Dilshan R Jayakody’s Web Log

A few months ago, our AMD Ryzen™ 5 computer started giving some startup issues. At first, this problem happened randomly, and then it started happening at every bootup. The symptom is that if the computer shuts down after a boot, it will not start on the next power cycle(s). If we turn it off for 30 or 45 minutes and then turn it on, it will start working without any problems. This problem did not occur on warm restarts. After changing power supply units, we realized that the problem was with the PSU. This suspicious unit is a Corsair VS550 PSU . Corsair VS550 PSU PCB. Based on the symptoms, we thought the problem was with a capacitor on the PSU board. We disassembled the PSU and checked all the electrolytic capacitors, but we could not find any faulty capacitor(s). To further investigate this issue, we connected the PS-ON terminal to the ground ( GND ) and started the PSU. During this test, we see that the PSU is performing well on this condition. As we examine further, we find t...

13.8V power supplies are commonly used in amateur radio experiments. Most of the portable amateur radio transceivers are designed to work with a 13.8V power source. We mainly build this power supply unit to power some of our amateur radio circuits and modules. This design is based on the popular LM338 5A voltage regulator. We choose this regulator because of to it’s higher current rating, short-circuit protection feature and higher availability. The prototype version of 13.8V - 5A power supply unit. Apart from that, we include MC3423 based crowbar sensing circuit to preventing an over-voltage condition of a power supply unit. We design this circuit by using commonly available 18V×2 (5A) + 12V (1A) transformer. This transformer is available in the market because it’s commonly used with some AF power amplifier systems/kits. We use its 12V terminal to drive 120mm - 12V cooling fan.

Couple of months back we decided to create our own media server to store our MP3s and digital photographs. But it gets postpone several months due to unavailability of main-boards and other resources. Finally, after reviewing several prototypes we decided to build our media server using Banana Pi (BPI) and MiniDLNA . Before finalize BPI we checked several main-boards which including Raspberry Pi B+ , Orange Pi One and BeagleBone Black . Out of all above main-boards we choose BPI M1 because of its inbuilt SATA2.0 interface, Gigabit Ethernet port and availability in local market. Final view of DLNA media server setup. As an operating system we use Bananian Linux , which is Debian derivative for BPI platform. To sore all our content, we use Seagate 1TB SATA 3.5 inch hard disk drive. Bananian OS and other packages are loaded into 8GB SD card. To power both BPI and SATA disk drive we design PSU using LM2576-5.0 step-down switching regulator IC. Also during the prototyping sta...

In this post, we introduce simple and flexible, regulated low voltage power supply unit. This power supply has provision for 4 outputs such as 1.5V, 1.8V, 2.5V and 3.3V. We mainly build this low voltage power supply unit to test (and power-up) low voltage MCUs, CPLDs, and radio receivers. For this power supply, we choose 1.8V, 2.5V and 3.3V to get it compatible with most of the LVTTL/LVCMOS devices. Other than that, we include 1.5V because there are several analog ICs are available for that voltage level. This power supply unit is based on LM1117/AMS1117 voltage regulator series and for this design, we use AMS1117-1.5, AMS111-1.8, AMS1117-2.5, and AMS1117-3.3 fixed voltage regulators. Except to above regulators, this board can be used with AMS1117-2.85 and AMS1117-5.0 regulators. Internal view of the low voltage power supply unit. In our prototype, we use center-tapped 6V (1A) step down transformer with this power supply unit. All the wiring diagrams to transformer and rotary...

This is a second article related to Mullard 3-3 Amplifier Project and in this article, we introduce HT transformer and HT power supply related to this amplifier. As mentioned in the previous post, the power supply unit of this tube amplifier is constructed using 400V 5A bridge rectifier, 220µF (400V) and 82µF (400V) electrolytic capacitors. Homebrew HT transformer and PSU The most vital component of this power supply is the HT transformer and due to limited availability, we construct this transformer by ourselves. We construct this transformer to obtain the following voltages and primary winding is design for 230V AC mains lines.

The phantom power supply is widely used in the audio industry to power the active microphones over single audio cable. Most of the phantom power supplies deliver 48V DC over the balanced audio link and power supply unit described in this article is also based on the same technique. The phantom power supply in this article is based on TL783 high voltage regulator IC and 230V - 50V step down transformer. Like most of the phantom power supplies, this power supply is also design to connect in between an active microphone and audio mixer devices. PCB of 48V Phantom power supply. Schematic of this power supply unit is self-explanatory and PCB design is also based on commonly available through-hole components. For the step-down transformer, we use commonly available 230V - 25V-0-25V 1.5A transformer. During the construction, we recommended using shorter wires between PCB and XLR sockets to reduce the noise. PCB and schematic of this power supply unit are available to download at...

This is 5V 3A power supply to drive two USB based devices simultaneously. This power supply is design around LM2576-5.0 switching regulator IC and the main reasons to choose this IC is its low parts count, small heat sink requirements and its inbuilt current limit protection feature. Prototype version of 3A USB power supply We specially design this power supply to work with development boards / single board computer (SBC) platforms such as Raspberry Pi , Banana Pi , BeagleBone , etc. This power supply can also be used to provide power to USB OTG peripherals over USB Y cables. We test this setup and got successful results with Huawei Ascend P6 mobile phone.

