Re: 70V questions

>> >>
>> >> >> >> >> >Hi John >> >> >This is brilliant to see that your calculations tie up with what I >> >measured on the 24V. >> >> >How do I measure the inductance? What do you mean about the spike? >> >Some magnetic force or a current? Is it the opposite of capacitance? >> >Then I guess the falling magnetic field will cause a current and then >> >probably in opposite direction... >> >> >BTW I'm using this to knock a little ball the same way as a pool que >> >hits a pool ball. I presume that a solenoid is the best electrical >> >component to do this?? My 72V plan should be able to give me the force >> >required but maybe there's some magical component that can give more >> >bang per volt. >> >> >I'm also considering a solenoid with a higher resistance, which to me >> >means it must have more wounds/windings to more work. (Surely this >> >logic is correct - If it's the same brand, looks more or less the >> >same, then, if the wattage is higher, it must work harder and maybe I >> >can get away with lower voltage and current for the same performance) >> >> >Anyway.. How do I measure inductance? >> >> --- >> There are several ways. >> >> But first, before we get to the rest of your questions, what kind of >> test equipment do you have? >> >> -- >> JF > >I have a digital Volt, Current and resistance meter. (Made by El >Cheapo). I see they call it a domestic meter: >
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>This is the only measuring tool I have. :-s

-- Well, we\'re kinda stuck then, I think. If you had a signal generator you could connect a capacitor in series with the solenoid, sweep the LC, find the resonant point, and then calculate the inductance knowing the resonant frequency and the capacitance. Or, if you had a DMM which could measure inductance you could do it directly. But, now knowing your application, knowing the inductance doesn\'t matter all that much. What I\'m thinking is that you could charge up a capacitor to 72V and then dump it into the coil to get the action you want, like this: (View in Courier) .+V>--[R]------+-------+-------+ . | | | . [R] | | . | S | . +-----G PCH | . | D |+ . [R] | [BFC] . | | | . C | | .I/O>--[R]--B NPN [COIL] | . E | | . | | | .GND>----------+-------+-------+