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smakkneo.jpg (1099 bytes)smcd80.jpg (1775 bytes)Mystery Corner

Does anyone know what any of these items is ? Mail me or use the Feedback Page if so!

More mystery stuff here and Some mystery valves here

Mystery object #5

This is some sort of infra-red detector device. it was encased in a very heavy aluminium casting, with a label saying "Mullard Infra-Red Detectors" and VX8578-01. The base connections are made by four 33-way flexi-print cables, onto which are soldered fine wires which dissappear up the middle of the inside of the tube - this is filled with resin and so hard to see exactly how the wires get inside. Height is 150mm.

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From Ed Gisske : In all likelihood a thermopile IR detector with a Gadolinium lens. Gadolinium (and Germanium too) will pass IR but not visible light. A thermopile is a number of dissimilar junction thermocouples connected in series to increase the voltage for very small heat rise.

From Malcolm : Yes I know exactly what this is. Lord knows how you got Bae came up with the idea of a kind of small trailer portable passive infra-red radar - it was all costed and trialled but then shelved. It was a sort of infra red telescope filled with liquid nitrogen (this being the sensor at the eyepiece end) which itself whas whirled around inside an evacuated enclosure at several thousand RPM while being dithered up and down.The array of sensors is not to produce an image but each sensor is sensitive to a different 'signature' spectrum and can identify jet from rocket from the sun etc. the image was produced by knowing which part of the sky the thing was pointing at when it gave the signals. It was eventually pipped to the post on the contract by a very low power very narrow beam conventional radar.

Mystery object #4

This is some kind of sensor. The large cylindrical base (7cm dia) contains some electronics. amd has a circular 7-pin connector on the underside. It is obviously intended to screw into a bulkhead, and when I got it, it was screwed into a small sealed box with a removable clear lid. The PCB has 3 chips, 3 multi-turn trimmers and several precision resistors, and the overall construction suggests a high-performance device, being very solid, and mostly made of stainless steel. The finned end part unscrews, and appears to be a heatsink. The use of stainless steel suggests it needs to be resistant to corrosion or chemicals. The underside is sealed with a large amount of white silicone sealant.

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Below the fins (removed) is a brass cylinder, the outer and inner surfaces of which have a rough appearance, and the low weight of the cylinder suggests it may be made of sintered powder, and therefore porous. (if anyone cares to calculate the density, outer dia is 20.9mm, inner dia 17.9mm, height 11.6mm (=1060mm2) mass 5.35 grammes. The second picture below is with the cylinder removed. This shows two wires entering the top secton, and a red plastic sleeve which contains a thermocouple.

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View on removing top section. There are two holes in the base on the left, through which a LED and photodetector are visible, set at a 90 degree angle between them. The upper assembly (right) has what looks like a peltier cooler bonded to it. The second image shows the PCB removed from the base. On the left is a photodetector, containing a large-area photodiode, and an internal chip. This device is marked OSI 5K Centronic KN. The LED on the right lights up red, but appears rather dim, so could be a near-IR device. The stainless tube contains a thermocouple and what appears to be a ceramic heater.

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My guess is that it is some sort of  moisture/humidity/vapour content sensor

From Geoff. Sweet : You are right it is some kind of moisture sensor. It is in fact a dew point sensor. The electronics control the temperature of a mirror using the Peltier cooling device you found. Light is directed on to the mirror, and when moisture forms on the surface, at the dew
point, the reflectivity changes sharply. The temperature of the mirror is measured; hence you have dew point. The mirror temperature is usually cycled, so that the rate of change of reflectivity can be detected. This is supposed to minimise the effects of any, inevitable, contamination of the mirror. The sintered filter in the photo also supposed to help this. Contamination is always a problem, though. Nevertheless, these are quite good and accurate dew point meters, with +/- 0.5deg C accuracy on dew point
achievable. They are still made Michelle Instruments of Cambridge being one manufacturer. From the photos I think yours may be made by EG & G. The temperature sensor may be a resistance thermometer, to give greater accuracy.

Mystery Object #1

Below is a clear 2.5 x 3.5 x 1" encapsulated plastic block containing what appear to be the component parts of an item made by a company named Collins.

My first thought was that it's something like an LVDT position transducer, but I don't think this is the case.There are two coil forms, each containing two series windings of fine enamelled wire, with a 1.5mm hole through the middle of them. these appear to fit in the ends of the upper tube, which consists of two brass cylinders, joined by a series of 9 silver-coloured rings or discs (can't see which), supported by longditudinal wires spot-welded to them. The terminal/endcap assemblies below the coils look like they fit into the ends of the bottom tube, but the 2mm tube on the right-hand terminal cap is NOT central, and so cannot pass through the centre of the coils (it would be too thick anyway), or through the top brass/silver tube.

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Update (from Radiomatt) : A Collins Radio Co (Cedar Rapids, IA)(now Rockwell Collins) mechanical filter
(actually electro-mechanical). The transducers excite the disc which has a high "Q", so much so that each disc is off frequency just a bit to make the passband wider...enough to pass readable audio. I can't read the number, but it is usually used in the 455 kC IF stages of a radio.

