Strange how-to question(s)
Dan Beck
I own a vintage (1968) automobile, equipped with a vintage radio. The
previous owner installed slightly more modern speakers. The radio works,
adequately. However, it is not able (of course) to accept my mp3 player as
a signal source. As I stare at the pinout data of a USB connector methinks
I could cobble a few devices together, splice it into the connections for
the radio, and it would work, while drawing the 12 VDC current from the
battery for power. (I like the look of the old radio; yes it would be easy
to install a modern radio with the USB connector, but that is not what I
want...) However, I do not understand exactly the D- and D+ signal lines
from the USB; are these considered line level sources? Also, I probably
would need some type of step down device to convert the 12 VDC to 5 VDC?
Thank you in advance for any and all ideas!
Regards,
Dan
Tom Biasi
"Dan Beck" <do...@v8.invalid> wrote in message news:gbu3cu$61b$1...@aioe.org...
Hi Dan,
The D lines are data lines. The USB port is a sereal connection not audio.
There are ways to get the audio into your radio but a schematic would be
nice.
Sometimes you need only tap the volume control and supply the proper level
audio to the radios amp section.
I can't tell without seeing a diagram.
Tom
Tim Wescott
If the radio receives FM, you can get little flea-powered transmitters
that connect to the headphone jack and let you listen on the radio.
If it only does AM you can do similar, but you may have to build the
thing yourself.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
john jardine
"Tim Wescott" <t...@seemywebsite.com> wrote in message
news:faSdnYjJW_FaM3_V...@web-ster.com...
Exactly.
Just now working up a small AM Tx design for a friend who does old car
radios. Goes ... device audio connector, into modulator of battery powered,
couple of mW, Tx oscillator, trimmed to Tx in a quiet area of AM band.
biscui...@cableone.net
Hello all,
thank you for your messages! Some followup information/questions are
following.
The radio is AM/FM; I have used those FM transmitters before, with
only mediocre performance.
Are the signals that come out of the headphone jack analog? I would
presume so; please correct me if I am wrong. If they are indeed
analog, does it follow that those signals could be routed into the
amplifier circuit of the vintage radio? If this is feasible, what
would I need to do to make sure the signals from the radio reception
are not "combined" with the new (mp3 device) signals, resulting in a
garbled mess?
Again, thank you for your patience in reading my messages, and for any
ideas you may have!
Regards,
Dan
Tim Wescott
least he is if you can get your hands on schematics).
Tim Wescott
Yes, the headphone jack signal is analog. So far at least headphones
are dumb devices, they don't get signal so much as they get audio drive,
which must be analog.
To really do this right you'd need to switch out the audio from the
receiver and switch in the audio from the MP3 player. This can be done
with varying levels of success and attractiveness by a good audio
technician with a schematic of the radio. Someone who's _really_ good
may even be able to figure out how to switch the thing over
automatically, without putting some out-of-place modern button on your dash.
I'd hate to rip into a vintage piece of hardware like that, though.
pork...@yahoo.co.uk
this could be even easyer.. right 2 questions,
1, do you realy need to use the radio... or could you just have it for
show..
2, have you a place to hide small electronic devices...
well heres my idea, buy a small amp, set the volume to 50-75% of max
of amp, then connect the speakers to the amp connect the mp3 player at
low volume then power on. you use the mp3 player volume up and down
Dan Beck
>> Yes, the headphone jack signal is analog. So far at least headphones
> are dumb devices, they don't get signal so much as they get audio drive,
> which must be analog.
>
> To really do this right you'd need to switch out the audio from the
> receiver and switch in the audio from the MP3 player. This can be done
> with varying levels of success and attractiveness by a good audio
> technician with a schematic of the radio. Someone who's _really_ good may
> even be able to figure out how to switch the thing over automatically,
> without putting some out-of-place modern button on your dash.
>
> I'd hate to rip into a vintage piece of hardware like that, though.
>
> --
>
> Tim Wescott
> Wescott Design Services
> http://www.wescottdesign.com
>
> Do you need to implement control loops in software?
> "Applied Control Theory for Embedded Systems" gives you just what it says.
> See details at http://www.wescottdesign.com/actfes/actfes.html
Hi Tim,
thank you for the additional thoughts. I suspect a schematic for this radio
may be a dinosaur egg. Couple that with the small possibility that I could
actually find someone to do the work you suggested makes me think this
project is not possible. Tearing into the vintage hardware may not be the
best thing, either... However, I will start looking for a schematic now!
:-)
Regards,
Dan
Michael A. Terrell
I have most of the Sams car radio manuals, and they covered US
factory radios of that era. http://www.servicesoftware.com/sams.asp has
an online index, or you can download the database for your persoanl use
on your computer.
http://www.samswebsite.com/photofact/pf_search.asp?aff=ServSoft is the
online directory.
--
http://improve-usenet.org/index.html
aioe.org, Goggle Groups, and Web TV users must request to be white
listed, or I will not see your messages.
