July 24, 2012

Join the "CWTD Yahoo Group" for email discussion in between our weekly sessions by clicking here.

Guide to Component Selection

Tips for selecting the right resistors, capacitors, IC's, transistors, toroids, displays, microcontrollers,
and many other components when you are trying to adapt or modify a project for your own usage.


Many times when we see a good project described in QST, QEX, the Handbook, RADCOM or even the W1FB QRP Workbook, we often say something like "Hey, I'd like to make this project but I don't need as powerful a transmitter," or maybe "I'd like it work with my existing frequency counter," or sometimes it's "Gee, I don't have that specific transistor but maybe I could use a 2N3906 that I do have."

Well, this week's episode of CWTD is going to be a good overview of the various parameters that are important when selecting capacitors, resistors transformers, IC's and other components that we play with daily on our homebrewing benches. Whether it is a replacement part, or a lower-spec'd part, or a part from another vendor, we'll give you some guidelines for helping you make your selection.   

73, George N2APB  & Joe N2CX

Audio Recording ... (Listen to the MP3 podcast)

Discussion Notes:

<20:12:11> "N8ET - Bill": George - I just got word from Dick Tormet that it is OK to post info from his book on your whiteboard
<20:14:18> "Alan W2AEW": Nice! Interested!
<20:14:39> "N8ET - Bill": N8YSK is his call
<20:16:05> "John WA8HSB": Have both books! As George says, both are excellent.
<20:25:33> "George - N2APB": What are polyesters best used for?
<20:25:57> "Pete - WB2QLL": Great for audio
<20:29:14> "Chris - W0ANM": can you enable my sound. I promis to be a good boy...
<20:30:54> "George - N2APB": I didn't disable you! You should be good to go.
<20:32:52> "George - N2APB": Can you hear us? I don't see your callsing on the list.
<20:33:48> "N8ET - Bill": you can still get silver micas from Digikey
<20:35:02> "George - N2APB": Yeah for $$$$$
<20:35:09> "N8ET - Bill": yup!
<20:35:40> "Alan W2AEW": There's a lot of them in the CCFL inverter supplies in flat panel monitors - I've repaired a lot of them
<20:38:19> "John WA8HSB": The comparison chart will be great George - thanks!
<20:39:52> "N8ET - Bill": There is a company called Oren Elliot in NW Ohio that stil0l makes real variable caps. I buy 100 at a time from them every so often, but they are about $12 each.
<20:47:48> "Alan W2AEW": recently built a QRP mWattmeter for a friend, and the directional coupler used two toroidal transformers...
<20:48:20> "Alan W2AEW": ...each were made with two identical cores stacked together. Can you comment on why? Prevent saturation?
<20:49:56> "Alan W2AEW": Excellent, thanks!
<20:54:43> "Alan W2AEW": Where did the table for semiconductors come from? Some of those prices aren't bad...
<20:57:07> "Charles WC5MC": Torroid Salad ;q
<20:57:38> "Joe N2CX": semi info is from Diz parts and kits.com
<21:05:10> "Alan W2AEW": used a lot in AGC circuits
<21:05:51> "Mike WA8BXN": dual gate ?
<21:06:14> "Pete - WB2QLL": 40673?
<21:07:28> "George - N2APB": Yep, the ol' 40673 ... such memories!
<21:08:20> "N8ET - Bill": I have to run George - I will send you an e-mail about the books in an hour when I get back
<21:08:34> "George - N2APB": VN10K used in the Rainbow Tuner
<21:08:47> "George - N2APB": RR Bill, thanks much.
<21:16:20> "Alan W2AEW": that would be GREAT!
<21:20:47> "John ZL1AZS": Toroids...definitely
<21:25:24> "Alan W2AEW": I will DEFINITELY be interested in the uBlox-6 - it will be a great 10MHz reference for my bench!
<21:29:39> "John WA8HSB": My first session - what have I been missing!! Look forward to future sessions and will begin listening in to the previous sessions. Thanks Joe and George... 73/72


If you purchase just one book in your homebrewing lifetime, it should be one of these two ... fabulous!



Capacitors:  Different types, standard values

The charts in this section are from the wonderful reference book ...









from Kits and Parts website ... http://www.kitsandparts.com/toroids.php  






1) The first video takes a basic look, on paper and via measurements, at the voltage and current relationships in capacitors and inductors - thus visually showing the concepts of leading and lagging...



2) The second video builds upon what was learned in the first video and discusses LC resonant circuits, again on paper and with measurements:



3) The 3rd video talks a little about the real-world aspects of these components, including things like parasitics and self-resonance:




Kits and Parts dot com toroid info:  http://www.kitsandparts.com/toroids.php  ... Click on top page links for toroid turns calculator, toroid core spec page etc.

GQRP Technical pages:  http://www.gqrp.com/tech.htm

NA5N Handyman's Guide to Capacitors ... http://www.gqrp.com/na5ndatasheet.pdf

Coax cable data ... http://www.thewireman.com/coaxdatacurrent2.pdf


Back to CWTD Home