• WSscaisson



    Viewing 15 replies - 1 through 15 (of 303 total)
    • in reply to: Uninstalr — “World’s best cup of coffee” #2589798

      I ran and tested Uninstalr portable.
      At reboot, Uninstalr made my Window 10 Pro into endless reboot loop.

      I let it reboot close to 20 times, just in case it made changes one item at a time that required several reboots. Finally I gave up, and did the repair to my Win10 Pro.
      Even if you do not do cleanup, its scan shows details of installed programs.
      Uninstalr does not have safety built-in, like RevoUnistaller. RevoUninstaller creates a restore point first. Using advanced mode, you can see the list of registry items to be deleted. I think this is a safer method. And…
      in my case, Uninstalr does corrupt the registry, causing endless reboot loop.
      Warning: for any app that makes change to registry, better do a restore point or a complete back-up first.
      In my case, I used Windows Repair to fix the endless reboot loop problem, by restoring to a backed up restore point. (Restore point includes registry back up.)
      How I fix the endless reboot loop:
      1. When rebooting, while seeing the circling dots, push and hold the power button to force a power-off. Reboot. Do this two to several times. Then it’ll reboot to Repair menu.
      2. Click ‘Advance’ button. Then click the ‘Restore’ button. You are now presented restore points.
      3. Choose the latest Restore point and run it. Windows will then boot up normally.

    • in reply to: Powerline Ethernet #2584129

      Sorry, I haven’t checked back on the forum for a while.

      Here is the pics on how to add a single 0.01uF 600V-1000V capacitor, to bridge the 2 phases (240V for USA) on house wiring.
      All you need is a single capacitor. Choose one that fits in the 240V receptacle or plug.
      The type of capacitor: polyester type or paper type. These types will burned open, a safety advantage.
      0.01uF capacitor will pass a tiny juice from one phase AC line to another (0.45mA), when the other phase is switched off. The current is tiny. This could happen if you turn off one AC phase yet leaving the other phase on (i.e. hot). Then the 0.01uF capacitor will pass a very small AC current to the off phase and may make you feel a tingle if you touch it.  However, usually the loading (lights, appliances, etc.) will absorb this tiny AC current, rendering not feeling anything at all.
      For those concern about it, do not install the capacitor as shown. Again, it is dangerous high Voltage, not to be mess with, and mess with it at your own risk.

    • in reply to: Powerline Ethernet #2584124

      The main problem with powerline Ethernet adapter is heat.

      Usually the design is ‘under-designed’ on heat.

      When overheated, it’ll slow down or malfunction/intermittent. In earlier design products, they were even so hot that it burned its fuse. Yes, they have a soldered in fuse. Yes, I checked! Apparently, to save money, the heat problem was for typical home use environment. However, if the location is a closet or poor ventilation, the device would over heat, then becoming intermittent, or totally self shut off. You would have to unplug, cool it down, re-plug in to make it operational again. Yes, I tried that! I used a PC fan to blow on and cool a misbehaved powerline adapter. No more problem! (Just for proving it.) Later I disassemble the adapter. Drill holes on top and bottom of the box, and added some heat sinks on ICs. Have the two TP-Link adapters working non stop for over 7 years.

      BTW, you MUST DIRECTLY plug the adapter into AC outlet, not through extension cord, and NOT sharing the same AC outlet with other device, even if it is a dual AC outlet.
      If you have to share the AC outlet, use an extension cord of at least 8 ft long for other device(s), and also not those extension cord with noise and electrical impulse protection (has MOV device built-in.) Best is just the powerline adapter alone on that AC outlet.

      If you have a switching power AC adapter (aka power brick) sharing the dual AC outlet, you are looking for trouble. If the dual AC outlet is sharing with a laser printer, I can almost guarantee intermittent problem with the powerline adapter.

      There is a reason for the over heating. The impedance of the AC line is very complex, and unpredictable. It may even be only 1 Ohm impedance (the RF ‘resistance’). (Yes, crazy me even measure it!) At such low load, the powerline adapter is hard pressed to transmit RF power into this 1-Ohm load.

