These are useful tools to have or your workbench, installed on your computer, or bookmarked on your browser:
Resistor Value and Ratio Calculator
Sometimes we need a resistor value more precise than what is offered in the standard series. For this task, use the Resistor Value Calculator.
A more complicated task is to pick resistors to satisfy a ratio. This is often done to set the division ratio in a voltage divider, for example. This is where the Resistor Ratio Calculator comes in handy.
There are many good online unit converters. None include decibel conversions. Here are two that will cover most of your needs:
- General Unit Conversion: http://www.onlineconversion.com/
- Decibel Conversions: http://www.daycounter.com/Calculators/Decibels-Calculator.phtml
Op-Amp Filter Design
Most of the ic fabricators have comprehensive online parts selectors and circuit designers:
Along with many other useful tutorials is one on bandpass filters:
- A mathematical pdf from Texas Instruments: http://www.ti.com/lit/ml/sloa088/sloa088.pdf
- A very concise approach from TI: Filter Design in 30 Seconds
Stripboards, also known as Veroboards, are great for rapid prototype development. Parts density is less than that of printed circuit board design but that means if you can fit your circuit on a stripboard it will certainly fit on a PCB of similar or slightly smaller dimensions. In the prototype stage there is a larger scope for moving parts or changing connections than with PCBs.
Most of the freeware designers have antiquated or quirky user interfaces and many are no longer supported. The best is VeroDes. Others are reviewed at:
If you become a stripboard fan Lochmaster from Abacom is essential. It is easy to use, comes with a large parts library, and allows creating your own custom components and boards. It costs €50 but you do not have to pay VAT if you live outside the EU.
You will also need an inexpensive swivel-head pin vise and a 3mm or 7/64-inch bit to cut the traces.