KOB stands for Key On Board. A KOB has a key and a sounder mounted on a single base. The first KOBs appeared in the 1860's. Before that, the individual components of a telegraph office, such as the key, sounder, and relay, would be mounted separately on the operator's table.

Some KOBs were designed to be simple practice sets for learning Morse Code, while others were actually used in telegraph offices. Box Relays were likely the earliest type of KOB to be used in telegraph offices. With a Box Relay, the sounder electromagnets are enclosed in a wooden box that was mounted on the wooden base with a telegraph key. The box acted as a sound amplifier.

Other KOBs were used in large homes as communication devices between rooms. These were known as Private Line Sets, or PL Sets. Most were made of cast iron with only the moving parts made of brass, and were ornately painted in order to fit in with the Victorian style in the home.

In Europe, especially in Germany, it was common to see a different version of the KOB, in which a key and a tape register were mounted on a single board.

Below are some pictures of KOBs dating from the 1860's up to the early 1900's. Click on each thumbnail to view the full size image:

James Clark Box Relay, Philadelphia. Ca. 1860's The Camelback Key on the Clark Box Relay J.S. Keeling Box Relay, NY. Ca. 1865 Charles T. & JN Chester, NY. Ca. 1860's
Henning Box Relay. Ottawa, Illinois. Ca. 1860's Another View of the Henning Box Relay Top View of the Henning Key Henning Name Stamped on Armature Frame
G.M. Phelps Combo Set, NY. Ca. 1860's Charles Williams, Boston. Ca. Late 1860's L.G. Tillotson Splitdorf Patent Box Relay, NY. Ca. 1870 Lake Shore & Michigan Southern Railway Box Relay. Ca. 1870
W.H. Johnson Combo Set. Louisville, Ca. 1870 Charles Williams, Boston. Ca. 1870 Charles Williams, Boston. Ca. 1870 Bliss-Tillotson "Cheapo" Practice Set, NY. Ca. 1870
L.G. Tillotson Box Relay, NY. Ca. 1870 LG Tillotson Relay With Caton-Pattern Key. Similar to the Splitdorf Patent Box Relay but Minus the Resonating Box. Ca. 1870 Close-Up of the Caton-Pattern Key on the Tillotson Relay Tillotson Practice Set. Ca. Early 1870's
Box Relay by George Bliss, Chicago. Ca. 1870 Close-Up of the Caton-Pattern Key (With Snapper Circuit Closer) on the Bliss Box Relay George Bliss Practice Set, Chicago. Ca. Early 1870's Knox & Shain, Philadelphia. Early 1870's
KOB Made by Louis Schaefer in Japan. Ca. Early 1870's (See Page on Special Telegraph Instruments) Another View of the Schaefer KOB Rear View of the Shaefer KOB Set Charles Williams, Boston. Early 1870's
California Electrical Works Cylindrical Box Relay, San Francisco. Ca. 1870's A "Fake" Version of the Cal. Electrical Works Cylindrical Box Relay Made to be Used as a Prop in Hollywood Movies. Several of These Units Were Produced As You Can See, the Coil End of the Relay is Just a Brass Plate With Fake Coils ! The Wooden Cylinder Contains No Wires The Fake KOB Has a Very Early Style Camelback Key to Give the Appearance of a Very Old Telegraph Instrument
A Screenshot From the Movie "Denver & Rio Grande" Showing the Fake Cylindrical Box Relay. This Set Was Also Used in Several Other Old Movies as Well as the TV Show "Hogans Heroes" Late Charles Williams KOB, Boston. Early 1870's Top View of the Williams KOB Box Relay by Electrical Improvement Co, Chicago. Ca. 1872
Key is Marked "A.S. Wetmore, Maker" Combo Set by George Bliss & Western Electric, Chicago. Ca. Early 1870's Partrick-Bunnell, Philadelphia. Early 1870's Co-Operative Mfg. Co, Philadelphia. Ca. 1870's
Another Example of a Cooperative Mfg KOB. This One Has Probably Been Re-Based Another View of the Cooperative Mfg KOB Early Western Electric Private Line Set, Chicago. Ca. Early 1870's Close-Up of the Neat Artwork on the Private Line Set
Partrick & Carter PL Set, Philadelphia, Ca. 1870's L.G. Tillotson PL Set, NY. Ca. 1870's Western Electric Lewis Key PL Set. Ca. 1870's Ornamental Paint Variations on Western Electric Lewis Key PL Sets
