ask about the transformer coupling i don't find it . how can i make it or replace by R coupling or RC coupling ?
i need help
the picture is attached



The circuit is really old, early 1960s.

It uses poor quality germanium transistors and a distorting audio transformer both of which will be very expensive.

Use a modern op-amp such as the TL071 which can drive 2k headphones directly or add an LM386 to power pair modern 32R headphones.


New Member
You can get mag pickups for telephones complete with suction cups. Putting it over the earpiece gives you the benefit of the phones internal anti-sidetone circuit.


Well-Known Member
Most Helpful Member
Old phones sprayed a magnetic signal all over the place. Then this old circuit worked fine.

Some modern phones do not have an earpiece that produces a magnetic signal for a coil to pick it up. They must be labelled, "hearing aid compatible".
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