something like that. :)
the price sounds about right for the IC and the associated components.

DE n7zzt Eric

On Nov 26, 2015, at 1:13 PM, Richard B. McDonald wrote:

> Hi Tom and Eric!
> 
> see the link that follows (you have to scroll down just past the "Shopping
> Cart").  Here I found a "1Hz - 2MHz XR2206 Function Generator Kit" for ~$30.
> Is this what you guys are talking about?
> 
> http://www.electronics-diy.com/store.php?sel=kits&sub=function_generator
> 
> 73,
> Richard KK6MRH
> 
> -----Original Message-----
> From: For blind ham radio operators [mailto:[log in to unmask]]
> On Behalf Of Tom Fowle
> Sent: Wednesday, November 25, 2015 8:42 PM
> To: [log in to unmask]
> Subject: Re: Fox Hunting Directional Antenna for the Blind
> 
> Eric,
> I'm pretty sure that the XR2206, like many of the neat XR chips, is no
> longer available, but yes that is a good option if available.
> Tom Fowle WA6IVG
> 
> On Wed, Nov 25, 2015 at 09:24:20PM -0700, Eric Oyen wrote:
>> ok,
>> let me chime in here. I had some experience building vco circuits back 
>> = when I could see to do so.
>> 
>> the simplest (assuming you can still find them) are the XR-2206 
>> function = generator IC (it has a vco built in) and a standard garden 
>> variety op = amp. use the op-amp on the non-inverting input and use a 
>> negative = feedback system (run a line through a resistance from 
>> output to = inverting input). Once the gain level is set, the vco will 
>> have = sufficient voltage to work with. Properly setup, this has a 
>> wide number = of applications and can be run on a single 9 volt 
>> battery. check with = your sighted tech friends and see if they can put
> this puppy together.
>> 
>> DE n7zzt Eric
>> 
>> On Nov 25, 2015, at 8:40 PM, Tom Fowle wrote:
>> 
>>> richard,
>>> How you adapt the directional system depends entirely upon what kind 
>>> =
>> of
>>> signal is available from it.
>>> =20
>>> Let's assume the unit to be modified has a regular old fashioned 
>>> meter  movement  which indicates how well the antenna is aimed at the 
>>> fox.  =
>> If the
>>> meter simply reads "higher" when more closely pointed, it's pretty =
>> easy.
>>> =20
>>> In that case you need a VCO which can look at the voltage across  
>>> the meter,  usually 50 to 100 Milivolts
>>> =20
>>> A slightly trickier system uses a so-called "zero center" meter 
>>> which =
>> shows
>>> whether you're aimed left or right of the fox. These meters actually 
>>> =
>> measure
>>> current in either direction  This would need a bit of fiddling 
>>> before =
>> being
>>> applied to a VCO.
>>> =20
>>> =20
>>> There are gobs of such vco circuits available from transistorized 
>>> ones  designed in the 1950s to specialized chips and 
>>> microcontrollers.=20
>>> =20
>>> If all you need is a "relative" indication, not the ability to get 
>>> an =
>> exact
>>> measurement, I'd suggest the transistorized circuit for its =
>> simplicity.
>>> =20
>>> You and your friend can find many such circuits in plain text format 
>>> =
>> in:
>>> The Smith-Kettlewell Technical File
>>> https://legacy.ski.org/rehab/sktf/index.html
>>> =20
>>> Search the magazine for "audio gimmick" circuits or "meter readers" 
>>> =
>> and
>>> you'll find more than you'll ever want.
>>> =20
>>> the only issue for your presumably sighted friend is that the =
>> schematics are
>>> text discriptions not schematic drawings. Sometimes it's fun to have 
>>> =
>> the
>>> sightlings be at a small disadvantage <GRIN>
>>> =20
>>> If I can help with more specific choice of circuits or related 
>>> stuff, =
>> please
>>> email me either on list or directly.
>>> Tom Fowle WA6IVG
>>> =20
>>> On Wed, Nov 25, 2015 at 09:36:41AM -0800, Richard B. McDonald wrote:
>>>> Hi!
>>>> =20
>>>> =20
>>>> =20
>>>> In a few months, my club is going to do some fox hunting 
>>>> activities.  =
>> My
>>>> question here relates not so much to making the "antenna" itself 
>>>> per =
>> say,
>>>> but rather to making an audible tone direction indicator.  I think 
>>>> =
>> this
>>>> thing is called a "V C O?"  Basically, the V C O causes the pitch 
>>>> of =
>> a tone
>>>> to change as the direction finding antenna is pointed towards the =
>> fox.
>>>> =20
>>>> =20
>>>> =20
>>>> A very techy friend of mine in the club is going to build this =
>> contraption
>>>> for me, including the antenna itself.  He has some ideas.  However, 
>>>> I =
>> wonder
>>>> what others here on our list have done?
>>>> =20
>>>> =20
>>>> =20
>>>> 73,
>>>> =20
>>>> Richard KK6MRH