Shared Projects

The problem with piezoelectric and contact mics is that they are not well matched to typical audio inputs. The reason why these devices often sound tinny is because the piezo sensor presents its signal through a series capacitance which is small, typically 15nF or less. When wired to a normal 50 kilohm line input this forms a 200Hz high-pass filter, which eliminates the bass. Because the piezo disc has a very high impedance (1 MΩ typical), it should be buffered to avoid possible impedance mismatch with an existing audio system. This circuit acts as a impedance buffer, and some amplification does not hurt as long as it is around 40dB. The best piezoelectric sensors for listening is based on Aluminum Nitride and molybdenum. PZT-5 also known as SensorTech BM500,Channel 5500,Morgan PZT5A1 is widely used.

The diodes are there to avoid overloading the circuit if it is dropped or bumped in to something hard.

NOAA technical memorandum NMFS 2008NOAA-TM-NMFS-SWFSC-417 also known as A guide to constructing hydrophones and hydrophone arrays for monitoringmarine mammal vocalizations, describes how to build a single crystal hydrophone.

If the piezo electric crystals are a suitable distance and 45° degrees apart from each other in a flat circular array with 8 piezoelectric sensors, they should be compatible with Manyears or ODAS.

Approximate values for fresh water and seawater, respectively, at surface pressure are 1450 around 1500 m/s. The speed of sound in water increases with increasing pressure, temperature and salinity.

Also, read: https://github.com/Supermagnum/passiveSonar

Github: https://github.com/Supermagnum/xSoundsMicrophones/tree/master/Hardware/Microphone-piezo

breakout for the mojo!

Allows you to easily attach a Wemos D1 Mini to a 2.8" or 3.2" with a 14 Pin Header. Examples of these displays can be found here (3.2") and here (2.4"). Many other vendors sell them as well.

The pins on the display header are connected to the pins on the D1 Mini as follows:

Note: The LED pin controls the brightness of the display backlight. It is connected to D0 on the D1 Mini, so your code will need to set that HIGH for full brightness, or PWM it for dimmer values.

The board also breaks out a spot to connect 5V and GND and another spot to attach an external reset button (RST and GND). You do not need to connect these.

BOM: This is just an adapter board. No components are required beyond the display and the D1 Mini.

Final version of Fuzztopia board

Fuzztopia board with two different transistor package options.

Top cover for my lame clock.

6xIV6 VFD Tubes. and drivers.

Motherboard for my lame clock. To lazy to add MCU and RTC to the board, so I made it breadboard instead so I can add whatever I want.

Fuzz design for Fuzztopia group

Support board to allow 2 RFID readers to be plugged into a single Raspberry Pi Zero W. Plus on board RTC.

Revision A

github.com/bkw777/BCR_Breakout

USB 5v power from the BCR port on “Model T” computers.
TRS-80/TANDY Model 100, 102, 200
NEC PC-8201, PC-8201a, PC-8300
Olivetti M10

https://github.com/bkw777/BCR_Breakout

Breakout board for the BCR port on “Model T” computers.
TRS-80/TANDY Model 100, 102, 200
NEC PC-8201, PC-8201a, PC-8300
Olivetti M10

Simplifying the pinout for the 74X273 IC. Has inputs and control on left side of board, and power / outputs on right side. Optional 0805 decoupling caps for power rail and pullup resistor for master reset

Adapter for connecting servo, Arduino, and DC adapter

584 D/R D Side

“Just in time for 36C3 edition” dev board for XC2C32A/64A.

BUGGY VERSION