I've been wondering if there is any way to eliminate voltage drop in a diode?
If there is not, what could I use to replace the function of the diode without any voltage decrease?
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4\$\begingroup\$ I've heard of diodes made from unobtainium that do this. \$\endgroup\$– Andy akaJan 26, 2017 at 19:16
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4\$\begingroup\$ @Andyaka I was reading about some diodes from a company called "Ideal" than do this as well. \$\endgroup\$– John DJan 26, 2017 at 19:27
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1\$\begingroup\$ They're probably made of that stuff. \$\endgroup\$– Andy akaJan 26, 2017 at 20:13
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\$\begingroup\$ No, but see if you can figure it out. When you do make a diode with no resistance, I have a pile of money waiting for you. \$\endgroup\$– Voltage Spike ♦Jan 26, 2017 at 21:35
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1\$\begingroup\$ Ignore the rude and idiotic comments - most seem to be from people who have lost all knowledge of electronics in the new year. With some extra components you can arrange for a MOSFET to turn on when you require diode conduction. While zero loss is not practical, very low loss is achievable. For example a MOSFET with on resistance of 1/1000th of an Ohm when on, will pass 10 Amps with a loss of 0.1 Watts. That is very small compared to the energy used overall in most circuits. eg if the system is 12V based then 0.1V drop loses about 0.8% of the total power. \$\endgroup\$– Russell McMahon ♦Jan 27, 2017 at 11:23
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2 Answers
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Look for "Active diode" circuits that use a FET for the series element. These can have very low voltage drop.
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\$\begingroup\$ No, nothing has no drop unless you can cool it to near absolute zero. (Or maybe a little higher for certain alloys.) \$\endgroup\$– John DJan 26, 2017 at 19:02
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\$\begingroup\$ @OskarSkog No, I was saying that NOTHING has no drop unless it's a superconductor. I wasn't implying that there could be no-drop diodes at low temperatures. Though see Spehro's comment below. \$\endgroup\$– John DJun 26, 2017 at 21:07
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There is no such thing under room temperature conditions. You can make an almost perfect signal rectifier - supplying a voltage from an external power supply that mimics a rectified version of the input voltage. You can also switch a very low resistance device such as a large MOSFET, but it will still have some resistance and thus some drop if current is flowing.
There is also physics-experiment type asymmetric behavior possible in certain superconducting structures at < 2K, but that's not exactly practical. See for example Controllable Disorder in a Hybrid Nanoelectronic System: Realization of a Superconducting Diode in Nature. The paper does not describe a working device, only an avenue that may be followed to develop such a device in the future.
answered Jan 26, 2017 at 21:26