ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Negative Dynamic Resistance Circuit

Updated on November 2, 2012

Negative dynamic resistance


With a normal resistor the current flowing through the resistor increases with voltage. With a negative dynamic resistor the current decreases with increasing voltage at least over some portion of the input voltage range. Figure 1 shows a little known negative dynamic resistance circuit. As voltage V2 increases the current at first increases as per a normal resistor. However at slightly over 1 volt the current starts to fall in a very linear fashion with increasing voltage (see figure 2) until you reach 1.7 volts where the negative resistance region ends.


Figure 1

Negative dynamic resistance circuit.
Negative dynamic resistance circuit.

Figure 2

Negative dynamic resistance region.  The current in Amps is shown on the vertical axes.  The voltage V2 is shown on the horizontal axes.
Negative dynamic resistance region. The current in Amps is shown on the vertical axes. The voltage V2 is shown on the horizontal axes.

Simplifying application of the circuit

A slight disadvantage of the circuit in figure 1 is that you must supply an additional voltage V1. If you are willing to accept a lower degree of linearity (figure 4) and a reduced frequency response then you can run the entire circuit using a supply voltage of about 0.7 volts. This is easily obtained by forward biasing a standard silicon diode and results in the circuit show in figure 3. You can experiment with different diodes to put the supply voltage in the middle of the negative resistance range.



Figure 3

Simplified circuit.
Simplified circuit.

Figure 4

The negative resistance curve of the simplified circuit.  Notice that the negative resistance region for V2 is in the same range as the forward bias voltage of D1.  This means you don't need an extra voltage source.
The negative resistance curve of the simplified circuit. Notice that the negative resistance region for V2 is in the same range as the forward bias voltage of D1. This means you don't need an extra voltage source.

Figure 5

An example oscillator circuit using negative dynamic resistance.
An example oscillator circuit using negative dynamic resistance.

Applications

Negative dynamic resistance can be used to create oscillators, Q multipliers and regenerative radio circuits. It can also be used in feedback control systems. Figure 5 shows how to easily make a radio frequency oscillator. This is idea for creating equipment like grid-dip meters and similar devices. The amount of negative resistance can be increased by reducing R2 in figure 5. It is also possible to inductively couple negative resistance to LC circuits. Causing the LC circuit to resonate.

Comments

    0 of 8192 characters used
    Post Comment

    No comments yet.

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://hubpages.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)