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Donkey Learning IT
Austria
Registrace 18. 01. 2016
-Linux LPIC (Linux Professional Institute) certifications
-Cisco® network certifications (CCENT, CCNA, Security, Voice, CCNP)
-Labs for certification tracks, both real hardware, Linux server and GNS3
-Teardown, repair and detailed analysis of IT equipment
-Applied electronics and Microcontrollers
-Raspberry Pi and Banana Pi
-Linux servers and KVM based virtualization
-Arcade and Pinball machines (yes, all Donkeys need fun too ;)
Welcome to Donkey Learning IT channel!
I am Donkey, a Linux/network technician who is really enthusiastic about IT.
Considering how quickly IT changes, I think that no matter how long people are
in this business, in many areas they still remain a donkey who needs to learn new tricks.
Hence, there is room for improvements for all of us, especially for me, the Donkey!
I have created this CZcams channel to share with you my passion, experience on
IT certifications and getting a job in IT.
-Cisco® network certifications (CCENT, CCNA, Security, Voice, CCNP)
-Labs for certification tracks, both real hardware, Linux server and GNS3
-Teardown, repair and detailed analysis of IT equipment
-Applied electronics and Microcontrollers
-Raspberry Pi and Banana Pi
-Linux servers and KVM based virtualization
-Arcade and Pinball machines (yes, all Donkeys need fun too ;)
Welcome to Donkey Learning IT channel!
I am Donkey, a Linux/network technician who is really enthusiastic about IT.
Considering how quickly IT changes, I think that no matter how long people are
in this business, in many areas they still remain a donkey who needs to learn new tricks.
Hence, there is room for improvements for all of us, especially for me, the Donkey!
I have created this CZcams channel to share with you my passion, experience on
IT certifications and getting a job in IT.
Raptoreum profit: Intel Xeon E5 vs AMD Ryzen 9 3900: too late for the party
FIY: My content is also available now on Odysee.com:
odysee.com/$/invite/@DonkeyLearningIT:9
Raptoreum is a new CPU-mineable crypto currency, which is really promising.
The price of Raptoreum (RTM) is relatively high, causing an overheated race for CPU mining rigs.
Right now the most profitable way to mine Raptoreum is by getting AMD Ryzen 9 3900X systems.
However, is it really worth it now to still invest into mining hardware after a massive difficulty increase due to many people jumping on this?
Conclusions based on personal mining rigs:
- the Intel Xeon E5 series single or dual-socket (whether v0, v2 or v3 is irrelevant) Xeons are not even breaking even when it comes to the cost of electricity. I got a dual socket Xeon E5-2630v2 and a dual socket E5-2670v0, but they are practically useless. The old AMD FX8350 is even worse.
- it is only worth to mine it on AMD Ryzen 9 systems, however, the ROI is now over 300 days
- mining hardware is way too expensive, long term profitability is unclear
- those who took a risk early on made a good profit, but the hashrate has increased
way too steep
- best strategy is most likely to only mine this coin if you already own a Ryzen 9 system
odysee.com/$/invite/@DonkeyLearningIT:9
Raptoreum is a new CPU-mineable crypto currency, which is really promising.
The price of Raptoreum (RTM) is relatively high, causing an overheated race for CPU mining rigs.
Right now the most profitable way to mine Raptoreum is by getting AMD Ryzen 9 3900X systems.
However, is it really worth it now to still invest into mining hardware after a massive difficulty increase due to many people jumping on this?
Conclusions based on personal mining rigs:
- the Intel Xeon E5 series single or dual-socket (whether v0, v2 or v3 is irrelevant) Xeons are not even breaking even when it comes to the cost of electricity. I got a dual socket Xeon E5-2630v2 and a dual socket E5-2670v0, but they are practically useless. The old AMD FX8350 is even worse.
