Pickett N515-T Duplex Slide Rule for Electronics

This ten-inch white aluminum linear slide rule has a nylon cursor. (The N in the model number is for "nylon," and the T denotes the rule's "traditional" white color.) The rule is held together with stamped aluminum contoured posts. The front of the base has (Lr) H, (fx)2Π, A, D, L, and Ln scales. The front of the slide has (Cr) B, S, T, CI, and C scales. The left end of the slide is marked (facing vertically): ELECTRONIC (/) MODEL N-515-T. A gray Pickett logo in the style used between 1958 and 1962 is at the right end. The number 349 is printed above the logo.
The back of the rule contains various formulae relating to electronics, such as temperature conversion, Ohm's Law for AC and DC circuits, parallel resistance, coupled inductance, and efficiency. Short (approximately 2.5 inches) scales on the slide are used with the reactance and resonance decimal point located at the left end of the rule. A logo at the right end of the slide has an i superimposed on a C, superimposed on a book, superimposed on an atom. The number 340 is to the right of the logo and above a registered trademark symbol.
There is a red-orange leather case lined in gray plastic. A faded Pickett logo in the style used between 1958 and 1962 is below the slot for the flap. The front of the case is also stamped: CLEVELAND INSTITUTE OF ELECTRONICS and has a yellow label marked: URIE. The back of the case has a metal ring, leather strap, and metal clasp for attaching to a belt.
The lower right corner of the back of the rule is marked: CLEVELAND INSTITUTE (/) OF ELECTRONICS (/) CLEVELAND, OHIO 44114 (/) PATENT NO. 3,120,342 (/) MADE IN U.S.A. The Cleveland Institute of Electronics worked with Pickett & Eckel, Inc., to develop this slide rule. In 1958, Darrell L. Geiger, an instructor at the Cleveland Institute, applied for a patent for a slide rule useful in calculations relating to electronics. Patent 3,120,342 was granted in 1964 and incorporated into the Pickett Model N-515 slide rule. Since the logo on the instrument was only used until 1962, it seems likely that this rule was made soon after the patent was issued.
Geiger wrote about a dozen instructional booklets on electronics and elementary mathematics in the 1950s and 1960s. The Cleveland Institute, a distance education institution, utilized programmed learning in the 1950s.
References: Darrell L. Geiger, "Slide Rule" (U.S. Patent 3,120,342 issued February 4, 1964); Darrell L. Geiger, Electronics and Your Slide Rule (Cleveland, Ohio: Cleveland Institute of Electronics, 1962); Rodger Shepherd, "Pickett Metal Slide Rules," Journal of the Oughtred Society 1, no. 1 (1992): 5–8; Brian Borchers, "Five Pickett Electronics Slide Rules," Journal of the Oughtred Society 11, no. 2 (2002): 4–7; Cleveland Institute of Electronics, "New . . . Electronics Slide Rule with Four-Lesson Auto-Programmed Instruction Course," (Cleveland, Ohio, [1969]), http://sliderulemuseum.com/Pickett/Pickett_N515-T_Electronic_CIE_Pamphlet.pdf.
Currently not on view
Object Name
slide rule
date made
ca 1964
Pickett & Eckel, Incorporated
Physical Description
plastic (cursor material)
aluminum (overall material)
leather (case material)
overall: 3.5 cm x 33.5 cm x 7.3 cm; 1 3/8 in x 13 3/16 in x 2 7/8 in
place made
United States: California, Santa Barbara
ID Number
accession number
catalog number
Rule, Calculating
Engineering, Electrical
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Slide Rules
Data Source
National Museum of American History, Kenneth E. Behring Center


"This is the exact one I have, N-515-T. It is in great shape, with the case. I am an electrician. I haven't used it on a job, but it has some basic formulas, like ohm's law and others."
I have identified a model N=515-T Slide Rule with the number 349 above the logo. It was a present from my Grandfather to me while I was in college and need a slide ruler for class.

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