Hello,

When going through the threads I ofthen see pictures that are blurry, to much light from the flashlight.
I found a simple way to make pictures of a PCB.
I have used a epson flatbed scanner to produce the attached picture from a sound card.
The resolution is 300 dpi at the moment, but much higher is possible.

Bertus

 

Yes, bertus, that will make things hundreds of times easier to troubleshoot.

I hope folks still have flatbed scanners.

They seemed to have fallen out of favor with the availability of low-cost high-res digital cameras.

I still have a few so I will definitely use this tip!

 

Alot of printers now have scanners built in.

 

Hello,

To show the capability of my scanner I scanned a part again on 1200 DPI.
See attachement.

Bertus

 

Ahhh.. You can see how sharp the tops of the caps are, and the traces are getting blurry.

Do you lose depth of field as resolution increases?

 

Hello,

Yes, the distance from the glassplate to the actual PCB is giving the trouble.
You can see the top of the electrolitic capacitor is very sharp,
but the small caps on the PCB are getting a bit blurry, but still good visible.
You can still read the resistor values, wich is amazing.

Bertus

 

Hello,

Yes, the distance from the glassplate to the actual PCB is giving the trouble.
You can see the top of the electrolitic capacitor is very sharp,
but the small caps on the PCB are getting a bit blurry, but still good visible.

i think being able to adjust focus involves physically moving the sensor's distance from the glass no?
to increase depth-of-field, without an iris control, i propose an elaborate relay lens system.

 

Nice information like it

Good sharing thanks bro

 

Ever need an odd value of resistance and want to know what combinations of resistors to use, without having to do all the math?

Then this little DOS and Windows-compatible utility I wrote is for you. You just tell it what series resistors you have on hand (if you're not sure, use E12 or E24) and then start feeding it the resistance values you need. It will give you up to 80 different combinations of series/parallel configurations that you can use to get close your desired resistance, and roughly what the percentage of error will be, up to 20 results per page.

Example output from requesting a 62.5 Ohm resistor using E24 series:

It's a bare-bones utility, nothing flashy - just functional. The idea was to write a reasonably compact (260kb) and useful utility program that would run without installation on any Windows or DOS platform; just copy the executable to a convenient location (like your desktop) and click on it to run. Be aware that on slow machines it will take awhile to find all the combinations for E96 resistors.

I used a freeware compiler called "Yabasic" - Yet Another Basic - that has compilers that will run on Windows and Unix platforms:
http://www.yabasic.de/
with the idea that if this works well for Windows users, I'll try compiling it under Ubuntu and see how that goes.

I'd appreciate it if some of you would give it a try, and post back here if you find bugs with it.

A known limit is the accuracy of the error percentage when displaying low-value resistors; it's a limitation of the language and I'm not very inclined to come up with a work-around.

[eta]
Added rescalc.yab - Yabasic source code to .zip file

[eta]
Updated ResCalc.zip - both source code and executable updated:
1) There was a bug that resulted in higher-value resistance pairs not being calculated; bug fixed.
2) Improved internal documentation.
3) Replaced some GOTO statements with while/wend constructs.

 

Hello,

Here I have a RF power conversion chart:
power_chart_test.pdf

This chart was created a long time ago by a colleage of mine.

Bertus

 

Hello,

Here is a PDF with some tricks for the calculations with Db's.

Bertus