MUSE delivers outstanding results to the scholarly community by maximizing revenues for publishers, providing value to libraries, and enabling access for scholars worldwide. Project MUSE is a leading provider of digital humanities and social sciences content, providing access to journal and book content from nearly 300 publishers. With warehouses on three continents, worldwide sales representation, and a robust digital publishing program, the Books Division connects Hopkins authors to scholars, experts, and educational and research institutions around the world. With critically acclaimed titles in history, science, higher education, consumer health, humanities, classics, and public health, the Books Division publishes 150 new books each year and maintains a backlist in excess of 3,000 titles. The division also manages membership services for more than 50 scholarly and professional associations and societies. The Journals Division publishes 85 journals in the arts and humanities, technology and medicine, higher education, history, political science, and library science. ![]() The Press is home to the largest journal publication program of any U.S.-based university press. Without the capacitor, the charge just slowly "trickles" through the LED and transistor as there's nowhere else for it to go, which means that there's no way for the LED to turn off.One of the largest publishers in the United States, the Johns Hopkins University Press combines traditional books and journals publishing units with cutting-edge service divisions that sustain diversity and independence among nonprofit, scholarly publishers, societies, and associations. This also means that the LED will flash slower the larger the capacitor is, and faster as you supply more current (lower the value of the resistor, or increase the supply voltage). This happens in an endless cycle as long as you supply a charging current to the capacitor, causing the LED to flash. Now the capacitor has to charge back up to 10V for the LED to light up again, which takes a while due to the limited charging current. It keeps passing current until the capacitor's voltage drops down to 9V (because it gets discharged through the LED), at which point it turns off again. As soon as it hits 10V, the transistor goes into breakdown and passes a current through the LED, making it light up. What happens in the circuit is this (using the example voltages I gave above): The capacitor slowly charges up to 10V the transistor is off during that time, and the LED doesn't light. To give you some numbers, the transistor might start passing current at 10V, and only stop again once the voltage is 9V or lower. You can view it as a strange kind of Zener diode. Due to the negative differential resistance, the breakdown voltage drops as soon as current flows through it, which means that it'll only stop passing current once the voltage across it is much lower than its original breakdown voltage. In simpler terms, the transistor starts to break down at a certain voltage, which means that it starts to pass current once the voltage across it gets high enough. ![]() ![]() This is a so-called relaxation oscillator which exploits the fact that a reverse-biased transistor exhibits negative differential resistance.
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