      2 users thanked author for this post.
    • in reply to: Powerline Ethernet #2480050

      My 2-cent worth re Power Line Network Adapter (PLNA).

      1. I am a very early user. PLNA loses the war to wifi products because of the rapid improvement by wifi products. The infighting between PLNA makers did not help either. Even today, still has two PLNA standards, and theystill do not play well with each other. Wifi products have a single standard. All wifi products are interchangeable.

      2. I still use PLNA for remote locations, and for privacy (not easily accessible because you need hard wire connection).

      3. House AC wiring, and whatever plugged into it, has very complex RF behavior, hard to adapt. A surge protector device (such as in an extension cord) presents large capacitance. Motor devices (e.g. blender) cause too much noise. Turning laser printer power on/off creates a nearly RF deadly short!

      4. At one of my AC outlets, the RF impedance (nee ‘resistance’) seen by the PLNA is only 1 Ohm! Eventually the PNLA burned its internal fuse. (Yes, I open it and fixed it!)

      5. My solutions:

        a. Plug PLNA directly to AC outlet, no extension cord.
        b. Only PNLA alone in an AC outlet, even if dual outlets. NEVER share.(Or you’d lose usability + speed.)
        c. When initially pairing two PNLA, plug them into two separate but nearby AC outlets.

      6. Hardware additions (require technical knowledge).

        a. AC outlets are usually dual outlets, to plug in an extension on the 2nd outlet, or to make that AC outlets more usable…

          Build a box with coil(s) (one is OK, two are more than enough), 100uH, capable of 2-3A current (~200W-300W, increase current capability if needed).
          Plug this box into the 2nd unoccupied outlet as RF isolator. All other AC loads and extension cords will be plugged into this box. This makes the PNLA sees only the true impedance of the house wiring, not the various (and varying) loads on the same outlet. This single isolation box saves a lot of grief.
        b. AC house wiring may have two separate phase wiring, not connected as far as RF is concerned. In an AC outlet that has both phases present, such as a 240V power outlet (for USA wiring), bridge the two wiring with capacitors. Or you can open the plug of a clothe dryer/cook ranch, install the capacitor into it. Or build a plug with the capacitor(s) in it. 0.1uF, 600V is good enough. 1000V is even better but (too big) size does matter. Because the 2 neutral wires may also be separate wiring, use another 0.1uF capacitor to bridge them too. That is, total 2 capacitors.

        c. Interesting fact: Without the 0.1uF bridging gizmo, you may still temporarily ‘bridge’ the two phase wiring for RF to pass through. Turn on your electric cook range, or turn on your electric clothe dryer. The heater coil forms the resistor bridge for RF to go through!

        d. 0.1uF 600V capacitor is small. The entire capacitor bridge can be built into a 240V power plug (for USA wiring, EU wiring is different).

        e. The capacitor or coil is less than US$1 a piece.

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    • in reply to: 3.0 USB port has issues #2470513

      There are 2 things about USB3.0 and USB3.1 ports (female connectors), especially for older products: 1. Weak copper blade contacts, 2. RF noise created from the much faster USB3.0/3.1 clock, at the open mouth of the port.

      1. Weak copper blade contacts. This is especially true for old products. USB3.x has extra contacts than USB2.0. For compatibility, added contacts are leaner and weaker than the USB2.0 contacts. The blade contact could be easily push in folded inside the port. Depending on luck, on each insertion, the male contact blades may or may not make contacts to the female port’s damaged contact(s).
      The curse is when USB2.0 male is push into USB3.x female. This damaged is most frequent.
      Solution for problem 1.: Use a USB3.x hub. Plug everything into the hub instead. The 3.x-to 3.x mating is much better and prone to damaging the contacts. Highly recommend plug in a USB3.x hub instead. Then everything is to the hub.

      2. RF noise. The USB3.x port, though metal wrapped, still has a big opening. RF noise spills out. This is particularly bad for wireless system when the receiver is plugged into the USB3.x port. Some wireless mouses would work erratically when its receiver is directly plugged into a USB3.x port.

