Free Reference Point System Disk During the 1930's, Supreme Instruments supplied a Free Reference Point System Disk with many of their vacuum tube testers and radio analyzers. This two sided disk allowed easy identification of which tube pin jacks on the tester to use by rotating the inner wheel to the tube number under test Size: 5" Larger Photo Side A Larger Photo Side B

De Forest OHM's Law Wheel Chart - 1926 Single sided. More like heavy paper than cardboard. This is the oldest wheel chart in my collection so far. It was given out by De Forest's Training Schools . The wheel shows the OHMs Law formula by setting the circle over the value you are trying to calculate. I'm not sure of its purpose since the three formulas are printed next to the wheel. Size: 6" X 2¾" Larger Photo

Sylvaina Resistor Color Code Wheel Guide This is a metal standard color code guide for the colors used on older "Dog Bone" resistors from the late 1920s and early 1930s. It is rectangular and has three wheels to spin for finding the resistance value for the body, tip, and dot markings. (see the older IRC chart here) The back is an advertisment for Sylvaina vacum tubes. Size: 3.75" X 2" Larger Photo

IRC Standard R. M. A. Dog Bone Resistor Color Code Chart This early wheel chart from International Resistance Company (better known as IRC) shows the resistance color markings for early "dog bone" resisters used in the 1920s and early 1930s.. It is rectangular and has three wheels stacked on top of each other to rotate for finding color and resistance value. The back shows instructions for setting and reading the wheel chart. Size: 4.5" X 2.125" Larger Photo - Front Larger Photo - Back

Carbon Resistor Color Code Wheel This Standard R.T.M.A carbon resistor color code wheel chart from Continental Carbon Inc. shows resistance color markings for carbon resistors. The back shows instructions for setting and reading the wheel chart. This one was supplied by Beacon Electronics Inc., Utica, NY. Wheel is 1¾" in diameter. Larger Photo - Front and Back

Ohiohm Resistor Ohm Dial This 1932 Ohiohm R.M.A resistor color code wheel chart from the Ohio Carbon Co. Three color wheels show end and dot color markings for early resistors. The back has instructions for setting and reading the wheel chart. Printed by G. Felsenthal & Sons, Chicago. Wheel is 4½" x 2¼". Larger Photo - Front and Back

IRC "Resist-O-Guides" The 1946 Resist-O-Guide (Top Left) from International Resistance Company (IRC) shows the resistance color markings for standard carbon resisters. It is rectangular and has three wheels to spin for finding color and resistance value. The back shows a chart and has a diagram comparing the "New" standard color code to the old color code used on older "Dog Bone" resistors (see the older IRC wheel chart above). Size: 4.5" X 2.125" Larger Photo 1946 Ad Photos for two later versions: 1951 Version      1963 Version Resist-O-Guides were produced by the Perrygraf Slide Chart Corp.

Ohmite "Little Devil" This small coder from Ohmite shows the resistance color markings for standard carbon resisters. It is rectangular and has three wheels to spin for finding color and resistance value. The back shows a chart with a diagram showing the meaning of the four standard color bands. Size: 4¾" X 2" Larger Photo

Radio Shack Resistor/Capacitor Color Code Calc. This small coder from Radio Shack shows resistor and capactor color markings on one side and the inductor color code on the other. Size: 4¼" X 2¼" Larger Photo

National OHM's Law and Battery Life Calculator - 1959 This wheel calculator has a dial on one side to compute OHM'S Law (resistance, voltage, and amps) and a battery life calculator on the other. This chart was produced by the Perrygraf Slide Chart Corp. Size: 5" across X 6" high. Larger Photo

Sprague Capacitor Indicator - 1949 This small plastic 6 wheel cap indicator from Sprague shows the capacitance color markings for tubular capacitors. It is rectangular and has six wheels to spin for finding capacitance value. The back has a chart for converting MFD to MMFD. Size: 5" X 1½" Larger Photo

Aerovox Dial-A-Cap Capacitor Decoder Double sided, one side for JAN-C-62 caps, other side for JAN-C-25 paper capacitors. Size: 8" X 2½" Larger Photo

Daven - Thomas A. Edison Industries "Resisto-Dial" (No date or manufacturer) This wheel calculates confidence level (Failure Rate) of several types of resistors. The reverse calculates deviation by tempeture and has charts for wattage derating. Size: 7½" Larger Photo Front Larger Photo Front

Radio Time Around The World Wheel Chart to calculate radio time around the world from your U.S. time zone. Nothing on back, no date. Size: 3½" x 5" Larger Photo

Dial-O-Map Map of world time zones and a Wheel Chart to calculate short wave brodcast times around the world from any time zone. Size: 9" by 5 1/2" Larger Photo Dial

Shure Replacment Guide 1950 "Shure Replacment Guide" wheel chart for all crystal pickup cartridges with list of special quite-tracking cartridges on back. Size: 8½" X 10" Larger Photo - Front Larger Photo - Back This chart was produced by the Perrygraf Slide Chart Corp.

