Universal Sensor Amplifier
My latest (and perpetually unfinished) project is a universal amplifier for signals in the frequency range of 0Hz-200kHz. It includes several specialized preamps (lo-Z, hi-Z, RF detector, differential), a programmable analog chain that offers variable highpass and lowpass filters, a 24 bit ADC, DSP processor (dsPIC), a microSD card, an LCD display, headphones output, and optically isolated USB serial output. Currently implemented in software are oscilloscope, spectrogram, voltmeter, and pitch shifting functions (the pitch shifting is for listening to ultrasonic signals). The design evolution started with a simple B-field amplifier in an Altoids tin that needed programmamble filters, which required a microcontoller, which allowed the addition of several other features, which would work much better with a DSP, which would be so much better with the addition of an LCD, and so on... The goal was then a device that could be a B-field listener, electrometer, EKG, bat listener, telluric current receiver, and all-band radio receiver. Basically it was a weekend project that swallowed up much more time than intended. Currently the hardware portion is completed, and the software is in a just-barely-working state. Schematics and source code are available upon request, although this is far from being in a finished state.
The guts. On the left, the analog board with analog inputs available through BNC sockets and a DB9 socket. On the right, the digital circuitry and headphones output. Up top, the battery, LCD, and button panel. |
All assembled, with an ultrasonic receiver on the DB9 and an inductive pickup on a BNC port. |
An inductive pickup (in stereo!) and an ultrasonic receiver. |