The anti-Radio

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I have often eyed one of these electromagnetic field recorders which can record sounds from much further away than the one I currently have:

they seem to create some amazing sounds…

I’m pretty sure I must be able to build my own “radio that doesn’t work” circuit with the time I have on my hands, without TOO much bother and for less than £140… (current knowledge on this is pretty much zero however!)

There seems to be a fair bit of maths involved in creating a band pass filter that rejects radio signals you don’t want… and most online projects/advice seem to be understandably geared towards improving this.

I’m sure I can work this one out, but while we’re all stuck at home I was just wondering if anyone has any brilliant advice on resources/ways to make a radio tune to everything possible at once and provide some entertainingly weird audio at the end of it.

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This is so interesting. I have a cousin who swears that emf fields play havoc with her health, but she has neve been able to evidence whether it does or not. This could be a solution for her…

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I think maybe what I am trying to do is build a crystal radio?

and then use transistors to amplify it. The bit I don’t quite have a handle on is how to get it receiving the maximum possible bandwidth of signal, rather than trying to get it under control IYSWIM.

Thought this “broadband signal booster” also seems to be in the direction I am thinking…

He also mentions that it has a regenerative circuit:

and a demodulation circuit.

I think I may try just building the crystal radio and work from there…

the difficulty is definitely that everyone else is trying to tune in to a radio station wheras I want to pick up everything

actually, this circuit seems really useful as it has switchable capacitance to choose between frequency bands…
So in theory I can maybe make several separate signal paths with different capacitance, amplify and then mix them to an audio out… Hmm


this might be interesting stuff for her

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Can you use software defined radio?


@joeatkin2 and @Courty?

Thanks Duck. Only problem is she has no electrical gismos let alone a computer! I will need to print it off and send it by post. :slightly_smiling_face:

I read the blurb and i would guess that it’s a super- regen recever with a front end like a chainsaw wound .

it should also be noted that super regions are banned under U.K. law… The are dreadful.

If you want something more elegant I would go for a up conversation superhet , should be quite easy with bords fro China

A log IF might be quite fun

Loads of good bits available to do something fun.

Please note that the bits I have linked to are random and not a recommendation as to what you need

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thanks - super regens are banned?
Useful to know! Because they interfere with other radio traffic?

tbh a lot of the attraction here is bodging something out of coiled wire and transistors, so not AS interested in buying integrated circuits from China in this instance, but at that price maybe I’ll just order one to play with.

Or just play with building a crystal radio and a big aerial

So, am I reading it right, that that RF Logarithimic detector is going to give me a 1mhz-8000 mhz signal? looking at others, it seems to helpfully output this around line level voltage (great)… but I’m going to need to do some demodulation to make that audio band I guess?

Maybe using something like this;

That is a mixer conveys to baseband

Super regens do tend to wee out RAF

Zn414 might intrest you .

these are interesting too! Wonder if I can Raspberry Pi my way into portability…