July 24, 2012
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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.
Overview
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
SESSION NOTES
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 ...
TOROIDS
from Kits and Parts website ... http://www.kitsandparts.com/toroids.php
SEMICONDUCTORS
VIDEOS from W2AEW
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...
http://www.youtube.com/watch?v=ykgmKOVkyW0
2) The second video builds upon what was learned in the first video and discusses LC resonant circuits, again on paper and with measurements:
http://www.youtube.com/watch?v=hqhV50852jA
3) The 3rd video talks a little about the real-world aspects of these components, including things like parasitics and self-resonance:
http://www.youtube.com/watch?v=vi24SpKYYoQ
REFERENCES
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