The Yamaha AN1x Synthesizer mailing list

Peter,

>Could it be an idea to use standard power supplies, that you just shove into
>your piece of equipment? All synths take the same voltages (12v, 5v,
>0v, -12v I'd imagine) anyway.

That approach is often used, and it helps with the time-to-market, but it 
doesn't solve the main issue:  power hazards inside the box.  Regulatory 
agencies say to the manufacturers, "Look you're responsible for any power 
that goes INSIDE your devices; your not responsible for anything that goes 
on OUTSIDE the devices."  Then they define a fairly difficult set of 
standards for voltages above 40-50V, and an easier set of rules for lower 
voltages.  Why?  Because the safety of electrical products is based on two 
things:  the distance between parts at different voltages, which affects 
the tendency to arc or short-circuit; and the amount of power that might be 
dumped into a device in the case of a failure, causing fire.  In both 
cases, the higher the voltage, the more likely that the result is hazardous.

As a designer, if I allow 120/240V into a product, I have to demonstrate 
that there is an extremely low chance of that voltage linking to a part 
that would either a) shock the user or b) cause a fire.  Because of the 
nature of high voltages -- i.e., their increased ability to arc through the 
air or break through insulating materials -- this can be difficult, 
especially in small spaces.  If I can lower the voltage, many of the 
problem areas become safe.  It also becomes easier to demonstrate their 
safety, so I win twice.

Regards,

-BW

--
Bruce Wahler
Design Consultant
Ashby Solutions™
www.ashbysolutions.com
CloneWheel Support Group moderator
978.386.7389  voice
978.964.0547 fax
bruce@ashbysolutions.com