Thread: toroid cores?
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Old July 19th 06, 08:37 PM posted to rec.radio.amateur.homebrew
Gregory D. MELLOTT Gregory D. MELLOTT is offline
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First recorded activity by RadioBanter: Jul 2006
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Default toroid cores?

Jamie wrote:

In ,
Scott mentions:
Well, I'm not sure about a lot of the questions you asked, so I would
suggest waiting to hear from others for ideas or, in true hamming
spirit, give it a go and see what happens

I wish you good luck...it sounds like an interesting project!


Thanks.

Looks like I may have fried the FET. :-(

No matter what I did, I simply could not get feedback. I hooked an LM368 audio
amp pretty much directly to the RF signal generator and I could vaguely hear it,
so... I'm thinking the reason it was working the way it did (with the "station"
comming in stronger as I tuned it) was simply the LM386 acting like a detector
in a TRF radio :-/ (The thing that confused me was, if I held an AM radio really
close to the coil, I DID get some interference, but I couldn't hear a squeal in
the speaker of my radio.

I put it away for now, I do have another FET I could f^Htry, but.. I don't want

to
damage it.

I was thinking about removing the pot entirely and using a rotating "inner coil"
serve in it's place:

+v ------ (tickler coil) --- [D|G|S] --- audio out

(Basically using both sides of the FET)

Hooking the tank circuit up to the gate, just as before but eliminate the
parts for controlling the tickler, sort of like this:

() with being the tank coil and the () being a coil inside the 's
in such a way you could turn it, controlling the tickler by changing
it's angle.

I've seen old regen radios that appear to do something like this, but

constructing
a coil that can be turned (w/out changing the tank and input coil's value) look
tricky. A plastic ink pen could be the shaft for turning it, but keeping it
in the center w/out wobbling..

As the parts MUST come from garbage, precise values are hard to get.

To remove them is a good thing. :-)

Not today though....

Jamie


Hi,

My luck (quite some time ago) with FETs was not nice either. Someone may have to
correct my, yet the only way I think one can get away with fiddling with the
things the way most people construct, might be to use zener diodes between the
gate and source and drain. Once its all together and apparently functioning one
probably could remove them then with less worry about then getting a little
static jolt and ruining the junction. Tubes are a lot more forgiving.

Sincerely,

Gregory D. MELLOTT