Harold Edgerton (Wiki) was an innovator in the areas of strobe light photography and invented the Strobe light, Strobotac which was the first strobe light to operate at frequencies higher than twice the US line frequency ( 2 * 60 = 120 Hz). See my separate web page linking to Doc Edgerdon's MIT notebooks.
He also was involved in the development of SONAR (Wiki) as well as an underwater camera-strobe system used by Jacques Cousteau (Wiki). The company "Edgerton, Germeshausen & Grier" later changed their name to EG&G (Wiki) [probably because no one could spell it].
He came up with and made a strobe light fitted into W.W.II bombers with a power of 50,000 Watt Seconds for night photography. It was used to photograph Stonehenge at night (BldgBlog) in 1944. The company making the capacitors (and maybe the trigger tube) was taken over by the Manhatten project to supply parts for the firing circuit1 used to fire the 64 exploding bridge wire donators (Wiki).
EG&G made the Krytron tube (Wiki) which is a gas filled cold cathode tube (as is the flash tube used in the Strobotac) and uses the same triggering method, i.e. a high voltage pulse to the control grid. It can switch 3,000 Amps at 5,000 Volts in under a nanosecond, just the thing for triggering atomic weapons.
Edgerton was involved in the development of the camera flash unit that ended up being the Graflex Stroboflash IV.
2331317 below) and uses a Neon (Wiki) gas filled strobe tube. It appears the 631 Stroboscope (Wiki) was invented solely by K.J. Germeshausen.
YouTube - Using a Vintage Strobotac -
The TS-805 is the military version of the 631.
TM 11-6625-396-12 - TS-805B, TS-805C, TS-805D, TS-805E User
TM 11-6625-396-24P - TS-805E Parts
TM 11-6625-396-40P - TS-805B Parts
TB 11-6625-396-35/11 Calibration Procedure for Stroboscope TS-805C/U, 3 March 1966
60 - 15,000
60 - 15,000 TS-805D 6625-00-196-2858
600 - 15,000
100 - 25,000
Fig 4 Property label "Sperry Gyroscope".
Fig 5 1/4-20 standard tripod socket.
Fig 6 Inside
Fig 7 tall cap at left is 2uF @ 600V
max energy = 600 * 600 * 2E-6 / 2 = 0.36 Watt Seconds
which is a very weak flash at best.
Fig 8 631-P1 flash tube
Note on back of reflector:
Use # 40 pilot lamp. Would fit the GR 358 Wavemeter.
Fig 9 Manual lists as 631-P1
Tube base: General Electric, GL-1D21/SN4, Made in U.S.A.
GE tube data sheet (Franks's tube data sheets)
Strobotron Type SN4, 1D21/SN4
aka: Sylvania 631-P1
National Valve Museum 'Strobotron' Neon Discharge Tube 631-P1 (CV220) - UX4 base -
1: Grid, 2: Anode, 3: inner Grid, 4: Cathode.
Popular Electronics July 1957: The "Varistrobe" High Speed Stroboscope Freezes Motion by Harvey Pollack (AntiqueRadio example)
The 1532 Design goes back t 1942, but the 1538-P1 (IET Labs) xenon flash tube dates from _____. Xenon tubes were used in 1916 as surge indicators in power plants, but not as light sources then.YouTube - General Radio StroboTac 1531-AB Demo -
TM 9-6625-2465-15 Operator's Organizational, Direct Support, General Support and Depot Maintenance Manual (Including Repair Parts) for Electronic Stroboscope [General Radio Type 1531-AB Strobotac), December 1969
TB 9-6680-284-35 Calibration Procedure for Stroboscopes, General Radio, Models 1531-A AND 1531-AB, & July 2004
GR Experimenter Sep. 1960 (IET Labs) - New Eyes for Modern Industry 1531-A Strobotac & Type 1532-C Strobolume
The 1531-A has a flash duration about 10 times shorter than the 631-BL and 70 times more light. Xenon gas lamp.
patents: 2966257 & 2977508
Fig 1 Closed
Fig 2 Note "socket" for line cord.
