 | | Solar cells and caps: lego part #s —John Barnes
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| | | This whole Lego capacitor thing strikes me as somewhat intriguing. The super-caps, which are doubtless used, absolutely cannot be charged backwards, they have to have the correct polarity. And all the Lego electrical "stuff" like the RCX sensors, (...) (23 years ago, 27-Mar-01, to lugnet.robotics)
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| | | | | Re: Solar cells and caps: lego part #s —Micah J. Mabelitini
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| | | | | (...) The capacitor is very much polarity-sensitive. It has +/- polarity indicators on either side of the standard 2x2 9V terminal, as does the solar cell, and it will not work if the polarity is reversed. (23 years ago, 27-Mar-01, to lugnet.robotics)
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| | | | | lego cap, polarity, etc —Bruce Boyes
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| | | | (...) I don't have one, but can make some guesses. A bridge only works with an AC input - it can't correct the polarity of a DC input. So the Lego cap either has an AC input possibly through a bridge or a DC input which is the correct polarity by (...) (23 years ago, 27-Mar-01, to lugnet.robotics)
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| | | | | | Re: lego cap, polarity, etc —David Powell
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| | | | | (...) connectors. Uh, a bridge wouldn't be very good if it didn't handle inputs that switched polarities. A bridge should work just fine with a DC input of any polarity (of course for any DC input, only half of the bridge is actually being used). (...) (23 years ago, 27-Mar-01, to lugnet.robotics)
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| | | | | | Re: lego cap, polarity, etc —Bruce Boyes
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| | | | (...) Right, what I was trying to say is that a bridge can't 'invert' a DC input of one polarity to make an output of another polarity - it can't "correct" anything, a diode can only conduct or not conduct. All a bridge can do is route the given DC (...) (23 years ago, 27-Mar-01, to lugnet.robotics)
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| | | | | | Re: lego cap, polarity, etc —Andy Gombos
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| | | | | If I read correctly, it sounds as if there are + and - signs on the capacitor, which would imply that there is something that would block an incorrect polarity on the terminal. Maybe the diode and the 2 transistors on the board do this, I do not (...) (23 years ago, 27-Mar-01, to lugnet.robotics)
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| | | | | | | RE: lego cap, polarity, etc —Tilman Sporkert
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| | | | | | | That's right - it only needs to protect the capacitor from wrong polarity, but does not have to compensate. Maybe the instructions simply say "if it doesn't work, rotate the connector 90 degrees". Maybe the LED gives some indication if it is (...) (23 years ago, 28-Mar-01, to lugnet.robotics)
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| | | | | | | | | (canceled) —Micah J. Mabelitini
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| | | | | | | | | Re: lego cap, polarity, etc —Micah J. Mabelitini
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| | | | | | | | (...) The capacitor doesn't come with any instructions, at least not when purchased individually. The LED indicates when the capacitor is fully charged; when it reaches full charge, the LED begins flashing. I'm assuming at least one of the other (...) (23 years ago, 28-Mar-01, to lugnet.robotics)
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| | | | | | | Re: lego cap, polarity, etc —Jim Choate
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| | | | | | No. DO NOT UNDER ANY CONDITION CONNECT AN ELECTROLYTIC (ie one with +/- on the terminals) IN REVERSE. The electrolyte is a high resistant in one direction only. The other direction is nearly a short. You may end up hurt as the capacitor blows up in (...) (23 years ago, 28-Mar-01, to lugnet.robotics)
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| | | | | | | | Re: lego cap, polarity, etc —Micah J. Mabelitini
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| | | | | | | (...) <snip> The polarity markings Andy Gombos was referring to are printed on the LEGO-compatible package itself. The LEGO "capacitor" is in fact an electrolytic cap with plenty of support circuitry, and I assure you there is no danger of blowing (...) (23 years ago, 29-Mar-01, to lugnet.robotics)
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| | | | | | | | Re: lego cap, polarity, etc —Matthias Jetleb
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| | | | | | (...) This is generally true, but not as dire as you make it sound. (...) Actually, electrolyte is a good conductor of electricity (in any direction). It comprises one of the terminals in an electrolytic capacitor. The other terminal is aluminum, (...) (23 years ago, 31-Mar-01, to lugnet.robotics)
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| | | | | | Re: lego cap, polarity, etc —Jim Choate
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| | | | | (...) A couple of comments on this... An 'inverter' with respect to DC creates AC, it doesn't swap polarity. If you're going to use the term correctly always use 'invert polarity' and never 'invert' by itself. If you go into a store and ask for a (...) (23 years ago, 28-Mar-01, to lugnet.robotics)
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| | | | | | RE: lego cap, polarity, etc —J Kevin McCoy
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| | | | | (...) Agreed - a bridge is not an inverter. Pardon this poor representation of the circuit: +---|<----+----|<---+ | | | | B (batt) | | | | +---|<----+----|<---+ | | +--------| |--------+ + (cap) The bridge is able to correctly 'route' the current to (...) (23 years ago, 28-Mar-01, to lugnet.robotics)
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| | | | | | RE: lego cap, polarity, etc —Bruce Boyes
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| | | | (...) Yes, thanks for the sketch. Bruce ------- WWW.SYSTRONIX.COM ---...--- Real embedded Java and much more High speed 8051 systems +1-801-534-1017 Salt Lake City, USA (23 years ago, 28-Mar-01, to lugnet.robotics)
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