Hey guys,
As a newbie I do not have a dedicated lab supply, so usually play (breadboard and stripboard/veroboard) using LiPo's (I fly RC heli). Not sure when I get a hold of a real lab supply, so when I saw this tiny and cheap adjustable voltage/current with CC and CV from Shenzhen/China (yeah I know the stuff from there is low-quality and frowned upon by Dave) I had to order one. I plan to mount it permanently to a large breadboard, add 2 multi-turn 10K pots for better control of voltage/current and use an external 12V DC adaptor to feed it (meaning a 1.3V - 10V output range), which would make it possible for me to "play" even while sitting in the living room relaxing at night:
http://www.ebay.com/itm/LED-Voltage-and-current-display-LM2596-DC-DC-Step-Down-CC-CV-Adjust-Power-Supply-/150878659741It's based on TI's LM2596 DC-DC conveter and appears to be an implementation of the reference design outlined in the data sheet:
http://www.ti.com/lit/ds/symlink/lm2596.pdfObviously I am concerned about ripple and noise; the data sheet does outline how to filter most of this ripple using a post-ripple LC filter but this reference design does not appear to contain one.
- For the L in the LC filter, the sheet mentions a low ESR cap. This internal resistance thing is a bit new to me, what kind of caps would I typically have to go for here? It looks like plain electrolytes on the diagram but on reference boards it looks like a super-cap.
- What kind of noise trouble could I run into even when applying this LC filter? I assume for general digital circuits there would be no problem, what about op-amps and other analog work?!
- Would there be any difference looking at the output with a scope, depending on whether the circuit would be fed via mains (transformer, rectifier bridge and cap) or a battery?
- Last but not least, I noticed that in one of Dave's video (USB power supply?) he uses a linear IC, but somehow lowers the voltage feeding this, in order to minimize power draw and heat dissipation. Could I somehow do the same; such as to let an effecient but noisy switching frontend feed a less effecient but cleaner backend such as an lm317 or better? (Obviously doing this, means the voltage/current display as well as protection mechanisms of the product I linked to above will mean nothing, but I'm still wondering about the theory.)
Thanks in advance,
/Casper