[Elecraft] KPA100 speaker connector / iPod keyer

[Mike Markowski]

Hi Peter,

As Lew K6LMP says, you must jailbreak your iPod to install it from
http://iditdahtext.com/iDitDahText.html .  My son is 13 and of course had no
hesitation.  It's good to be young!  Like Lew, I was a little more anxious.  But
before I could pass along my worries, my son was showing me the running app.  He
says using you can restore your old settings to un-jailbreak the gadget.

As to the circuit, it's basically a bare bones VOX circuit & is exactly what you
guessed - PTT from audio.  The first op amp is set up with a gain of about 200.
 Its output goes into an op amp comparator whose other input comes from a pot,
and that output goes to an npn transistor's base to do the telegraph key
"tapping".  It was a fun effort.  The comparator output would at first switch at
the frequency of the iPod audio, so it was more of a gurgling sound.  Instead of
calculating numbers, we just tried different capacitors to fill in the
comparator breaks and watched on the scope, which made it more concrete and
easier to understand cause and effect for my son.  There are also coupling
capacitors and clamping diodes as well, but that's about it.

73,
Mike ab3ap

On 03/24/2010 08:10 AM, Peter Wollan wrote:
> I can't find this app on the iTunes Store, even with spelling
> variations.  There are several straight key apps, but no iambic that I
> can find.  Can you give a more detailed source for iDitDahtext?
> 
> The keyer circuit sounds interesting -- does it do a PTT from audio input?
> 
>     Peter N8MHD
> 
> On Tue, Mar 23, 2010 at 9:42 PM, Mike Markowski <mike.ab3ap at gmail.com> wrote:
> 
>> ... an avid iPod Touch user.  He put iDitDahText on it so that he
>> can web surf, text, email, all with cw input via an iambic keyer on the
>> iPod screen. ...  So now the ipod keys the rig (no modulated cw)
>>