Altoona Shops Box Relay, Altoona, PA. Ca. 1870's An Unusual KOB With a Camelback Key and Drum Sounder. Made by Watts & Co, Baltimore, Maryland. Early 1870's (Smithsonian Museum) Top View of the Watts Drum KOB. (Smithsonian Museum) Watts PL Set, Baltimore. Patented 1872
Another View of the Watts PL Set A Watts PL Set of Different Design Watts Practice Set, Baltimore. Ca. 1870's J.A. Lannert, Cleveland. Ca. 1870's
M.A. Buell, "Eureka" Practice Set, Cleveland. Ca. 1870's Another "Eureka" Practice Set. This one Was Made by W.B. Cleveland, Cleveland, Ohio Cast Iron Private Line Set by Jerome Redding, Boston. Ca. 1870's Combination Set Consisting of a Key, Sounder, and Relay by Watts & Co., Baltimore. Ca. 1870's
Combo Set by LG Tillotson, NY. Ca. 1870's Partrick & Carter Combo Set, Philadelphia. Ca. Late 1870's L.G. Tillotson Practice Set, "The Home Telegraph Instrument", NY. Ca. Late 1870's Western Electric Box Relay with Lewis Key, NY. Ca. Late 1870's
J.H. Bunnell, NY. Late 1870's Altoona Railroad Shops, Altoona, PA. Ca. Late 1870's M.A. Buell, Cleveland. Ca. Late 1870's A.B. Lyman, Cleveland. Ca. Late 1870's
Another KOB by M.A. Buell, Cleveland. Late 1870's Close-Up of the Buell Key Private Line Set by RK Pearce, Philadelphia. Late 1870's Close-Up of the Pearce Name on the Private Line Set
R.K. Pearce Combo Set, Ca. Late 1870's Jerome Redding, Boston. Ca. Late 1870's An Odd KOB With a Plunger-Style Key. Maker Unknown Another View of the Odd KOB
Thomas Hall "Washington" Set, Boston. Ca. 1880 Tillotson Combo Set With Phillips Key, Ca. 1880 California Electrical Works, San Francisco. Ca. 1880 Electrical Supply Co, San Francisco. Ca. 1880
Partrick & Carter Box Relay, Philadelphia. Ca. 1880 Another View of the Partrick & Carter Box Relay Showing the Camelback Key Partrick & Carter, Philadelphia. Ca. 1880. Key Has a Steel Lever Which Pre-Dates the Bunnell 1881 Patent KOB by CE Jones, Cincinnati Ohio. Ca. 1880
Another View of the CE Jones KOB Altoona Shops Cain Set. Ca. 1881 Jerome Redding, Boston. Ca. Early 1880's Jerome Redding KOB With Camelback Key. Ca. Early 1880's
Another KOB by Jerome Redding KOB With 1st Model Victor Key. LG Tillotson, NY. Ca. 1882 Another View of the 1st Model Victor KOB Partrick & Carter, Philadelphia. Ca. Early 1880's
Another Partrick & Carter KOB With Different Ornamental Painting An Earlier Version of the Partrick & Carter KOB With Non-Adjustable Spring Tension Western Electric KOB With Steel Lever Lewis Key. Ca. 1884 Viaduct Mfg. Co, Baltimore. Ca. 1884
Another KOB by Viaduct Mfg. Co, Baltimore. Ca. 1884 A View of the Viaduct KOB From the Rear AF Fleischmann, Philadelphia. Ca. 1884 Another View of the Fleischmann KOB
KOB with Victor Key by LG Tillotson, NY. Ca. 1880's E.S. Greeley Box Relay with Victor Key, NY. Ca. 1880's Electrical Supply Co, NY. Ca. 1880's C.H. DuBois Box Relay, NY. Ca. 1880's
Utica Fire Alarm Co. Ca. 1880's Unmarked KOB With Camelback Key Close-Up of the Camelback Key J.H. Bunnell Box Relay, NY. Ca. 1880's
Canadian KOB by Foster, Toronto. Ca. 1880's Standard Electrical Works, Cincinnati Ohio. Ca. 1880's Close-Up of the Standard Electrical Works Name Stamp California Electrical Works, San Francisco. Ca. Late 1880's
British GPO Baseboard Set. Ca. Late 1880's E.S. Greeley Ludwig Instrument, NY. Ca. Late 1880's New Haven Clock Co. Key-Sounder Set. Ca. 1888 New Haven Clock Co. Ca. Late 1880's
Western Electric Box Relay, Chicago. Ca. Late 1880's A.B. Lyman, Cleveland. Ca. Late 1880's KOB by A.B. Lyman, Cleveland. Ca. Late 1880's Western Electric Private Line Set with Steiner Key, Chicago. Ca. Late 1880's
Western Electric Box Relay with Steiner Key. Ca. Late 1880's Another View of the Steiner Key Box Relay Western Electric Steiner KOB. Ca. Late 1880's Another View of the Western Electric Steiner KOB
E.S. Greeley, NY. Ca. Late 1880's Shaw Electrical KOB. Ca. Late 1880's J.H. Bunnell Practice Set, NY. Ca. Late 1880's Fire Alarm KOB by Conrad-Young, Baltimore Md. Ca. 1880s
Altoona Shops KOB, Altoona Pennsylvania. Ca. 1890 Altoona Shops KOB, Altoona Pennsylvania. Ca. 1890 Novelty Electric Co, Philadelphia. Ca. 1890's American Electrical Works, Cleveland. Ca. 1890


