The fixed resistors commonly used in DIY stompboxes look like small cylinders with leads (or wires) coming out of each end. Such components are called axial leaded. Resistors can be soldered onto a circuit board oriented either way; the leads are interchangeable. The leads are bent so that they can stick into holes on the circuit board. As a result, this type of resistor is also called through-hole. These resistors have a fixed value and the color bands on the cylindrical case of a resistor tell this value. The case itself identifies the type of resistor. Carbon film (labelled B and C) and metal film (labelled D) resistors are common types in stompbox builds. Older guitar effects were usually made with carbon composition resistors (labelled A).
Ryan made this guide to different common electronics connecters. He writes:
Online vendors, particularly sites like Jameco and Digikey, tend to be targeted at engineers who already know exactly what they’re looking for. If you don’t know the right search terms, finding the right part can be a bear. Since I made my start in electronics a few years ago, Octopart has made finding parts much easier, but you still have to know what you’re looking for! In hopes of helping people who’re building their first homebrew boards know what to look for, I’ve tried to compile a bit of what I’ve picked up. [via]
Connectors Demystified - [Link]
Neat adjustable voltage regulator, Rason writes -
Many amateurs have stopped by their local Radio Shack store and have noticed the famous LM317T adjustable voltage regulator. But, did you know that all voltage regulators are adjustable? Yes, any IC voltage regulator can be adjusted to a higher voltage than its fixed voltage by just adding a couple of resistors.
The adjustable voltage regulator - [Link]
uCHobby does an instruction MindBite video about Digital Multimeters (DMM). You can view the MindBite here. In this short article I describe the new MindBite service and how I constructed a camera stand by modifying an old swing arm desk lamp.
MindBites is a new community service that should be very popular with the Maker crowd. The site offers Hot-To videos that are uploaded by users. Some of the videos are free but most cost a bit more then a dollar to view. You can upload your own instruction video and when it’s viewed MindBites pays you $1.
MindBite DMM 101 - [Link]
Today I came across this nice online led calculator. It will generate the circuit for you and will calculate the circuit parameters and the current limiter resistor. You have to specify the supply voltage, voltage drop across led, desired led current and click on ”Calculate” button. Several parameters are calculated including:
- Exact calculated resistance
- Nearest higher rated resistor
- Wattage recommendation for the resistor
- Actual Single LED Current
- Power dissipated by the LED
- Power dissipated by the Resistor
- Circuit’s total current consumption
Online Led calculator - [Link]
What is an oscilloscope, what can you do with it, and how does it work?
For those makers who have had little experience in working with oscilloscopes and would like to learn more about them, check out these tutorial sites.
- Oscilloscope tutorial
- Use of the Oscilloscope
- Using an Oscilloscope
- Oscilloscope Tutorials
This Dummy Alarm project makes an LED flash briefly once every 5 seconds to imitate the indicator light of a real alarm. The circuit is designed to use very little current to prolong battery life so that it can be left on permanently. An on/off switch is not included, but could be added if you wish.
The 7555 timer IC used is a low power version of the standard 555 timer. A ‘superbright’ red LED is used because this provides a bright flash with a low current. The LED is off for most of the time so the average total current for the circuit is less than 0.2mA. With this very low current a set of 3 alkaline AA cells should last for several months, maybe as long as a year.
Dummy Alarm - [Link]
There are six (or more) push switches. To ‘unlock’ you must press all the correct ones at the same time, but not press any of the cancel switches. Pressing just one cancel switch will prevent the circuit unlocking. When the circuit unlocks it actually just turns on an LED for about one second, but it is intended to be adapted to turn on a relay which could be used to switch on another circuit.
Simple Electronic Lock Project - [Link]
Don’t know anything about Embedded Electronics? Start here! Sparkfun has put together a nice lecture collection. Here it is:
Lecture 1 – What’s a microcontroller? Breadboard power supply
Lecture 2 – Loading code and compiler basics
Lecture 3 – Oscillators and fuse bits
Lecture 4 – UART and serial communication
Lecture 5 – AVR GCC and printf compiling
Lecture 6 – Soldering basics
Lecture 7 – SMD soldering Simon!
Lecture 8 – Eagle: Schematics
Lecture 9 – Eagle: PCB layout
Lecture 10 – Eagle: Creating a new part
Common Mistakes – Tips and tricks
An LED is the device shown above. Besides red, they can also be yellow, green and blue. The letters LED stand for Light Emitting Diode. If you are unfamiliar with diodes, take a moment to review the components in the Basic Components Tutorial. The important thing to remember about diodes (including LEDs) is that current can only flow in one direction.
To make an LED work, you need a voltage supply and a resistor. If you try to use an LED without a resistor, you will probably burn out the LED. The LED has very little resistance so large amounts of current will try to flow through it unless you limit the current with a resistor. If you try to use an LED without a power supply, you will be highly disappointed.
Learning to use LEDs and Transistors - [Link]