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The Detectors Used in the First Radios were Memristors

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The recent discovery of memristor has sparked renewed interest in the scientific community about state dependent resistances. In the current paper, we show that the detector used in the first radios, called cats whisker, had memristive properties. We have identified the state variable governing the resistance state of the device and can program it to switch between multiple stable resistance states. Our observations are valid for a larger class of devices called coherers, including cats whisker. We further argue that these constitute the missing canonical physical implementations for a memristor.

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  1. 1.

    In this paper, we are referring to memristor as defined in [10, 20], which includes the ideal memristor as defined in Chua’s 1971 paper [7] as a subclass. Throughout the paper, the reference is to memristor and not ideal memristor [1, 10].

  2. 2.

    Philmore 7003 cat’s whisker is easily available from various antique radio or radio hobbyists shops and can also be ordered online through sites like eBay. On the other hand, it is easy to build it oneself using one of the semiconducting crystals and a metallic wire.

  3. 3.

    Hotspots are found by the following process. The device is either connected to an oscilloscope or a radio receiver circuit. Then the point of contact between the crystal and wire is changed till a diode-like characteristics is observed. The point(s) on the crystal where rectification is observed are hotspots. Finding hotspots is generally a time consuming task for non-experts [14].

  4. 4.

    These values may change according to the metal, the contact, pressure, etc.

  5. 5.

    Note that the non-linear DC resistance changes appreciably only when the maximum current through the device has changed. This can be seen through color correspondence, where each color shows a new stable non-linear DC resistance-state and the transitions are marked by the first pulse of higher amplitude: P1, P2 and P3 being the time interval where these pulses are applied. In case the maximum current passed through the device does not change, the non-linear DC resistance feebly oscillates around the same value, as seen in the time-interval of A1, A2 and A3. Furthermore, we have observed that the non-linear DC resistance remains fixed even when the amplitude of the pulse is decreased, since the maximum current has not changed.

  6. 6.

    Whereas triangle current pulse is symmetrical with respect to center axis shown in Fig. 9, voltage response during that time interval is not symmetrical. This causes hysteresis loop. We refer to different stable V-I characteristics as different states of the device.

  7. 7.

    It is evident by looking at regions depicted by A0 to A6 that the change in resistance happens at the first pulse of the transition. One may also note that these observations show recovery of resistance to a higher non-linear DC resistance: A4 resistance is higher than A5 resistance.


  1. Adhikari, S.P., Sah, M.P., Kim, H., Chua, L.O.: Three fingerprints of memristor. IEEE Trans. Circ. Syst.-I 60, 3008–3021 (2013)

    CrossRef  Google Scholar 

  2. Bose, J.: On the change of conductivity of metallic particles under cyclic electromotive variation. Originally presented to the British Association at Glasgow, September (1901)

    Google Scholar 

  3. Bose, J.: Patent USA 755, 840 (1904)

    Google Scholar 

  4. Bose, J.: On a self-recovering coherer and the study of the cohering action of different metals. Proc. R. Soc. Lond. 65, 413–422 (1899)

    Google Scholar 

  5. Bondyopadhyay, P.: Moore’s law governs the silicon revolution. Proc. IEEE 86(1), 78–81 (1998)

    CrossRef  Google Scholar 

  6. Chua, L.: Resistance switching memories are memristors. Appl. Phys. A: Mater. Sci. Process. 102(4), 765–783 (2011)

    CrossRef  Google Scholar 

  7. Chua, L.: Memristor-the missing circuit element. IEEE Trans. Circuit theory 18(5), 507–519 (1971)

    CrossRef  Google Scholar 

  8. Chua, L.: Nonlinear foundations for nanodevices. I. The four-element torus. Proc. IEEE 91(11), 1830–1859 (2003)

    CrossRef  Google Scholar 

  9. Chua, L.: Memristor, Hodgkin–Huxley, and Edge of Chaos. Nanotechnology (Special Issue on Synaptic Electronics) 383001 (2013)