Fig 3 Patents:
It's powered from 115 VAC and draws no more than 100 Watts. But the power in the flash can be much higher than that depending on the duty cycle. The energy storage capacitor appears to be larger than anything I've seen in the equipment I have although the bank of capacitors in my photographic strobes may in total be larger.
It turns out the cap is 12.0 uF at 600 Volts. Energy = 2.16 Watt Seconds = 2.16 Joules This is rather low, so the speed at which it flashes may be high?
In order to remove the chassis from the box a flat blade (-) screwdriver with a blade about 7" long is required, preferable a skinny one.
There are two electrical connectors. The 2 male pin probably for tghe AC line input and the 6 male pin probably for trigger signals, but why so many pins?
Some types of Thyratron tube (Wiki) when conducting emit a dim flash of light. I think this effect was seen by Egerton when working on AC motors that lead to his development of tubes optimized for light output rather than for electrical switching parameters. The early flash tubes were essentially Thyratrons.
Flash Tube (Wiki)
Modern photo flash tubes have the same color temperature as sunlight making for nice color photos outside with mixed lighting.
The energy stored in the high voltage capacitor is commonly referenced and related to the brightness of the flash. The flash in a throwaway camera might be 12 Joules.
Note you can interchange Joules with Watt Seconds.
Energy (Joules) = 0.5 * C (Farads) * Volts * Volts (same as joules)
Measuring a super capacitor requires techniques different from normal capacitors.
The duration of the flash is governed by the impedance in the electrical loop containing the high voltage capacitors and the flash tube. For common camera type flashes it's in the range of 100 micro seconds to 1,000 micro seconds. But can be much shorter or longer for special designs.
There are three circuit designs related to flash duration and efficiency.
All of the Edgerton strobe units are of this type where the circuit consists of the energy storage capacitor connected directly to the flash tube. When the tube is triggered the flash lasts until the capacitor voltage drops low enough that the tube turns off. There is very little energy left in the capacitor.
A way to short out the capacitor was added in order to turn off the flash. This was done to control (reduce) the light output of the flash. The down side is that it wastes energy, not good if battery powered.
A way to open the circuit between the capacitor and the flash tube provides both the ability to turn off the flash but also the ability to save the energy in the capacitor.
The Nikon SB-900 controls the amount of light using pulses which remote flash units "see" and are controlled by. See the light output waveform on my Nikon web page. The pulses appear to be about 10 uS wide, but I expect the technology could make much narrower pulses.
DigitalPhotography101 Digital Photography 101: The Basics
Digital Photography 201 Stacking Images
Digital Photography 202: Close-Up, Macro & Micro
Digital Photography 203: Color Management
Digital Photography 204: Studio Flash
Digital Photography 205: Astrophotography
Digital Photography 206 Micro Photography
Nikon SB-25 flash
Photoflash - includes Graflex Stroboflash IV
Sonobuoys - CRT-1 Sonobuoy -
Tachometers - mechanical & Optical
2181879 Cutting Machine, Eugene Edgerton Harold, Filed: May 9, 1932, Pub: Dec 5, 1939, 83/520, 315/352, 315/241.00R, 315/241.00S, 315/237, 83/345, 356/23, 315/76, 83/312 - uses stroboscope
2185183 is mentioned in some patents and this may be a typo for 2185189.
