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Search: Posts Made By: Curious.George
Forum: Custom Tweaks, Modifications, and Revisions Today, 12:10 PM
Replies: 21
Views: 232
Posted By Curious.George
Re: My basic project - needs simplified - Digital TTL circuit maybe

That's the fallacy. Software often costs considerably more to develop often because it is called on to do more for the same recurring dollars than a "hardware" solution would ever consider...
Forum: General Electronics Technical Discussion Today, 11:47 AM
Replies: 9
Views: 85
Posted By Curious.George
Re: Questions about leds in series.

The potential (voltage) you will need to overcome (to cause meaningful current to flow) is determined by the SUM of all of the forward voltages of the LEDs in the string AT THE CURRENT YOU PLAN ON...
Forum: Custom Tweaks, Modifications, and Revisions Today, 09:22 AM
Replies: 21
Views: 232
Posted By Curious.George
Re: My basic project - needs simplified - Digital TTL circuit maybe

The problem with discrete components is that they tend to have very little "value added" potential. You can turn on a lamp with an SCR/thyristor but can't do much beyond that (for that "lamp...
Forum: General Computer Discussion 04-17-2018, 11:24 AM
Replies: 1,982
Views: 317,536
Posted By Curious.George
Re: best cheap/free scores 1.1

Another Z800 and a pair of 2x2 Ergotrons! Time to rearrange the office...
Forum: Custom Tweaks, Modifications, and Revisions 04-16-2018, 11:48 PM
Replies: 21
Views: 232
Posted By Curious.George
Re: My basic project - needs simplified - Digital TTL circuit maybe

[Note that polarities of signals can -- should -- be changed. But, I present them here in "positive logic" for ease of explanation]

Each button is conditioned appropriately for the environment...
Forum: Troubleshooting Power Supplies and Power Supply Design 04-16-2018, 06:13 PM
Replies: 35
Views: 288
Posted By Curious.George
Re: APC Back-UPS 1500 erratic behavior

If you could measure a cell's internal resistance, the short (separator failure) would be apparent. But, if you could access a cell, individually, you would also see this short as 0V potential...
Forum: Custom Tweaks, Modifications, and Revisions 04-16-2018, 09:27 AM
Replies: 21
Views: 232
Posted By Curious.George
Re: My basic project - needs simplified - Digital TTL circuit maybe

Do you allow for ties? I.e., what granularity of time do you want to support (ties happen when two events occur in the same time quantum -- nearly improbable in "real time" as there are usually...
Forum: Troubleshooting Power Supplies and Power Supply Design 04-15-2018, 11:10 PM
Replies: 35
Views: 288
Posted By Curious.George
Re: APC Back-UPS 1500 erratic behavior

Sorry, I guess I wasn't clear enough in my earlier comment re: FOSS.

I don't run FOSS software "products" under Windows -- because they have been disappointing, there.

And, as I have *BSD...
Forum: Troubleshooting Power Supplies and Power Supply Design 04-15-2018, 01:37 PM
Replies: 35
Views: 288
Posted By Curious.George
Re: APC Back-UPS 1500 erratic behavior

Actually, that is really only the case for low volume production. When your quantities get high enough, there's very little recurring cost penalty for many "trivial" design decisions. We often joke...
Forum: Troubleshooting Power Supplies and Power Supply Design 04-14-2018, 11:11 PM
Replies: 35
Views: 288
Posted By Curious.George
Re: APC Back-UPS 1500 erratic behavior

Their UPS products are all over the map in terms of what types of connectors they use and how they are pinned-out. From what I have on hand (and easily accessible):
BackUPS XS 1500 LCD RJ45 USB...
Forum: Troubleshooting Power Supplies and Power Supply Design 04-14-2018, 10:49 PM
Replies: 35
Views: 288
Posted By Curious.George
Re: APC Back-UPS 1500 erratic behavior

I've never looked closely enough to be able to comment. APCC offers lots of different products (models) but, I suspect, they are all very closely derived designs (beef up the FETs for higher load...
Forum: Troubleshooting Power Supplies and Power Supply Design 04-14-2018, 02:31 PM
Replies: 35
Views: 288
Posted By Curious.George
Re: APC Back-UPS 1500 erratic behavior

You can "see" the charging voltage by monitoring the terminals that would normally connect to the battery and increasing the battery pack's apparent impedance (so the battery doesn't "load down" the...
Forum: Troubleshooting Power Supplies and Power Supply Design 04-13-2018, 07:35 PM
Replies: 35
Views: 288
Posted By Curious.George
Re: APC Back-UPS 1500 erratic behavior

OK. It was a possible explanation for the discrepancy, hence my reason for mentioning it (having no idea as to the equipment to which you have access)



OK. So, you're not seeing the voltage...
Forum: General Computer Discussion 04-13-2018, 06:20 PM
Replies: 18
Views: 229
Posted By Curious.George
Re: Old workstation cards uses?

