Roman - I've sort of got half way.

I've got a super-regen working at about 60MHz and it can detect my GDO from
accross the room - using a scope on the output as a detector.
I haven't got as far as connecting it to a micro and writing the software
- let alone making 2 of them & getting them to talk to each other.

Note that the circuit values used in my example are NOT the same as I have
used in my prototype. The demo schematic was only a simulation example.
If anyone's interested I'll update the circuit with real world values,  - I
just can't remember them & haven't got the item here.

Basically I'm trying to come up with a pcb so I can make the receiver
circuit sensitive, reliable & reasonably robust at a useful frequency. Then
the micro stuff & the peripheral stuff will follow.

I have however noted that the receiver will also detect the presence of
nearby micros - which could also be a problem - I'll have to look at my
operating frequency.

I'm gaining enthusiasm however so will get back into it again shortly
Richard P




Very cool circuit Richard, using the same transistor
for RF transmit/receive depending on the one PIC pin.
Have you actually got this to work or is it still a
design idea??
-Roman


Richard Prosser wrote:
>
> OK - Here's the circuit so far - Setup for about 22MHz as the transistor
is
> only a 2N2222
>
> L2 and C4 basically determine the frequency, with some help from C1 & C2.
>
> In RX mode an approx 20kHz pulse train appears at the output with about
> 2.1V to 3.0 V range.  The actual pulse frequency depends on the received
> feild strength in a roughly logrithmic relationship.
> So, the PIC has only to count the number of pulses in a given interval -
or
> measure the time for a number of pulses and it should be able to figure
out
> if there is a signal being received (i.e. it maintains a record of the
> timing under idle condition and looks for a change).
>
> Under TX, the PIC pin changes to output and pulls low. This changes the
> bias conditions and removes the super-regen effect, turning the circuit
> into an oscillator.
> For short ranges, this can be sufficient (I hope) to be regarded as a
> transmitter.
> Modulation by manchester coding should be OK to pass data at a few
> kbits/sec - depending on range etc. required.
>
> A small aerial connected to Q1 Collector appears to assist reception.
>
> Note: this circuit is copied from a working PSpice simulation. I have
used
> the same basic circuit but with component values altered & a better
> transistor at about 70MHz but have not yet tried making 2 of them &
> connecting to PICs for communication.
>
> One area of possible difficulty is that according to the simulation, the
RX
> frequency is centred at about 22MHz, while the TX frequency is about 1MHz
> higher. Possibly a better transistor would reduce this effect.
>
> As with most minimal component circuits, there is a fair amount of
> interaction between components and frequency, sensitivity etc. but it may
> serve as a starting point for someone.
> If anyone does play with it I'd be interested to hear of the results.
>
> Enjoy
>
> Richard P
>
> (See attached file: superregen.jpg)
>
> (See attached file: superregen.jpg)
>
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>
>                              Name: superregen.jpg
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