Antwort: Re: [sdiy] midi to mosfet - question

[Harry Bissell Jr]

If you want low noise, the mosfets should be
loacted as physically close to the solenoids
as possible... minimizing the 'loop' area for the
radiated EMI

Don't forget to have some form of snubbing for the
solenoid coils when you turn them off... (diode, 
g-mov etc) of there will be a very high voltage
generated which will make the noise MUCH worse.

Best if the power for the solenoids comes from the
solenoid box... and the ground return on the 36 pin
cable has nothing more than the reference for the mos
switches...

H^) harry



--- Christian.Bergmiller at daimlerchrysler.com wrote:
> 
> 
> 
> 
> i thougt i could use the four unused lines of the 36
> pin connector for the
> common ground..
> no good idea ?
> The number of switched on notes could be limited by
> software to maybe  8 or
> ten.
> This would give 5 ampere over four contacs.
> 
> Christian
> 
> 
> 
>                                                     
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>                                    
>                       asfi at eol.ca                   
>                                                     
>                                    
>                       Gesendet von:                 
> An:      synth-diy at dropmix.xs4all.nl                
>                                    
>                       owner-synth-diy at dropmi        
> Kopie:                                              
>                                    
>                       x.xs4all.nl                   
> Thema:   Re: [sdiy] midi to mosfet - question       
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>                       04.02.2004 09:02              
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> On Wed, 4 Feb 2004
> Christian.Bergmiller at daimlerchrysler.com wrote:
> 
> > Hi,
> >
> > i'm currently building a midi to mosfet "open
> drain" 32 channel
> interface.
> > It uses the AT90S2313  uC, 4* 4094 shift registers
> for I/O extension and
> > 32* 2SK1904 mosfets on the outputs.
> > On breadboad it worked ok so i am prototyping it
> on some kind of
> > stripboard.
> >
> > I want to put the whole thing in a box and connect
> it to the world via 36
> > pin centronic connector.
> > My question is if swirtching 32* 24V Solenoids at
> 500ma connected via
> > 3meters of Cable (just an example)
> > will produce hf noise (or whatever :-) that would
> couple into equipment
> > used around it ??
> > is shielded Cabel enough protection. do i have to
> use some kind of "slew
> > rate limiting" ?
> > Or should i put this interface just as close as
> possible to the solenoids
> > has to power ?
> 
> The "common" side of the solenoids isn't connected
> through the Centronics
> connector, correct? (I *do* feel compelled to ask
> these sorts of things,
> please forgive me.)
> 
> How many outputs will be switching simultaneously?
> 
> - Colin Hinz
>   Toronto, Canada
> 
> 
> 
> 
>