If you have broadband, your ISP may have a NNTP news server included in
your account: http://www.usenettools.net/ISP.htm
There are two kinds of people on this earth:
The crazy, and the insane.
The first sign of insanity is denying that you're crazy.
Bob Masta
Actually, you can do this without a schematic. As
Tom Biasi suggested earlier, you need to tap into
the volume controls. Find the "top" lug (the one
the slider contacts when the volume is at max) and
unsolder the wire(s) going to it. (In this
vintage radio I suspect that this will be a normal
wired connection, not a PC-mount pot.) That wire
is the radio's audio signal, and the now-bare top
lug is the volume control input to the power amp.
If the radio is stereo, then you'd do this for
both channels (dual-ganged pot). You then use a
DPDT switch (SPDT if mono) to switch that top lug
between the orignal wire or the headphone output.
Note that car radios typically have a second
function on the same shaft as the volume (either
tone or balance), so you need to pay attention to
which pot sections are volume... always the inner
knob AFAIK.
Depending on the oufput level from the MP3 player,
you might need to provide extra attenuation there.
Or, if the radio is mono, you might need to add
series resistors from each headphone channel to
the SPDT lug, to sum them together. (Try 10K)
Other than that, this is a conceptually simple
mod, whose difficulty mostly depends on how hard
it is to get at the pot lugs. There may be a lot
of mechanical stuff in the way due to the station
selector, tuning dial, etc.
Best regards,
Bob Masta
DAQARTA v4.50
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
FREE Signal Generator
Science with your sound card!
Dan Beck
"Bob Masta" >
Hi Bob,
thank you for your input! If I may indulge you with another question that
will display my ignorance...
Ok, so now I have my wire coming out of the headphone jack, that I need to
splice into the SPDT switch (the radio is mono). I believe that wire will
actually consist of two wires in the plug connector. My presumption is I
cut off the plug connector, isolate and strip the two wires, splice them
together, and solder to one of the posts on the SPDT switch? If they are
necessary, where should I insert the resistor(s)?
Regards,
Dan
ehsjr
Below shows MONO (2 wire) out from the MP3 to the radio.
The resistors aren't needed and you do not splice the
two wires in the plug together. One goes to the radio
ground, the other goes to the switch.
Radio SPDT Player
-----------o o--------------------+
o |
| |
/ ====PlUG
\ |
------->/ |
\ |
| |
|
Gnd --------------------------------+
The resistors are needed if you use STEREO out from the
player, and there will be two wires plus ground in the plug.
Radio SPDT Player
-----------o o---+---[R]---------+
o | |
| +---[R]--------- ====PLug
/ |
\ |
------->/ |
\ |
| |
|
Gnd -------------------------------+
Usually, the ground wire is a braided shield around the
other two wires.
Ed
Jasen Betts
> Are the signals that come out of the headphone jack analog? I would
> presume so; please correct me if I am wrong. If they are indeed
> analog, does it follow that those signals could be routed into the
> amplifier circuit of the vintage radio? If this is feasible, what
> would I need to do to make sure the signals from the radio reception
> are not "combined" with the new (mp3 device) signals, resulting in a
> garbled mess?
>
> Again, thank you for your patience in reading my messages, and for any
> ideas you may have!
I have a vintage radio book somewhere ("Lamphouse Radio Data Book" (two
shillings and sixpence)) that explains how to connect a phonograph pickup
to the volume potentiometer of a valve radio...
basically what you do is examine the potentiometer behind the volume
knob, it'll have three terminals one is in, one is out, and one is ground,
usually the middle one is out. and one of the end ones is ground, and
the other is in.
what you do is disconnect the in wire and connect your programme source
(phonoghaph, cd player, whatever) to the in terminal.
if you want to get tricky you can use a switched socket here so
unplugging your source will recconnect connect the radio's tuner.
if care is taken this modification will be reversible, so it may not
devalue the radio...
Bye.
Jasen
Nemo
...
>mp3 player
...
>drawing the 12 VDC current from the
>battery for power.
>I probably
>would need some type of step down device to convert the 12 VDC to 5 VDC?
Hmmm... that 12V rail could be very noisy. Back in 1968 they may not
have appreciated the value of suppression devices on the rails (these
days you have a capacitor or something across the spark plugs) - so you
probably want some kind of fast voltage clamp on the supply which can
protect against fast positive and negative spikes. Not just a zener
diode (they may not be fast enough) but perhaps a unidirectional
tranzorb. So your supply should probably be something like
12V / 0V rail from battery ---> pass the 2 wires through a tube of
ferrite to filter out common mode noise, possibly looping the wires
through more than once ---> 1A slow-blow fuse ---> 18V tranzorb across
supply ---> 7805 linear regulator, possibly with small heatsink.
On second thoughts the 7805 has a fairly high quiescent current which
could drain your battery so you need an on/off switch too.
--
Nemo