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Crystal sets, POW radios, spy sets & radio related thread

ISTR that the Jodderell Bank techs would track down leaky microwaves and ask the owners politely could they do something with them. Can't recall where I got that from though.
1600815260715.png

Top Interesting Facts About Jodrell Bank Observatory
A very short article about interference at Jodrell Bank (old page with out of date links)
The SKA | Jodrell Bank Centre for Astrophysics

ETA - just found this from 2016. This demonstrates the conflict of probable increased interference vs pressures for housing. When JB was built the site was chosen for it's relative freedom from interference.

Jodrell Bank: Inquiry considers whether new houses would affect telescope
 
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We shall use Navy drill for this post...


"Beards....Beards Ho!"


"Beards...you will welcome the newest member to the bearded Brethren- pree-zent muff!"


Gentlemen... It lives.

2020-09-23 06.40.49.jpg


I believe I am now suitably qualified to rub my chin and cast a 'critical eye' on all manner of things whilst muttering about "well I personally would have done it this way..."



I'm just off out to the bins to stow away my social and sex life :)

Attach files
 
We shall use Navy drill for this post...


"Beards....Beards Ho!"


"Beards...you will welcome the newest member to the bearded Brethren- pree-zent muff!"


Gentlemen... It lives.

View attachment 506587

I believe I am now suitably qualified to rub my chin and cast a 'critical eye' on all manner of things whilst muttering about "well I personally would have done it this way..."



I'm just off out to the bins to stow away my social and sex life :)

Attach files
Very good! What does it do and why?
 
Very good! What does it do and why?

At a rough guess, it’s an ultrasonic scanner. Looks like TX and RX modules on the vertical board. The display is showing red where the monitor is, and green before it. Looks like it has a range of 2ft or so there. I’d be interested to see what it would do say on a lawn (flat surface) with a box or something further out. Also be curious as to any distortion with detected objects off the centerline. Pretty sure you could fix that with software.

Edited to add, the scanning head appears to be mounted on a servo, so ignore the centerline comment, as it will scan azimuth within the range of the servo (or wires connected to the head). Bit like radar but sound rather than RF.

Well done, @supermatelot. Are you going to install this on your desk at work so you can tell when someone is behind you? :)

If you could figure out some kind of slip ring, you could have a 360 degree scanner. It’d be just like being back on a frigate, but without the drunken behaviour. Well, at least different drunken behaviour :)
 
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At a rough guess, it’s an ultrasonic scanner. Looks like TX and RX modules on the vertical board. The display is showing red where the monitor is, and green before it. Looks like it has a range of 2ft or so there. I’d be interested to see what it would do say on a lawn (flat surface) with a box or something further out. Also be curious as to any distortion with detected objects off the centerline. Pretty sure you could fix that with software.

Edited to add, the scanning head appears to be mounted on a servo, so ignore the centerline comment, as it will scan azimuth within the range of the servo (or wires connected to the head). Bit like radar but sound rather than RF.

Well done, @supermatelot. Are you going to install this on your desk at work so you can tell when someone is behind you? :)

If you could figure out some kind of slip ring, you could have a 360 degree scanner. It’d be just like being back on a frigate, but without the drunken behaviour. Well, at least different drunken behaviour :)
OK then: Why?
 
Very good! What does it do and why?


A couple of years ago I bought "The most complete Arduino starter kit".

A big box of electrical components and an Arduino. I started project #1 which was getting an LED to blink in a set pattern. I then decided to quit whilst I was on a winner and it was then consigned to the cellar. My eldest lad is now 7 and I think it's about time he started learning this sort of stuff. My reasoning is- I ought to 'prove concept' before I attempt to learn him about things. I'm basically re-learning electrical concepts I have long since forgotton in order to get my son interested in it and probably-him rapidly overtaking me in knowledge in around 2 years-and me then asking him for advice.
 
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A couple of years ago I bought "The most complete Arduino starter kit".

A big box of electrical components and an Arduino. I started project #1 which was getting an LED to blink in a set pattern. I then decided to quit whilst I was on a winner and it was then consigned to the cellar. My eldest lad is now 7 and I think it's about time he started learning this sort of stuff. My reasoning is- I ought to 'prove concept' before I attempt to learn him about things. I'm basically re-learning electrical concepts I have long since forgotton in order to get my son interested in it and probably-him rapidly overtaking me in knowledge in around 2 years-and me then asking him for advice.
I have to confess, that is a much better answer than I anticipated.
 

endure

GCM
New toy :mrgreen:

new toy.jpg
 

endure

GCM
Edited for accuracy. Congratulations though. You might want to watch the microphone termination. Have heard of them coming loose.


It's alright. I've unplugged the mike so Uncle Xi can't hear me...
 
@Joshua Slocum should recognise this circuit

2020-09-26 20.56.48.png

Reproduced as thus:

2020-09-26 21.34.06.jpg


And it works! It's very very faint and hard to make out much but I think Its BBC Talk Sport. The aerial is only around 5m long and just pulled across the furniture in the dining room. The radio itself is on the cat's climbing thing and Odin & Loki are very keen to try and bugger it all up!

