Bypass capacitor types?

H

harolds1956

New Member
Hi, been using various picaxes over the years and have used whatever I had on hand for the bypass cap. Small electrolytics, ceramic discs, tantalum, polyester, polypropylene etc. From .1uf to 100uf. Never had a problem with them performing perfectly with some projects running continuously for years. However, the projects were simple, using simple code. Going forward I'd like to do it "right" using the best, most appropriate cap for the picaxe. I know the manual says .1uf polyester. Any advice or opinions?
 
I

inglewoodpete

Senior Member
This is how Rev-Ed did it for the schools experimenter. In my own designs, I would normally mount the same capacitor at the 'head' or pin-1 end of the 08M/08M2/14M2/20M2/20X2.

The second image is how a colleague mounted the capacitor/s for 28X2/40X2.
AXE-092 LoRes.jpgDecouplingCap.jpg
 
hippy

hippy

Ex-Staff (retired)
harolds1956 said:
I know the manual says .1uf polyester. Any advice or opinions?
Click to expand...
100nF Polyester is what I have always used, is what most people seem to use; for everything, not just PICAXE. The usual recommendation is one per chip and to keep it as close as possible to that chip.

When using vero-board I have sometimes used two tracks at the bottom to carry power bread-board style across the board, jumper up to the chip power pins and put a decoupling cap across the supplies below the chip.

Soldering under the board, across power pins, or tucking it within a DIL socket, are also tricks I have resorted to.

When putting the cap at the head of a DIL socket, remember not to also put one at the bottom or you can't insert a screw driver to help lift it out, and if it's a 28 or 40-pin chip you might want to use that technique from both ends. Not a problem with an IC puller, but who has one or can find it whan it's needed!
 
Technoman

Technoman

Senior Member
As in #2 and #4 (SMD soldered on the track side), MLCC (Multilayer Ceramic Capacitors) are widely used. Due to their poor frequency response, avoid tantalum and electrolytics for that use or not alone.
 
You must log in or register to reply here.
Top