On Jul 10, 1:26*pm, "N_Cook" wrote:
Seemed a neat idea but ...
There is space inside this 1950s dashboard radio for one of those keyfob/
matchbox size FM radios, this one based on a TDA7088T. The original AM radio
works fine, well minimal hash from the buzzer mechanism of the vibrator 12V
to HV supply and the FM works fine with a proper linear mains derived HV
unit and the 12V to 3V ps. But try the FM off the original HV supply and the
hash from the buzzer mechanism makes it unlistenable to. Whatever I try in
the way of screening/ wire routing makes little difference. Any ideas before
rejecting the project?

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list onhttp://home.graffiti.net/diverse:graffiti.net/
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There used to be this FM tuner, back 30-40 years ago when most cars
came only with AM radio standard; FM and/or cassette cost extra. You
would mount this paperback-book sized unit below the dash, hook it
into power and add an antenna to a fender to pick up signal. On the
back was a switch that allowed you to select one of three AM
frequencies to which this FM Tuner's AM transmitter would broadcast
the audio to. You would then turn on the existing factory AM radio
and tune it to the AM frequency that matches that selected on the FM
tuner box. Voila - FM - mono! - but FM for sure! I don't know if
this is still manufactured or if most of them are in wrecking yards or
in peoples' garages gathering dust.

Basically it contained an AM transmitter similar to the FM transmitter
you'd plug a MP3 player into, nowadays, to transmit the MP3's audio
over a selected FM freq, IE 88.7 or 108.1 .

-CC