    CrossRef  Google Scholar 

  10. Chua, L.O.: The fourth element. Proc. IEEE 100(6), 1920–1927 (2012)

    CrossRef  Google Scholar 

  11. Chua, L., Kang, S.: Memristive devices and systems. Proc. IEEE 64(2), 209–223 (1976)

    MathSciNet  CrossRef  Google Scholar 

  12. Dilhac, J.: Edouard Branly, the Coherer, and the Branly effect [History of Communications]. IEEE Commun. Mag. 47(9), 20–26 (2009)

    CrossRef  Google Scholar 

  13. Falcon, E., Castaing, B.: El efecto branly. Investigaci’on y ciencia 404, 80–86 (2010)

    Google Scholar 

  14. Fleming, J.: The Principles of Electric Wave Telegraphy. New York (1908)

    Google Scholar 

  15. Gandhi, G., Aggarwal, V.: mLabs report ( (2010)

  16. Jo, S., Lu, W.: CMOS compatible nanoscale nonvolatile resistance switching memory. Nano Lett. 8(2), 392–397 (2008)

    CrossRef  Google Scholar 

  17. Kim, T., Jang, E., Lee, N., Choi, D., Lee, K., Jang, J., Choi, J., Moon, S., Cheon, J.: Nanoparticle assemblies as memristors. Nano Lett. 9(6), 2229–2233 (2009)

    CrossRef  Google Scholar 

  18. Kim, K., Jo, S., Gaba, S., Lu, W.: Nanoscale resistive memory with intrinsic diode characteristics and long endurance. Appl. Phys. Lett. 96, 053106 (2010)

    CrossRef  Google Scholar 

  19. Lodge, O.: The history of the coherer principle. Electrician 40, 86 (1897)

    Google Scholar 

  20. Pershin, Y.V., Ventra, M.: Teaching memory circuit elements via experiment-based learning. IEEE Circuits Syst. Mag. 12(1), 64–74 (2011)

    CrossRef  Google Scholar 

  21. Prodromakis, T., Toumazou, C., Chua, L.: Two centuries of memristors. Nat. Mater. 11(6), 478–481 (2012)

    CrossRef  Google Scholar 

  22. Strukov, D., Snider, G.S., Stewart, D.R., Williams, R.S.: The missing memristor found. Nature 453(7191), 80–83 (2008)

    CrossRef  Google Scholar 

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This paper is supported in part by AFOSR grant no. FA9550-10-1-0290 and mLabs.

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Correspondence to Leon O. Chua .

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1.1 Detailed Method to Find Average Resistance

Refer to Fig. 12 (a reproduction of Fig. 10). Here we will describe how to calculate the average resistance for the given curve during the time interval A1 for current range \(I_1\) (0.1 mA) to \(I_n\) (3.5 mA).

For input current \(I_1\), at point \(P_1\), the voltage is \(V_1\). Here, the non-linear DC resistance is \(r_1\) (\(V_1\)/\(I_1\)), the inverse of the slope of the line segment joining \(P_1\) to origin. Similarly, at current In, the non-linear DC resistance is \(r_n\). For any current between \(I_1\) and \(I_n\), the non-linear DC resistance is similarly defined, as shown in the figure.

Fig. 12
figure 12

Calculating average resistance and non-linear DC resistance. We stress here that we introduce the names “average resistance” and “states” merely to improve the clarity of our exposition. They are not new technical names or concepts

To calculate the average resistance, the non-linear DC resistance is measured at regular time interval starting from point \(P_1\) to \(P_n\). The average of these values is the average resistance. Mathematically this is equivalent to:

\(R_{avg}=\sum \limits _{i=1}^{i=n} R_i/n , \text { where } R_{i}=V_{i}(t=t_{i})/I_{i}(t=t_{i}),\)

here \(t_{i} = t_{p1} + \text {time interval}*(i-1)\).

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Gandhi, G., Aggarwal, V., Chua, L.O. (2019). The Detectors Used in the First Radios were Memristors. In: Chua, L., Sirakoulis, G., Adamatzky, A. (eds) Handbook of Memristor Networks. Springer, Cham.

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