- it is only worth to mine it on AMD Ryzen 9 systems, however, the ROI is now over 300 days
- mining hardware is way too expensive, long term profitability is unclear
- those who took a risk early on made a good profit, but the hashrate has increased
way too steep
- best strategy is most likely to only mine this coin if you already own a Ryzen 9 system
zhlédnutí: 4 037
Video
SMPS repair series #11: Basics of Feedback Loop and Control Theory in power supplies
zhlédnutí 45KPřed 5 lety
A basic introduction is given for loop control theory from the perspective of a power supply. Namely, negative feedback loops as control loops are being used in almost every linear and switch mode power supply in order to stabilize the output. The major concepts like input, output, controlling element, controller, desired output value and error and feedback are presented in a simple fashion. As...
SMPS repair series #10: Temperature compensated Zener diode in linear regulators
zhlédnutí 36KPřed 5 lety
We will cover the topic of the positive thermal coefficient of Zener diodes and the negative thermal coefficient of standard forward biased Silicon diodes. Namely, when Zener diodes with Zener voltages above 6V are being heated up with one Centigrade, their Zener voltage will increase with about 3mV. In contrast to this behavior, when we heat up a Silicon diode with one Centigrade, its forward ...
460W Switch Mode PSU teardown, detailed overview and repair: Cisco 3550 PWR PoE
zhlédnutí 64KPřed 5 lety
Teardown and repair of a 460W switch mode power supply (SMPS) from a 24-port Cisco 3550 PWR Ethernet switch with PoE functionality. The SMPS is providing -48V DC for the PoE controller, and also 12V DC for the switch motherboard. Throughout the video a detailed overview is given, together with explanation of what is the functionality of the components, and how does the circuit operates. The 355...
Article 13: Should I turn on YouTube monetization? Your opinion matters
zhlédnutí 3KPřed 5 lety
Long story short: in order to try to keep my channel online after the 22 of January due to EU law called Article 13, I am afraid that I will have to monetize the channel, even if it means losing some money on the deal. According to SocialBlade.com, my channel will only make around 70 Euros per year, and it will cost me over 600 Euro to try to keep the channel alive (not including my time and ef...
IKEA Ledare 1800lm 22W LED lamp: Teardown and overview
zhlédnutí 4,3KPřed 5 lety
I own four Ledare 1800lm LED lamps from IKEA. These are 220-240V 22W version. The lamps are really bright, and they were available for a reasonable price. However, after 16 months two of the four LED lamps have failed. This high power LED lamps are no longer being sold at my local IKEA shop. Since my lease is expiring next month, I was thinking whether one could eventually repair the lamps, or ...
AC voltage Part 2: root-mean-square (RMS) value explained in Python
zhlédnutí 10KPřed 5 lety
In the second video of the AC power series the basic mathematics behind calculating the root-mean-squared (RMS) value is being explained step-by-step. Furthermore, the process is also shown in form of a Python 3 code run inside a Jupyter notebook. First we describe the general formula for a sinusoidal function, and this is being implemented for 230V AC voltage, having a value of the peak amplit...
AC vs DC voltage Part 1: RMS Equivalent heating value explained
zhlédnutí 9KPřed 5 lety
This is the first video of a three part series, where the root-mean-square (RMS) average value of the AC voltage is explained and compared to DC voltage. When it comes to the 110V AC or 230V AC line voltage, people have the tendency to think that from the wall socket they receive a fixed 110V or 230V voltage. In contrast to this popular believe, the line voltage fluctuates between 0V and a peak...
SMPS repair series #9: Zener diode and power transistor without feedback loop
zhlédnutí 41KPřed 5 lety
Today we will look into the behavior or a basic linear regulator circuit based first of a Zener diode, after which we extend the circuit with a power transistor. The goal is to understand how do these devices behave in a simple configuration, and how are they used in practice. For this, we will build simple circuits on a prototyping board. Also, we will look at the regulated output voltage as a...
Electron flow vs. Conventional current: Thompson's cathode ray experiment
zhlédnutí 7KPřed 5 lety
Today we will discuss the difference between these two concepts. The direction of the conventional current has been established in the beginning of the 18-th century, where scientists assumed that some positively charged atoms are flowing from the positive terminal of a power source towards the negative terminal. Since this direction was based on an old convention still used in physics and elec...
