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Hello! I have got 2 short questions. I'm using Circuit Lab since a few days for trying out some stuff. I want to improve my model for a current source for a LED. Is there a possability to simulat a 100V LED? Currently I am using a Zener diode with 100V, would be nice if its possible to use a LED... Second question is, how can I realize a current transformer to measure the output current of my buck converter? I need to measure the current and want a voltage/current related to ground. But because a shunt in a converter would not be related to ground, how can I realize this? This is my model for the buck converter mentioned. https://www.circuitlab.com/circuit/kg6x52/buckconverter/ |
February 08, 2013 |
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LEDS: https://www.circuitlab.com/forums/optoelectronics/topic/6vu3zs7w/how-to-add-an-anonymous-led/ https://www.circuitlab.com/circuit/47ngm4/n-parameter-sweep-in-edited-led-model-01/ https://www.circuitlab.com/circuit/y42f62/n-parameter-sweep-in-edited-led-model-02/ Current transformer: Do you mean a current to voltage converter? Sorry but your "Buck Converter" isn't. At all. See: https://www.circuitlab.com/circuit/wh3d6v/generic-voltage-mode-buck-converter-01/ If you want to drive a constant current through a LED string then you do not need a current to voltage converter as such. Read up on LED drivers from Linear Technology, TI, OnSemi, Diodes Inc etc., etc. e.g: http://www.diodes.com/_files/design_note_pdfs/zetex/dn81.pdf |
February 12, 2013 |
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Sorry for the late reply. At first, thank you for your answer! You really helped me out with the LED. To my second question: I think you understood me wrong... I know that my Buck converter is not a current to voltage converter. Its a small simulation how to drive a LED with a stable current of 1A. Therefore Im using a small Buck, with small differences to the schematic in your last link. 1 Switch instead of 2, LED not related to ground. But thats not the point. What i meant with a current transformer was a part, for the current feedback. At the moment a resistor and a voltage controlled current source are used for this application. Practically I would use a secondary winding in my inductor for the ZVD and the current feedback. But this seems to be not working as Im expecting in Circuitlab's... I hope you are able to understand my problem now... |
February 18, 2013 |
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Have a look at this thread: https://www.circuitlab.com/forums/basic-electronics/topic/w2ks25f4/volts-or-amps/ |
February 21, 2013 |
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A very helpful paper on current sensing for PSU designers: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.131.5176&rep=rep1&type=pdf |
February 22, 2013 |
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Wow, very interesting paper and site - thanks! Regards, Sancho |
February 22, 2013 |
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