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| 06-07-2018, 02:23 PM | #16 |
 Originally posted by h4yn0nnym0u5e  *snip* The aperture solenoid may work better at higher supply voltages (as long as the battery can sustain the current draw), because it could be an exception to the "everything runs at 3.3V" rule, and be run more-or-less directly off the raw battery power rail. Cheers Jonathan Regarding the solenoid, magnetic field should be IIRC proportional to the current, not the voltage... Can't quite figure out how this would pan out in real life, with the battery kneeling (that's how we call the voltage drop in Italian... is it the same in English?) under load. | |
| 06-07-2018, 02:51 PM | #17 |
| Originally posted by LensBeginner Makes sense... everything you said. Regarding the solenoid, magnetic field should be IIRC proportional to the current, not the voltage... Can't quite figure out how this would pan out in real life, with the battery kneeling (that's how we call the voltage drop in Italian... is it the same in English?) under load. | |
| 06-07-2018, 02:59 PM | #18 |
| Originally posted by h4yn0nnym0u5e You're correct about the field being proportional to current, but it gets complicated! The solenoid will have a resistance, so the current will itself be proportional to the voltage (Ohm's Law) in a steady-state condition. BUT a solenoid coil also has "inductance" which means the current doesn't rise to the steady-state value immediately the voltage switches on, but rises gradually (at least in electro-mechanical terms). And as that happens the battery voltage will gradually kneel - not sure of the English term, but I like the Italian one! - so the best magnetic field is quite hard to predict...  The strange thing is that both the "good" and the "bad" actuators have, reportedly, a 30Ω solenoid. Either the issue is mechanical, or it is magnetical and has to do with magnetization over time of some component (I don't think it's the U-shaped bit, since mine wasn't sticking to anything when I took apart mine), or with the small magnet positioned in the fixed part of the actuator (the one that is marked with a permanent marker by the author of I can't remember which tutorial - the French pdf perhaps). | |
| 06-07-2018, 05:05 PM | #19 |
| Originally posted by LensBeginner The strange thing is that both the "good" and the "bad" actuators have, reportedly, a 30Ω solenoid. Steve | |
| 06-08-2018, 12:49 AM | #20 |
| Originally posted by stevebrot Everything about the aperture actuator issue involves voodoo and about the only thing that hadn't been tried the last time I looked (short of actually using the Pentax replacement part) is blood sacrifice. Steve | |
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Post #9 by LensBeginner 
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