Water bottle crystal set with sound! - UK Vintage Radio Repair and Restoration Discussion Forum

Pete_kaye · 10th Feb 2013, 2:15 pm

I was trying to construct a conical horn to improve the volume from a basic home made crystal set. I cut up a 1 litre water bottle and folded under the rough edge. The speaker is a 40 Ohm phone earpiece run from a transformer (22:1) which has the bottle sitting on it. The sound wasn't exactly deafening from a 70 foot loft aerial but audible from a few feet in a very quiet room. I can send a short WAV file to anyone who wants to hear it. Can sound files be posted on this site?

Paul Stenning · 10th Feb 2013, 3:28 pm

Sound files (as long as they don't breach copyright obviously) can be attached if you put them in a ZIP file.

Peter.N. · 10th Feb 2013, 7:31 pm

Excellent idea, you might get more sound from a crystal earpiece.

Peter

Herald1360 · 10th Feb 2013, 8:31 pm

A decent horn loaded (I suppose matched would be a better term) speaker will convert about ten times as much of the input electrical power to sound as a simple cone speaker, so at best you'll only get about 10dB increase in volume. Every little helps, though

PWH · 11th Feb 2013, 6:39 am

Pink crystal earpiece, you know the ones, with a styrofoam (polystyrene) cup carefully cut out?
Even a 'normal' speaker with the output transformer attached can produce quite good sound in a quiet room in the evenings.

Pete_kaye · 13th Feb 2013, 12:48 pm

I have tried using a crystal earpiece from a smoke detector. It needed a resistor in parallel. A very thin sound but improved by a trumpet.

Radio_Dave · 13th Feb 2013, 1:45 pm

Crystal earpieces can still be purchased from Maplin http://www.maplin.co.uk/crystalearpiece-3256 . There's no spec on the website but I'm sure they have (or used to have) an impedance of 1000 ohm.

Somebody once told me, back in the day, an earphone would be, simply, placed into bowl to amplify the sound. Don't know how true this?

David

Peter.N. · 13th Feb 2013, 4:54 pm

Yep, that's correct, a lot of people were still constructing crystal sets when I were a lad and that was one of the ways of increasing the volume.

Peter

Pete_kaye · 15th Feb 2013, 3:15 pm

My Mark 2 version has RIBENA plastic bottle cut down to form a horn about 8" high and tapered outwards..It is slightly clearer sound.

DigitalNoMore · 21st Mar 2013, 8:08 pm

I think you'll find that crystal earpieces typically have an impedance of 20kOhms or more.

Jerry

Andrew2 · 1st Apr 2013, 12:01 am

Indeed, and they have no DC path so to make the diode detector work properly you have to put a resistor in parallel.

llama · 7th Apr 2013, 7:54 pm

...and use the bottle as the coil former?

Graham

10th Feb 2013, 2:15 pm	#1
Pete_kaye Octode Join Date: Jun 2005 Location: Sheffield, South Yorkshire, UK. Posts: 1,227	Water bottle crystal set with sound! I was trying to construct a conical horn to improve the volume from a basic home made crystal set. I cut up a 1 litre water bottle and folded under the rough edge. The speaker is a 40 Ohm phone earpiece run from a transformer (22:1) which has the bottle sitting on it. The sound wasn't exactly deafening from a 70 foot loft aerial but audible from a few feet in a very quiet room. I can send a short WAV file to anyone who wants to hear it. Can sound files be posted on this site? Attached Thumbnails

10th Feb 2013, 3:28 pm	#2
Paul Stenning Administrator Join Date: Dec 2002 Location: Cardiff Posts: 9,071	Re: Water bottle crystal set with sound! Sound files (as long as they don't breach copyright obviously) can be attached if you put them in a ZIP file. __________________ Paul Stenning Forum Admin/Owner and BVWS Webmaster

10th Feb 2013, 7:31 pm	#3
Peter.N. Dekatron Join Date: Jul 2008 Location: Charmouth, Dorset, UK. Posts: 3,601	Re: Water bottle crystal set with sound! Excellent idea, you might get more sound from a crystal earpiece. Peter

10th Feb 2013, 8:31 pm	#4
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Water bottle crystal set with sound! A decent horn loaded (I suppose matched would be a better term) speaker will convert about ten times as much of the input electrical power to sound as a simple cone speaker, so at best you'll only get about 10dB increase in volume. Every little helps, though __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

11th Feb 2013, 6:39 am	#5
PWH Heptode Join Date: Mar 2003 Location: Waiheke Island, New Zealand Posts: 503	Re: Water bottle crystal set with sound! Pink crystal earpiece, you know the ones, with a styrofoam (polystyrene) cup carefully cut out? Even a 'normal' speaker with the output transformer attached can produce quite good sound in a quiet room in the evenings. Last edited by PWH; 11th Feb 2013 at 6:41 am. Reason: typo

13th Feb 2013, 12:48 pm	#6
Pete_kaye Octode Join Date: Jun 2005 Location: Sheffield, South Yorkshire, UK. Posts: 1,227	Re: Water bottle crystal set with sound! I have tried using a crystal earpiece from a smoke detector. It needed a resistor in parallel. A very thin sound but improved by a trumpet.

13th Feb 2013, 1:45 pm	#7
Radio_Dave Nonode Join Date: Jun 2004 Location: Norwich, Norfolk, UK. Posts: 2,543	Re: Water bottle crystal set with sound! Crystal earpieces can still be purchased from Maplin http://www.maplin.co.uk/crystalearpiece-3256 . There's no spec on the website but I'm sure they have (or used to have) an impedance of 1000 ohm. Somebody once told me, back in the day, an earphone would be, simply, placed into bowl to amplify the sound. Don't know how true this? David __________________ http://www.youtube.com/ My Nixie Clocks

13th Feb 2013, 4:54 pm	#8
Peter.N. Dekatron Join Date: Jul 2008 Location: Charmouth, Dorset, UK. Posts: 3,601	Re: Water bottle crystal set with sound! Yep, that's correct, a lot of people were still constructing crystal sets when I were a lad and that was one of the ways of increasing the volume. Peter

15th Feb 2013, 3:15 pm	#9
Pete_kaye Octode Join Date: Jun 2005 Location: Sheffield, South Yorkshire, UK. Posts: 1,227	Re: Water bottle crystal set with sound! My Mark 2 version has RIBENA plastic bottle cut down to form a horn about 8" high and tapered outwards..It is slightly clearer sound.

21st Mar 2013, 8:08 pm	#10
DigitalNoMore Pentode Join Date: Jan 2013 Location: Nottingham, Notts. UK. Posts: 228	Re: Water bottle crystal set with sound! I think you'll find that crystal earpieces typically have an impedance of 20kOhms or more. Jerry

1st Apr 2013, 12:01 am	#11
Andrew2 Nonode Join Date: Mar 2010 Location: Dukinfield, Cheshire, UK. Posts: 2,037	Re: Water bottle crystal set with sound! Indeed, and they have no DC path so to make the diode detector work properly you have to put a resistor in parallel. __________________ Andy G1HBE.

7th Apr 2013, 7:54 pm	#12
llama Octode Join Date: Jun 2006 Location: St Osyth, Nr Clacton, Essex, UK. Posts: 1,482	Re: Water bottle crystal set with sound! ...and use the bottle as the coil former? Graham __________________ Half my stuff is junk - trouble is, I don't know which half!