Regenerative Radio Receiver Circuit

This circuit should be of interest to hobbyists and home-brewers alike:

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Reply to
iiiijjjj
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On a sunny day (Tue, 28 Aug 2012 00:40:27 -0700 (PDT)) it happened iiiijjjj wrote in :

The problem with thsoe thingies is that they radiate a lot at the Rx frequency, causing reception problems for others.

Reply to
Jan Panteltje

Practical Wireless magazine published a design/kit for a regen with a grounded gate JFET front end that pretty much isolated the antenna from the possibly lively bit.

It was called the Knapp receiver IIRC.

Reply to
Ian Field

Regens don't oscillate. Superregens do.

I like the LEDs as bias voltage sources, especially if you use different colors. Makes the board look cool.

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Reply to
John Larkin

frequency,

You nearly made it:

Regens *should* not oscillate (but they occasionally do).

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Tauno Voipio
Reply to
Tauno Voipio

Amateur radio regenerative receivers used for CW reception are adjusted to oscillate -- the audio tone is generated by the mixing of the self- oscillating frequency and the desired signal.

But that's a corner case -- a regen that you might find in some piece of consumer gear shouldn't self-oscillate (but might, depending on how well and how long ago it was adjusted).

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Reply to
Tim Wescott

tp://evospice.site88.net/regen/regen.html

I thought regens went out after Major Armstrong's invention became popular.

Reply to
spamtrap1888

The tiny outlay is popular with many experimenters & SWLs.

Reply to
Ian Field

AFAIK they're still used in el-cheapo consumer equipment like toy cars, key fob remotes, garage door openers & such.

Slowly being overtaken by super-small "regular" radios, but still out there.

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Reply to
Tim Wescott

alike:

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As detectors, that's right. However, positive feedback (regenerative) circuits used to be used quite widely to sharpen up the response of HF receiver front ends, where they were called "Q multipliers".

Cheers

Phil Hobbs

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Reply to
Phil Hobbs

On a sunny day (Tue, 28 Aug 2012 21:37:48 +0100) it happened "Ian Field" wrote in :

Xcuse me with that many components you can make a good superreg!

Reply to
Jan Panteltje

Xcuse me with that many components you can make a good superreg!

SORRY I MENT TO SAY SUPERHET :-)

Reply to
Jan Panteltje

Are you squaking like the receiver?

Reply to
Robert Baer

On a sunny day (Wed, 29 Aug 2012 18:56:42 -0700) it happened Robert Baer wrote in :

frequency,

No but you are

Reply to
Jan Panteltje

I guess an interesting point is that the (AC linked) differential pair has = a tanh input amplitude versus gain curve. The requirement that the transis= tors be matched in the usual (DC linked) long tail pair is a DC biasing onl= y requirement. The two transistors in the AC linked version can be very dif= ferent and still give symmetrical behavior. Anyway the slightly compressiv= e tanh response allows for a smooth transition into oscillation with increa= sing positive feedback. A lot of circuits on the internet use FET's for reg= eneration. There you have to hope that you can bias the FET into a region = of its operating curve where the gain it provides is compressive (decreases= slightly with increasing input amplitude). Even the well know designs by C= harles Kitchin in QEX do not address that problem and are kind of hit and m= iss.

Reply to
iiiijjjj

Hmm, that can't be right. Surely you meant output vs. input (i.e., transfer function), not input vs. gain? Also, atanh?

Tim

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Reply to
Tim Williams

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