2185189 Gaseous discharge tube, Joseph Germeshausen Kenneth, Filed: Nov 7, 1935, Pub: Jan 2, 1940, 313/566, 313/356, 313/346.0DC, 327/602, 313/265, 315/241.00R, 313/240 - cold cathode w/Mercury spot as light source + arc starting electrode (631)
2186013 Motion-picture apparatus, Eugene Edgerton Harold, Filed: Mar 10, 1934, Pub: Jan 9, 1940, 352/200, 315/207, 315/241.00S, 315/243, 315/352, 315/240, 315/237, 315/241.00P, 315/188, 315/181, 315/241.00R, 315/76, 315/209.00R, 315/340, 315/208 - instead of a mechanical shutter it uses a flash tube
2201166 Electric circuit, Joseph Germeshausen Kenneth, May 21, 1940, 315/233, 327/602, 315/238, 315/203, 315/237, 315/341, 315/230, 315/188, 315/337, 315/353, 252/181.4, 315/336, 315/241.00S, 313/566, 315/190 - (631) - includes oscillator, Calls: 2185189 & 2201167
2201167 Gaseous-discharge device, Joseph Germeshausen Kenneth, May 21, 1940, 313/566, 313/346.0DC - (631) -
2205248 Synchronous-motor-control system, Eugene Edgerton Harold, Filed: Jun 12, 1937, Pub: Jun 18, 1940, 318/706, 327/142, 307/87, 318/532 - tubes 9 & 10 seem related to strobe tubes with mercury cathodes
2269338 Flash-producing system, Eugene Edgerton Harold, Joseph Germeshausen Kenneth, Filed: Sep 27, 1939, Pub: Jan 6, 1942, 315/181, 313/171, 315/354, 315/208, 315/243, 313/594, 315/342, 315/237, 313/166, 315/344, 315/340, 315/241.00P, 315/339, 313/167, 313/156 - "5" is a Mercury cathode. High frequency flashes of light.
2277697 Electric system and apparatus, Grier Herbert Earle, Mar 31, 1942, 362/10, 362/12, 315/238, 315/DIG.100, 396/155, 362/216, 315/182, 315/245, 315/353, 315/241.00R - (1531-A)
2277698 Flash-photography apparatus, Herbert E Grier, Mar 31, 1942, 362/10, 362/216, 396/180, 362/12 - GR 1531 Strobotac
2331771 Gaseous electrical discharge tube system, Earle Grier Herbert, Joseph Germeshausen Kenneth, Oct 12, 1943, 315/129, 315/177, 315/341, 315/157, 315/238, 315/243, 315/200.00A - trigger transformer with wire near flash tube
2331317 Stroboscope, Joseph Germeshausen Kenneth, Filed: May 9, 1940, Pub: Oct 12, 1943 - (631)
315/129, 331/144, 315/241.00S, 315/241.00R, 73/649, 331/177.00R, 315/241.00P, 315/201, 331/44, 315/353, 331/156, 315/350, 315/238, 315/230, 315/232, 331/64, 315/183, 315/341 -
It looks like the patent office could only find a marked up copy of this patent.
Fig 1 & FIg 2
2351603 Condenser-discharge electric system, Eugene Edgerton Harold, Filed: Dec 6, 1941, Pub: Jun 20, 1944, 315/230, 315/241.00P, 315/238, 315/353 - first mention of Xenon gas in flash tube. (1531?)