I re-wound the coil earlier today and was a bit more careful than last time.
One thing I have noticed..If I disconnect say earth...as expected..it cuts out but, upon reconnection...it's not instantanious regaining..almost as if it needs to 'warm up'. I'll put the clip back and it'll be silent then very slowly build back up to its very faint crescendo. What is the reason for that please?
 

Joshua Slocum

LE
Book Reviewer
@Joshua Slocum should recognise this circuit

View attachment 507522
Reproduced as thus:

View attachment 507525

And it works! It's very very faint and hard to make out much but I think Its BBC Talk Sport. The aerial is only around 5m long and just pulled across the furniture in the dining room. The radio itself is on the cat's climbing thing and Odin & Loki are very keen to try and bugger it all up!

I re-wound the coil earlier today and was a bit more careful than last time.
One thing I have noticed..If I disconnect say earth...as expected..it cuts out but, upon reconnection...it's not instantanious regaining..almost as if it needs to 'warm up'. I'll put the clip back and it'll be silent then very slowly build back up to its very faint crescendo. What is the reason for that please?
not a clue about the delay, perhaps their is a stronger signal in the area and it takes a while to get past it
try turning the wifi off next time you do it, and see if it start quicker
not bad for a drawing done from memory
I will try and find soem of the radio books i have up in the attic and scan a few up, but at the moment Franko is taking every spare minute I have, got to have him complete for Haloween otherwise the kids on the local council estate will kick the crap out of me
we have an agreement they leave the wheels on my car, and I give them a big surprise every year
he is also going to have an email addy so kids in hospital can facetime him
 
@Joshua Slocum should recognise this circuit

View attachment 507522
Reproduced as thus:

View attachment 507525

And it works! It's very very faint and hard to make out much but I think Its BBC Talk Sport. The aerial is only around 5m long and just pulled across the furniture in the dining room. The radio itself is on the cat's climbing thing and Odin & Loki are very keen to try and bugger it all up!

I re-wound the coil earlier today and was a bit more careful than last time.
One thing I have noticed..If I disconnect say earth...as expected..it cuts out but, upon reconnection...it's not instantanious regaining..almost as if it needs to 'warm up'. I'll put the clip back and it'll be silent then very slowly build back up to its very faint crescendo. What is the reason for that please?
The reason for delay is the time taken to charge the RC circuit (Earphone and capacitor). The time should be 5RC seconds. As the coil is in parallel to the capacitor, it is offering some conductance which offsets the resistance value to some degree, but I cannot to do the mental sums to work it out (Three Krombachers in).

It is probably something like:

5 x (1/L) x R x C seconds (Where L is the inductance of the coil in Henrys, R is the value of the resistor [earpiece] in Ohms and C is the value of the capacitor in Farads).
 
Having snags finding 'earth' in my house also. I've tried radiator pipe (bare metal) etc etc but nada. Only solution is to wire a plug to earth only and use that. Not a big deal hut - try explaining to an 8 year old why I have to plug something in to work-even though it does not need power!
 
@Joshua Slocum should recognise this circuit

View attachment 507522
Reproduced as thus:

View attachment 507525

And it works! It's very very faint and hard to make out much but I think Its BBC Talk Sport. The aerial is only around 5m long and just pulled across the furniture in the dining room. The radio itself is on the cat's climbing thing and Odin & Loki are very keen to try and bugger it all up!

I re-wound the coil earlier today and was a bit more careful than last time.
One thing I have noticed..If I disconnect say earth...as expected..it cuts out but, upon reconnection...it's not instantanious regaining..almost as if it needs to 'warm up'. I'll put the clip back and it'll be silent then very slowly build back up to its very faint crescendo. What is the reason for that please?
Anyone into amateur radio should recognise that circuit in a heartbeat.

Wish those earpieces were easy to get a hold off. They're going the way of butterfly capacitors in this neck of the woods.
 
Anyone into amateur radio should recognise that circuit in a heartbeat.

Wish those earpieces were easy to get a hold off. They're going the way of butterfly capacitors in this neck of the woods.
Shitloads on amazon / ebay

 

Joshua Slocum

LE
Book Reviewer
we have an old fashioned father and son shop
he is a radio ham, they seem to sell everything in there
there are still lots of old fashioned shops like this in many towns and cities
takes a while to find them
other thing used to be to go to a swapmeet/carboot sale for radio stuff
 
AFter much deliberation - I've decided this thread is the place to put this:

I've been doing a bit of googling lately (when had chance) and have looked into WebSDR etc- I have a few links to buckshee receivers you can tweak and listen into various freqs on.
Tonight I learned about something called Zello. Its a free app on Iphone / Android etc. Basically-there are "channels". You can create your own and get people to joing or- you can search and find an appropriate channel. It's all radio-based though. You click a PTT icon and speak over God knows what freq but..on my brief foray into it..appears to be very much a radio Ham community. I just typed nearest big town to where I live in the channel search option and was presented with variouys choices- I clicked on one and saw 3 people were 'online'. Gave it a quick "testing testing 123" and someone came straight back. WIthin seconds was straight into radio-talk and frequencies/setups etc. It appears to be just like radio Ham but without the formality.

I think I'll give this a whirl and see if it aids beardage :)
 

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