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17 september 2011

Composition in Electronic Components: Experiment I

A musical composition. A composition maybe made from the point of view of a computer or other electronic device.

Do computers like us? Do they like the interaction we have with them. 

We don't know. All we know is that we most probably slow them down with our presence, almost grind them to a hold.

There is a huge difference in the computational abilities between us. If we want to compute something, we need to go sit behind the keyboard and mouse, that slows down the computer. It needs to listen. Even if there where fast way's to interact, like speech or even brainwaves, it would slow the computer down.

This little experimental musical piece explores this. We got a little micro controller that happily sends it's serial communication to his companion, a little emulated SID chip. This serial communication consist of random registry entries so the SID can generate some random sounds.

But there is a opportunity for a human to interact with this micro controller, a PIR motion detector. If there is any movement registered this electronic circuit needs to slow it's activity down (by a factor of 10).

More info on the emulated SID chip can be found here ->

Maybe I will write down how I made this. But should be clear if you dig around on above mentioned website.

10 september 2011

Op Amp experiments I

Op Amp Experiments (necessities):

I been dabbling in electronics for a little while now, and of course I used Op Amps in a few circuits. A lot of those circuits were adaptations from what I found in books and datasheets.

However, I never fully understood how things worked.

So I set myself the goal to get a better understanding of Op Amps. What can you do with them, and how. Back to basic!

Also I decided to do these experiments with as few parts as possible. For the Op Amp I choice the lm358, readily available and cheap (and I had some laying around). A breadboard, wires, a few potmeter, some capacitors of different standaard values and some other knickknacks.

I use a DSO nano and cheap multimeters to measure things.

A while back I made myself a function generator from a xr2206 which I use for signal generation.

There is a little audio amplifier build into the function generator (well the function generator is build into the audio amplifier). I based mine of a circuit I found in an Elektor magazine from the ‘70’s (could be ‘80’s), but here you can find something similar.

SparkFun used to sell a xr2206 kit, but it’s retired now. The one I build is a little more involved. I can choose between DC offset or not and I can manipulate the symmetry and amplitude of the waves. Don’t have schematics laying around anymore but if I find them I will post. To be honest the xr2206 isn’t the easiest thing to find.

Maybe it’s time for someone to design a cheap and useful function generator kit based on more modern techniques.

One of the first things I want to explore is the use of positive voltage, negative voltage, ground and virtual ground with Op Amps. I always seem to screw that up when designing a circuit.

To do this I first needed a power supply that could deliver positive voltage, negative voltage and ground.

I found this nifty little circuit based on a 555 timer that could deliver just what I needed. It works well with a 12 volt DC walwart.

I found this circuit on my computer in a folder with hunderds of circuits. I unfortunately don’t know who the designer was. I believe I got it from somewhere. I just added a 7812 volt regulator to it on my prefboarded circuit.

The first experiment will be “How to amplify a sinusoidal signal with no DC offset (aka audio signal)”