Earlier this year, I decided to design my own mic preamp. I wanted my preamp to sound better and cleaner than most commercial preamps out there but I also wanted it to be inexpensive. I believe that great sound doesn't need to cost thousands of dollars.

I created a blog documenting my adventure. Pretty soon, I had a dedicated following on the web watching/reading my struggles as I worked through problems with my design, noise issues and other things. A lot of my readers expressed interest in buying a couple of channels, and pretty soon, I was adding more features and making it user-friendlier to build and assemble for the DIY'er.

After months of working on this project during my spare time, it's ready. I am calling it the SC-1 Mic Preamp Kit. It's basically a transformerless, all solid-state design using chipsets from THAT Corp and Burr-Brown. It boasts clean gain from 6dB to 72dB, via a 12-position gain control switch. This high-gain, transparent mic preamp is especially suitable for dynamic and ribbon microphones. Phantom Powering via a slow ramp-on +48Volts is also included for working with condenser microphones. Other features under the hood are RFI protection on input and outputs, input clamping protection and output surge protection.

No special tools were required in building this preamp kit. No SMD parts or esoteric construction techniques. All parts in the kit are labeled in individual zip bags so the user doesn't even need to know resistor color-coding or capacitor coding! The only special tool I used is a magnifying glass but that's only because my eyesight is not as good as it used to be.

The preamp board itself measures around 3"x4". Everything on the board is clearly labeled with the part# and part value. In fact, you can assemble this board without looking at the printed instruction and just follow the part values written on the board.

All components used are through-hole mounted. The only critical part to solder is the selector switch. Only because there are lots of pins, and they're spaced very close together.

Here's a photo of the finished preamp kit. The controls, from left to right, are the 12-step gain selector switch, LED lamp to indicate +48V phantom power, Phantom Power Switch, and Trim/Volume level control.

All you need is a project case or rack-mounted case.

And here's a photo where I put 4 channels of this preamp in a half rack case. I also designed the Power Supply circuit to power this preamp. It features regulated +18, -18 voltages and also a regulated +48Volts for phantom power.

And there you have it I hope this little write-up has inspired you to pick up that soldering iron and do a DIY project!

For more info visit Ruel's FiveFish Studios.

working on cool hardware? submit blogs to contact@octopart.com

Two weeks ago we added a news feature to Octopart and we've been really happy with how it's developing. So far the submissions have been very interesting. They've varied from a discussion about fluorescent bulbs and dimmer switches to a FOXNews study on the environmental impact of flush toilets.

My favorite conversation on Octopart News so far has been on the correlation between Intercourse and Intelligence. If any Octopart users would like to continue this thread and conduct a quantitative analysis of dating, we're willing to dedicate quite a bit of computing resources to the task.

There were several hardware specific posts which I found very interesting as well. iamwil found a 3D scanner from NextEngine which is pretty amazing. The iPhone launched just a few weeks ago as well so appropriately, there were 62 submissions involving the iPhone. Another particularly useful submission which made it to the top of the rankings was a PCB Cost Comparison Calcuator.

Thank you to everyone who has beeen submitting stories to Octopart News. If you haven't visited Octopart News yet, check it out here. Also, please install the "octo-post" bookmarklet to submit any web page in 250ms. If you have any ideas for the News site, send me an email or join us on this discussion forum.

working on cool hardware? submit blogs to contact@octopart.com

Graffiti is one of the most powerful and most personal displays in the urban experience, and can be used to make statements, tag territory, spread messages - urban markup language in practice. However, the output is nearly always visual in nature, making this experience one-dimensional. Furthermore, rarely does the work have a brain of its own, and is usually incapable of reacting to anybody observing it. Concrete Crickets was created to address this deficit, creating small devices that will be aware of passers-by as well as other units of their kind. Each unit consists of a sound generator, amp, speaker and sensory system, and is housed in camouflage appropriate to the streets of the city - soda cans, cigarette packs, and the like.

I love the streets of NYC (and just about any other city), but it seems to me that the "magic" moments of serendipity are harder to come by. If this project can just create one moment of magic and beauty (corny as both those terms can be), than it will have succeeded with flying colors. Inspired by field crickets and fireflies on one hand and street artists on the other, this project aims to create, by installing small "crickets" in a small area of city space, a multi-directional audio experience. Each device is programmed with a particular voice, with each bieng part of a larger whole. When night falls, the crickets go active for a few hours, singing out in their particular way. When approached, the crickets fall silent (as would crickets and cicadas in nature). Each are sensitive to what happens to the others, and the end result will be waves of songs, changing and adapting to their surroundings.

Each unit contained an Atmega8 chip running Arduino, an OpAmp circuit, an ultrasonic rangefinder, two relays, a few capacitors to smooth out readings and values, a 1" flat speaker, an itty bitty speaker (which I dont't think I'll bother using in future versions), a hacked MP3 player, a AA battery for the MP3 player, a 9V batery to power the rest of the circuit, and a few other odds and ends. This was all soldered onto a perfboard which was then wrapped in a plastic bag and shoved into a crumpled soda can.

For more info visit Mike's ITP Projects and participate in the Concrete Crickets discussion forum at Octopart News.

working on cool hardware? submit blogs to contact@octopart.com

Today we are releasing a new feature that, I hope, will make searching for parts a lot easier and a lot more fun: Octopart News.

Octopart News is an experiment that we are very excited about. We envision it as an open forums site where you can post technical questions and hopefully answer some too. You can also post links to interesting engineering/tech news stories. For instance, the discusion thread to Sam's last blog is here and the first mention of the word "Semiconductor" in the NY Times can be found here.

One of the great things about places like Reddit and Paul Graham's Startup News is that you can find interesting stories everytime you visit. We wanted to build a place for engineers, researchers and hobbyists to go and find find interesting tech stories all in one place. Selfishly, this is going to be our way of keeping up to date with cool new hardware projects. Hopefully you'll find the same is true for you.

When we were building a laser for our experiment at the South Pole we needed a communications device that operated at -50 C over 2.5 km of cable. It took us 3 weeks to find what we were looking for. Now, you can submit a discussion topic to Octopart News and somebody who has had the same problem can tell you what their soution was (an ethernet extender). For our part, we will be adding tools to make this process easier.

Tell everybody you know about Octopart News and help us build a useful and fun site that will make it easier for you to keep building things.

working on cool hardware? submit blogs to contact@octopart.com