Modify Arduino 5v relay module to work from 3.3v

I am implementing a power-off function for my Ender 3 using OctoPi. For that, I need a relay and I happened to have one. Unfortunately, after connection relay to Raspberry Pi GPIO pin, the relay was always on and not listening to any commands from OctoPi. It appears this module was designed for 5v logic levels and Raspberry Pi works with 3.3v logic levels. After investigating relay one can see that its circuit is: For JC817C forward voltage Vf=1.2V and forward current If=20mA For Raspberry Pi output high (when VDD…

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Removing supervisor password (SVP) on ThinkPad T42

Recently received two ThinkPad T42 laptops ( some company decided to upgrade its IT and were giving away them almost for free ). After turning them on got an 271 error and later was prompted to enter password. It seems battery was dead on both of those laptops and when its dead, real time clock goes bananas and you are asked for supervisor password to set the clock again ( if supervisor password was set ). Offcourse nobody knew anything about what password it was. So had to figure it out…

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ZX Spectrim 128 +3 composite video output and drive belt replacement

Did some work on ZX Spectrum 128 +3 I have. One thing was I wanted to make it work with small "TFT Color monitor" (for a car rear view). This monitor has a composite video input. First I tried using CSYNK and GND signals for a composite video input. You get the video but it was terrible quality. It seems that "The 128 ZX Spectrums including the +3 (and +2A, +2B) have audio sound modulated onto the video, which reduces the clarity of the composite signal that is available at…

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Sony Ericsson that have tx-rx connection

Sony Ericsson that have tx-rx connection: 2218z, A2618s, A2618sc, A2628s, A2628sc, F500, F500i, J200c, J200i, J300a, J300c, J300i, K300a, K300c, K300i, K500c, K500i, K506c, K508i, K600, K608i, K700, K700c, K700i, P800, P802, P900, P908, P910a, P910c, P910i, R300d, R300LX, R300z, R310s, R310sc, R320s, R320sc, R380e, R380sc, R380s, R380WORLD, R520LX, R520m, R520mc, S700c, S700i, S710a, T200, T202, T20e, T20ec, T20s, T20sc, T238, T28s, T28sc, T28z, T28WORLD, T290a, T290c, T290i, T292a, T29s, T29sc, T300, T306, T310, T312, T316, T39m, T39mc, T60c, T60d, T608, T60LX, T610, T61c, T61d, T616, T618, T61LX, T61z, T628,…

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Making an adjustable “lab” power supply from scrap
Regulated power supply

Making an adjustable “lab” power supply from scrap

Had an old power supply board lying around that was ripped from dead/old printer. PSU model is CZ57PSE EPSON To make it work one should connect PSC line to ground. Schematics of similar power supply: To regulate output, made an adjustable voltage regulator using LM2575 that was ripped of some dead router or something similar: Finished power supply in a box:

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Making old webcam to work on Windows 10

Was investigating some old Fujitsu Siemens Webcam for some project, but it did not work on Windows 10 - windows did not recognize and did not have any drivers for it. Hardware ID in device manager shows: USB\VID_0C45&PID_613B&REV_0101 USB\VID_0C45&PID_613B Searching by vendor and PID did not help. On PCB of the webcam, I found that it is SN9C120 + S0I766 Finally searching by SN9C120 that this may be same as HP Basic Starter Camera. That led me to this Microsoft Update page where finally I have found working* driver. This driver installed on Windows…

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PSU mounting – fan facing up or down

My two cents rant about PSU fan facing up or down when it is mounted in the bottom of the case when talking about semi fan less power supplies. Facing up: Heat goes up. When PSU fan is off, all that little heat will go up directly to the GPU. When PSU fan is on, you are cooling PSU with a warmer air from inside of the case. Facing down: When PSU fan is off. Heat goes up. But between PSU circuit board and GPU you have PSU metal case…

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MasterWatt 650W coil whine when loaded by graphics card

Cooler Master – MasterWatt 650W 80+ Bronze Certified Semi-Modular ATX Power Supply is whining like a bitch when loaded by Gigabyte 1070 G1. When I installed Gigabyte 1070 G1 to my PC and started testing it with various benchmarks and games noticed unpleasant sound from PC case that was related to what was happening on screen (FPS, brightness etc ). Got worried that that is video card as you cannot exactly determine source of sound when everything was in case. Google tough me that this is probably combination of coil whine and…

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