      3. Try, as few times as possible, plugging USB2.0 male into female USB3.x port. Best is USB2.0 to a USB2.0. USB2.0 hub is cheap nowadays. Use a USB3.x hub to your laptop/PC, then connect the USB2.0 hub to the USB3.x hub. In short, USB2.0 to USB2.0, and USB3.x to USB3.x. The reason: Though ‘backward compatible’, USB 3.x extra but weaker copper blade contacts are easily damaged by USB2.0 insertion.

      4. Recent new products do have better quality and tighter dimensional control of the USB3.x connectors. So newer products USB3.x ports are less prone to the damage by frequent insertion of USB2.0 connectors. But still, try to avoid USB2.0 male to USB3.x female.
      Recommend use a USB3.x hub. It protects physically and electronically. In case there are problems, accidents, it is the hub that is the sacrificial lamb.

      5. USB2.0 cable and power problem: USB2.0 can only supply about 500mA per port (but it is a loose specification; can be 600mA, 650mA, but no more than 700mA in real world practice). Also, cable too long and its wire resistance may lower the Voltage at the cable’s other end. USB requires that the Voltage be 5V+/-0.25V, or 4.75V to 5.25V in all cases (except when charging, which could be as low as 4.2V). Some devices do not care about the 5-V tolerance, as CMOS logic are very tolerant. Some products do mine very much. Apple product is famous that it actually measures the 5-V. If it fails the +/-0.25 tolerance, Apple product will issue a error warning and refuse to work.
      Some USB2.0 device draws very near the max (500mA) USB2.0 current. A long USB2.0 cable will have too much induced Voltage drop, causing failures. A short USB2.0 cable helps. BTW, it is more reason to use a USB2.0 hub with its own power supply adapter. Amazingly, less ‘qualified/quality’ USB2.0 hub can supply as much Amp. as the device needs, not upholding the 500mA limit. This is particularly important for portable USB-power-only mechanical hard drive. And older USB2.0 portable mechanical hard drive is very sensitive to this. Some of the old portable mechanical hard drives draws 600mA or more. Direct connect to a PC (which enforces the 500mA limit) will always fail these old portable mechanical hdd.

      Luckily, USB3.x solves this Amp. problem. USB3.x allows 0.9A max. USB-C goes one step further. Voltage is programmable, from 5V, to 8V, to 12V, to >20V, up to 100W! The USB power issue is now completely resolved! But then be very careful using USB-C port. It can be 100W! And it can be any thing  5V, 12V, 20V! Could burn down a house or damage a product.

    • in reply to: Can not connect AOL email account to Mozilla Thunderbitd. #2423139

      This maybe a late reply. I hope it’ll be saved as a reference when people have the same problem with AOL mail (as of 2021-2022), when accessing by a 3rd party mail handler/client, such as Thunderbird.

      I had it working on my Thunderbird, Version 91.5.1, 64-bit, on Windows 10.
      Here is how (make the change manually on Thunderbird):
      (1) go to menu-Tools-Account Settings
      (2) On the left column, click ‘Server Settings’ of the email of concern
      (3) On the right, on POP3, or POP, Server,
      enter “pop.aol.com’. Port is 995 (default is 995)
      (4) For User Name, enter the full email address, such as xyzabc@verizon.net
      (5) Under Security Settings, Connection Security is ‘SSL/TSL”
      (6) For Authentication Method, choose “OAuth2”   [this is the trick]

      Now try to access AOL email.
      When asked, enter your most recent password. If it reports back ‘wrong password’, enter your LAST OLD password.
      AOL, when changing security to using OAuth2, for some reason, retains only your last old password, and the most recent password is discarded. At least, this was for me. I had to enter the old password to get it to work. Of course, after that you can later change your password if you’d like to.

      On the SMTP setup (for sending out email via AOL),
      The SMTP server name is smtp.aol.com. Port is 465 (default is 465).
      The ‘User Name,’ again, requires to enter the full email address. You cannot enter only the front part of the email address before the ‘@’. You must enter the entire email address, such as ‘xyzabc@verizon.net’.


    • in reply to: Router Range in 2021 #2381497

      The longer the antenna the farther it can transmit

      No true.
      Physical length does not equal electrical length or gain.
      Buying a higher gain antenna might work, depending on the building.
      Note: a new router / extender may be cheaper than a high gain antenna.

      cheers, Paul

      I believe I’m correct,
      within the context of wifi router antenna.
      I am using consumer way of saying it, to help consumer looking for wifi antennae.

