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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details. |
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10th Sep 2020, 1:27 pm | #1 |
Heptode
Join Date: Apr 2010
Location: West Midlands, UK.
Posts: 659
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What is this, some kind of Alarm?
Does anybody know what the remains pictured are of? There is a crystal mic insert, a PCB with 3 OC71 transistors and some very small transformers, a crystal which could be 77 kHz from the markings, a mercury switch and a battery holder for an unknown battery at one end, possibly part of some kind of ultrasonic alarm?
Mike. |
10th Sep 2020, 2:57 pm | #2 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
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Re: What is this, some kind of Alarm?
A pager, perhaps?
David
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10th Sep 2020, 3:49 pm | #3 |
Nonode
Join Date: Jan 2010
Location: North Somerset, UK.
Posts: 2,129
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Re: What is this, some kind of Alarm?
The mercury switch does perhaps suggest some type of alarm.
Perhaps a break glass detector ? with both acoustic detection of partial breakage/attempted breakage, and the mercury switch to detect substantial destruction, when the glass or remains thereof is no longer upright in the frame. I have fitted a more modern version to glass display cases holding valuable items. These detect both attacks and complete breakage. They are bonded to the glass and cant be removed. Any breakage of the glass OR failure of the sensor required replacement of the glass and the sensor as one item. |
10th Sep 2020, 4:03 pm | #4 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,145
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Re: What is this, some kind of Alarm?
The components appear to date from the 1958-60ish. J.
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10th Sep 2020, 4:18 pm | #5 |
Dekatron
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,637
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Re: What is this, some kind of Alarm?
What orientation switches it on, assuming that is what the mercury switch does?
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10th Sep 2020, 5:46 pm | #6 |
Nonode
Join Date: Jan 2016
Location: Stafford, Staffs. UK.
Posts: 2,529
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Re: What is this, some kind of Alarm?
The company seems to have been involved in radio comms gear. I've found reference to airport systems.
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10th Sep 2020, 7:01 pm | #7 | |
Dekatron
Join Date: May 2010
Location: Greater Manchester, UK.
Posts: 18,676
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Re: What is this, some kind of Alarm?
Quote:
I thought "Cosmocord" just made the transducer. They seem to be the same company as Acos, which I know well having used their microphones and crystal pick-ups.
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10th Sep 2020, 7:31 pm | #8 |
Heptode
Join Date: Apr 2010
Location: West Midlands, UK.
Posts: 659
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Re: What is this, some kind of Alarm?
When the board is vertical the mercury switch connects it to the battery.
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10th Sep 2020, 7:45 pm | #9 | ||
Nonode
Join Date: Jan 2016
Location: Stafford, Staffs. UK.
Posts: 2,529
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Re: What is this, some kind of Alarm?
Quote:
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10th Sep 2020, 7:54 pm | #10 |
Heptode
Join Date: Apr 2010
Location: West Midlands, UK.
Posts: 659
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Re: What is this, some kind of Alarm?
The crystal was actually made by Brookes.
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10th Sep 2020, 8:14 pm | #11 |
Nonode
Join Date: Jan 2016
Location: Stafford, Staffs. UK.
Posts: 2,529
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Re: What is this, some kind of Alarm?
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11th Sep 2020, 10:17 am | #12 |
Moderator
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Re: What is this, some kind of Alarm?
Brush Clevite were an early maker of piezo-electric ceramic elements. And that idiotic memory in the back of my head also threw up that Brush was a major maker of tramcars and trolley buses... but were they related to Brush Clevite?
Brookes were a well known quartz crystal supplier. David
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11th Sep 2020, 10:37 am | #13 | |
Nonode
Join Date: Aug 2015
Location: Cambridge, Cambs. UK.
Posts: 2,196
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Re: What is this, some kind of Alarm?
Quote:
See https://www.brushindustries.com/abou...e.aspx?id=1396 Fascinating! Martin
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11th Sep 2020, 2:18 pm | #14 |
Moderator
Join Date: Mar 2012
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Re: What is this, some kind of Alarm?
Fascinating!
It sounds like Charles Francis Brush was what Edison wanted to be (and worked so hard at faking it!) Have you uncovered a still practicing maker of tape heads? David
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Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |
11th Sep 2020, 4:08 pm | #15 | |
Nonode
Join Date: Aug 2015
Location: Cambridge, Cambs. UK.
Posts: 2,196
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Re: What is this, some kind of Alarm?
Quote:
Martin PS An entrepreneur as creative as Charles Francis Brush always makes me feel inadequate. Still, he was unfortunately rather premature with his crystal pickup.
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14th Sep 2020, 8:49 am | #16 | ||
Heptode
Join Date: Jun 2017
Location: Southport, Merseyside, UK.
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Re: What is this, some kind of Alarm?
Quote:
Our old ( 1937 ish ) Garrard RC4 autochanger had a crystal pickup head. It had the name Brush - Rothermel on it. There was also a high frequency crystal "tweeter" of the same make; but I never remember it being connected up. I suspect my father had tried it and found the 78 surface noise unbearable!
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