my love grows thin
somewhere in the mist of another morning
I reach out
only twisted metaphors
where is the thick warmth of a body?
layers of tendons and blood vessels
I am the moon
against a backdrop of creased bedsheets
vainly pulling towards me
a red sea
a good starting point – stethoscope mic made from a contact mic and preamp
power supply for a condenser mic
Electret Microphone and Pre amp:
“Description: This small breakout board couples an Electret microphone (100Hz–10kHz) with a 60x mic preamplifier to amplify the sounds of voice, claps, door knocks or any sounds loud enough to be picked up by a microcontroller’s analog-to-digital converter. Each breakout comes fully assembled and works from 2.7V up to 5.5V.
The Electret Mic Breakout translates amplitude (not volume) by capturing sound waves between two conducting plates (one a vibrating diaphragm and the other fixed) in the microphone and converting them into electrical waves. These electrical signals are then amplified and picked up by your microcontroller’s ADC.”
This TI Precision design details the design process for a preamplifier to be used with electret microphone capsules. It explains the basic construction and operation of an electret microphone and uses an OPA172 to amplify the output of the microphone to common analog line level voltages.
Circuit Board Resources :
Handmade Electronic Music the art of hardware hacking by Nicolas Collins looks like a great resource. When I get back to London I want to modify the contact mics so that they can be placed on the body without the getting a humming sound this means i may need different wire or simply to use Plasti-Dip as described bellow:
Rule #11: Don’t drink and solder.
- When you are sure you have an electrically functional contact mike, cover the ceramic side with a piece of electrical tape—you can trim it around the circumference with scissors or a knife, or you can wrap the edges over to the other side of the disk.
- Find a well-ventilated space. Open up and stir your can of Plasti-Dip. As per the instructions on the label, slowly dip the contact mike end of your cable into the goop until you have covered the wire past the electrical tape (see figure 7.5). Slowly with- draw it and hang it up (preferably outside) to dry. Go away and take a break—this stuff is stinky. You can dip a second layer after the first one dries thoroughly, which can take a few hours. More than three layers tend to muffle the sound, so don’t overdo it without listening carefully after each new layer.
The tape and Plasti-Dip treatment serves several functions:
- It strengthens the connections between the wires and the piezo disk.
- It insulates the disk from electrical shorts, and prevents hum when you touch it.
- It waterproofs the contact mike, so you can use it to record underwater sounds, freeze it in ice-cubes, dangle it in a drink, etc.
- It deadens slightly the pronounced high-frequency resonance of the disk similar to the effect of gaffing tape on the head of an unruly snare drum.)
How can chelsea balance it’s self-taught ethos with class based teaching and a greater interdisciplinary bleed between the “fine arts” and other forms of creative practice
“You have to ask yourself what IS “the sound of a heartbeat” – To a layman its the bass “lub-dup” you can hear when you put an ear to someone’s chest, whereas a cardiologist is listening to the opening and closing noises of your mitral and aortic valves etc etc.
A: I actually tried this last night. When I pressed the piezo against my skin, it just made a loud buzzing sound no matter where I put it on my skin.
B: From my experiences with piezos this means it’s shorting or you are pressing to hard. Make sure the connections are sound, especially on any audio wires you’ve spliced in, and put something between your hand and the buzzer, maybe even a thin piece of cloth between your neck and the disk too.
I’ve used one up against my throat as a mic but it may not be sensitive enough to pick up a resting heart beat.
C: An electret microphone cartridge would be a good sound pickup. Some are pretty small. You might be able to find one small enough to stick in the end of the stethescope tube. Sparkfun makes one with an atached pre-amp: https://www.sparkfun.com/products/9964?
To power the speakers, we have a nice compact amplifier module: http://www.adafruit.com/products/987