# Regenerative receiver on a chip ?

#### Externet

Joined Nov 29, 2005
1,424
Hi.
Looking for an integrated circuit, device or tiny module as RF receiver that can turn on a LED when a 123MHz transmitter is nearby. Simple, no heterodyning. To work around 3V. NO demodulating needed. No audio stage nor data output used. Just a LED indicating RF activity.

These similar show in a search results :

Or something else...

How would you do it ?

Edited... Cannot find data on IC SCSR121

Last edited:

#### DickCappels

Joined Aug 21, 2008
6,009
Side note: Your chosen frequency is in an aircraft band and may interfere with aircraft, particularly in the vicinity of airports. You would be safer to use an ISM (Industrial, Scientific, Medical) band in which licenses are not required and the chances of interfering with critical services are small.

https://en.wikipedia.org/wiki/ISM_band

#### Externet

Joined Nov 29, 2005
1,424
Thanks.
I know very well it is in the aircraft band, and that is the frequency I have to detect activity, not on ISM. Regenerative receivers emit interference ?

#### DickCappels

Joined Aug 21, 2008
6,009
(Some text removed for clarity) Regenerative receivers emit interference ?
Yes they do. That is why many of them have a preamp ahead of the detector.

#### Ylli

Joined Nov 13, 2015
850
Unicom frequency. You looking to control airport lighting?

#### jpanhalt

Joined Jan 18, 2008
8,340

ak

#### Externet

Joined Nov 29, 2005
1,424
What you bought were FM radios. Maybe better luck buying AM radios as AM is used in aircraft communications.
In post #1 :
NO demodulating needed. No audio stage nor data output used. Just a LED indicating RF activity.

#### AnalogKid

Joined Aug 1, 2013
8,227
Pedantic picking ...

Actually, *some* demodulation is needed. What you are doing basically is OOK - On/Off Keying, a grunt form of AM. Detecting the presence/absence of a carrier meets every aspect of what demodulation is. Granted, you don't want to recover any information modulated on the carrier, but still ...

ak

#### jpanhalt

Joined Jan 18, 2008
8,340
In post #1 :
Can you expand on your post #12. If the FM receivers are "working," what's the problem lighting an LED?

#### AnalogKid

Joined Aug 1, 2013
8,227
Can you expand on your post #12. If the FM receivers are "working," what's the problem lighting an LED?
unfriendly to hack further (and shrink).
My guess is that "unfriendly" means difficult. Looking at that kit, there is a whole lot of gorp he doesn't need for this application.

ak