Circuit setups for pulse motors

[capthook]

On reed switches:

Will placing a "backing" magnet behind the reed switch to reduce it's sensitivity cause a failure/improper operation over time as the reed switch will become magnetized by the "backing" magnet?

The AT 22/28 reeds (1A, 250V) I got are WAY to sensitive!  My .75" x .25" N42 mags will activate it from 2" .

I'm thinking I can't even get one that will provide the desired 1/4" activiation zone??

What AT rating are you guys using?

Can someone recommend an AT rating that I should try?

CH

[capthook]

b-u-m-p

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[capthook]

Circuit to limit power draw from capacitor?

I want to limit my 4700 uF 35 V capacitor that is charged to between 2V to 16 V from dumping it's charge all at once.

I would like the capacitor to provide 1.5 volts to the load.  What do I need to do?  What about amps (.5 A)?

I could put diodes in between the capacitor and load for voltage drops - but the capacitors charge will vary from 2V to 16V....

CH

[Nastrand2000]

Hey capt,

You can use a voltage regulator to control the voltage to the load. They can be picked up from radioshack.
Jason

[gyulasun]

Yes, you can use a switch mode DC/DC converter as the voltage regulator, that gives out 1.5V at 0.5A, see this chip here on page 17 and 18 of this data sheet but of course there are several other integrated circuits from different manufacturers:
http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1042,C1032,C1082,P37748,D25042

However you have to combine a switch in series with your 4700uF in the wire leading to the DC/DC converter to disconnect it (and its load at 1.5V) when the DC voltage of the capacitor goes down to about 3V or so (usually converter chips do not work at 2V, it's too small for them).  The switch should be combined with a voltage sensor circuit like a simple voltage comparator to sense the charged state of your capacitor between 3V and 16V.
There is a patent application on just such a circuit you need, it is US20070222411 from Jean-Michel Cour.
(go here http://www.pat2pdf.org/ and copy and paste 20070222411 to freely download this patent)

Of course if you study thorougly the patent description you can figure out what you need from it. (hint: Capacitor #14 in Fig. 1 will be your 4700uF and Battery #16 will be replaced by (the input of) the DC/DC converter IC from above or from elsewhere.

rgds,  Gyula