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Old 07-09-2008, 09:16 AM
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studiot studiot is offline
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Default Electronics Tips and Tricks Thread

It has occurred to me that a thread where posters could pass on useful tips, tricks, rules-of-thumb, and conventions that may be of use for when you need a 'how to answer' not an in depth understanding. Please don't use this thread for asking questions.

I will kick off with a very simple but useful formula for making a non standard resistor by adding a parallel resistor to a standard one.

is the required shunt resistor

is the desired non preferred value

is the (next) higher preferred value

Last edited by Dave; 07-09-2008 at 11:02 PM.
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Old 07-09-2008, 09:50 PM
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In retaliation for StudioT's post...

Attached files:
1) - contains an Excel spreadsheet that has StudioT's formula in it, and also does series of lookups on standard E6 thru E192 series resistance tables to ensure use of only the standard values in the results. Just put in the resistance you want where indicated, and resistor combinations for all E-series are displayed.
2) E24PLL.ZIP - contains E24PLL.TXT, a rather large (224kb) text file that you can scroll through to find pairs of resistors to use in parallel to obtain a particular resistance.

Here's a handy web page that does both series and parallel calculations for you, for E12 and E24 series resistors:
Note that you must select E12 or E24 each time you enter a new value, or you will receive an error message.

3) CapSMTMarkings is an excerpt from a KEMET Packaging and Marking document, for identification of SMT capacitor values.
If there are two letters and a number, the manufacturer is the first letter. If just a letter and a number, only the value and multiplier is specified.

Attached Images
File Type: png CapSMTMarkings.PNG (78.7 KB, 1244 views)
Attached Files
File Type: zip (8.7 KB, 860 views)
File Type: zip (64.6 KB, 637 views)
General info:
If you have a question, please start a thread/topic. I do not provide gratis assistance via PM nor E-mail, as that would violate the intent of this Board, which is sharing knowledge ... and deprives you of other knowledgeable input.

Last edited by bertus; 02-08-2014 at 03:38 PM. Reason: showing image full size
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Old 07-10-2008, 05:07 AM
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Rule of thumb for calculating power supply filter capacitors:

C = 0.7(I)/ΔE(f)

Where I = load current, ΔE = acceptable ripple voltage, and f = pulses per second from the rectifier.

For full wave rectified 60Hz, this works out to:
C = 0.00583 * I / ΔE
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Old 07-10-2008, 07:46 AM
miconos miconos is offline
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Default RFIC inductance calculation

Rule of thumb for RFIC inductance calculation:
1mm ~ 1nH
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Old 08-16-2008, 12:09 AM
yubyub yubyub is offline
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Tip: check things more than once when soldering a big project. (i just soldered 50 transistors backwards)
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Old 11-04-2008, 07:36 PM
KL7AJ KL7AJ is offline
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If any of you can get a copy of the November 2008 QST, I have an article in Technical Correspondence called "Making the Glass Half Full." I discuss in detail the reciprocal impedance parameters: conductance, susceptance, and admittance. These GREATLY simplify otherwise daunting parallel impedance problems.


REAL men don't need voltmeters.
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Old 12-18-2008, 01:15 PM
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If your 9V battery connection is too short for the power supply, why not try the following and kill your project.

You won't need to power it up anymore.
Attached Images
File Type: jpg 9VBat.jpg (42.0 KB, 1807 views)

Last edited by bertus; 07-13-2014 at 07:41 AM. Reason: showing image full size
Old 01-14-2009, 12:47 AM
electratech electratech is offline
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VIP chart for quick guide

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Old 01-30-2009, 03:09 PM
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Remember the skin effect. When trying to rid yourself of EMI, don't try to run it out of your system on a regular wire, rather ensure the wire has a large surface area (i.e. shielding).
Old 01-30-2009, 06:32 PM
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When designing power supplies be sure to size the input protection fuse so that the equipment being power blows up first so as to protect the power supply fuse from blowing open first.

Measurement changes behaviour
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