crystal1.mpg

Great enjoyment was had in watching many YouTube Videos about crystal radio receivers. So thought I would make one as well... Starting with the very simplest possible sort. Of course, that wasn't too much trouble, besides being great fun. Any follow-up will be a bit more difficult though! In this video I also try to explain how they work; and though I am not an expert I hope it is mostly correct? I'm sure that people will tell me what has been got wrong!

Category:

Science & Technology

Tags:

• Crystal set
• Long Wave
• BBC Radio 4
• Droitwich

[1981dasimpson]

your videos helped explain in more detail then over a hundred vidoes and websites i have looked at have been able to thank you.

i had an idea if i made a coil with lets say 1000 turns and every 10 turns i make a loop. would i be able to get short, meduim and long wave by just moving to a different loop and have a variable capaciter to closer tune the stations

[bixanorak]

You're absolutely right: it would work as you say. In fact, very early on, that was probably the most common way of getting medium and long wave on one set without having the bother of unplugging one coil and plugging in another. In the earliest times, you just had a coil with many taps, selected by a rotary switch (or a slider) and relied on the capacitance of the aerial & other 'stray capacitance' to tune the circuit. Short wave reception is possible, but too difficult for me! Cheers.

[1981dasimpson]

so if i make a coil and use a slider think that be best more tuning ability couls i also use a 365pf varible cap in parallel with the coil for finer tuning is so how would i wire this i looked at loads of circuits and they all do it diferent ways so im very confused at present moment radio five live kills any channel selection on my fox hole radio

[bixanorak]

A 365 pF variable capacitor is ideal for tuning a Medium & Long wave crystal set. If 'Radio 5 Alive' is very powerful and 'swamps' other signals, you must first reduce the coupling of the aerial (antenna) into your foxhole crystal set. The simplest way to so this is by putting a small capacitor in series with the aerial. Say 100 pF, 200 pF. That will increase the selectivity, albeit at the expense of volume. I think this is illustrated in part 2 of my videos. Good luck!

[1981dasimpson]

@bixanorak funny you should say that i have a varible 125pf cap to the other idea i thoght about 2 sliders on the coil one for the diode and the other the antenna then place a 365pf varibale cap between the diode terminal and the ground terminal of the coil i think this way i should get a very large varation of coil winds to tunabailty what you think

[bixanorak]

Yes, that would work. Take the aerial in through the 125 pF variable to a tap on the coil, probably fairly low down it. Then take a tap higher up it to your 365 pF variable, & the other side of it to the bottom of the coil. Then take the signal from the 'hot' (upper) end of the 365 pF to your diode & from there to your headphones or amplifier. In this usage, the coil is called an 'auto-transformer' and the method was widely used in the early days.

[EvilPacketMonkey]

Stumbled on to this while searching on similar topics. I enjoyed watching and subscribed. Very informative and helped fill some gaps of things I already knew, but just not as well.

Thank you for taking the time to make this (and others) and sharing what you know.

[1981dasimpson]

ty think i gor that pictured in my mind

[lindyhoppers]

I really enjoyed it Norman!