I.H. Moses, Cleveland. Ca. 1890's Another View of the Moses KOB Western Electric Box Relay with Rod-Lever Key. Ca. 1890's Western Electric Private Line Set with Rod-Lever Key. Ca. 1890's
Western Electric Combo Set, Chicago. Ca. 1890's Knapp Electrical Works, Chicago. Ca. 1890's German Key & Relay Set. Ca. Late 1800's British GPO Key, Sounder & Galvanometer. Ca. Late 1800's
J.H. Bunnell Barclay Box Relay, NY. Ca. 1890's Western Electric Barclay Box Relay, Chicago. Ca. 1890's J.H. Bunnell Combo Set, NY. Ca. 1890's A Very Small Bunnell KOB in Metal Box Used by The US Army During the Spanish-American War. Ca. 1898
Close-Up of the Bunnell Military KOB Small KOB With Barclay Box Relay Marked "N.T.Co" (Northern Telegraph Co.) Another View of the Small Barclay Box Relay. Note the Key is the Same as on the Bunnell Military KOB Gem Practice Set, Horace Martin, NY. Ca. 1903
Novelty Electric Mini KOB, NY. Ca. 1904 Novelty Electric KOB with Regular Size KOB German Key & Sounder Set. Ca. Early 1900's Postal Telegraph Skirrow Patent KOB, NY. Ca. 1904
Ohio Transmitter Co. Practice Set. Ca. Early 1900's J.H. Bunnell Ghegan Patent KOB, NY. Ca. 1905 Foote-Pierson Compact KOB, NY. Ca. 1905 Foote-Pierson Practice, NY. Ca. Early 1900's
KOB by MESCO (Manhattan Electric Signal Co), NY. Ca. Early 1900's Another View of the MESCO KOB Small Bunnell Practice Set. Early 1900's J.H. Bunnell KOB with Pennsylvania Railroad Keystone Tag, NY. Ca. Early 1900's
Nickel Plated Bunnell KOB, NY. Ca. Early 1900's Bunnell Navy KOB, NY. Ca. Early 1900's European Mini KOB. Maker Unknown. Ca. Early 1900's British Baseboard Set With Key, Sounder, Relay, and Galvanometer. Tyer & Co. Ltd. 1917
Another View of the Tyer Baseboard Set Edison-Swan Key-Sounder-Galvanometer Set. Marconi-Wireless Markings on the Edison-Swan Set L.M. Ericsson Swedish KOB. Ca. 1919
Bunnell Beeko Practice Set. Ca. 1919 Side View of the Beeko Set Another Beeko Style Practice Set by L.E. Knott, Boston Mass. Ca. 1920 Western Union Learner's Set 1A. Made by JH Bunnell, NY
Western Union Portable Telegraph Set. Used by Telegraph Operators at Places Like Sporting Events, Political Rallies, etc A Rear View of the Western Union Portable Set Showing the Western Union Logo KOB by Signal Electric Mfg. Co. Menominee, Michigan. Ca. 1920 Signal Electric R-68 Practice Set With Buzzer and Morse Code Plate
Close-up of the R-68 Buzzer Practice Set Made by EF Johnson, Waseca Minnesota A Later Plastic-Based Practice Set by EJ Johnson, Waseca Minnesota Signal Electric Sheet Metal Key & Buzzer Practice Set
J-38 Practice Set by Fred Cramer Canadian RCAF Key & Buzzer Practice Set. Wilson Mfg. Co, Toronto

Key & Buzzer Practice Set. Wilson Mfg. Co, Toronto

Modern Bunnell Mini KOB. 1.5" wide. Ca. Made in the 1990s



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