TTL homebrew CPUs - OT radio

[dwight elvey]

>From: Allison <ajp166 at bellatlantic.net>
>
> >
> >Subject: Re: TTL homebrew CPUs - OT radio
> >   From: woodelf <bfranchuk at jetnet.ab.ca>
> >   Date: Wed, 11 Jul 2007 14:52:31 -0600
> >     To: General Discussion: On-Topic and Off-Topic Posts 
><cctalk at classiccmp.org>
> >
> >Roy J. Tellason wrote:
> >
> >> Since a lot of parts like UJTs aren't ax commonly available as they 
>used to be
> >> I poked around some and found stuff  online as to how one might "make" 
>one
> >> using a complementary pair of transistors.  Couple each base to the 
>other
> >> one's collector,  and you have an SCR,  an SCS,  or a PUT,  depending 
>on how
> >> you wire it up.  Not all that much difference between them...    :-)
> >
> >Well I found this surfing last night. Fet + Pnp = Strange radio.
> >http://www.schmarder.com/radios/solidstate/homodyne.htm
> >
>
>That is a simple DC coupled amp that is used to first amplify RF then
>the detected audio is passed through again.  The fet is for high input
>impedence and the transistor is for increased gain. Other wise know as
>a reflex receiver.
>
Hi
No, it looks a little like that but it is not a reflex. It is a homodyne.
It uses feed back to cause oscillation of the first stage that zero
beats the incoming RF. This makes the reciever very selective.
The signal isn't rectified until it goes to the audio stage.
The two circuits are similar. I've seen the combination of homodyne
and reflex as well. These are usually just called reflex.
Another similar method of getting selectivity is to make a
super-regenerative.
Dwight

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