      In antenna theory, the physical appearance and size of the antenna are very much related to it’s receiving and emitting radio energy/power.
      When PaulT says ‘high gain’ antenna generally, it is also a way for consumer to differentiate products.
      What is exactly ‘high gain’?
      Does it have a built-in radio frequency amplifier? You can identify this type. They come with/require AC power supply adapter.
      A more complex question is:
      Is the amplifier an approx. flat frequency response, or is it tuned to certain range of frequencies, or is it AI auto tuned?…
      Forget that! Too complex.
      How about just differentiate whether the antenna has an amp. or not? With built-in amp. it always requires external power supply. That, is easy for consumer to identify.

      What about passive antennae, which do not have built-in amplifier?
      Here, THE ‘high’ gain PASSIVE antenna also has TWO meanings:
      1. Directional. In order to increase ‘gain’, aka receiving more or transmitting more power, needs to focus into a narrower beam. Higher sensitivity but loses coverage area.
      2. The physical size of the antenna, where the receiving/transmission elements have appropriate length (aka tuned to the RF wavelength); may also either stack 2 or 3 element(s) or something, thus it is still longer physically.

      In the market, you can see 3dBi, 6dBi, 9dBi PASSIVE antennae. Invariably the 9dBi antenna is the longest. Usually marketing people call 9dBi (sometimes 6dBi too) ‘high’ gain antenna.
      When you want ‘high gain’ –passive– antenna, it actually means LONGER antenna.

      So let’s skip the actively powered antenna (those with built-in amplifier).
      We now only talk about passive antenna, and how to increase ‘gain’ even though it has no amplifier.

      How can passive antenna have more gain, if not directional at all?
      It first has to do with tuning. To receive/transmit RF power, the antenna element physical length must be a multiple of the RF wavelength.
      One full wave length:
      100MHz FM is 3m (9.8ft)
      VHF is 1m to 10m (3.3 ft to 33ft[!!!])
      UHF is 10cm to 1m (3.9 inches to 3.3ft)
      2.4GHz is about 125mm (4.9 inches)

      To tune for maximum power, best is the antenna length equals full wavelength. Rather pessimistic! The antenna is so long!
      Luckily we can still tune and receiving power when tuned to 1/2 wavelength. Even better, even 1/4 wavelength can do it too.
      The problem?
      Less and less sensitivity!

      Another way is to make the antenna ‘looks’ longer in electrical circuit point of view. This, we use coil. The coil ‘elongates’ the physical antenna ‘length’ to matching the electrically ‘seen’ length.

      For those has been in the army, you will see antennae with top loaded, mid-loaded, and bottom loaded coils. The antenna tip loaded coil has the best efficiency (but top heavy). The bottom loaded approach has least added effective gain. But we usually use the bottom loaded coil system, as a compromise, because the ‘coil’ can be doubled as a spring for the antenna.

      For a typical wifi 9dBi consumer antenna, they use 1/4 wave dipole as the antenna element. Then stack another 1/4-wave di-pole to double the gain. Naturally two 1/4-wave di-poles are twice as long as a single di-pole antenna.

      For a view of how a 5dBi/9dBi passive antenna looks like, go here:

      1 user thanked author for this post.
    • in reply to: Router Range in 2021 #2379615

      Re increasing wifi reach distance.

      The cheapest way is to buy a wifi router with removable/replaceable antennae. The longer the antenna the farther it can transmit. So buy replacement antennae as long as possible. However, avoid the replacement antenna with cable to the router antenna connector. The replacement antenna must be directly connected to the router’s antenna connector. With cable, you’d lose at least 3 dB of signal strength. This is a big loss by the cable itself.

      Antenna power output strength is technically hard to explain, you may research to gain more understanding.

      Another option is to buy self powered antenna with its own amplified power, to increase transmission reach. However, this kind of antenna is expensive (as much as 1/2 value of a wifi router). Might as well invest in a more capable wifi router with more antennae itself. (The more antennae, in general, can reach farther distance, by using various techniques.)

