Lee Zhi Xian writes:
I often use Arduino to test out my project prototype before complete it. Sometimes, I wanted to test more than one project at the same time. I would need more Arduino, but the original Arduino is over my budget for prototyping purpose. Therefore, I decided to make my own Arduino. Some of the benefits of making your Arduino (at least for me) are it is cheap, easy, learn to design PCB and electronics at the same time. Although there are a lot of guides on how to make your own Arduino, I decided to make one so as I can share with my readers, and at the same time document it for myself.
Build your own Arduino Uno - [Link]
This is a walk-through for making cheap high quality SMD metal stencils at home, using commonly available materials.
DIY home-made SMT metal stencil - [Link]
Tutorial on how to make your own custom LCD at home!
DIY Custom LCD - [Link]
David A. Mellis writes:
For a little over a year, I’ve been working on an open-source, DIY cellphone as part of my PhD research at the MIT Media Lab. The current version of the phone is based on the Arduino GSM shield and Arduino GSM library. It sports a deliberately low-resolution screen (8 characters, each a 5×7 matrix of LEDs), a laser-cut wooden enclosure, flexure (living hinge) buttons, and a ~1000-line Arduino program that powers the user interface. The phone can make and receive phone calls and text messages, includes a phone book and caller id, and keeps the time. Everything you’d expect from a 20-year old Nokia! (Except snake.) I’ve been using various iterations of the project as my primary cellphone for the past six months or so.
Open-source, do-it-yourself cellphone (built with Arduino) - [Link]
Scott W Harden writes:
I re-vamped my DIY ECG project. This new project is fully documented and uses extremely common and cheap parts, all of which could be purchased at RadioShack. It serves at both an ECG *and* a pulse oximeter, depending on which leads are attached. It uses a single chip (LM324, a quad operational amplifier) with a virtual ground to eliminate the need for a negative voltage. As a pulse oximeter with a 12V supply it outputs clean 10V swings when pulses occur. It’s intentionally unsophisticated, and made to be easy to replicate by anyone interested in electronics. Although you could view its output on an oscilloscope, it’s designed to be output into a PC sound card for recording (if attenuated to microphone levels). I even describe how to spectrally process the data on the computer to clean it up, downsample it, and graph it in Excel or with a Python script.
Simple DIY ECG + Pulse Oximeter - [Link]
Jianyi Liu wrote a tutorial on PCB fabrication at home. He states: [via]
A few years ago, I started experimenting with homemade prototype PCBs as an alternative to professionally fabricated PCBs from board manufacturing company. My company was flexible enough to give me some resources and time to explore the subject matter. What I discovered was that with a small initial investment, you can make reasonably high quality two sided boards. In addition, all the equipment needed was easily accessible. I’ve decided to put my findings into this guide. Hopefully some of my fellow hobbyists will find the information useful
DIY PCB tutorial - [Link]
Unit is based on Arduino Atmega328P MCU, with over 430 UV LEDs. The PCB board is made using Toner transfer method and isn’t perfect. It was just too big and I was too lazy to do it again. However, marker here, scratch it there and it it good enough.
The unit itself is on single sided copper clad board, no additional cables, no narrow paths (except for one for power on the MCU). Design is straight forward. It’s designed to be powered from 12V source (computer) and take around 2,7Amps @ full power which means around 30Watts.
DIY UV Exposure Unit with LED and Arduino - [Link]
Getting into microwave but having problems finding an accurate method of measuring the RF power at these frequencies? If you are like me, you can’t afford to buy even a used HP 432, 435 or 436 version power meter via eBay. I have to admit I was tempted recently when I spotted a HP435A listed for here in Australia and then noted that there was no sensor with it. Quite a while later after searching eBay for sensors, I came away for a reality check – I might get the 435A for under $200 but a suitable sensor was going to cost somewhat more than $300. Sorry, but $500 doesn’t figure into my budget for a device which might be up to 40 years old, with calibration status unknown and sensor status questionable – and expensive to repair if damaged.
DIY Microwave RF Power Meter – 100MHz – 12GHz - [Link]
They say you are only as good as your tools. This is a statement I can vouch for, as better tools can make the difference between a sleek and well designed prototype and a rats nest covered breadboard. Unfortunately as an electronic hobbyist you don’t always have the budget of a big tech company at your disposal. But hey, that’s what DIY projects are for!
Starting off as a hobbyist or even small tech company designing and building electronics you will soon learn that most of the fun IC or MCU chips are either cheaper in, or only available in, surface mount form, and fancy reflow ovens are expensive. But a soldering oven isn’t much different from a toaster oven– the only difference is the accuracy and temperature settings.
That is why I’m going to show you how to build your very own Soldering Reflow Oven for under $100 from an old/new standard toaster oven, thermocouple and a microcontroller.
DIY Soldering Reflow Oven - [Link]
This is not really an app note, but more of a tutorial on DIY op-amp based linear regulators. The article describes the basics of op-amp regulator, and includes schematics and in-depth explanations of how the various circuits work. [via]
This article follows the history of a popular series of DIY linear regulators. Starting from initial concepts basically idential to the archetype block diagram above, this particular thread through history will wind up in a very sophisticated design. Because this final design developed piecemeal over the course of two decades, that’s how I’ll show it. I think showing the steps this series of designs went through aids understanding of the final design.
Op-amp based DIY linear voltage regulators - [Link]