Well average TV transmitter is around 100-250KW and you get 4+ up a standard mast.
Think broadcast AM is broadly similar.
Which mat be why in the end BBC3 is moving online. It could be that it costs less for the number of actual viewers.
My father said he once knew a man who lived near Crystal Palace and claimed he could hear the radio all the time because of a poor metal filling in a tooth.
Robert
but, in those days CP only broadcast tv!
I bet I had that book too. One of Bernard Bababani's publications probebly written by Clive Sinclair. It harvested energy from 200kHz to power a one or two transistor MW circuit.
It would if you didn't LPF it first, which would be essential.
No, you are going to have to
Oh yes, AM broadcasts have been much the same since 1922. My dad gave me my first crystal set when I was about six, I think the baseboard was a slab of slate with four binding posts for aerial, earth, and headphones. The tuner, I later found out, was called a variometer, and I am quite sure it was exactly like this (you just wouldn't forget something like that would you?
The detector was clearly originally a bare crystal and an adjustable cat's whisker but someone, presumably my dad, had bridged it with a new fanged crystal diode, something like this, although not as symmetrical
IIRC it picked up the Light programme from Droitwich (100 miles) and the Home service from Moorside Edge (30 miles)
basically a coil and tuning capacitor like from an old tranny radio., plus a oa91 germanium diode and a crystal earpiece should all still work.
Certainly, high impedance headphones were necessary. Ex-WD ones were easily available in the early 1950's, wire-wound, several kilohms, with steel diaphragms. A good earth was also important.
I'd guess it would be stealing energy or somesuch.
Trouble is it removes or reduces the RF signal beyond that point. Story was a farmer or something used it to light a cow shed or whatever - close to the BBC LW tramsmitter and caused a vast shadow in its output. Many many years ago.
To get any appreciable current, you'd need a very large and efficient aerial and be close to the transmitter. Likely cost far more than anything you could get for free.
And these days, only FM radio wise? Which would be less likely to produce an audio output under those conditions.
Perhaps it was the old AM TV sound.
This looks like the booklet I had. Maybe you too. :-)
It says 1981 but I thought I had it before then.
"Electronics Simplified: Crystal Set Construction"
LPF?
'Radio for Boys', E.N. Bradley, 1956 edition, Junior Teach Yourself Books.
Covered crystal set, one- two- three- and four-valve TRF battery receivers, battery and mains supehets. Still got the book! I don't recall ever getting beyond the one-valve receiver, although I have component costs for the others scribbled in pencil in the margins, e.g. Mullard DL35 output valve 12/6, Octal valve holder 6d etc. Those were the days!
Lowpass filter. probebly an series R and a shunt C to remove the modulation and just leave DC.
A crystal set should pick up any stations still broadcasting in AM on medium wave (perhaps long wave if tuned properly). There's quite a few.
The first one I made was very primitive: a diode with an aerial on one side and an earth on the other, and headphones across it. No tuner so it picked up everything at once, but Radio 4 was dominant, which suited me. This was near Brookman's Park so maybe that influenced what I could pick up.
Don't forget to factor in the disapointment due to our hearing not being what it was 50 years ago!
I'm guessing that would have been the World Service. At 1MW DC input power, it dominated the xtal radios of the small boys all over Britain. Does this sound familiar:
rectifier and capacitor actually
>
Funny you should mention this... A couple of weeks ago, I stayed over at my parents, and in the bookshelf was my old Ladybird book on making a radio, which takes you through the stages of making the receiver and then adding an amplifier to it. If you can still buy OC71's, it would still work today. ;-)
Well done for getting as far as that one-valve receiver! Valves are before my time.
This table says 12/6 in 1960 is equivalent to a bit more than ?11 in today's money. That seems too little.
In message , "Dave Plowman (News)" writes
These days, Crystal Palace actually does transmit MW - 720kHz Radio 4 fill-in. It used to be at Lots Road power station
Valves were almost all there were in those days. Transistors were only just becoming available. 'Practical Wireless' had pages and pages advertising all sorts of valves with their prices, like this
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