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"...Friis and Jensen had made the same distinction Black used between 'positive feed-back' and 'negative feed-back', based not on the sign of the feedback itself but rather on its effect on the amplifier’s gain. In contrast, Nyquist and Bode, when they built on Black’s work, referred to negative feedback as that with the sign reversed. Black had trouble convincing others of the utility of his invention in part because confusion existed over basic matters of definition."

"...Friis and Jensen had made the same distinction Black used between 'positive feed-back' and 'negative feed-back', based not on the sign of the feedback itself but rather on its effect on the amplifier’s gain. In contrast, Nyquist and Bode, when they built on Black’s work, referred to negative feedback as that with the sign reversed. Black had trouble convincing others of the utility of his invention in part because confusion existed over basic matters of definition."

“ ... ... Friis 和 Jensen 对 Black 在 "正反馈 "和 "负反馈 "之间的区分是一样的，不是基于反馈本身的符号，而是基于它对放大器增益的影响。相反，当Nyquist和Bode基于Black的工作基础时，将负反馈称为符号相反的反馈。Black难以说服其他人相信他的发明的实用性，部分原因是在基本的定义问题上存在混乱。"

“ ... ... Friis 和 Jensen 对 Black 在对"正反馈 "和 "负反馈 "的区分方法是一样的，都不是基于反馈本身的符号，而是基于它对放大器增益的影响。与之相反的是，当Nyquist和Bode基于Black的工作基础时，将负反馈称为符号相反的反馈。Black难以说服其他人相信他的发明的实用性，有一部分原因是在基本的定义问题上存在混乱。"

== Examples and applications ==

== Examples and applications ==

Regenerative circuits were invented and patented in 1914 for the amplification and reception of very weak radio signals. Carefully controlled positive feedback around a single transistor amplifier can multiply its gain by 1,000 or more. Therefore, a signal can be amplified 20,000 or even 100,000 times in one stage, that would normally have a gain of only 20 to 50. The problem with regenerative amplifiers working at these very high gains is that they easily become unstable and start to oscillate. The radio operator has to be prepared to tweak the amount of feedback fairly continuously for good reception. Modern radio receivers use the superheterodyne design, with many more amplification stages, but much more stable operation and no positive feedback.

Regenerative circuits were invented and patented in 1914 for the amplification and reception of very weak radio signals. Carefully controlled positive feedback around a single transistor amplifier can multiply its gain by 1,000 or more. Therefore, a signal can be amplified 20,000 or even 100,000 times in one stage, that would normally have a gain of only 20 to 50. The problem with regenerative amplifiers working at these very high gains is that they easily become unstable and start to oscillate. The radio operator has to be prepared to tweak the amount of feedback fairly continuously for good reception. Modern radio receivers use the superheterodyne design, with many more amplification stages, but much more stable operation and no positive feedback.

再生电路于1914年被发明并获得专利<ref>{{cite patent |inventor-last=Armstrong |inventor-first=E. H. |country-code=US |patent-number=1113149 |title=Wireless receiving system |date=1914}}</ref>，用于放大和接收非常微弱的无线电信号。仔细控制单晶体管放大器周围的正反馈，可以使其增益增加1000倍或更多<ref>{{cite web|last=Kitchin|first=Charles|title=A Short Wave Regenerative Receiver Project|url=http://www.electronics-tutorials.com/receivers/regen-radio-receiver.htm|accessdate=23 September 2010|url-status=live|archiveurl=https://web.archive.org/web/20100710100031/http://www.electronics-tutorials.com/receivers/regen-radio-receiver.htm|archivedate=10 July 2010}}</ref> 。因此，一个信号可以在一个阶段被放大20000甚至100000倍，通常只有20到50的增益。再生放大器在这些非常高的增益下工作的问题是，它们很容易变得不稳定，开始振荡。无线电操作员必须准备相当连续地调整反馈量，以获得良好的接收效果。现代无线电接收机采用超异构设计，多了许多放大级，但工作更稳定，没有正反馈。

再生电路于1914年被发明并获得专利<ref>{{cite patent |inventor-last=Armstrong |inventor-first=E. H. |country-code=US |patent-number=1113149 |title=Wireless receiving system |date=1914}}</ref>，用于放大和接收非常微弱的无线电信号。通过仔细控制单晶体管放大器周围的正反馈，可以使其增益增加1000倍或更多<ref>{{cite web|last=Kitchin|first=Charles|title=A Short Wave Regenerative Receiver Project|url=http://www.electronics-tutorials.com/receivers/regen-radio-receiver.htm|accessdate=23 September 2010|url-status=live|archiveurl=https://web.archive.org/web/20100710100031/http://www.electronics-tutorials.com/receivers/regen-radio-receiver.htm|archivedate=10 July 2010}}</ref> 。因此，一个信号可以在一个阶段被放大20000甚至100000倍，而在通常只有20到50的增益。而再生放大器在如此高的增益下工作带来的问题则是信号很容易变得不稳定，开始振荡。无线电操作员必须不断地调整反馈量，以获得良好的接收效果。而现代无线电接收机采用超异构设计，多了许多放大级，去掉了正反馈并使其工作更稳定。

The oscillation that can break out in a regenerative radio circuit is used in electronic oscillators. By the use of tuned circuits or a piezoelectric crystal (commonly quartz), the signal that is amplified by the positive feedback remains linear and sinusoidal. There are several designs for such harmonic oscillators, including the Armstrong oscillator, Hartley oscillator, Colpitts oscillator, and the Wien bridge oscillator. They all use positive feedback to create oscillations.

The oscillation that can break out in a regenerative radio circuit is used in electronic oscillators. By the use of tuned circuits or a piezoelectric crystal (commonly quartz), the signal that is amplified by the positive feedback remains linear and sinusoidal. There are several designs for such harmonic oscillators, including the Armstrong oscillator, Hartley oscillator, Colpitts oscillator, and the Wien bridge oscillator. They all use positive feedback to create oscillations.

在再生无线电电路中能爆发出的振荡被用于电子振荡器中。通过使用调谐电路或压电晶体(常见的是石英)，经正反馈放大后的信号仍然是线性的、正弦的。这种谐波振荡器有几种设计，包括阿姆斯特朗振荡器、哈特利振荡器、科尔皮茨振荡器和维恩桥振荡器。它们都是利用正反馈来产生振荡。<ref>{{cite web|title=Sinewave oscillators|url=http://www.educypedia.be/electronics/analogosciltypes.htm|work=EDUCYPEDIA - electronics|accessdate=23 September 2010|url-status=dead|archiveurl=https://web.archive.org/web/20100927094330/http://www.educypedia.be/electronics/analogosciltypes.htm|archivedate=27 September 2010}}</ref>

在再生无线电电路中产生的振荡还可以被用于电子振荡器中。通过使用调谐电路或压电晶体(常见的是石英)，经正反馈放大后的信号仍然是线性的、正弦的。这种谐波振荡器有几种设计，包括阿姆斯特朗振荡器、哈特利振荡器、科尔皮茨振荡器和维恩桥振荡器。它们都是利用正反馈来产生振荡。<ref>{{cite web|title=Sinewave oscillators|url=http://www.educypedia.be/electronics/analogosciltypes.htm|work=EDUCYPEDIA - electronics|accessdate=23 September 2010|url-status=dead|archiveurl=https://web.archive.org/web/20100927094330/http://www.educypedia.be/electronics/analogosciltypes.htm|archivedate=27 September 2010}}</ref>