Crazy DC Voltage Booster

324

05:23:22

What the heck is going on here?  Where is that quarter of an amp coming from?  Certainly not the battery.

Have I discovered the holy grail of free energy? 

published 9 years ago

floriel

9 years ago

No, the 0A at + and - input of the op-amp are what's confusing you. That and the two connectors of the op-amp that have been left out in this simplified notation. And those two are for... jep, power supply. So no, no free energy, the op-amp is simply doing what got it it's name: amplifying the voltage difference between the + and - inputs by it's fixed gain value (in this case 8 times). And since there's 1.5V between + and - we end up with 1.5 * 8 = 12V And with the lightbulb's reaistance you end up with I = 12V ÷ 48 Ohm = 0.25A

floriel

9 years ago

Oh, and one more thing: the outout voltage is limited by the power supply voltages. Tap on the 8V/V on the bottom left and you'll see the options for max an min Vout

floriel

9 years ago

Sorry: tap on the op-amp, then on the wrench and then on Gain 8V/V

floriel

9 years ago

And I just realized the lamp is only defined by it's power consumption (3W) so we can calculate: I = 3W ÷ 12V = 0.25A

hurz

9 years ago

Here is an explanation which might help you to better understand bulbs/power and current relation http://everycircuit.com/circuit/6237778512707584

fluxicon

9 years ago

Welcome to the world of op-amps. Virtually limitless gain and just as many applications.

psteichen

9 years ago

So, the op-amp is a simplified simulation that ignores the fact that it needs power inputs? That's a pretty big simplification. Do you think someday this app will realistically represent components?

hurz

9 years ago

It does already simulate as realistic component today. We wish you success in learning electronic.

psteichen

9 years ago

How so? Without the power inputs I can't create a realistic complete circuit. Kind of like how the MOSFET is unusable because I can't set a realistic logic level gate threshold voltage. Don't get me wrong, I love the app. It just needs the ability to better define the components.

hurz

9 years ago

Make a proposal to Igor. Only that much, output configuration min max voltage for opamps represents the supply configuration. Mosfet threshold voltage can be tuned by Vto parameter. However, you know the mosfets are analog components and do not have a comparator like threshold. Hope this helps

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