Subject: OT-- need plans for a wireless switch

From: [email-masked]
Date: Thu Jul 17 10:58:37 2003

I'm posting this here because, on the average, you guys are pretty 
smart.

I'm trying to put a push-to-talk switch on the steering wheel of my 
car so I can key the 2-meter ham radio while keeping both hands 
on the wheel. I've got a little boom mic and have built an interface 
box, but how to mount the switch has me stumped.

I picked up one of the velcro aircraft ptt buttons, which mounts 
nicely, but even with the relatively short turning radius of my 
Subaru it's still a good number of turns lock-to-lock and the coiled 
cord has a tendency to get snagged in the space between the 
wheel and steering column.

My next thought is to use the aircraft button, but with a tiny 
transmitter/battery mounted on the wheel, with a receiver mounted 
under the steering column with a keying relay.  Hit the button, the 
relay turns on, let up, the relay releases.

I've been Googling for a while, but most tiny transmitters are either 
for "spy" audio apps, or are multi-button jobs for garage doors and 
things like that.  All I need is a simple on/off fm transmitter that 
controls a simple relay on the receiver end, preferably powered by 
a couple of AA cells or similar, and the transmitter needs to be 
hackable so I can connect the wheel-mounted ptt switch.

Any suggestions?

I know this isn't directly related to Classiccmp, but it IS related to 
ham radio and electronics, and ham radio and electronics are 
related to hamfests, and hamfests attract computer collectors, so 
there.  I just made the connection.

Thanks.

Paul Braun
Cygnus Productions
[email-masked]

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From: Marvin Johnston <[email-masked]>
Date: Thu Jul 17 12:02:02 2003

> hackable so I can connect the wheel-mounted ptt switch.

It should be fairly trivial and inexpensive to use a wireless FM lapel
mike. The ones I've had were about 2" long and maybe 3/4" square. The
bigger problem would be to keep interference from keying your
transceiver, *especially* if you left it turned on in the vehicle.
Adding PL encode/decode might be one fairly inexpensive way of dealing
with that problem.

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From: John Lawson <[email-masked]>
Date: Thu Jul 17 12:33:00 2003

Why not just put a foortwitch on the floor - allowing hands-free
operation with no wire mess and trying to press a button and turn a corner
at the same time....

 Of course if you have a manual transmission this might be slightly less
than optimal, but I've done it many times with several vehicles - never
had a problem.

  Cheers

John  KB6SCO

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From: Tothwolf <[email-masked]>
Date: Thu Jul 17 12:51:00 2003

On Mon, 14 Jul 2003 [email-masked] wrote:

> transmitter/battery mounted on the wheel, with a receiver mounted under
> the steering column with a keying relay.  Hit the button, the relay
> turns on, let up, the relay releases.

Perhaps a near-IR LED with a 555 and a 9V battery would work for the
"transmitter"? Somewhere I have some plans filed away for something
similar. Depending on the output of the LED, and sensitivity of the IR
transistor used by the detector circuit, you might not be able to key
while making a turn, but then how often would you need to do that?

-Toth

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From: [email-masked]
Date: Thu Jul 17 13:09:00 2003

> I'm posting this here because, on the average, you guys are pretty

Not THAT smart, we just try harder than most people.
> there.  I just made the connection.

Scrap the button on the wheel idea --- I'd mount a good rugged switch on
the floorboard off to the left of the brake pedal.  Something on the order
of a headlight dimmer switch.

With power steering, you really don't need both hands on the wheel
anymore.  I can't remember back when, when I needed both hands to steer.

And I'd say a radio controlled 'PTT' might be a tad illegal under FCC
rules of controlling a radio with a radio link.  That, if you remember,
has to be done on frequencies higher than 222 MHz.

One thing I did years ago and people thought I was crazy until they tried
it --- mounting the microphone so that it hangs handy for the LEFT HAND
instead of the right.  Once you get used to it, it makes consommate sense.
 Keeps right hand free for steering, and automatic tranny shifting.  This
might entail an extension cable, and another mic jack mounted next to the
door somewhere on the dash.  In my case, the radio fit best on the LH
side.

Gary Hildebrand WA7KKP

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From: "Dave Brown" <[email-masked]>
Date: Thu Jul 17 16:50:01 2003

If you're really stuck on the 'wireless' solution, I think the cheapest
option has to be buying one of those 'el cheapo' wireless doorbells and
hacking it to do what you want.
DaveB
Christchurch, NZ

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From: Bryan Blackburn <[email-masked]>
Date: Thu Jul 17 16:54:00 2003

I second the motion! Use an IR link! Use of a frequency selective IR 
Tx/Rx system will prevent unwanted keying of your transmitter, and if it 
is anything like the ones I have built, the reflected signal will be 
enough to make it work (no need to be line of sight).

