Search found 226 matches

by Garth
Sun Aug 23, 2020 3:14 pm
Forum: Brads Projects University
Topic: oximetry
Replies: 1
Views: 824

Re: oximetry

What do they detect? Transmission of a particular wavelength of light compared to another? I'm sure there's no need to re-invent the wheel though. I think these have even been used in aircraft, for the pilots to make sure they're getting enough oxygen, especially in non-pressurized aircraft where th...
by Garth
Mon Jul 13, 2020 11:46 am
Forum: The off topic lounge
Topic: A digital dark age may be coming, Google VP warns
Replies: 18
Views: 15148

Re: A digital dark age may be coming, Google VP warns

I'm trying to post a reply, and I get the error message:
Forbidden

You don't have permission to access this resource.
Let's see if this simpler one will post. It does. Why not the other? I have a picture in it and a link to a 90-second demo video on my site.
by Garth
Wed Jun 17, 2020 8:47 am
Forum: Programming PIC's with Swordfish Basic
Topic: I2C LCD Displays with PCF8574
Replies: 6
Views: 3390

Re: I2C LCD Displays with PCF8574

It sounds pretty easy. If its I²C clock rate is limited to 100kHz (max of 12.5KB per second), you won't be overrunning the LCD's ability to keep up for most instructions, especially with the 4-bit interface. I should probably get some of those ICs to have on hand and play with.
by Garth
Wed Jun 17, 2020 6:48 am
Forum: Programming PIC's with Swordfish Basic
Topic: I2C LCD Displays with PCF8574
Replies: 6
Views: 3390

Re: I2C LCD Displays with PCF8574

Thanks. I've usually used these LCDs in 4-bit mode, with 6 lines (just grounding the R/W, which just means you have to give it enough delay that you know each instruction is finished, since you can't poll it). I have working sample code in different forms at http://wilsonminesco.com/6502primer/LCDco...
by Garth
Wed Jun 17, 2020 4:47 am
Forum: Programming PIC's with Swordfish Basic
Topic: I2C LCD Displays with PCF8574
Replies: 6
Views: 3390

Re: I2C LCD Displays with PCF8574

That looks nice. Do you sell the I²C module? I don't see any way to buy it. Actually, I'm sure it could be used for a lot of other things besides an LCD, right? And there are undoubtedly a lot of I²C-to-parallel adapter ICs on the market, probably from Maxim and others; but this one is already made ...
by Garth
Tue Apr 07, 2020 7:35 am
Forum: The off topic lounge
Topic: great danger from cell-phone use
Replies: 25
Views: 25288

Re: great danger from cell-phone use

It would be interesting to see the results of an experiment (or multiple experiments) that have all the correct control measures in place.
Dr. Devra Davis with data on studies with controls:
https://www.youtube.com/watch?v=BwyDCHf5iCY
by Garth
Fri Feb 14, 2020 4:19 pm
Forum: Brads Projects University
Topic: soldering SOJ (& similar) parts without special equipment
Replies: 7
Views: 13666

Re: soldering SOJ (& similar) parts without special equipment

Here's another one, an SOIC. These were taken with a very cheap camera. First I tack one corner, and get the IC really straight, then tack the opposite corner, and again make sure I haven't rotated it out of being straight. Then I do the two remaining corners. Then I flood a whole side with solder, ...
by Garth
Wed Dec 11, 2019 6:13 am
Forum: PCB Design
Topic: Analysis of the basic process and steps of PCB circuit board design
Replies: 1
Views: 7639

Re: Analysis of the basic process and steps of PCB circuit board design

I find a lot of problems with the post above. For starters, I would recommend going through Dr. Howard Johnson's articles indexed at https://web.archive.org/web/20120302190123/www.sigcon.com/Pubs/pubsKeyword.htm . He is quite an industry guru, and the author of "High Speed Digital Design: A Handbook...
by Garth
Tue Sep 17, 2019 3:06 pm
Forum: The off topic lounge
Topic: CHEAP board houses?
Replies: 6
Views: 9377

Re: CHEAP board houses?

There are so many now. I've been using DirtyPCBs , and getting excellent prices, no quality problems, and relatively fast service. I've been using them for hobby boards and for prototypes of the simpler ones of our products at work. (When we're ready for production, we go to more-professional board ...
by Garth
Wed Apr 24, 2019 3:04 pm
Forum: Brads Projects University
Topic: Mixed Voltage Systems: Interfacing 5V and 3.3V Devices
Replies: 8
Views: 16043

Re: Mixed Voltage Systems: Interfacing 5V and 3.3V Devices

I see now the link in the head post, http://www.savagecircuits.com/content.php?85-Mixed-Voltage-Systems-Interfacing-5V-and-3-3V-Devices, is dead. I don't remember what was in the original, but one it might have been is http://nutsvolts.texterity.com/nutsvolts/201104/?folio=46&pg=46#pg46, and another...
by Garth
Thu Apr 04, 2019 2:10 pm
Forum: The off topic lounge
Topic: great danger from cell-phone use
Replies: 25
Views: 25288

Re: great danger from cell-phone use

Brussels Becomes First Major City to Halt 5G Due to Health Effects
http://www.greenmedinfo.com/blog/brusse ... th-effects
by Garth
Thu Apr 04, 2019 1:25 pm
Forum: Great video clips
Topic: Vulcan-74: A 6502 Retro MegaProject
Replies: 8
Views: 99719

Re: Vulcan-74: A 6502 Retro MegaProject

Brad, how nice to see you here! There are a few 6502.org members here as well. Two who immediately come to mind are BigEd and Dr Jefyll (Jeff Laughton). I don't know how often they check in. This forum used to be more active, apparently when Brad Slattery (the owner) was having his students post pro...
by Garth
Fri Nov 30, 2018 8:58 am
Forum: PCB Design
Topic: Beginner PCB design for LED clock
Replies: 1
Views: 3134

Re: Beginner PCB design for LED clock

A small board like that with 74HC logic will be more forgiving than some. The matter of grounding, ground bounce, bypassing, transmission lines, terminations (which you definitely do not need on this board), etc. is complex and is discussed in a 6502.org topic at http://forum.6502.org/viewtopic.php?...
by Garth
Thu Nov 29, 2018 9:48 am
Forum: The off topic lounge
Topic: Comments on a metronome schematic and board?
Replies: 1
Views: 3596

Re: Comments on a metronome schematic and board?

It's pretty clear that you're trying to sell PCBGOGO services here. It's ok though, since at least you're on topic and not giving us unrelated spam like we often have to delete. I was not able to download the dropbox files without starting an account, which I don't really want to do. You can attach ...
by Garth
Tue Oct 02, 2018 4:37 am
Forum: PCB Design
Topic: Circuitmaker
Replies: 8
Views: 41854

Re: Circuitmaker

I just got an email from Digi-Key saying they now had a free online symbol and footprint library for KiCad, at https://www.digikey.com/en/resources/design-tools/design-tools#kicad . On a related note, I just finished my first dense design of parts on both sides. Up until now, I have sometimes put ju...