Grundig Tape Head Calculator Used to set up "overdubbing" using the SYN function that allowed playback of a track, while recording another, and mixing the two together. Size: 7½" Larger Photo Side A Larger Photo Side B

Calculaide Frequency Computer The Calculaide Frequency Computer wheel chart by American Hydromath Corp. was produced in 1955. It gives the frequency and wavelength of a coil and condenser circuit using physical dimensions of the coil and the value of the condenser. Instructions are printed on the back. Size: 6" Size: 7½" Larger Photo - Front Photo - Back

TV Quick-Check Trouble Finder This two sided wheel chart from 1956 helps troubleshoot TV problems. Turn the wheel till your picture problem appears in the top window and read the tubes you need to test in the bottom window. Size: 7½" Larger Photo - Front Larger Photo - Rear

Sperry TV Trouble Tracer This Sperry TV Tube Trouble Locator wheel chart from 1958 helps troubleshoot TV problems and find which tubes need to be tested. Turn the wheel till your picture problem appears in the top window and read the tubes you need to test in the bottom window. Also lists some common componet problems on the back. Published by John C. Sperry, Lincoln Nebraska. Size: 7½" Larger Photo - Front Larger Photo - Rear

Zenith Color TV Instructions This wheel chart shows how to properly ajust the picture and color settings on early Zenith color Televisions. The back has general Color TV operating instructions and general information. No date. Size: 8" x 10½" Larger Photo - Front Larger Photo - Rear

Dumont Picture Tube Selector This two sided wheel chart shows Dumont replacement TV picture tubes and specifications. Size: 5½" Larger Photo

This is a large wheel chart that calculates Proportional Scale. Although it does not directly relate to antique radios or electronics, it can be used in my wood shop. It comes in handy when I need to reduce something by a percentage and want the results in inch measurements. Produced by the C-Thru Ruler Company Size: 8¼ Larger Photo

This large wheel chart (over 10" in diameter) calculates postage and lists addresses world wide for Ham Radio QSL card mailing. Both sides show Continent, Zone, and Country. Published by Ham Radio Magazine circa 1976 - Size: 10+" Larger Photo

This small metal wheel calendar calculates dates by year and day of week from 1965-1992. It has the Bell Telephone logo on the back and was probably given out as a promotion. Manufactured by Anderson and Sons, Westfield Mass. Size: 1¼" x 1¼" Larger Photo

General Electric Radar Range Computer This wheel chart has 5 ranges on the front for Pulse Repetion Rate, Transmitter Power, Wave Length, Pulese Duration, and Target Size. There are 4 additional scales on the back for Wave Length, Frequency, angle, and Gain. Published by the GE Heavy Military Electronic Equipment Department, Syracuse NY, 1955. This chart was printed by the Perrygraf Slide Chart Corp. The wheel chart stores in pocket inside the instruction book. I grew up in Syracuse and remember driving by the GE plant in the 1960s and seeing all the types of radar arrays outside the plant that are listed on the back page of instruction book below. Wheel Size: 8" Larger Photo - Front Larger Photo - Back Instruction Book (Adobe PDF File)

General Electric Date Calculator This 1963 General Electric wheel chart calculates project start/finish dates for 1964 and 1965. It is 6"x7¼". This chart was printed by the Perrygraf Slide Chart Corp. This wheel chart has instructions printed on the back. Larger Photo - Front Larger Photo - Back w/Instructions

The Merit Output Transformer Selector allows you to select needed specifications on the top of the wheel. Merit part number and type are then indicated in the window. This wheel is two sided and was printed by the Perrygraf Slide Chart Corp. Size: 6.5" Larger Photo

E6B Flight Computer, or "whiz wheel" This aluminum aviation flight computer qualifies as both a wheel chart (front) and a slide chart (back). It was commonly used before computers and software were developed to plan fuel burn, wind correction, route time, ground speed, and other calculations. This particular flight computer was manufactured by Jeppesen & Co., Denver, Colorado. Jeppesen web site Front and Case Front and Back

This GE Lighting Systems digitaldiscwheelTM and the one below are a unique promotional and distribution idea combining Wheel Charts with new digital technology. This type of wheel can be configured with information on the face of the disk like a wheel chart and opens to reveal it's a recordable DVD that can contain digital files such as catalogs, price sheets, or any other type of file. This one contains a GE Lighting time line on its face. Manufactured by Flexigroup, New York. Size: 4 7/8;" x 5". Larger Photo

This is a Star Wheel digitaldiscwheelTM. It provides a star chart by date & time and like the digitaldiscwheelTM above can also be loaded with digital files for distribution. Manufactured by Flexigroup, New York. Size: 4 7/8;" x 5". Larger Photo