    • Audio crackling speaker sound maybe from many areas.
      Troubleshoot, easiest 1st:

      1.  Maybe the source is noisy itself (such as the amp itself). Try wholesale replace entirely the electronic source to the speaker. Or drive the speaker entirely from another source and amp.
      2.  Earphone, or other connector, has contact problem. Test: Do not wiggle, just twist the connector barrel circularly back and forth. If sound gets better, or worse (especially high frequency sound) it is contact problem. Clean or replace connectors with… gold plated connectors; real metal, not just the color. Gold is only second best. Real silver plated is best. Copper (real metal type, not the color that looks it) is good. Thick chrome plated is good. Thinly plated Chrome type worst. Earphone type connector is worst.
      3.  Wiggle the wire/cable of the connector, (not the connector itself), while holding steady and tight of the connector. If crackling sound ‘follows’ the wiggling, the wire to the connector is loose. Re-solder the wire to the connector, or re-tighten (some use screws). Better, replace with new cable/wire.
      4.  Get another speaker and connect (just one channel, left or right channel, would do). If crackling sound goes away on the replaced speaker, the original speaker itself is damaged. Replace speaker.
      5. Volume turns too loud. Either the amplifier is over driven, or the speaker is over driven. Test: turn down the volume.
      6. Amplifier goes bad: unstable/conditional-stable amp causes this crackling sound non-stop, not an occasional thing. [Amps are always in stable negative feedback mode (even switch-mode audio system such as class D or class T. Even not their pre-amplifier is still a feedback system by itself). When components, especially capacitors go bad, there is not enough phase margin for stability, causing instability, thus the crackling noise.]
      7. Power supply to the amp is going bad, generating excessive noise, especially those switch-mode power supplies. If the sound source is from another device, sometimes, its bad power supply may generate enough noise that propagates to the amp output. Crackling noise is not hum noise leaked to amp. It is sharp spike pulsive noise, which is from electronic circuit going bad (or the going-bad components causing it).
      8. If the source is from a laptop or a PC, it could be noise from it. Capacitors inside it go bad, unable to filter out the spiky digital noise that can now propagate to the audio circuitry.
      1 user thanked author for this post.
    • in reply to: Does it exist? #2364607

      The best way is to use a USB hub. USB is not designed to be in Y connection, just like Ethernet wiring.

      However, rules are made to be broken!

      If you know enough you might be able to make it work, though it might limp along. But mouse, keyboard are slow devices, even USB1 works well for mice and keyboards, with speed to spare. So the Y thing might work. But you need to know how to solder, and some knowledge of USB2.0.
      USB2.0 uses differential signal in Voltage (+side – -side = 402mVdc), using constant current drive (aka current mode, at constant 18.77mA, no bigger or smaller). Uses twisted pair (again, like Ethernet). The impedance is 90 Ohms (Ethernet is 100 Ohms, ‘close enough’!). Impedance is not resistance (a DC point of view). Impedance is frequency domain. At zero frequency (DC) the terminal is still made to be 90 Ohms. That is, each wire to ground is a 45-Ohm resistor. From +D wire to -D wire will then be 45+45=90 Ohms, the twisted wire native impedance!
      Connect two +D (and two -D) wire together (for Y connection), you’d half the terminal impedance (and 1/2 the DC resistance too!). Well, if you put a 45-Ohm resistor in series with EACH data wire (on EACH branch of the Y cable) you lower the parallel connection mismatch impact. Noise and IL (insertion loss) are high. But for slow devices like mouse, it might work!
      Soldering is a must. If use SMD (surface mount device) resistor, the tiny thing can fit inside a USB connector.
      Commercially, though, you cannot sell a truly Y-connected USB cable. It violates USB standard and might cause damage (highly unlikely because USB2.0 is current mode, only 17.88mA max).  But legal department is the more scary part. Same reason you don’t sell Ethernet Y-cable or Y-connector (hint: there IS one on the market!). But look, telephone cable (600-Ohm impedance twisted pair) do have sale of Y-cable and it works. Why? Slow speed; can tolerate large signal loss.

