Quick Condenser Mike question.....

[Les & Claire]

Hi all....
I know these things work on capacitance but do the lead in
wires have to be a certain length? Can I just tack some 2core on the board
and have a, say, 8ft length of wire to the mike? It's a mini fm transmitter
btw....

Les



--
Top PostingŠ Since 1997

"Oh Bother!" said the Borg, "We've assimilated Pooh!"

"That's 10 times I've explained binary to you. I won't tell you a 3rd time!"

 

[Lizard Blizzard]

Les & Claire wrote:

Hi all....
I know these things work on capacitance but do the lead in
wires have to be a certain length? Can I just tack some 2core on the board
and have a, say, 8ft length of wire to the mike? It's a mini fm transmitter
btw....

If the leads are short, you could use some twisted pair wire. The
capacitance of the wire has almost nothing to do with it. The reason
why you should use shielded microphone wire for longer lengths is
because the signal levels are only a millivolt or less. Using shielded
wire keeps out the AC hum.

One other factor that you have to consider with a mini FM Tx. The unit
itself radiates RF, and the microphone leads will be a part of the unit,
and also radiate RF. So shielded cable will help keep the RF out of the
mic input. Another thing that should be included is a ferrite bead RF
choke on the mic input lead, to reduce RF even further. A small 1 nF
capacitor at the base of the audio amp transistor will bypass any
remaining RF to ground.

Les
--

--
----------------(from OED Mini-Dictionary)-----------------
PUNCTUATION - Apostrophe
Incorrect uses: (i) the apostrophe must not be used with a plural
where there is no possessive sense, as in ~tea's are served here~;
(ii) there is no such word as ~her's, our's, their's, your's~.

Confusions: it's = it is or it has (not 'belonging to it'); correct
uses are ~it's here~ (= it is here); ~it's gone~ (= it has gone);
but ~the dog wagged its tail~ (no apostrophe).
----------------(For the Apostrophe challenged)----------------
From a fully deputized officer of the Apostrophe Police!

<<Spammers use Weapons of Mass Distraction!>>

I bought some batteries, but they weren't included,
so I had to buy them again.
-- Steven Wright

FOR SALE: Nice parachute: never opened - used once.

(Problem) Evidence of leak on right main landing gear
(Solution) Evidence removed

F
o
d
d
e
r

f
o
r

s
t
u
p
i
d
"
n
o
t

e
n
o
u
g
h

i
n
c
l
d
u
d
e
d

t
e
x
t
"
e
r
r
o
r

m
s
g
..

 

[Les & Claire]

Thanks very much... off to experiment!
Les


--
Top PostingŠ Since 1997

"Oh Bother!" said the Borg, "We've assimilated Pooh!"

"That's 10 times I've explained binary to you. I won't tell you a 3rd time!"


"Lizard Blizzard" <NOSPAM@rsccd.org> wrote in message
news:bljvpp$4bak7$1@hades.csu.net...

Les & Claire wrote:
Hi all....
I know these things work on capacitance but do the lead
in
wires have to be a certain length? Can I just tack some 2core on the
board
and have a, say, 8ft length of wire to the mike? It's a mini fm
transmitter
btw....

If the leads are short, you could use some twisted pair wire. The
capacitance of the wire has almost nothing to do with it. The reason
why you should use shielded microphone wire for longer lengths is
because the signal levels are only a millivolt or less. Using shielded
wire keeps out the AC hum.

One other factor that you have to consider with a mini FM Tx. The unit
itself radiates RF, and the microphone leads will be a part of the unit,
and also radiate RF. So shielded cable will help keep the RF out of the
mic input. Another thing that should be included is a ferrite bead RF
choke on the mic input lead, to reduce RF even further. A small 1 nF
capacitor at the base of the audio amp transistor will bypass any
remaining RF to ground.

Les
--




--
----------------(from OED Mini-Dictionary)-----------------
PUNCTUATION - Apostrophe
Incorrect uses: (i) the apostrophe must not be used with a plural
where there is no possessive sense, as in ~tea's are served here~;
(ii) there is no such word as ~her's, our's, their's, your's~.

Confusions: it's = it is or it has (not 'belonging to it'); correct
uses are ~it's here~ (= it is here); ~it's gone~ (= it has gone);
but ~the dog wagged its tail~ (no apostrophe).
----------------(For the Apostrophe challenged)----------------
From a fully deputized officer of the Apostrophe Police!

Spammers use Weapons of Mass Distraction!

I bought some batteries, but they weren't included,
so I had to buy them again.
-- Steven Wright

FOR SALE: Nice parachute: never opened - used once.

(Problem) Evidence of leak on right main landing gear
(Solution) Evidence removed

F
o
d
d
e
r

f
o
r

s
t
u
p
i
d
"
n
o
t

e
n
o
u
g
h

i
n
c
l
d
u
d
e
d

t
e
x
t
"
e
r
r
o
r

m
s
g
.