 | | Re: LEGO Electro-magnet
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| There is a description of a magnet actuator at Andreas Peter's site: (URL) (see Elect.Actuator) But two modifications IMHO are needed to this design : - Use heavier duty diodes than 1N4148 indicated in Andreas shematics. 1N4148 is rated 20mA and is (...) (24 years ago, 19-Apr-01, to lugnet.robotics)
| | | | | Re: LEGO Electro-magnet
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| (...) Hi Philippe, you're right, but you don't need this flyback diode, as Philip Taylor mentioned here : (URL) you don't need a flyback diode, you also don't a diode in series. Rainer P.S.: I had the same ideas than you mentioned above ;-) (24 years ago, 19-Apr-01, to lugnet.robotics)
| | | | | Re: LEGO Electro-magnet
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| Hello Rainer, True! But simplicity sometimes takes a long time to be acheived ;) But there may be some use in flyback and series diodes: Andreas says that his magnet consumes 9mA, below what is available through sensor ports in active mode. So a (...) (24 years ago, 20-Apr-01, to lugnet.robotics)
| | | | | Re: LEGO Electro-magnet
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| Hi Philippe, (...) Hmm, I guess they are NOT protected. (...) Not sure, (I'm not an electrical-engineer please Andreas Peter, help :) ) But, when the coil has a consumption of 9mA at 9V it's 1k. (81mW) So if I undestand it right, you're in parallel (...) (24 years ago, 20-Apr-01, to lugnet.robotics)
| | | | | Re: LEGO Electro-magnet
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| To be more precise: in passive mode there is a 10K pullup (to 5V) introducing some current (0.45 mA) in the coil. This small current may be enough to retain something stuck to the magnet... Philo (...) (24 years ago, 20-Apr-01, to lugnet.robotics)
| | | | | Re: LEGO Electro-magnet
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| (...) I think this could happen. Even without this low current present all the time, an electro magnet powered by a DC supply always in the same direction can develop a residual magnetic field (samll things would stay stuck even after the electro (...) (24 years ago, 21-Apr-01, to lugnet.robotics)
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