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Is there any reason that one dosn't "have to" use safety caps on lower ac voltage, around 28VAC. Don't want to burn my landlord's house down, well, on second thought??? Tweaker
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@28VAC we can assume its not connected to mains directly but tell us more about the circuit/environment
ET
These caps go across the secondaries of the JR digital filter. Wall 120VAC to 28VAC to 120VAC. Thanks, Tweaker
Gotcha and yes I think safety caps are in order and I'm pretty sure John would say so.
ET
So much more choice of caps without having to resort to Type X. Tweaker
Re: Question about Jon Risch's new digital filter
Posted by Jon Risch (B) on October 15, 2001 at 20:23:39
In Reply to: Question about Jon Risch's new digital filter posted by Batman on October 15, 2001 at 19:52:19:
Try different values and see. I would start out with 2 uF and a smaller 0.1 uF bypass, and see what you think. One of the units in use and being experimented with is using a 10 uF cap, bypassed with a 0.22 uF stacked foil low inductance cap.
If the transformer steps down and the second one steps back up, then the caps will only see some fraction of the full AC line voltages, and any transients will be blunted by the transformer inductance. So full X or Y rated caps are not absolutely necessary. How close you want to cut the margin depends on how much the step down and back up is. Too much, and you need gobs of current capacity to retain any amount of wattage capacity, too little step down, and you will need to use full AC line rated caps for safety.
See Steve Eddy's post:
http://www.AudioAsylum.com/audio/tweaks/messages/44145.html
the second diagram may be what you seek.
Jon Risch
If you are worried, consider what happens if it fails short. Will failing short energize a piece of user accessible metal with dangerous levels of voltage? Will failing short cause fire starting levels of heat from the current that flows? If the answer to those questions is no then it's safe regardless of what nec says.
can or should consider these things independent of fire safety codes.
his may help
http://www.wima.com/EN/pulseselection.htm
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