2399222 Flash-photography apparatus Joseph Germeshausen Kenneth, Filed:; Nov 8, 1941, Pub: Apr 30, 1946, 362/10, 315/335, 362/265, 362/216, 396/180 - flash tube inside a glass envelope to protect photographer from HV
2408764 High-speed flash-photography, Edgerton Harold E, Filed: Jun 14, 1940, Pub: Oct 8, 1946 - studio electronic flash system
Strobotac2478901 Electric system, Edgerton Harold E, Filed: Aug 16, 1933, Pub: Aug 16, 1949 (16 year delay for WWII), 315/183, 315/353, 315/354, 315/238, 315/252, 315/230, 315/201, 315/241.00S, 315/162 (1531-A)
2478902 Electric system, including a vaporelectric discharge device, Edgerton Harold E, Filed: Aug 16, 1933, Pub: Aug 16, 1949 (16 year delay for WWII), 315/238
2478903 Stroboscope, , Edgerton Harold E, Filed: Aug 16, 1933, Pub: Aug 16, 1949 (16 year delay for WWII), 315/238
2478904 Light-flash-producing system, Edgerton Harold E, Filed: Dec 30, 1939, Pub: Aug 16, 1949, 315/162, 315/353, 315/291, 315/238
2478905 Electric system, Edgerton Harold E, Filed: Dec 30, 1939, Pub: Aug 16, 1949, 315/188, 315/208, 315/230, 315/190, 318/794, 315/241.00S
2478906 Electric system, Edgerton Harold E, Filed: Oct 2, 1946, Pub: Aug 16, 1949, 315/237, 315/227.00R
2478907 Flash-producing device, Edgerton Harold E, Filed: Jul 29, 1935, Pub: Aug 16, 1949, 315/188, 315/354, 315/353, 315/208, 315/230, 315/241.00R, 315/241.00P, 315/238 - (1531-A)
2478908 Electric light-flash-producing system, Harold E Edgerton, Filed: Feb 11, 1946, Pub: Aug 16, 1949, 340/331, 315/230, 362/35, 340/947, 315/325, 340/953, 315/241.00R, 315/241.00P, 315/353 - multiple strobe lights in a circle to replace rotating search light
2492142 Electric system embodying coldcathode gaseous discharge device, Germeshausen Kenneth J, Dec 27, 1949, 315/238, 419/19, 313/594, 313/346.0DC, 241/15, 315/241.00R, 241/16, 313/25, 315/241.00P, 252/513 - (1531-A) - about coiled tube flash lamp
2588368 Light intergrator, Harold E Edgerton, Filed: 1947-05-02, Pub: 1952-03-11, 356/215; 73/1.56; 250/229; 250/214R; 250/225; 324/102- see the GR 1501 strobe light meter
2722629 Electric system, Germeshausen Kenneth J, Filed: Jun 28, 1946, Pub: Nov 1, 1955, 315/163, 315/245, 315/289, 315/241.00S, 315/164, 315/239, 315/241.00P, 315/183, 331/127, 315/243, 315/173, 315/177 - eliminates trigger wire
2756361 Gaseous-discharge device and method of making the same, Germeshausen Kenneth J, Jul 24, 1956, 313/623, 65/60.4, 313/318.1, 445/44, 65/62, 313/266, 65/59.23, 220/2.30R, 403/271, 228/124.6, 313/634 - glass blowing
2756365 Electric-discharge system, Germeshausen Kenneth J, Jul 24, 1956, 315/234, 315/243, 315/238, 315/289 -
2893289 Microscope flash-photography system and apparatus, Edgerton Harold E, Jul 7, 1959, 359/363, 315/241.00P, 362/8, 313/570, 359/389, 396/432, 315/200.00R
2933647 Electric-discharge system, Edgerton Harold E, Germeshausen Kenneth J, Apr 19, 1960, 315/163, 315/169.1, 315/239, 315/241.00S, 315/173, 315/230, 315/241.00P, 315/241.00R -
2939984 Flash device and method, Edgerton Harold E, Edgerton Germeshausen & Grier, 313/634, 315/241.00R, 315/237, 313/594, 315/241.00P - modern photo flash tube with external trigger electrode
2943222 Electric-discharge device, Colson Edward A, Edgerton Germeshausen & Grier, Jun 28, 1960, 313/594, 315/238, 315/241.00R, 315/241.00P, 315/234 - Xenon gas
Calls:2960380 Flash-photography apparatus and method, Edgerton Harold E, Edgerton Germeshausen & Grier, Nov 15, 1960, 396/171, 396/187, 396/281, 352/174, 396/56, 73/167 - Schlieren technique (Wiki)