Switch mode power supply repair #8: Pulse Width Modulation explained (PWM)
zhlédnutí 55KPřed 5 lety
In this video we talk about pulse width modulation (PWM), which is a basic technique used in many electronic circuits like LED drivers, servo and motor controllers, switch mode power supplies, etc. PWM is used to regulate the amount of power flowing through the circuit, but without the disadvantages of linear regulators, where a large fraction of the power is being dissipated as heat. The wavef...
Switch mode power supply repair #7: Basics of Pulse Width Modulation (PWM)
zhlédnutí 74KPřed 6 lety
In the seventh video in the Switch Mode Power Supply (SMPS) repair series we introduce the basic concept of power pulsing. Through power pulsing we use a switching element instead of a series resistive element to limit and regulate the average value of the power flowing through the circuit. This is shown through a simple experiment using a push switch and an incandescent lamp. In contrast to li...
Howto repair switch mode power supplies #6: Basics of Linear Regulators and voltage references
zhlédnutí 174KPřed 7 lety
In the sixt video of the Switch Mode Power Supply (SMPS) repair series we look at the basic ideas and priciples of operation of linear serial regulators. Serial regulators are used in every power circuit in order to generate stable supply voltages. Even in SMPS we will rely on linear regulator circuits to get stable voltages in order to feed integrated circuits like the APFC controller, the Pul...
Howto repair switch mode power supplies #5: Magnetic core materials, ferrite vs steel
zhlédnutí 138KPřed 7 lety
In the fifth video in the Switch Mode Power Supply (SMPS) repair series we continue with a bit more background in the magnetic core materials. In this episode we focus on the fact of why in the case of SMPS one need to use high frequency switching circuits paired with ferrite core material. Furthermore, the ferrites are directly compared to the traditional humming transformers with iron cores c...
Howto repair switch mode power supplies #4: Inductor in electronic circuits P2
zhlédnutí 151KPřed 7 lety
This is the follow-up video on the Switch Mode Power Supply repair series, where we continue on the t opic of inductors in a circuit. Here we look at electromagnetic induction, magnetic saturation of the inductor core, and we describe the full energy transformation cycle for an inductor, which is a simi lar picture compared to a simple mechanical spring. For comparison, in the mechanical spring...
Howto repair switch mode power supplies #3: Inductor in electronic circuits P1
zhlédnutí 226KPřed 7 lety
Howto repair switch mode power supplies #3: Inductor in electronic circuits P1
Repair Cisco ASA5505 firewall not powering on: video reply to subscriber question
zhlédnutí 12KPřed 7 lety
Repair Cisco ASA5505 firewall not powering on: video reply to subscriber question
Howto repair switch mode power supplies #2: Stand-by circuit and its functionality
zhlédnutí 268KPřed 7 lety
Howto repair switch mode power supplies #2: Stand-by circuit and its functionality
Howto repair switch mode power supplies #1: basics, and block diagram of a PSU
zhlédnutí 935KPřed 7 lety
Howto repair switch mode power supplies #1: basics, and block diagram of a PSU
RAID arrays: RAID0 striping, mean time between failure, tracks, sectors, onsite and offsite backup
zhlédnutí 1,3KPřed 7 lety
RAID arrays: RAID0 striping, mean time between failure, tracks, sectors, onsite and offsite backup
KVM hypervisor install on virtualization server: BIOS, VT-x, VT-d, Debian bootable USB
zhlédnutí 10KPřed 7 lety
KVM hypervisor install on virtualization server: BIOS, VT-x, VT-d, Debian bootable USB
Type 1 bare metal vs Type 2 hosted hypervisors, and the VT-x extension: Basics of virtualization
zhlédnutí 18KPřed 7 lety
Type 1 bare metal vs Type 2 hosted hypervisors, and the VT-x extension: Basics of virtualization
Setting up APC7920 PDU power distribution unit: IP address, web management HTTP, HTTPS, SSL, SSH
zhlédnutí 50KPřed 7 lety
Setting up APC7920 PDU power distribution unit: IP address, web management HTTP, HTTPS, SSL, SSH
Building an IKEA table-rack mounted lab for virtualization, CCNA-CCNP studies, and ZFS