From David Stockton :  It is definitely a Collins mechanical filter. Coils operate magnetostrictive transducers in early versions, then conventional magnetic transducers in later versions, discs work as filter resonator elements, wires provide support and coupling. Japanese company Kokusai did a copy but used piezo-electric transducers. Collins redeveloped to lower the distortion of their transducers. 455kHz is most popular centre freq, I've seen 100kHz and 45kHz... But
Collins did specials for anyone prepared to pay. Rockwell-Collins still make mech filters.. try webpage.

From Rich Oliver : Collins Radio Corp. of Cedar Rapids, Iowa was a premier manufacturer of fine radio equipment. Their gear exhibited state-of-the-art performance due in part to two devices they developed to a very high standard of performance. Your Mystery Object #1 is one of them, a mechanical filter. A transducer at one end converts the electrical signal to a mechanical, torsional force at the end of the resonator stack. Precisely machined discs are positioned down the central rod of the resonator; each is resonant at a slightly different frequency. At the far end the torsional motion is converted back to electrical energy. The result of this is a filter with excellect characteristics - a very flat passband with very steep skirts on the edges. These mechanical filters are typically used at intermediate radio frequencies, most commonly at 455 kHz or 500 kHz for Collins gear. You appear to have a display piece showing the "guts" of the filter. The other Collins device I referred to is the Permeability Tuned Oscillator, or PTO. Unlike the typical RF oscillator with a fixed coil and a variable capacitor, these units vary the inductance. A precisely machined leadscrew moves a slug within the coil changing its inductance. Collins was able to produce oscillators of exceptional accuracy and stability in this way.

From Bill Noble : You have a display paperweight - When I worked at collins in the 70s, these were used as gifts - I actually made my own from some discarded filters.

Mystery Object #2

**SOLVED** Full info on this device here

This is a stainless steel cylinder about 4" long by 1.5" dia, with an octal plug base on one end, and a single electrode, mounted in a ceramic insulator on the other. The label reads ' E.I ? Vibron'. The plate which retains the octal base has the number 9654 engraved on it. The unit is very well made, and looks as if it was very expensive.

The single electrode is retained by a screw-in ring. Inside, the electrode is fixed to a 19mm dia highly polished gold plated disc 1.5mm thick, with a chamfered edge. There is an identical plate in the bottom of the cavity, and when assembled, there is a spacing of approximately 2mm between the plates, determined by the size of a rubber o-ring which the end cap rests on when the retaining ring is screwed down.


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Removing the base reveals a large adjustment grubscrew with a locking nut. Further dismantling reveals a coil, two spring discs and the plate which appears at the bottom of the cavity seen above, attatched to a shaft which passes through the centre of the coil. It appears that the coil is intended to make this plate vibrate or move towards the top disc.

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My guess is that it's for testing piezoelectric materials.

Bill Conrad writes : Mystery object number two is an electrically variable capacitor, One applies a current to the coil to move the plates closer together. I found two of them is some strange test equipment that compared
sine waves. They are made rather well. I wonder how much gold is in them?

Salty Dog writes : In my career, I worked for EIL (Electronic Instruments Limited) at
Richmond in Surrey. This enables me to confirm that the "Vibron" device shown in your mystery items page is a vibrating capacitor. This employs the electrophorus effect to convet a tiny DC current into an AC one. This was then amplified in a gain controlled amplifer and fed to a phase sensitive rectifier. The rectifiers other input being a portion of the 60 or 400Hz signal used to drive the solenoid in the base of the Vibron.
This method enabled very stable measurement of tiny DC currents typically 10^-16 A. These currents are typical of those produced by PH electrodes and ion chambers. The bulk of the instruments made by EIL were based on this Vibron technology for which (I believe), they held the patents.

Mystery Object #3

OK, this is a real hum-dinger - a Nobel prize is due to anyone who figures this one out!

This is a small glass tube, 18mm dia, with a metal base bonded onto one end, which has wires emerging and a pip for evacuating. On the other end a circular translucent red-orange disc has been bonded on. The disc initially appears to be glass, having a very smooth polished appearance, but can be scratched and cut with a sharp knife, but in a way unlike any plastic I've encountered - there's a 'squeaking' noise as you cut, a bit like a heavily filled polymer, and tapping on the surface with a hard blunt object leaves slight indentations. Maybe a crystal ?

Inside, there is a small coil containing a pellet, which looks like a small length of 2.5mm dia. copper tube crimped nearly closed at each end, containing a white powder. I suspect this may be something like a getter, used to remove traces of gas after evacuation.

At the disc end are four sharp points facing the disc, the tip to disc spacing being about 4mm. Each point looks like a 7mm length of approx.0.75mm wire, the end of which has been filed to form a wedge-shaped point, Two of the points are gold in colour, and two silver. All four are black for about 1mm at the sharp end, either coated, plated or burnt. They seem to be mounted in mica blocks 1 x 3 x 3 mm, clamped into a metal frame by two very small screws. A wire from the base is soldered to the base of one of the points, on the other side of the mica block. Two other wires connect to the metal frame, but these appear to be for mechanical support.