2031722 Braun Tube
2293529 Image Tube
2478908 Electric light-flash-producing system (above)
2358577 Device for lifting weights? (come-along)
2590821 Potted electrical subassembly?
2691120 Ionizing flash lamp,
2825000 Photographic light unit, GE
2966257 Instrument carrying case, Henry C Littlejohn, Gen Radio Co, Dec 27, 1960, 312/244, 73/431, 206/752, 206/305 - (1531-A)
2977508 Gaseous-discharge device and system, Kenneth J Germeshausen, Edgerton Germeshausen & Grier, Mar 28, 1961, 315/241.00S, 315/336, 315/84.61, 315/241.00R, 313/570 -
3075121 Flashtube and system, Goncz John H, Jacob Israelsohn, Seymour Goldberg, Jan 22, 1963, 315/168, 315/325, 315/241.00R, 315/238, 313/112, 315/241.00P, 313/595 - very small pixel size and UV output
3350602 Gaseous-discharge device having a trigger electrode and a light producing spark gap to facilitate breakdown between the trigger electrode and one of the principal electrodes, Kenneth J Germeshausen, John L Turner, Eg & G Inc, Filed: Feb 11, 1965, Pub: Oct 31, 1967 - solves the "dark start" problem
Side Scan Sonar (Wiki)
EG&G developed their model 259 Side Scan Sonar with help from Edgerton. Many entries in his notebooks about it.3098210 Echo ranging with reference to boundary conditions, Sparling Stanley Capel, Haslett Roy William George, Hopkin Peter Roy, Sothcott John Ernest Leon, Kelvin & Hughes Ltd, Filed: May 1, 1956, Pub: Jul 16, 1963
4197591 Facsimile recording of sonic values of the ocean bottom, Julius Hagemann, Filed: Aug 4, 1958, Pub: Apr 8, 1980 (note 22 year delay because of military classification), 367/6, 367/106, 367/113, 367/115, 367/96, 367/88
3975704 Method of and apparatus for sonar and related signal texture enhancement of recording, Martin Klein, Aug 17, 1976 -
4198702 Time varying gain amplifier for side scan sonar applications, Peter J. Clifford, E G and G, Inc., Apr 15, 1980
4232380 Underwater mapping apparatus and method, Roger L. Caron, Peter J. Clifford, Francis R. Germain, Eg & G, Inc., Nov 4, 1980
Krytron tube (Wiki) & Misc EG&G
Edgerton developed 50,000 Watt Second airborne photo-flash systems carried in bombers because they weighed in the thousands of pounds. These systems consisted of capacitor banks where both high voltage and high currents were involved. The Plutonium implosion "Fat Man" (Wiki) bomb needed this type of "firing set" they took over the Boston company making the airborne photo-flash systems for use in the firing set. After W.W.II ended the government wanted to give MIT a contract for instrumentation of H-bomb testing, but MIT did not want it and EG&G was formed to handle atomic bomb instrumentation.
The "E" in EG&G is for Edgerton. These patent choices are just guesses. Let me know of kryton patents.Bernard J. O'Keefe author of the 1983 book Nuclear Hostages, co-founder and former chairman & CEO of EG&G and has a little info on what they were doing during.
Bernard has an excellent way of explaining difficult physics concepts.
The ceramic thyratron tubes patented by EG&G probably were aimed at radar applications.
The 1973 data sheet for the KN 2, KN 11B, KN 6, KN 22, KN 12 and KN 14 is on line. The KN 6B is rated 8kV & 3kA whereas the KN-2(1) is rated 4kV @ 500 A.
Used to ground on end of the HV caps in a strobe or Exploding Bridge Wire (Wiki, patent)
3040660 Electric initiator with exploding bridge wire, Lawrence H Johnston, Filed: Nov 8, 1944, Pub: Jun 26, 1962 (18 year delay because of classification), 102/206, 361/248, 102/202.7
Similar in appearance to a blasting cap (Wiki) it's very different. A 2 uF condenser charged to 1500 Volts will explode a tungsten wire. or a Nichrome wire 0.006" dia using 500 Volts from a 50 uF capacitor.2919368 Gaseous reservoir and method, Edward J Goon, Goldberg Seymour, Edgerton Germeshausen And Grier, Dec 29, 1959, 313/547, 313/346.00R - 313/547, 313/346.00R
This was invented specifically for the Fat Man bomb.
