Ham Spot Presents #002: Potential Capacitors

In this video we examine a variety of specialty capacitors as well as some common components.  I smash open a high voltage capacitor to see what's inside.  I show you a vintage resistor-capacitor tester.  Another look at how I store all of these devices.  And at the end is a tidbit for Ham Radio operators who have need for high power medium-wave/short-wave antenna matching.

There are an endless variety of capacitors available on the market as well as many you can salvage from old equipment.

Capacitor Sources

Be careful about where you purchase capacitors, as well.  There are plenty of counterfeit devices on the market today, unfortunately.  Newark.com and Digikey.com are excellent, reliable and inexpensive sources for components.

I usually buy new electrolytics just to be safe.  Electrolytics deteriorate with age.  Some are very poor quality to begin with. 

However many types of capacitors are ripe for salvage.  Air dielectric, high voltage, high capacity and many specialty capacitors are worth the trouble of salvaging.  Some types of capacitor simply are no longer manufactured and suitable replacements do not exist.  In those cases you are forced to purchase work-alike circuits from antique vendors such as Antique Electronics Supply that are often disguised to look like the original part.  Not always ideal especially if you can find a working original replacement part.

Air dielectric capacitors can be purchased directly from MFJ Enterprises, as well.  These will be the type more suitable to building radios and antenna matching circuits.  Other commercial sources for these components have largely gone extinct.

Common Capacitors

Your best bet is to grab an assorted parts bag from someone or somewhere.  Honestly, you don't need all of these values.  Which values you'll need are entirely dependent of the types of devices you build.  When in doubt, remember you can (almost) always combine smaller values effectively.  Tolerances on capacitors are pretty loose unless you're dealing directly with RF and usually you can adjust the other nearby components a little to make up for not having an exact value.  These tables may also help you select the correct type of capacitor for the function it will be performing.

Standard Capacitor Values
1pF 10pF 100pF 1000pF 0.01µF 0.1µF 1.0µF 10µF 100µF 1000µF
1.5pF 15pF 150pF 1500pF 0.015µF 0.15µF 1.5µF 15µF 150µF 1500µF
2.2pF 22pF 220pF 2200pF 0.022µF 0.22µF 2.2µF 22µF 220µF 2200µF
3.3pF 33pF 330pF 3300pF 0.033µF 0.33µF 3.3µF 33µF 330µF 3300µF
4.7pF 47pF 470pF 4700pF 0.047µF 0.47µF 4.7µF 47µF 470µF 4700µF
6.8pF 68pF 680pF 6800pF 0.068µF 0.68µF 6.8µF 68µF 680µF 6800µF
Standard Capacitor Voltages
CeramicElectrolyticTantalumMylar-PolyesterMylar-Metal-Film
16V 10V 10V 50V 250V
25V 16V 16V 100V 400V
50V 25V 20V 200V 630V
100V 35V 25V 400V  
600V 50V 35V    
1000V 63V 50V    
  100V      
  160V      
  250V      
  350V      
  450V