We Built a Scope Out of a Raspberry Pi and a $60 ADC Hat — Here's Where It Crushed (and Choked)

Every maker hits the same wall eventually. You're debugging a sensor, checking a PWM signal, verifying a crystal is actually oscillating — and you're doing it blind, because a real oscilloscope costs more than your entire project budget. The used market helps, but even a battered Rigol DS1054Z will set you back $300-350 these days.

So when the claim started circulating that a Raspberry Pi plus an ADC HAT could replace a bench scope for around $100 all-in, we had to find out ourselves. We built one. We benchmarked it. And we've got opinions.

The Build: What's Actually on the Bench

The parts list is refreshingly short:

• Raspberry Pi 5 (4GB) — $60
• Waveshare High-Precision ADC HAT (or similar 16-bit digitizer board) — $35
• MicroSD card — $10
• BNC-to-screw-terminal adapter and a couple of probes — $15

Total damage: roughly $120, and you can shave that if you've already got a Pi gathering dust in a drawer somewhere. The software side runs on open-source tools — most builds use a Python frontend or one of the community scope applications that pipe samples from the HAT's SPI interface into a scrolling display with cursors and measurements.

Assembly took under an hour, and half of that was wrestling the GPIO standoff headers. If you've ever stacked a HAT, you already know everything you need to know.

Benchmark Round One: Rise Time and Bandwidth

Here's where the dream hits the first speed bump. Our bench reference, a Siglent SDS1102, has a 100 MHz analog front end with a rise time around 3.5 nanoseconds. The Pi-based rig, bottlenecked by its ADC sample rate of roughly 100 kSPS per channel in continuous mode, tops out around a few kilohertz of usable signal bandwidth.

Let's be blunt: you are not probing a 16 MHz crystal with this thing. You're not looking at SPI clock edges or I2C bus traffic in any meaningful way. The Pi rig sees slow analog signals — thermistor drift, photodiode responses, battery discharge curves, audio-range waveforms — and that's it.

But within that lane, it's genuinely good. Our 1 kHz square wave came through clean, with amplitude readings within 1.5% of the Siglent. For a $120 instrument, that's respectable.

Benchmark Round Two: Noise Floor

This is where the DIY build flipped the script. The 16-bit ADC on the HAT delivers an effective noise floor that made our 8-bit bench scope look like it was viewing the world through a screen door. When we measured a precision 2.5V reference, the Pi rig resolved ripple and drift that the bench scope simply smeared into flat line.

If your measurements live in the millivolt range — sensor bridges, audio, low-level analog — the Pi rig actually wins this round outright. Resolution beats speed when you're staring at a DC signal.

Benchmark Round Three: Trigger Stability

The bench scope's hardware trigger fires like clockwork, every time, on edges the Pi rig can't even see. The software trigger on the Pi build works, but it's bursty. Memory buffers fill, the display hitches, and capturing a one-off glitch feels more like fishing than measuring.

For repetitive, slow signals, it's fine. For anything intermittent or fast, you'll want real hardware.

The Candid Verdict

Trust the Pi rig for: DC and low-frequency analog measurements, high-resolution voltage readings, slow sensor work, logging, and anything where 16-bit depth matters more than speed.

Don't trust it for: anything above ~10 kHz, timing measurements, protocol debugging, or transient capture. That's the territory where a real scope earns its price tag.

The honest framing: this isn't a scope replacement. It's a precision slow-channel digitizer that happens to cost less than a nice dinner for two. Pair it with a cheap handheld scope or a used bench unit and you've got a two-instrument setup that covers both speed and resolution for less than either alone would have cost a few years ago.

For a weekend build, it's a blast — and the logging and scripting capabilities you get from running everything on a Pi are something no bench scope can match. Your spreadsheet will thank you.

Got a DIY instrument build you're proud of? Drop it in the comments — we're always hunting for the next bench experiment.