Calls:3292049 Spark gap, Lucas Jr Louis, Edgerton Germeshausen & Grier, Dec 13, 1966, 361/117, 315/35, 361/120, 313/325 - surge protector
2497911 Hydrogen thyratron
2572881 Thyratron cathode design to prevent cleanup of hydrogen
2766397 Hydrogen-filled electric discharge device
2804563 Electron tube generator
2937034 Electric-discharge device and cathode, Germeshausen Kenneth J, Goldstein David S, Seymour Goldberg, Edgerton Germeshausen & Grier, Filed: Sep 25, 1957, Pub: May 17, 1960, 313/631, 313/632, 313/336, 313/346.00R, 313/630, 313/351
2937303 Electric discharge device, Germeshausen Kenneth J, Edgerton Germeshausen & Grier, May 17, 1960, 313/568, 313/341, 313/632, 313/620, 313/622 -
3098166 Gaseous reservoir and method, Goldberg Seymour, Edgerton Germeshausen & Grier, Jul 16, 1963, 313/547, 313/562 -
3207947 Triggered spark gap, Goncz John H, Sep 21, 1965, 315/109, 313/306, 313/602 - hydrogen thyratrons (5C22.pdf) limited to about 1,000 amperes. The minimum trigger signal was a 11.7 kv., 5 microsecond pulse. Similar devices have held off 60 kv. without static breakdown. When triggered at these voltages, the gaps passed currents on the order of 200,000 amperes. Ceramic envelope with high vacuum.
3319146 High efficiency converter circuit, Kearsley Wayne A, Eg & G Inc, Filed: Jun 10, 1966, Pub: May 9, 1967 - for photoflash cap charging, auto turn off when at voltage, independent of bat voltage. see Joule Thief
2854615 Circuit arrangement for providing a d. c. output, Philips Corp, Sep 30, 1958 - voltage limited output
2976461 Oscillator ignition system, Globe Union Inc, Mar 21, 1961 -
3324331 Gaseous reservoir and heater for hydrogen thyratrons, Reinhardt Nicholas, Eg & G Inc, Jun 6, 196 -
3458853 Underwater guidance method and apparatus, Daniels Charles K, Mccarthy John P, Eg & G Inc - Glomar Explorer? (sank April 1968)
3527535 Fingerprint observation and recording apparatus, John N Monroe, Eg & G Inc, Sep 8, 1970, - better optical properties lead to cleaner images.
3675069 Point light source, Crossen Kenneth R, Eg & G Inc, Jul 4, 1972, - fraction of a uS
WO 2000017600 A1 Improved chip slapper detonator, Eg & G, Inc. Mar 30, 2000 - (Wiki)
China Lake Patents
Photo Flash Units - Graflex Stroboflash IV -
GR Impedance Bridges
GR Sound measuring equipment
GR Strobotac with patent links - this page
LM631A Amprobe (Meterman) LM631A Digital Light Meter
Macbeth Illuminometer -
Nikon SB25 on camera strobe flash
Nikon on camera flash units
Photo Studio Strobe Flash w/ Einstein 640 & Thomas Strobemeter Model 1B -
Weston Model 594 Photronic Cell light sensor, & Weston 614, 615, 650, 703, 756, 819 & others
Ref-1: Nuclear Hostages, Bernard J. O'Keefe, 1983 - an excellent description of the key parts of the Manhattan Project (Wiki) from someone who was there. He was high up in EG&G from the beginning.
Harold Edgerton in World War II - 43 page pdf.
PRC68, Alphanumeric Index of Web pages, Contact, Products for Sale
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