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...

This 12V uninterruptible power supply initially designs to drive my fiber optic modem/router. The key reason to build this power supply is to get continuous internet and phone connection during power failures. Core components of this power supply are a constant voltage charger, 12V DC power supply, AC line monitoring unit, and 12V high capacity sealed lead-acid battery. The entire system designs using locally available components. Prototype version of 12V UPS system The charging circuit of this system builds around using the popular LM350 voltage regulator. This regulator calibrates to provide both 14.4V fast charging and 13.6V trickle charging. Based on the condition of the battery, the MCU will determine the appropriate charging mode. At the online state, the LM2576-12 switching regulator provides 12V output to the driving system. (in my arrangement, a fiber optic router). Block diagram of the 12V UPS system The PIC16F688 MCU monitors the AC line and battery to controls the output...

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.

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.

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...

This is a high current 5V bench power supply for digital (and analog) electronic experiments. This power supply is based around National Semiconductor's LM338K positive voltage regulator. Virtually this is an indestructible power supply unit with short-circuit protection and thermal overload protection. 5V 5A Power Supply in ATX Power Supply Casing In our prototype we assemble entire power supply (including step-down transformer) in an ATX power supply casing. When assembling this power supply take extra care about wirings and mountings. LM338K need proper heat-sink and make sure to mount it closer to the main PCB. While assembling makes sure that all the wirings are in correct order. Improper wiring and/or shot-circuits may leads to critical component failures (including voltage regulator IC and step-down transformer ).  Schematic diagram of this power supply unit is available to download at google drive