Donkey Learning IT
Donkey Learning IT
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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:
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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 electricit...
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Видео

SMPS repair series #11: Basics of Feedback Loop and Control Theory in power supplies
Просмотров 45 тыс.5 лет назад
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
Просмотров 36 тыс.5 лет назад
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
Просмотров 64 тыс.5 лет назад
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
Просмотров 3 тыс.5 лет назад
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
Просмотров 4,3 тыс.5 лет назад
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
Просмотров 10 тыс.5 лет назад
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
Просмотров 9 тыс.5 лет назад
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
Просмотров 41 тыс.5 лет назад
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
Просмотров 7 тыс.5 лет назад
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)
Просмотров 54 тыс.5 лет назад
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)
Просмотров 74 тыс.6 лет назад
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
Просмотров 174 тыс.7 лет назад
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
Просмотров 138 тыс.7 лет назад
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
Просмотров 151 тыс.7 лет назад
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
Просмотров 225 тыс.7 лет назад
Howto repair switch mode power supplies #3: Inductor in electronic circuits P1
Repair Cisco ASA5505 firewall not powering on: video reply to subscriber question
Просмотров 12 тыс.7 лет назад
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
Просмотров 267 тыс.7 лет назад
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
Просмотров 933 тыс.7 лет назад
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
Просмотров 1,3 тыс.7 лет назад
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
Просмотров 10 тыс.7 лет назад
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
Просмотров 18 тыс.7 лет назад
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
Просмотров 50 тыс.7 лет назад
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
Просмотров 24 тыс.7 лет назад
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
Просмотров 24 тыс.7 лет назад
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
Просмотров 39 тыс.7 лет назад
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
Просмотров 1,6 тыс.7 лет назад
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)
Просмотров 33 тыс.7 лет назад
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
Просмотров 43 тыс.7 лет назад
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
Просмотров 28 тыс.7 лет назад
How to reflow a GPU from start to finish #1 preparing the card for BGA reflow