PIC-based Voice Recorder

[Vinod] just finished building a voice recorder and it turned out even better than he thought it would. The video after the break shows him recording what is surely one of your favorite songs from his cellphone and then playing it back. The audio quality does sound quite good for a project with very few components.

A PIC 16F877A makes up the majority of the build. Its ADC is used to capture the incoming line from an amplified microphone input (you’ll find that amp schematic half way through his post). He’s storing the data on an MMC card, which was a bit of a hack since the PIC has limited RAM to manage that overhead. The stored data is in a raw format, as the card is not accessed using a file system. This makes it easy to record at a high bit rate, leading to better audio quality. Playback consists of connecting a speaker via a low-pass filter and amplifier circuit to the hardware PWM output on the PIC.

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Weekly Roundup 09/03/11

In case you missed them the first time, here are our most popular posts from this past week.

Our most popular post was about a ‘flashlight’ build. We are using the word flashlight loosely since this monster can draw up to 500 Watts!

Our next most popular post was about another [Jörg Sprave] project where he has built a very large slingshot that can shoot shot puts. He then proceeds to destroy a car with it.

This post describes an open-source Segway. It is built around an ATmega644 has a nice professional look to it.

If you live out in the country and have a problem with rats, this post could be for you. In this post, we look at [Snypercat’s] build where she has mounted a camcorder onto the scope for her pellet gun and also attached an infrared light source so that she can snipe rats at night.

Finally, we have a post about a custom V-12 Kawaskai Voyager. If you are looking for a great way to draw attention at your next motorcycle rally, this post might give you some inspiration.

Engine Hacks: Convert Your Yard Tools To Run On Steam!

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Are you tired of doing things the efficient way when using your lawn equipment? Look no farther. Here are some engine hacks where regular internal combustion engines have been modified to work on steam or compressed air. Surprisingly, all it takes to do this is to remove the carburetor and replace it with a steam line and to modify the valve timing.

First up is a lawn mower that runs on steam posted by [dquad]. This one is pretty great because it just looks so wrong. In [dquad’s] own words: “I am surprised by the fact that nothing at all failed during this test – other than a wheel catching fire!”


Check out some other examples of engines converted to run on air or steam after the break…
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