Adding digital frequency display on analog car radio?

[Chaos Master]

I have a good old Bosch(sp?) car radio. The main problem is that it has analog
tuning and frequency display (i.e. you have to read on the scale and the scale
is barely readable at night), and I am used to digital tuning. I wonder if I
could add digital frequency display or tuning on this radio?

Thanks.

 

[Roy J. Tellason]

I have a good old Bosch(sp?) car radio. The main problem is that it has
analog tuning and frequency display (i.e. you have to read on the scale and
the scale is barely readable at night), and I am used to digital tuning. I
wonder if I could add digital frequency display or tuning on this radio?

Thanks.

I had one cheap stereo with a "digital" frequency display that I had
schematics for, and what they did was to tap into the output of the local
oscillator, and then somehow manage the offset between that and the actual
tuning frequency. Not a project I think I'd care to take on...

 

[Joel Kolstad]

I have a good old Bosch(sp?) car radio. The main problem is that it has
analog tuning and frequency display (i.e. you have to read on the scale
and the scale is barely readable at night), and I am used to digital
tuning. I wonder if I could add digital frequency display or tuning on
this radio?

Absolutely; this is quite popular for amateur radio operators using older
equipment. See here for one popular option: http://www.aade.com/#dfd

---Joel Kolstad

 

[Chaos Master]

I found ancient runes from Joel Kolstad[[email protected]] in the
floor of sci.electronics.design:

Absolutely; this is quite popular for amateur radio operators using older
equipment. See here for one popular option: http://www.aade.com/#dfd

Interesting site. I remembered seeing, in some site, info about adding digital
readouts for ham radios. But I didn't remember the link. Thanks!

 

[Herbert Blenner]

Subject: Adding digital frequency display on analog car radio?

From: Chaos Master [email protected]
Date: 11/6/03 5:43 PM Eastern Standard Time
Message-id: <[email protected]>

I have a good old Bosch(sp?) car radio. The main problem is that it has
analog
tuning and frequency display (i.e. you have to read on the scale and the
scale
is barely readable at night), and I am used to digital tuning. I wonder if I
could add digital frequency display or tuning on this radio?

If you live near a city, the radio signal at the input to the first mixer would
be sufficient to drive a frequency counter.

Herbert

 

[Tim Shoppa]

I have a good old Bosch(sp?) car radio. The main problem is that it has analog
tuning and frequency display (i.e. you have to read on the scale and the scale
is barely readable at night), and I am used to digital tuning. I wonder if I
could add digital frequency display or tuning on this radio?

Your radio has one local oscillator for each band (assuming it
has both AM and FM). Measure the local oscillator frequency (frequency
counter) and add/subtract the IF frequency (different for AM and
FM, although I've seen some strange things...) to get the frequency you're
tuned to. This is a single-PIC thing for the AM band, for the FM band
you will probably need some sort of prescaler.

Most AM/FM radios shut down the LO for the band not in use, though not
all do.

Personally I don't see what's wrong with an analog tuning scale, and think
they're way superior to digital readouts if not-too-far-off-calibration.
Most OEM radios are very readable at night unless the light bulb
for illuminating the scale has burnt out. Lots of the aftermarket radios
are way inferior in this respect.

Tim.

 

[Tenho Hätönen]

I have a good old Bosch(sp?) car radio. The main problem is that it has analog
tuning and frequency display (i.e. you have to read on the scale and the scale
is barely readable at night), and I am used to digital tuning. I wonder if I
could add digital frequency display or tuning on this radio?

Thanks.

Hi, try get a Finly BBC-112 World Radio. It is a cheap (in finnish shops 9.9
Euros , ~10$ !!) multiband AM, 8 SW and FM receiver. It is powered by two
'AA' cells, has analog tuning and a digital display, which has ready
programmed selectable IF offsets for 455 kHz and 10.7 MHz . The dislay is a
separate unit and can be easily separated from the receiver and connecting
it to your Bosch should not be any problem. I have not seen a schema for
the Finly, but its main features including the connection pins of the
display have been 'reverse engineered' here http://finly.minidns.net/.
Unfortunately the text is only in finnish, but the pictures and tables
should be clear enough to get you going. In case you are interested, I can
translate the essential parts for you.
As a radio this set is not good, the sensitivity is poor and the image
rejection does not exist! The FM is quite usable though, considering the
size and price.
Hope this helps,
Tenho Hatonen