Richard,
That's the chip eric mentioned. Your friend would have to decide how that
particular kit might interface to the system you're planning to use.
Assuming the chip is available as a component, it should be much less than
$30.00.
Tom Fowle WA6IVG
On Thu, Nov 26, 2015 at 12:13:47PM -0800, 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
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