FM-10 won't work!
Chris Alexander
and the transmitting range was (drum roll, please...) 2 inches! We built
the kit exactly as the instructions said. We used the capacitor for the
low end of the FM range, then tried to tune it to the right frequency. As
far as we could tell, it was working fine except for the transmission
distance, and the audio quality left much to be desired. The kit was
hooked up to a CD player when we tested it. Also, we used a 9 volt
battery for power.
We double-checked the board and could find nothing wrong. Anyone
have any hints that might get it working? Thanks in advance.
-chris (chris.a...@launchpad.oit.unc.edu)
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Robert Smathers
> I just finished building an FM-10 with my friend. We hooked it up
>and the transmitting range was (drum roll, please...) 2 inches! We built
>
>have any hints that might get it working? Thanks in advance.
Did you put _some_ antenna on it?
With a 12 inch piece of metal coathanger that I put on the PCboard
antenna terminal hole, I was able to get about 50 feet range.
Robert
rob...@triton.unm.edu
bma1...@vax1.utulsa.edu
Just a thought. The CD player probably has a volume control on it. If this
was turned down so too would the 'range' Try turning it up if that was
the case.
Mark
Clint Dimick
> I just finished building an FM-10 with my friend. We hooked it up
>and the transmitting range was (drum roll, please...) 2 inches! [...]
> We double-checked the board and could find nothing wrong. Anyone
>have any hints that might get it working? Thanks in advance.
Chris,
Check for cold solder joints on the PC board. They're dull in color, not
bright and shiny like a good connection should make. Also, are all of your
electrolytic caps in the right way, that is, + and - on the right sides? If
you have an OHM/voltage meter handy, check to make sure the FM-10 is actually
getting the 9V you think it is. One other thing you may want to check are the
components in the audio circuitry area. Wrong resistor values will definately
hamper the audio quality.
- Clint
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William A. Goldsmith
>and the transmitting range was (drum roll, please...) 2 inches! We built
>the kit exactly as the instructions said. We used the capacitor for the
>low end of the FM range, then tried to tune it to the right frequency. As
>far as we could tell, it was working fine except for the transmission
>distance, and the audio quality left much to be desired. The kit was
>hooked up to a CD player when we tested it. Also, we used a 9 volt
>battery for power.
>
> We double-checked the board and could find nothing wrong. Anyone
>have any hints that might get it working? Thanks in advance.
Since you do get *some* signal out of the FM-10, it's obvious that the
audio circuitry & all wiring to and from the IC is O.K. That makes the
most likely culprit the output stage: the transistor & its associated
components. Check all solder joints carefully. Make sure the transistor
is oriented properly. If it's bad, it can be replaced with a Radio Shack
2N2222 at least temporarily.
And, as someone else asked, you *do* have an antenna, right?
Good Luck!
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Rick Harrison
> > I just finished building an FM-10 with my friend. We hooked it up
> >and the transmitting range was (drum roll, please...) 2 inches! We built
A friend of mine built an FM-10 and reported the same problem.
It turned out he had tuned his receiver to one of the "spurs"
put out by the transmitter, rather than the main signal.
Dan D
Any hints for tuning it up? Fine tuning won't be a problem,
but short of a frequency counter I'd like some tips on tuning
the inductor to find an initial frequency. The coil needs a PLASTIC
tool to tune it, as metal would probably alter it. The problem is
finding a plastic tool that will work!!! (Any tips here?)
-DanD
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Robert Smathers
>I just got my FM-10 and finished soldering the whole deal.
>Any hints for tuning it up? Fine tuning won't be a problem,
Put on an antenna of some kind, turn on an FM radio to a frequency
not in use, turn on the FM10, and tune the FM10 until you hear
a quieting. Once you hear a quieting, put on an audio source to
make sure the quieting was caused by the FM10 and not by something
else.
>the inductor to find an initial frequency. The coil needs a PLASTIC
>tool to tune it, as metal would probably alter it. The problem is
>finding a plastic tool that will work!!! (Any tips here?)
Make your own if you have a piece of plastic you are about to throw
out. Other option is to just go buy one at an electronics store.
Plastic has to be somewhat stiff (cannot be flimsy or it won't
work). Just cut it so it tapers toward the end that you are going
to stick in the coil. You need to match the inside diameter of the coil,
so start out larger and take off little by little of the plastic on the
tapered end until it fits and will do the job. No biggie.
Robert
rob...@triton.unm.edu
Jim Large
> tool to tune it, as metal would probably alter it. The problem is
> finding a plastic tool that will work!!!
I used a thin bamboo skewer (find 'em in supermarkets). I whittled the point
until it was more or less triangular.
If you don't want to get so creative, go to Radio Shed and ask them for some
"alignment sticks".
-- Jim Large