LCR-T4 transistor tester original firmware

Bought cheap transistor tester from eBay and currently experimenting with firmware updates. I was able to program it with this version of Markus transistor tester firmware: https://github.com/svn2github/transistortester/tree/master/Software/trunk/mega328_T4_v2_st7565 To build, use a WinAVR programmers notepad, open Makefile and select Tools->Make all. At first, was getting weir errors, but after adding msys-1.0.dll to \WinAVR-20100110\utils\bin everything built ok. Before doing firmware experiments, I have made backup of original firmware, if somebody needs it, you can download it here: Code Data Config I tried to reflash original firmware and it worked fine. For programming…

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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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Learning the Art of Electronics, Week 2

[latexpage]  2L1.1 Ok, I  form a simple low pass filter using unknown RC values. Then I measure time constant using scope and 500Hz square wave. Time constant is a time it takes for a voltage to reach ~63% of its total value. Measured time constant using RIGOL DS1054z is 0.268ms ( measured using manual cursors: I set Percent for Vert. Units, then Set range of the wave with vertical cursors and then measure time to rise to ~63% (bx-by) ) Measured time constant using Tektronix 2221A is 0.270ms ( I…

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Learning the Art Of Electronics

I have decided to get my self together and systematize my knowledge of electronics. It is very similar situation as for this guy. Electronics is my hobby. And actually one of many hobbies. I would say I have a lot of knowledge it but there are plenty of gaps and places just for intuition. Especially in circuit design. Once I have purchased a book "Learning The art Of Electronics" and used it as reference for this and that but never when through it. But this is it. My goal is…

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Essential toolkit from iFixIt

Love this toolkit. Nice packaging, tools seem quality made and should last more that one disassembly. Nice job iFixIt! Kit Includes: Custom iFixit Bit Driver Angled Precision Tweezers Spudger Jimmy iFixit Opening Tool iFixit Opening Picks set of 6 Suction Handle Easy-to-Open Magnetized Case Lid with Built-in Sorting Tray Sixteen 4 mm Precision Screwdriver Bits: Phillips - 000, 00, 0, 1 Pentalobe - P2, P5 Flathead - 1, 2.5, 4 mm Torx - T4, T5 Torx Security - TR6, TR8, TR10 Tri-Point - Y000 SIM Eject Bit

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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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Assembled and boxed Clone PI AVR metal detector

Some more photos of boxed Clone PI AVR metal detector and self made coil. I have made a coil from Ethernet cable between two round plywood sheets filled with Makroflex sealant. More about making coil from Ethernet cable can be fount here. Idea how to seal everything came from here. Clone PI AVR intself was boxed in a box I bought in local electronics store. I decided to add a switch to switch off external beeper so that sound will be provided only through headphone socket. For the coil connector…

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