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university:courses:alm1k:alm-lab-pv [16 Jan 2017 20:42]
dmercer [Procedure:]
university:courses:alm1k:alm-lab-pv [20 Jun 2018 16:33]
vanderghast The text is about the version on the left, not the one to the right
Line 210: Line 210:
 The regulated output voltage will be equal to the V<​sub>​BE</​sub>​ of transistor Q<​sub>​1</​sub>​ plus the forward drop of LED<​sub>​1</​sub>​. The current in the LED is set by the value of R<​sub>​1</​sub>​ and the V<​sub>​BE</​sub>​. A range of output voltages are possible by choosing different color LEDs. The forward voltage drop can range from around 2 V for red and up to 3 V for blue or white. Even more output voltage values can be made by inserting the forward voltage drop of one or more standard Si diodes in series with the LED. The regulated output voltage will be equal to the V<​sub>​BE</​sub>​ of transistor Q<​sub>​1</​sub>​ plus the forward drop of LED<​sub>​1</​sub>​. The current in the LED is set by the value of R<​sub>​1</​sub>​ and the V<​sub>​BE</​sub>​. A range of output voltages are possible by choosing different color LEDs. The forward voltage drop can range from around 2 V for red and up to 3 V for blue or white. Even more output voltage values can be made by inserting the forward voltage drop of one or more standard Si diodes in series with the LED.
  
-Looking at the version on the right, NPN transistor Q<​sub>​1</​sub>​ and collector resistor R<​sub>​2</​sub>​ form a common emitter amplifier stage. PNP transistor Q<​sub>​2</​sub>​ provides current gain. As soon as enough current is flowing through the LED and R<​sub>​1</​sub>​ such that the voltage across R<​sub>​1</​sub>​ is large enough to turn on Q<​sub>​1</​sub>​ the circuit starts to regulate. ​ Beyond the initial startup current in the LED, the majority of the current through the shunt regulator flows through Q<​sub>​2</​sub>​. The above explanation similarly holds for the complementary version on the right.+Looking at the version on the left, NPN transistor Q<​sub>​1</​sub>​ and collector resistor R<​sub>​2</​sub>​ form a common emitter amplifier stage. PNP transistor Q<​sub>​2</​sub>​ provides current gain. As soon as enough current is flowing through the LED and R<​sub>​1</​sub>​ such that the voltage across R<​sub>​1</​sub>​ is large enough to turn on Q<​sub>​1</​sub>​ the circuit starts to regulate. ​ Beyond the initial startup current in the LED, the majority of the current through the shunt regulator flows through Q<​sub>​2</​sub>​. The above explanation similarly holds for the complementary version on the right.
  
 {{ :​university:​courses:​alm1k:​alm-lab-e2_a5.png?​550 |}} {{ :​university:​courses:​alm1k:​alm-lab-e2_a5.png?​550 |}}
university/courses/alm1k/alm-lab-pv.txt · Last modified: 11 Sep 2019 20:15 by dmercer