    • in reply to: Risks of using a VPN #1594118

      Today, online secure access should not use http, instead, use https (secured and scrambled transmission).
      Using a VPN further scrambles the already scrambled.

      In that, your security is protected from VPN owner snooping, if … they are snooping.
      For file transfer via VPN, you can also scramble (encrypt) the file first, or secure zipped first, in case you do not trust your VPN.

      You must trust someone eventually. Only a lone wolf needs no trust.

      Most financial institutions detect your location when online. Deny access if from foreign country.

      Say, travel away from USA and you may be denied access. Or may require all kinds of verification. Your home cell phone may not work either in a foreign country, to receiving temporary pass code.

      Using VPN, say, select a VPN server located at home city/location, the bank will assume you are still local at home area. Then online access would post no problem. It is important to check credit card status while traveling.
      Option is to use remote access to your home PC. It is slow, as remote access must pass back-and-forth massive video data (display). If you do not trust VPN, how about your home PC is powered on 24-7 unattended, and all those massive transmission in the public lane?

      Another VPN use is to prevent your Internet Provider tracking you, collecting data on you, snooping on you. A partial solution is not to use your Provider’s DNS servers, instead use public open DNS servers (e.g. OpenDNS). VPN is still more private and secure.

      Depending on how you use VPN service, you may want one having many servers, in all the places you travel/surf. Or you want one providing fast servers.
      Some VPN providers have low hardware resource. Their servers are overloaded. The delay maybe unbearable for video streaming or even surfing.
      You can check delay by pinging the VPN server you want access, and see the delay (usually in 100’s ms. I have seen seconds!). Some VPN services provide app/software listing their server delays. Some VPN can be used by both Android cell phone and Windows, even TV set-top box. Some only for Windows, etc.

      Be aware though, some server delays seem OK but it has too many accesses (many users on it). You are as if in a crowded highway. Though fast and low delay, at some point you will hit congestion and a large temporary delay/hiccup. And it maybe right at the key time of a movie or sport event!

      I suggest use VPN trial period. Be aware, though, my experience is that some VPN services assign high priority to trial accounts. Or, pay for a short term period. Sometimes, time of the day, etc. affects specific VPN service. It is worth a little more expensive to know the service well.

    • in reply to: Power-over-Ethernet problem #1578410

      Typically, wire pair (1,2), two wires together, is for power positive, wire pair (3,6) is for negative.
      Sometimes it is reversed: (1,2) negative; (3,6) positive.
      A DVM will tell.
      I hope the load devices, one is not polarity-reversely connected. If it does, it shorts the POE.

    • in reply to: Power-over-Ethernet problem #1578409

      I forgot:
      Check one more obvious thing before the in depth measurement.
      If there are more than 1 device load, unplug one device/load at a time. If POE suddenly works, one of the devices is overloading the POE.
      If it happens that one extra load is newly added, then it is one too many loads for the POE. May have to get a more powerful POE injector. Or, POE max power spec is reached.

      About the POE-Tester, £35, is just that: a Voltmeter + Ammeter + nice plugs/connectors.

      I would buy two. £70, ouch!
      One to monitor the Injector power source side, the other at the load side.
      The Voltage drop (Vsource-Vload) is right there to see.
      Current should not exceed 600mA on the network wires.
      Mentally calculate (Vs-Vload)/I=R of the wire pair. R should not exceed 20Ω.

      I don’t know where the tester measures the Voltage+current.
      If it is right at the network wire (high Voltage, about 48V typical), then it is good.

      If it only measures right at the power output, and at the load directly, it is partially useful.

      As mentioned, the POE high Voltage is stepped down then applies this low Voltage to the load. So, if measured directly at the load, it is only measuring the already stepped down Voltage. This is the output of a step-down Voltage converter unit. One extra device in between.

      The measurement should be the [high] Voltage and current at the network wires, not directly at the source, nor directly at the load.
      (Obviously my aim is wire connectivity check. Any DVM will be good on Voltage monitor.)

      The single big problem using this POE-Tester is that all 4 wires (2 pairs) are tested, all together. (The current is carried by all 4 wires, the two pairs.)
      If you found wire resistance/connectivity problem, you still have to further identify the problem pair, or the 1 of 4 wires.