Using RF to create a link is asking for trouble, not to mention a lot 
more work. Check FCC regs, this is considered remote transmitter 
control. If you choose to go RF, use a coded transmitter similar to a 
remote entry key, not a PL based one, since even that is susceptible to 
interference. Holtek makes a few Tx/Rx chips with digital coding. You 
can buy the chips at digikey.com. (But don't use them! Go IR!)

-Bryan

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From: [email-masked]
Date: Thu Jul 17 21:40:00 2003

I'd think a bit about IR, because of the following:

My neighbor complained that my ham gear was turning her television set on.
 IR control was being triggered by sunlight wafting in through drapes and
blinds, and happened to hit the right pulse sequence to turn on the set. 
I've heard that is not unusual.

Being "outside", you might have something like that key up your
transmitter when you don't want it to.  I'd stick with a hardwire PTT
switch of some sort.

Gary Hildebrand WA7KKP

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From: Bryan Blackburn <[email-masked]>
Date: Thu Jul 17 22:09:00 2003

I wouldn't use a simple on/off IR signal. I'm talking about a modulated/ 
decoded signal. Sunlight will not affect that. An RF link is far more 
susceptible to RF interference than an IR signal (if the IR receiver is 
properly shielded, and most come already shielded). If the front end of 
an RF receiver becomes saturated, it is even more susceptible. Until 
now, I've never heard of a TV being activated by RF through the IR 
electronics. I won't say it can't happen, but I would not give it very 
good odds.

-Bryan

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From: [email-masked]
Date: Thu Jul 17 22:17:01 2003

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From: Mark Firestone <[email-masked]>
Date: Fri Jul 18 02:18:00 2003

I always wondered how they hooked up wiring to things that rotate, like 
helicopter blades.  With brushes?

>box, but how to mount the switch has me stumped.

[---------]
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From: Fred Cisin <[email-masked]>
Date: Fri Jul 18 11:27:00 2003

> helicopter blades.  With brushes?

by periodically running it in reverse to untwist the wires?

> >box, but how to mount the switch has me stumped.

disconnect the horn and use its button

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From: Vintage Computer Festival <[email-masked]>
Date: Sun Jul 20 12:31:00 2003

> there.  I just made the connection.

Nicely done.  You get a gold star :)

-- 

Sellam Ismail                                        Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger                http://www.vintage.org

 * Old computing resources for business and academia at www.VintageTech.com *

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From: "Paul Braun" <[email-masked]>
Date: Mon Jul 21 13:15:17 2003

> operation with no wire mess and trying to press a button and turn a
> corner at the same time....
>
Thought about that, but with the manual gearbox, the left foot gets 
a workout as well.  Plus, I have reasonably large feet, so the room 
up there is minimal.  I have a footswitch I can try for a while, to see 
if I can work it.
 
> than optimal, but I've done it many times with several vehicles -
> never had a problem.
> 
However, my main goal was to be able to talk while shifting, which 
requires my left hand to be on the wheel, my right hand on the 
shifter, and the left foot on the clutch....

I may not be able to make that happen.  The more I think about it, 
the IR or RF options have their own set of problems.  The hard-
wired, wheel-mounted switch works fine in race cars because they 
never have to go more than one turn lock-to-lock or so, therefore 
don't have to worry about the cable tangling.  Other option I just 
thought about is to put the switch on the column, on the left side, 
with a paddle that's wide enough to keep my finger on it while I'm 
making a mild turn.  If I need to make larger steering inputs, I can 
stop talking and concentrate on not hitting someone...

> John  KB6SCO

73,

Paul WD9GCO

Paul Braun WD9GCO
Cygnus Productions
[email-masked]

"A computer without a Microsoft operating system is like a dog without a bunch of bricks tied to its head."

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From: David Woyciesjes <[email-masked]>
Date: Mon Jul 21 13:23:01 2003

> stop talking and concentrate on not hitting someone...

	What about taking an idea from the NOS guys? They usually put the
switch for nitrous on the shifter handle, in the thumb position. Kinda
like a fire button on a fighter's control stick...

--
---   Dave Woyciesjes
---   ICQ# 905818

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From: John Lawson <[email-masked]>
Date: Mon Jul 21 17:48:37 2003

> up there is minimal.  I have a footswitch I can try for a while, to see

  Having a manual gearbox myself - it just now occurs to me that an
interesting place for the PTT switch might be on the gearshift lever,
under the knob somewheres...

   Hmmmm - got new truck, time for rig in same - hmmm...

  Cheers

John