zhlédnutí 24KPřed 7 lety
Building an IKEA table-rack mounted lab for virtualization, CCNA-CCNP studies, and ZFS
Cheap home lab build: virtualization server, GNS3 for CCNA-CCNP rack, and ZFS
zhlédnutí 25KPřed 7 lety
Cheap home lab build: virtualization server, GNS3 for CCNA-CCNP rack, and ZFS
Building an IKEA Lack Rack on wheels for Cisco CCNA and virtualization home lab
zhlédnutí 40KPřed 7 lety
Building an IKEA Lack Rack on wheels for Cisco CCNA and virtualization home lab
Introduction to RAID arrays, basic concepts, sequential vs. random I/O, mechanical vs. SSD drives
zhlédnutí 1,6KPřed 7 lety
Introduction to RAID arrays, basic concepts, sequential vs. random I/O, mechanical vs. SSD drives
Repair of a Cisco 2960G switch with amber LED via RAM chip replacement (FAIL/defect)
zhlédnutí 33KPřed 7 lety
Repair of a Cisco 2960G switch with amber LED via RAM chip replacement (FAIL/defect)
How to reflow a GPU from start to finish #2 reflow process and testing the repaired card
zhlédnutí 43KPřed 7 lety
How to reflow a GPU from start to finish #2 reflow process and testing the repaired card
How to reflow a GPU from start to finish #1 preparing the card for BGA reflow
zhlédnutí 28KPřed 7 lety
How to reflow a GPU from start to finish #1 preparing the card for BGA reflow
REPETITION is a very good way of learning/teaching! no one should tell you how to approach the Subject you are doing an excellent Job
Great Job keep up the good work
Bravo!!!! finally some one is really teaching/sharing information if you subscribed you will not regret it
This came up on my recommended channel list (on 2024) and I have to say that this is the absolute best explanation of how these circuits work, thank you so much for uploading this, it has given me a lot of confidence in moving forward to trying to repair these power supplies. Thank you 😎👍
thank you for great training materials. I had failed cisco asa 5606x, can cannot find nay backup of configured file 😞where is the config file or start-up file is saved? how can I recover the config file from old failed connected device. thanks
I like it
I was looking for your video for 3 weeks)😊
Please continue with this series, we are all hanging on the lurch like Homer off a cliff.
I do not think that the spring is a good analogy to an inductor. The sping would be a good analogy to a capacitor, because we fill it with potential elastic energy, just like a capacitor is filled with potential energy stored in an electric field. The good analogy to an inductor would be a flywheel, beacuse a flywheel is filled with kinetic energy of circular motion. Just like an inductor is filled with kinetic energy of the current stored as a magnetic field. Rest of the video is great though.
Absolutely wonderful videos! Thank you for sharing your knowledge!
Excellent Videos! WOW.
I would personally stick to Be quiet! because Corsair power supplies are known to sometimes blow up for no reason, while I have never seen a Be quiet! power supply blow up. I personaly stick to Cooler Master, Delta, FSP and Seasonic, whatever is avilible. Theese are really good units from my expirience.
I got significantly lost here 9:48
Will you ever be back Dr Donkey?😢
I bought a Nox Urano II 630w atx power supply, but it never turns off, with the fan always running without being connected to any motherboard, I think the green Power On wire is short circuited with the black wires? How can I solve this problem ?
And more importantly for many--HOW he teaches it. Personally speaking, Donkey has suceeded where professors, instruction and textbooks have failed. For that, I'm especially grateful🥺😁🤗😎🤙🤙🤙 Much respect and gratitude from the Aloha State. Keep doing good things brotha, gems like your channel are appreciated more than you know🤙
Excellent Explanation 💯
Very nice thanks dear..❤
Nálunk a mérnökök simán PÁRHUZAMOSAN KAPCSOLNAK AKÁR NÉGY TVS DIÓDÁT IS (SM6Txxx; SM15Txxx, ...) , ha nagyteljesítményű zener kell, szóval... :-)
Hi have You ever figured out the fault ? I have the same problem now …
OIC, from the bottom of my heart thanks for what you did for all of us, take good care of you self. I'm not in a position to contribute sorry.
