Using a oscilloscope for your projects is often an expensive endeavor. At the low end you are talking several hundred bucks at least%u2014but this DIY version fits in your pocket and only costs $33.

Features:

Max sample rate – 2M/s%uFF0C8 bits
Sample memory depth – 256 bytes
Analog bandwidth – 1MHz
Vertical sensitivity – 100mV/Div – 5V/Div
Vertical position adjustable with indicator
Input impedance – 1M%u03A9
Max input voltage – 50Vpp
DC/AC coupling
Horizontal – 5%u03BCs/Div – 10m(minute)/Div
Auto, normal and single trig modes
Rising/falling edge trigger
Trig level adjustable with indicator
Hold/run feature
Built-in 500Hz/5Vpp test signal
Frequency counter features with independant F and T read-outs (only for TTL level input signal)
9 – 12V DC or AC power supply
Dimension: 110mm X 65mm X 25mm (no case)
Weight: 70 gram
With Panels

The “Digital Storage Oscilloscope” may not be as fully featured as traditional models, but you definitely get a lot for your money. Plus, it’s open source so you can include the firmware in your tinkering. The oscilloscope comes in a kit version for the aforementioned $33, as well as a pre-built version for only $49.

Gizmodo – DIY Pocket-Sized Oscilloscope Kit For $33 – Digital storage oscilloscope