Im using a commercial EMI filter at primaries and would like to use Tantalum caps for the bypass. For a class A amplifier. Im using two stages one regulator for voltage amplification and for current amplification i would like to reduce the RFI.
Im thinking of using a .1uf or 100pf bypass for the psu caps Is it recommended to use that?
Im thinking of using a .1uf or 100pf bypass for the psu caps Is it recommended to use that?
tantalum don't do X/Y line safety rating - no application anywhere near line V
their only purpose today is hi C in small volume inside cell phones/PCs at single digit Vdc - other tech caps are used with better results everywhere else today
they were ubiquitous in 20+ year old op amp datasheet example bypass C - may be carried forward to some more modern chip datasheets by inertia
their advantage in those apps was that the sintered, dry electrolyte "orange drop" caps had small ESL and fairly reliable and high ~ 1 Ohm ESR to damp possible PS resonance with paralleled C
today smt parts let you design/control the bypass high frequency performance much more closely with cheaper, more reliable parts
the MnO2 solid electrolyte Ta cap failure mode is to emit flames if they short while connected in parallel to too much C
their only purpose today is hi C in small volume inside cell phones/PCs at single digit Vdc - other tech caps are used with better results everywhere else today
they were ubiquitous in 20+ year old op amp datasheet example bypass C - may be carried forward to some more modern chip datasheets by inertia
their advantage in those apps was that the sintered, dry electrolyte "orange drop" caps had small ESL and fairly reliable and high ~ 1 Ohm ESR to damp possible PS resonance with paralleled C
today smt parts let you design/control the bypass high frequency performance much more closely with cheaper, more reliable parts
the MnO2 solid electrolyte Ta cap failure mode is to emit flames if they short while connected in parallel to too much C
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The one thing never to do is use a tantalum in an unlimited current situation. Tears and flames are sure to follow. They have a bit of an undeserved reputation, but used with sufficient derating and only in current limited locations, they work great and never age. For example, I don't mind using them to bypass a zener and kill noise where the zener current is limited to 20 mA or so. I tend not to use them as general purpose supply bypasses where hundreds of mA or more are available.
Hiss can have a lot of different origins. Thermal noise from resistors, bad regulator, external interference, high gain to worsen all of the above. Bypassing the PSU caps will do nothing.
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