The problem was, I didn't want to PAY for a desk mic! hehe. What's a ham
to do? Then I got an idea. (that's alright, I winced too! hi hi)
I had previously bought a Radio Shack studio microphone model 33-3030
that I was using for I-Link and Echo Link contacts on the computer.
The audio level on the computer with this mic was a little lower than the cheap
plastic mic that I got with the computer but the sound was better.
The thing had a 1/4 inch mono jack so I had used an adapter to size it down
to 1/4 for the computer.
So that was my idea, I would build a 'break out' box for
my hand mic and for
this studio mic! Off to radio shack I went to pick
up the things (I thought) I needed!
I found a nice looking plastic project box there that
looked about right and then
went over to the components section to find mic connectors
and such.
They didn't have a mono 1/4 inch jack in stock so I grabbed
a stereo jack
and would only use 2 connectors. Found a really
neat looking ON|OFF|ON switch
to flip between the two mics. It was a double pole
double throw (think I got that right)
which was more than I needed but I figured I would just
use half of the switch.
(more on that later) Then I went hunting for the 4 pin
microphone connectors I needed.
What? Oh sorrry. Your right, I DO have an
Icom 730 and it DOES use an 8 pin
connector on the rig for the microphone. Well I
bought the rig used and it didn't come
with the standard mic, it came with a 4 pin icom mic,
don't know what model, and a
small home brew patch cable to size it down. One
end just has a rig-side connector
soldiered to it to attach to the mic. Anyway I
wanted to use the 4 pin mic.
Well as it turned out that was just as well because after
having now hit a few stores
I haven't found any 8 pin radio-side male plugs yet!
Have found some female mic
plugs but no males. Have a few more places to check
though.
(Yah yah, I could order them online)
Anyway after the first trip out of RS here is what I
had bought:
1 on|off|on switch
1 quarter inch stereo jack
1 male four pin mic jack (rig side)
1 female four pin mic jac (microphone side)
I also grabbed extras on some of these items and some
other stuff that I thougth I might
play with later on other projects.
A quick first shot, I used a battery powered dremmel
tool for most of the work.
I have a 120v powered dremmel but it does not have variable
speed and was
too much for some of the work, though I did use it a
bit. Anyway the reason
I left it in this picture is to point out that the round
sander tip that I have on it
is almost a PERFECT match size wise for the4 pin connector!
It dropped right in!
Top view, I have both microphone connectors installed
now for fit check.
There is the fancy on|off|on switch I liked so much!
Impressive! The hole on the side
is not where it mounts but is where I am going to mount
the connector to wire this box
to the microphone input on my rig.
Here is a shot with the switch insalled. As you
can see it has 6 terminals which is 3 more
than I had planned on needing for the job!
This works out to my benifit as you will see later!
Yes, there IS an extra switch there. I'm trying
to remember why but nothing
is coming! hehehe. At this point I had never actually
put anything down on
paper design wise. That was soon to change though!
I think I had originally
planned on using an on|on switch here to shunt the PTT
push to talk to one
mic or the other. The switch installed though is
just an on|off type.
The new 1/8 jack reciever there below the small switch
is for a PTT, or Push To Talk
switch that I will run out on a cable and lay on the
desk for the Studio Mic.
So we have the two microphone jacks on the left, the
small switch that I don't know
what I'm using it for yet, the PTT jack below that and
the master ON switch on the right!
Inside view. I had to use the dremmel to sand down
some of the ridges inside, the ridges
are if you wanted to put deviders in the box or slide
PC boards in here (which I should
have used, hi hi)
"What is that?" your asking! Well the rubber looking
thing on the top left sticking
out of the box is actually a rubber grommet designed
for sliding up over Coax
connectors and protecting them, In this case though I
had a design problem.
(that's spelled "Brain Fart" fror the rest of you!)
If you remember I said the previous owner hade made a
patch cable to go from the
rig to the microphone. The end that attaches to
the microphone is male (obviously)
so I either needed to replace the male with a female
and put the male on the box or
leave the male on the cable and figure out some way to
put a female connector on
the box. I didn't see any female connectors that
were made for a surface mount so
this rubber grommet is what I came up with.
The reason why I didn't change the ends and do it the
'easy' way was because
this patch cable was the only way I had to connect my
mic to my rig and I
hadn't (still haven't) made an extra cable. I just
extended the cable though. Later
I will make a short female to female and replace the
gromet thing on the side with
a flush mounting male connector.
Wiring up the On|off|on switch. At this point I
decided to use the bottom 3 connectors
to control the ptt and the top 3 to control the + side
to the mic element. I'll stuff the female
mic connector inside the rubber grommet after I get it
wired up.
Wiring up the mic connector, the knot in the wire is
to let me know that is a ground
wire. I do that since I don't use different color
hook up wire (yet). If you look hard
you will see that there is a capacitor attached to the
end of one of the wires. This is
there because my Icom radio has 8.2 volts on the microphone
pin. That's great if you
are using an electret mic that need voltage but a Dynamic
mic doesn't and therefore
I needed to block/drop the voltage. At this point
in the game I had (shaking head) assumed
that there was a preamp built into the mic. Not
so!
Now we're wiring in earnest! What's with the pig
tails you ask? I couldn't find my white
tape so I just put a loop in the wire for each pin number,
2 loops for pin 2, 3 for pin 3, etc.
did this for both microphones and tied knots in other
wires for the other switches that
required grounds.
