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A few days ago I posted a blog entry - Apple and Biscuit Microphone for Acoustics Laboratories - the STC 4034. I had three microphones of this type for sale. They quickly sold, two going to British collectors and one to a chap in New Zealand. One of the British collectors, John Howell (previously a BBC Sound Supervisor), has sent me a photograph of his new acquisition together with his other "Apple & Biscuit" microphones, STC 4021s. -
image © John Howell 2017 - all rights reserved
The 4034 is the microphone at the back with the silver tube. Of much more interest is the box next to it, labelled V.I.E. This contains two 4021s used by Alan Blumlein in the second World War, to acoustically detect the position of enemy aircraft. A system called VIE: Visual Indicating Equipment.
The VIE system developed by EMI used the signals from two 4021 microphones to indicate on a cathode ray tube the direction of approaching aircraft. The Air Ministry had already selected the STC 4021 for acoustic location work so EMI provided the CRTs but not the microphones. The use of a CRT as a display led directly to its use in Radar
Above is a drawing of the mic mounting found in Blumlein's biography, you can see how the elastic suspension on John's mic was used. His is still sealed and he's going to leave that way, as the other one shows all there is to see. Note that the 'biscuit' is dispensed with in favour of an iron 'basket', and the alternative end terminals on the 4069A connector.
The VIE kit, above, was a small transportable unit with one or two seats a bit like a gun turret and 3 Foot diameter parabolic reflectors.
Before putting my microphones up for sale, my knowledge of Alan Blumlein's work was solely his Blumlein transmission line, used to create high-voltage pulses with short rise and fall times. This set-up I used while building a nitrogen laser some years ago. Many thanks to my fellow collector John, in acquainting me with Blumlein's contributions to winning WWII.
John has kindly taken further photographs of his historically important STC 4021s, to further illustrate this document -
image © John Howell 2017 - all rights reserved
image © John Howell 2017 - all rights reserved
image © John Howell 2017 - all rights reserved
image © John Howell 2017 - all rights reserved
image © John Howell 2017 - all rights reserved
VIE 4069 connector
image © John Howell 2017 - all rights reserved
image © John Howell 2017 - all rights reserved
VIE 4069 connector fitted
image © John Howell 2017 - all rights reserved
image © John Howell 2017 - all rights reserved
VIE seal
image © John Howell 2017 - all rights reserved
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ANARCHIC EXPERIMENTAL SCIENCE
"Hodges emitted a scream the like of which
I hadn't heard since his scrotum was burned off
Unrelated to this post, below is an example of
eclectic science esoterica
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Replica of the Selden Road engine of 1877, built in 1905 by patent attorney and inventor George Baldwin Selden (1846-1922) and his sons for legal purposes, in the Selden-Ford lawsuit 1902-1911. G.B. Selden at the steering wheel.
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