There are a few flakes of a white substance (presumably from the copper tube), and two 1 x 3mm pieces of gold foil, each blackened on one side, loose inside the tube.

The construction suggests that this is a hand-made experimental item.

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Duncan Cadd provided the following suggestion: The Mystery Object number 3 looks like it may be an ion source. The small copper tube containing the flakes of white stuff is meant to be heated by a current passed through the coil, and an ionising/accelerating voltage applied to the sharp spikes. The orange disk I think would be removed when the thing is installed, or perhaps drilled with a very small hole. It looks like the sort of source which might have been used in an early caesium atomic clock or such like, but that's just a guess. Get the bits of white stuff analysed (stick some in a clear, colourless flame and see what colour it gives) and find out what kind of ions it was meant to produce! With the pellet inside the coil it's much more likely to be an ion source than a getter IMHO. Getters are usually heated in a relatively uncontrolled fashion with rf, and it doesn't matter if the metal goes all over the glass envelope. Ion sources need to be heated in a regulated way to control the number of ions produced, hence the coil for a variable heating current. That's my best guess anyhow.

Frank Gilliland wrote : About your Mystery Object #3. I took the pic to an old mentor of mine (I don't know if he wants his name public, so I can't give it), who said that your tube is "nothing more than a lamp".
Well, not just a lamp. During the early years of the study of phosphorescence (sp?) the scientists needed sources of light at pure wavelengths. As the laser had not been invented yet, and stimulation by UV light yeilded unwanted spectral lines, the only alternative was electrostatic stimulation.
Apparently the red lens is made of a substance that phosphoresces at a specific wavelength when stimulated by electrons, the mica screen in front of the heater is to filter out the infrared, two of the wires are to discharge the "plate", the other two to measure the "electron cloud" behind the plate, an indication of the level of electrical stimulation. At least that's his story.

John Garmendia writes :  I concur that it is a spectral source, and suggest that the red material may be an optical window, if I understand the construction properly. Likely it  was hand-built to support some special instrument, though some of the  "professional" stuff made years ago looked pretty rough, as it was buried within instruments, and aesthetics were secondary to function and price....

Decades ago, long-wave infra-red windows were made of pretty nasty stuff, such as KRS-5 or KRS-6. The former is a soft red semi-crystalline material, a Thallous-bromo iodide mixture invented by the Germans before WW II. It is rather poisonous, and should be treated with considerable respect.  The colour is a dull orange-red, and may vary depending on age , stoichiometry and moisture content. STOP SCRATCHING IT!

Standard KRS-5 optical windows for spectrometers and the like were made by several firms in Europe and the US, with windows having thicknesses of only a few mm,and diameters from 10 to 25 mm or so being most common. (It is still available from a few firms that produce optical crystals from low temperature melts.). They were optically polished, typicallly as flats. Because the
material is hygroscopic, atmospheric moisture will soon fog the material, degrading its surface figure, and ruining the window unless kept in a dessicator until use, and thence returned afterward. If I'm right about what you've got, wash your hands, wear gloves, and put the thing away , and keep it from children especially. Thallium poisoning is not something you want to contend with, and there are suggestions that long term low-level exposure may lead tosome chronic illnesses including cancer.

Am not trying to scare you, just caution you about the hazards of experimenting with substances that are unknown and may pose serious risks. I used to use KRS-5 optics, and we treated the stuff with great caution.

It is difficult to state with assurance, but I suspect that the electrode structure you describe for Mystery Object 3 might be as follows:  The coiled wire surrounding the "copper tube" is just a resistance heater, used to raise the temperature of the "copper" tube enough to vaporize some of the white powder within. The ends are crimped only enough to contain the solid phase of the source material. (It is likely some specially-compounded substance, having a desired specral emission) It may
not need to be heated very much,depending on what's inside. Incandescence of  the heater is certainly not desired
Perhaps it is an alkaline metal salt. (or it could even be something more exotic, such as one of the Lanthanide series, etc.) that provided the proper spectrum. The resistance wire heater might be platinum, if you are lucky... The mica
shield is a crude device used toforce the discharge to the center of the heater/pellet, I think. After some use, it might blacken. It may also reflect some heat back toward the cathode, especially if the tube has a gas fill (see below). It would not be desirable to let the red window become heated from within.
Now, what those four pointed electrodes are is unclear, but I suspect they are used to strike and maintain a discharge withi the tube. The discharge is, of course, necessary to ionize the vapor from the white powder and make it emit light, some of which is visible through the aforementioned KRS-5 window. The tube is constructed to emit long-wave IR, of unknown wavelengths.

Now, why there are four points , having two different appearances, I can't tell from the photos but it may be a design to assure a point-discharge. The points may be anodes. Your photos on the Web do not clearly show these elements, and it is impossible to know what they are without seeing them clearly. One last comment is that the exit window appears to be glued to the tube with an epoxy resin. A commercial product called "Torr-seal" was widely used for such purposes, and it could hold a fair vacuum for months, sometimes more.

I ampretty sure that what you have is simply a spectral line source, used by some physicist or other worker to produce light of particular wavelengths. That light may have been filtered (by a monochromator, etc.) down to one
particular line for some experimental purpose.

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