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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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2nd Jan 2020, 3:54 pm | #1 |
Octode
Join Date: Jun 2005
Location: Sheffield, South Yorkshire, UK.
Posts: 1,227
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Home made earphones
A few years ago , I made some simple crystal earpieces from old fire alarms . I fitted 47K across each one and they all worked fine . Yesterday I tried them again with crystal set and only one worked. I got readings of v. high resistance with my meter but not a peep .Do these earphones disintegrate with lack of use? Shall I just bin them?
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2nd Jan 2020, 4:09 pm | #2 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 14,007
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Re: Home made earphones
do you mean you used the type of 'sounder' things that are a flat brass disc with a piezoelectric element bonded to one face?
This sort of thing: https://uk.farnell.com/multicomp/abt...30v/dp/1675548 or the similar ones in a small circular plastic case. |
4th Jan 2020, 12:38 pm | #3 |
Octode
Join Date: Jun 2005
Location: Sheffield, South Yorkshire, UK.
Posts: 1,227
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Re: Home made earphones
Yes. I did not explain earlier very well that the high resistance readings were only when the 47 K was disconnected.
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4th Jan 2020, 3:58 pm | #4 |
Guest
Posts: n/a
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Re: Home made earphones
It would be high, only ceramic twixt the probes. Ceramic sounders last for ages (as long as clay pots I suppose which is a very long time).
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5th Jan 2020, 6:26 pm | #5 |
Rest in Peace
Join Date: Feb 2004
Location: Hexham, Northumberland, UK.
Posts: 2,234
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Re: Home made earphones
We scrap quite a few old style (80's ish) phones at work (and yes, they really are well beyond repair!) and I have found that using two earpieces from them connected in series make a usable set of phones with medium impedance for things like crystal sets. They seem quite sensitive too. I always find crystal earpieces sound a bit thin and tinny for my liking.
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8th Jan 2020, 5:07 pm | #6 |
Octode
Join Date: Jun 2005
Location: Sheffield, South Yorkshire, UK.
Posts: 1,227
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Re: Home made earphones
they've gone in the bin . It is easy to get bogged down in trivia.
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13th Jan 2020, 5:30 pm | #7 |
Hexode
Join Date: Apr 2007
Location: W Yorks, UK.
Posts: 407
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Re: Home made earphones
"earpiece from fire alarm" is the most bafflingly wonderful thing I've heard all day
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