Fair enough. Note that one down-side of a card like the 3450 in this sort of setup is that it is relatively heavy and will have a higher "center of gravity" (than a low profile card). Add to that...
Forum: Troubleshooting Power Supplies and Power Supply Design 04-13-2018, 06:13 PM
Replies: 35
Views: 288
Posted By Curious.George
Re: APC Back-UPS 1500 erratic behavior

No. A shorted cell will definitely lower the open-circuit potential of the battery.

The battery (by definition, a group of cells) consists of a string of ~2.4V cells wired in series (different...
Forum: Troubleshooting Power Supplies and Power Supply Design 04-13-2018, 06:07 PM
Replies: 35
Views: 288
Posted By Curious.George
Re: APC Back-UPS 1500 erratic behavior

Did you measure this with the batteries still connected to the UPS? Or, did you lift one of the legs from the charger so you were actually seeing the batteries' voltage? (ideally, you'd put a brief...
Forum: General Electronics Technical Discussion 04-13-2018, 02:15 AM
Replies: 10
Views: 141
Posted By Curious.George
Re: Equivalent thermistor for Cisco switch PSU

Ah. I couldn't say for sure how often I'd come across something like that. I typically see pallets of network kit and, from any distance, it all just looks like stacks of 1U-ish boxes (only the...
Forum: General Computer Discussion 04-13-2018, 02:04 AM
Replies: 18
Views: 229
Posted By Curious.George
Re: Old workstation cards uses?

I don't think I have any AGP machines left, anymore. So, I only keep PCIe video cards (and a few PCI video cards as many servers don't speak PCIe). The AGP cards I use "like cigarettes in a...
Forum: General Computer Discussion 04-13-2018, 01:35 AM
Replies: 18
Views: 229
Posted By Curious.George
Re: Old workstation cards uses?

The OP didn't say "he was building a new system and had his choice of anything he wanted". Rather, he said he "bought 4 for < $10/ea" and inquired as to how to use them. I.e., he's already made the...
Forum: General Electronics Technical Discussion 04-12-2018, 09:26 PM
Replies: 10
Views: 141
Posted By Curious.George
Re: Equivalent thermistor for Cisco switch PSU

If you're confident of the "problem", its a small additional investment (considering the time and effort already expended to get to that diagnosis) to address potential/likely problems that may be...
Forum: General Electronics Technical Discussion 04-12-2018, 04:21 PM
Replies: 10
Views: 141
Posted By Curious.George
Re: Equivalent thermistor for Cisco switch PSU

Fair enough. Often we get focused on trying to fix what we have instead of just replacing with identical/equivalent. Switches are (almost) simple commodity items (unless you've written some...
Forum: General Computer Discussion 04-12-2018, 04:00 PM
Replies: 18
Views: 229
Posted By Curious.George
Re: Old workstation cards uses?

And when (as well as how often) do I perform these upgrades/replacements? I.e., do I take the CAD system that WAS using the video cards and replace those cards to build a better CAD workstation? ...
Forum: General Computer Discussion 04-11-2018, 08:43 PM
Replies: 18
Views: 229
Posted By Curious.George
Re: Old workstation cards uses?

And replace each pair of 24" LCD monitors with LED variants; and the workstations with more energy efficient units, and the spinning rust with SSDs, ...

No thanks. Dirt cheap/free hardware can...
Forum: General Electronics Technical Discussion 04-11-2018, 04:35 PM
Replies: 10
Views: 141
Posted By Curious.George
Re: Equivalent thermistor for Cisco switch PSU

Have you sorted out why the bridge failed? I.e., do you have an idea as to how extensive the problem might be BEYOND what you are currently seeing as failed components?

Do you really need an L3...
Forum: Network Design & Troubleshooting 04-11-2018, 04:12 PM
Replies: 21
Views: 817
Posted By Curious.George
Re: ISP Router Problems

I'm sure there are folks whose concept of "entertainment" fits that bill...

But, music, videos, movies, etc. also fall into that category and for a larger portion of the population's notion of...
Showing results 1 to 25 of 389

 
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