      POE will have new standard spec. At present only 2 pairs of wires are allowed POE.
      New spec will allow all 4 pairs, and the network wire handling current will be 1A max.

    • in reply to: Power-over-Ethernet problem #1578325

      Suggestion: Check resistance of wires and POE power output at the plug. The plug is also a suspect.

      Start at the POE power injection point (A), to the losing power connector point (B). The wire resistance between the two points, A and B. POE spec says 20 Ω max.

      If high resistance, say, 10Ω and up (each wire from point A to point B), may have wire problem, or wire termination problem (poor punch or poor/old rack contacts, or nearly broken wire at the punch).

      But do the obvious first:
      1. Use DVM to measure POE power injector no load Voltage, typically 48V at the network wire, ranging 35V-57V. Load the POE at the end of network cable as in usual application. Measure Voltage at POE at the wire again. If it drops significantly, it is the POE power brick losing efficiency, going bad.
      2. Sometimes, it is the connector at the POE side that is loose or having intermittent contact. Wiggle the POE injector connector(s) to check.
      3. Finally:
      Use an Ohmmeter (of a DVM), first measure a roughly same length good cable (shorted at one end), to get some ideas of the wire resistance. (Or calculate it). Then, without POE power connected, short one end of the problem cable, measure Ω on the other side of the net work cable. This measures TWO wires of the cable at the same time. If you have a very long thick copper wire to use, you can use it to measure resistance of a single wire of the network cable.

      As for Internet access and networking, you may have slow down, or packet collisions, but network signal may still be good enough for a poor contact or bad wire.

      An easier way is measure the termination impedance of the cable (“AC” impedance, not DC Ω). A poor contact/bad wire changes the impedance characteristics.
      For power delivery, it may be a problem with a loosy contact or bad high-resistance wire (10 Ohms or higher), as follows:
      W=VxI. Example:
      For 5V, delivering 1A = 5W.
      If the wire resistance is 5Ω, and at 1A delivery, at the wire end it would have no Voltage left:
      5Vsource – (1Ax5Ω) = 0V at the end of wire.

      You can say the wire ‘eats’ all the power.

      That is why POE must boost up Voltage, to typically 48V.
      Same 5-Ohm wire, and 1A delivery, the Voltage at the wire end will be
      Still lots of Voltage for the load, even after going through the resistive wire.
      Then we’ll step down the POE high Voltage to 5V, for normal 5V load, such as USB, etc.
      This is not unlike high tension wire for AC power-line that uses kV to 10s of kV for long distance power delivery.

      Needless to say, ideally you want zero-DC-Ω wiring. POE spec is 20Ω max.

      May need ‘self-made tools’:
      1. Two network patch cables, one end cut; wire-end insulation stripped (for measurement).
      2. Two Y-adapters so that you can plug the above ‘cable(s)’ in, enabling Voltage measurement.
      some alligator-clip jumper wires.

      My way?
      1. Jury-rig a 100mA LED circuit (just add R) with 2 alligator clips.
      2. A USB cable, the two 5V/0V wires to alligator clips.
      How to use?
      Need the above two patch cables with open-end stripped-wires.
      1. Make sure no POE and network devices connected.
      2. The rigged USB cable connects to a USB charger (5V,1A).
      3. Alligator clips the USB 5V/0V to the network wire pair under-test
      4. The wire pair is now powered by 5V.
      5. Alligator clip the LED to wire pair under-test (note polarity). Reversed? No harm. LED can take it.
      6. The LED should light up normally.
      7. No light = open wire / open contact
      8. Dim light = contact problem

    • May I add, or a question (puzzlement) myself:
      In Firefox, is Favorite Toolbar = Bookmarks Toolbar?

      Slightly different subject but related:
      BTW, I turn off (not display) all toolbars (hence my question above).
      I need as much space vertically. Most displays are wide enough but not tall enough.
      Now ANOTHER question:
      Is there vertical screen display, rather than wide screen?
      I’d like to read like a book (say, 8.5 inches by 11 inches equivalent).
      Besides, web page is usually long too, not wide. Worse, some sites just have blank spaces left and right of there material page.

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