Different view, have some heat-shrink tubing on some
of the wires. Yes that is a resistor
soldiered on a wire there. Will explain that later.
Here is a good front shot when I thought I had everything
the way I wanted it. Note the femail
Mic sticking out the left side of the box.
Another shot.
THIS is the result of me finding out that I DID need
a microphone pre-amp inline
for the Studio Microphone. Day 1 picture. This is a very
simple 1 transistor microphone amplifier
that was designed by a guy (I'll insert links and name
here late when I find them)
((Dang! I just missed some dx on 10m in brazil!
Too slow.) that had built it for
some non-ham related project. The design called
for using either an electret mic or
a dynamic mic so instead of altering the plan (and because
I thought it would be neat)
I left it and drilled yet ANOTHER hole (1/8 inch) for
the electret mic and made this
a 3 microphone rig! hi hi hi :) Notice the new
outlet between the two mic inputs above.
Currently to use the 1/8" electret you have to unplug
the 1/4" dynamic but I will add a
flip switch later. I did not have one so
just went without it for now since I will
not use an electret very often I think. (but who
knows!) By the way, most cheap
computer plastic microphones are electret! A low
cost desk mic! hi hi.
Day 2 picture. Good thing I got some sleep and
then went back as I had connected a
resistor in the wrong place! Also note the diode
light on the right! The plan originally
called for running the circuit on a 9v battery which
is why you see the connector there
but I changed it below and wired it off of a 9v wall
wart plug transformer that I had laying
around in a box. I had a female socket that I had
scrapped from something that fit anther
9v adapter that was dead so cut the good end off of the
dead unit and soldiered it on
the good wall wart! I powered it off of a 9v battery
for test purposes and it lit up and
did NOT smoke and burn! heheh. Always a good thing!
Below is the final product!
Neat-o huh? :) I'm very happy with it so
far! It is always fun to build stuff.
Well fun when it goes well, hehehe. I will later
need to change the female mic
plug on the left to a male and make an adapter cable
and I need to find some way
to add some more weight to the box, it is very light
and slides around too much.
Some rubber feet in addition to weight will help too.
Here it is with the station all hooked up!
Will get a closer shot of it later! I want to replace
the microphone stand later with one of those clamp-on
models, this one takes up desk space
and tips over easily if you bend the flex-tube too much.
Not good! I have the Morse key on
the table hooked up to the front of the box and am using
it for a PTT Push To Talk circuit
right now until I can get around to making a push button
switch.
Just adding the main power switch for the box, to the left of the LED.
'Temporarily finished' with yet another toggle switch! To the
left of the power switch is a toggle
to flip between the two desk microphones!
Schematics and diagrams for assembly to come SOON!!
This is NOT a completed project, it's functional now but I have some more things that I want to add to it to add to it's functionality.
In the works will be adding an up/down scan button to control the VFO! I'm thinking about incorporating the ptt in the same control to minimize the wires laying out on the desk. Using a 3 button mouse is an idea I've been playing with!
Also I will (when I get around to doing the schematic) be adding in-line relays to control other devices. Should be fun!
(Update Feb 04, 2003)
Bought the relays today but (Doh!) forgot to pick up the switches and extra goodies that I needed. (brain dammaged I guess, hi hi!) Below is the schematic that I finally got around to drawing up. Please note the following though: I have the grounds marked either 'm' or 'c' for 'mic' or 'common'. The common grounds I have ran to the PTT ground and the mic grounds to the mic ground. I have not implimented a number of things that I have put on the schematic.
2. Relay assembly in the top-right section of the page. Have the relays bought but have not added them yet.
NOTE: The 4 pin connections for the hand mic and going to the rig are for my ICOM-730. I also have a box above with 8 pin connectors in it for reference. These are the pin-outs for my icom-730 rig. Refer to your MANUAL for YOUR microphone pinout!
update 2-6-2003: On the electret mic, if your using a stereo mcirophone plug (3.5mm) that has tip, ring and shaft then you need to MOVE the line going from the bottom of the 4K7 resistor away from the connection point where it now attaches below the 10UF capacitor and instead connect it to the RING section of the 3.5mm reciever. Sorry about the mix up. In my diagram it looks like my 3.5mm mount is stereo but what I have mounted is actually mono. I tried using my stereo jack in the mono and the thing just didn't work, I don't think it would go far enough in. I added a plug addapter to the stereo plug to make it mono and it worked just fine. Better yet don't mess with a stereo plug at all unless you just have one laying around, stick with mono.
Even though I have the above correction listed for the stereo connection. It will probably work just fine the way it is in the diagram since most microphones (computer electret) that have stereo plugs go right down to just two wires anyway.
LATEST UPDATE: The switch in the schematic that flips between the electret mic and the dynamic mic may be mis lableled. I'll change it soon, I actually went with a single pole double throw (just installed and tested) which has 3 pins. The center to ground and the ground wires from each of the mic receptacles to the other two. Easier. (that and I bought the wrong switch, hi hi!) Installation of the relays is postponed until I get a bigger box!
WARNING!The pin-out for the 4 pin microphone below is for MY microphone. If you have a 4 pin is is most likely different! Don't assume it is the same, check it! :)
If your not used to schematics then please pay close
attention to the way I have the resistors labeled, the writing is a bit
small. EXAMPLES: 120R Means a 120 ohm resistor, 2k2 means a 2.2K ohm resistor,
ect.