search

google / makerspace-auth

Designs for our makerspace access control devices
Apache License 2.0
63 stars 27 forks source link

C2 capacitor sizing #11

Closed brianredbeard closed 6 years ago

brianredbeard commented 6 years ago

The C2 filter capacitor is specified by part number C3216JB1E476M160AC is flagged by the manfucaturer "Not for use in new designs".

For a ceramic capacitor of that high of a voltage/capacitance it seems that its a pretty niche part.

Sticking in a 1206 footprint it appears that one can go as high as 33µF when sticking to 12v or 47µF if the voltage can drop to 10v.

Are there any suggestions for replacement parts?

thatch commented 6 years ago

My last build used EMK316BBJ476ML-T but that's out of stock at both digikey and mouser now too.

Originally, I was intending to PWM the LEDs, and included C2 defensively to cope with switching currents on underpowered power supplies... but driving with a nice power supply and slow output changes empirically works fine without C2.

Happy to answer other questions as well.

brianredbeard commented 6 years ago

Understood. I think this documentation sufficient for the time being to close the issue out.