This 300V AC/DC variable PSU is designed for our vacuum-tube, MOSFET and some IGBT related experiments. This PSU consist with 0-300V Variac (variable auto-transformer), 700VA isolation transformer, which is described in previous blog post and high voltage AC-DC converter. Because of the size and weight of these equipment’s we build this PSU as three separate units. Complete view of 300V AC/DC variable power supply unit. This PSU is capable to supply 20V - 300V 2.3A (max.) output in either AC or DC form. This PSU use high voltage and because of that, all the proper construction and precautions are necessary to take. Improper wiring or construction may leads to lethal electrical shock and/or fire. If you are not familiar with high-voltage practices do not attempt this project at home. Schematic of this PSU is available to download at google drive .

Now a days 3.3V PSU is essential for microcontroller, programmable logic devices and for some analog components also (especially with some new ADCs). This is ultra-simple 3.3V power supply unit, which is suitable for above mentioned experiments. This power supply is based on, ON semiconductor’s MC33269T-3.3 LDO regulator and it is capable to deliver 3.3V output with maximum of 800mA current. External view of 3.3V Power Supply The PCB design supplied with this article is also compatible with LD1117V33 (also known as LD33V) LDO regulator and it can use with this PCB without any changes. Dimension of the given PCB is 70mm × 35mm and it is design with all through-hole components. Our PCB design for this PSU is available to download at google drive . Maximum input voltage for this module is 20V (DC) for MC33269T-3.3 and 15V (DC) for LD1117V33 (or LD33V). In our unit we use 230V – 9V (1A) step down transformer as AC input for this unit.

Adjustable dual-rail power supply is an essential utility for analog electronic experiments. In this post we illustrate extremely simple, adjustable dual-rail power supply using LM317 and LM337 voltage regulators ICs. This PSU delivers 2A ±1.35V to ±18.5V output and thanks to 3 turn linear potentiometers output can be adjustable up to 2nd decimal point. Wiring diagram of dual-rail PSU The PCB of the PSU is simple to design and compact (65mm × 50mm). Both LM317 and LM337 need at least 60mm × 55mm or larger heat sinks (and both of these heat sinks need to be electrically isolated). The PCB and schematic of this PSU is available to download at here .

This is a quick post regarding my Commodore64 Power Supply restoration. This C64 is my first computer and two days back its power supply get burn because of some short circuit in its output connector. This is a first time I open this C64 PSU and its internal circuitry is really simple to track down. Commodore64 Power Supply Unit Main component of this PSU is its 6 terminal step-down transformer. Other than that its circuit it limited to 2 rectifier diodes, 7805 positive voltage regulator, 2 - 1W resistors and 4700 µF /16V electrolytic capacitor. In my C64 PSU, defective component is 7805 voltage regulator, once I replace it and rewire the output terminal its starts to work again (like good old days). Commodore64 Power Supply Schematic Above diagram illustrate the schematic of my C64 PSU (which I was traced using original PCB). The high resolution images of PSU, are available at my flickr photo collection .

This is a high voltage, low current, offline, AC adjustable power supply for electronic/electrical experiments. This power supply is mainly design for switch mode power supply (SMPS) experiments and to drive basic high voltage electrical circuits. Thanks to the isolated step-up transformer this power supply breaks the ground loop and provides shock free – safer high voltage output. This offline (or isolation) feature preventing accidental current from reaching ground through a person's body. This unit generates 50Hz or 60Hz (selectable at runtime) square wave AC output, and it is capable of generating output voltage between 150V – 290V AC (on no-load state). Prototype version of offline high voltage AC power supply As stated above this power supply unit is mainly design for SMPS experiments. This is not work well with liner power supplies because transformers in linear power supplies are get overheating from square wave inputs generated through this unit. This is a hig...

In this project we design high current, high accuracy single rail variable power supply unit using Micrel’s MIC29152 voltage regulator IC. Thanks to the Micrel’s Super Beta PNP fabrication process this regulator has 80mV to 600mV dropout at the full load. With the given values of R1, R2 and TR1, this unit delivers 1.3V to 20V with maximum of 1.5A current. This power supply unit is ideal for most of the analog electronic experiments, as a simple battery charger, as laboratory power supply, etc. Complete circuit diagram, PCB pattern and Eagle source files of this project are available to download in here . When building the circuit make sure to install suitable heat-sink to the MIC29152 chip. This circuit use 230V AC power source, so make sure to apply all the safety precautions while at the designing and testing phases.

In this project we developed 1.5A, 3V to 27V adjustable power supply unit based on LM723 voltage regulator IC. In this project we add some additional options to standard LM723 PSU circuit (available from National Semiconductors) to improve the safety and performance. When assembling the circuit it is necessary to attach suitable heat sinks to both 2N3055 transistors. Single heat sink for both 2N3055 are also acceptable. According to the initial design R8 must be 0.39ohms (5W), but most of the people say it is bit difficult to get 0.39ohms locally (Sri Lanka) so I change value of R8 to 0.47ohms (5W) and it is available in local market. During the testings and usage this system produce an excellent results for us. Complete circuit diagram of the power supply unit is available to download in here .

3.3V is now widely used in electronic circuit projects (especially in digital electronics). These days several MCUs, CPUs and Digital interfaces (e.g: USB, Ethernet) uses 3.3V and in this project we developed suitable compact power supply unit for these projects. This project is mainly based on National Semiconductors LM1086-(3.3) power regulator. With the suitable transformer this circuit may capable to deliver 3.3V (during the testing stages we get 3.29V) with 1.5A of maximum current. If you need more current please use LM1085 (3A) or LM1084 (5A) instead of LM1086 (U1). All the circuit diagrams and PCB patters for this project are located in here . To get the maximum performance, replace C2 and C3 with 10MFD/25V tantalum capacitors. Please note that it is necessary to install good heatsink to the LM1086-3.3 (U1) regulator.