Dear Dr. Donkey, I enjoyed you SMPS video's 1 ... 11 so much, refreshing my knowlegde/skills I used 50 -57 years ago when I was working in medical electronic industry. Looking forward for the error amlifier feedback video and of course all other video's to follow. By the way you are my hero because of how you teach and the depth of teaching. Best regards, from a Ducth donkey who has hit the electronic stonen more then often but don't wanna give up to improve my skills. Bought a handheld osciloscope and a diode/transistor/capacitor etc. tester is on the way to work on SMPS.
please be precise, short and to the point.
Please continue your series. Hope that you are doing very well. I saw so many videos but looks nobody here to explain like you so simple. Please continue the SMPS series. I wish for your good health.
Thankyou so much for share your knowlledge, I have study electronics in my twenties, and i am very pleased with your way to teach.
where is video number 9? Please
Can I use your videos in my website 😅
This was very insightful and interesting to watch. Thanks for taking the time to make it. I have a similar unit from another manufacturer that I want to try to fix the ammeter on and this has given me a good starting point. One random question - you said those relays were Murata but the label on them says Song Chuan. Are they the same company?
Very well explained, thanks !
adding subtitles helps when viewing the video in a quiet enviroment... . . please include subtitles on all your videos. .. . i am subscribed and like your videos. . .
it was a very informative series fr
where did Donkey go
the ba$tard left us half way at #11............ i really miss him
After 11 episodes, still have no idea how to fix SMPS...when it should take about 3 episodes. First one is the block diagram of a SMPS (with/with out PFC). Second episode is about where to check with multimeter for common voltages...along with it are the explanations why this voltage is good, why not good and the reasons or totally dead and why, what happened. Third one is how to replace components.
need next episode
1. where I can get smps diagram for Cisco 2600 2950 3550 3750
Nice, love the ping trap. Thank you.
What brand of gloves do you wear. Do they provide protection from low voltage electricity?
Best tutorial ever. Very sad to see it stopped here.
Thankyouforexplainingwithsimplewordsandaveryeloquenttalkingthattomeitshouldbethewaypeopleintheenglishspeakingworldshouldtalkfromnowon.
Excellent tutorials! Will be using a lot of this information. Thank you.
I hope someone still reads this in 2024. I have a semi-faulty 2960G: I plug in the switch to AC, the switch starts booting, and the FAN starts normal as well. After a couple of minutes of uptime, the FAN suddenly jumps to 100% speed and blows like crazy. After a couple of minutes, it goes down to acceptable level. Then another couple of minutes it goes up to 100% speed, and rinse and repeat. The CLI show env all reports both TEMP and FAN as OK. The show log does not report anything about TEMP or the FAN. I tried to find any CLI debug command to see TEMP or FAN behavior, but couldnt find anything. The environment is around 18-20 degree celcius, so perfectly normal (I would even say slightly cold) room temp, so the switch should not behave like that. Does it sound like a temp sensor malfunction? If so, why does the report not say TEMP NOT OK or something similar? Has anyone experienced this? Its just a lame home LAN switch, nothing money-generating thing, I bought it used from a server room. The previous owner wasnt aware that it behaves like that, as it was already very loud in the server room, and the initial check before purchase didnt reveal this defect. Any help greatly appricated. I know its youtube, so unlikely anyone will comment anything useful, but better here trying than on the braindead cisco community support forums, god have mercy dealing with the idiots there!
22:21 watts or volts?
The CM version is a horror to disassemble
Please continue the series that was initiated 5 years ago, if possible. There are several videos remaining to be made for diagnosing and fixing a PSU (Power Supply Unit). It would be greatly appreciated if you could condense the existing 11 videos into a single 20-minute video. Thank you very much for sharing.
Great video thank you very informative 🎉
Great video. Appreciated your explanations .
Why do you wear gloves?
Very good.. explain in electronics.. thanks you
❤❤❤ good explaining about how this works
Hi, how about demonstrating the software menu over the serial connection?