what oscilloscope to buy?

*For FRC use.

To look at PWM waveforms (signal and motor voltage).

To look at jitter in DIO outputs being set in threads.

To look at noise in circuits.

Clamp ammeter probes available to look at motor current.

Must have some storage capacity to capture data and non-periodic events.

Stuff like that.

Accurate, reliable, affordable.

USB scope to reduce price? If so, must run on XP or Linux.

And of course, where to buy.

I’m curious, do you have a price range on what you’re willing to spend? Are you willing to buy used?

That can help narrow your options pretty quickly :stuck_out_tongue:

I’d avoid a USB oscilloscope, they tend to suck. If you **have to **get something cheap the DSO Nano V3 is fine for most things.

Rigol scopes are popular in the entry level market right now. They have a few low end scopes that can be easily hacked with software to get additional functionality that would typically be in scopes that cost twice as much.

Keysight released a scope to compete with the Rigol offerings just a couple of days ago.

I’ll take this chance to share my own scope, a HP/Agilent 54622D which has some extra special functionality(pardon the crap video quality)

Maybe you are lucky?


Stay away from the DSO Nano’s… they aren’t bad but you can do better.

Check out this thread from a while back:


and I’m a huge fan of the Rigol Digital Oscilloscope DS2072A. Though there might be a newer version out now.

I would not condone doing anything illegal but I will tell you that the Rigol scopes can be “unlocked” to enable CAN bus, SPI, I2C, and a few other protocols.

They also have integration with LabVIEW out of the box.

Can’t go too wrong with scopes from the original Tektronix TDS digital series (TDS 320, 420, etc.). Working ones are generally priced at less than $500 on eBay (with basic accessories). There are two and four channel varieties. If it’s showing any kind of error in self-test it should be avoided (unless you want to a repair project).

Disclaimer: I own 7.

I don’t love the more recent LCD versions (TDS 1000, TDS 2000, etc.).

I’d also voice support for some of the Rigol scopes. Last I knew, Keysight/Agilent/HP were reselling rebadged mid-range Rigols as their lower end scopes (with a very expensive Keysight sticker).

I’ll throw a +1 for the early TDS line. I have a TDS 340A and it’s pretty great. Think I payed about $100 for it on eBay and picked up the probes on Amazon. I love having the floppy drive for capturing the display and other fun stuff. I’ve also got a HP 1631D, which is a logic analyzer with a scope built in. It’s not a purpose-built scope, but it gets the job done. Plus, I found it on the sidewalk so it was free.

TL;DR: can’t go too wrong with older Tektronix or HP gear.

Also, if any scope nerds want to see the two I have you can find them on my website:

A buddy at work is having fun playing with the semi-DIY oscilliscope he bought recently.

I think it is this one SainSmart for $23.00 plu $3.00 shipping.

At that price you can hardly go wrong, but you also can’t expect some of the features more expensive ones might have (such as a case…)

Look around the bottom of the web page to see some other inexpensive models. Some of them even have cases! :wink:


You beat me to this.

Still, Keysight released their 1000 X-Series literally yesterday, and I think it would deliver a lot of bang for your buck.

Plus, as Scott included above, they are having a giveaway in March for these scopes. They are raffling off five of them every week day, as well as 2 of their 4000 Series scopes every Friday (which would be a little overkill for FRC, but it’s free, so who’s complaining?).

The new keysight 1000X scopes look great for a price point around $700.

If there’s any universities or technology schools nearby I’d recommend taking a look around. They usually start getting rid of old stock around now, or at least parts that are “”"""“broken”""""".

That being said, I’m running a BWD 842 Analog CRO which is surprisingly capable for all of the tasks you’ve mentioned, bar the memory storage (single-shot capture is even possible if you’re creative)

Been very happy with my Rigol DS2072A DSO.
I’ve had Tektronics, HP, and Lecroy DSO in the past and they all cost more and eventually I always found something less than stellar if I looked around hard enough, an issue I forgive more when my tool costs less.
Back in the mid-80s I had a 19" computer rack with 5.25" floppy drive that was a DSO (yes the whole 6’ tall rack).
I’ve used my Rigol with a Tektronix current probe that had it’s own power supply.

However, because of the currents in the CIMs exceeding 30A you’d saturate the 25MHz+ rated current probe and amplifier I was using if you measured the current merely by clamping it around a motor wire to a CIM.

Keysight makes a set of current probes that could handle the CIM DC currents at less than 2MHz but it’s about $4k.

Frankly one could just use a low value resistor designed to measure current in-line to achieve this result rather than the whole hall effect sensor with clamp around inductor design that will drive much higher cost.

A few years ago I had some mint cans I put a small Atmel Mega based DSO in such that it could drive around on the robot. Made for interesting testing however I did not use it to measure current and have since changed the front end circuit to make it much more robust.

When I CSA I usually bring a cheap older analog oscilloscope with me.
I’ve had some interesting reactions where people tell me how useless it is to use an oscilloscope in FRC.
However an oscilloscope is clearly a valuable diagnostic tool and I see many valuable uses for it in FRC.

In place of a more expensive DSO with a protocol analysis function one can also use a cheap logic analyzer with protocol decode and a really cheap, maybe even free, analog oscillscope.

A logic analyzer like this for example: https://www.saleae.com/index
There are cheap Chinese knock-offs of those if you Google around.

Unless you are using a highly refined USB oscilloscope you’ll quickly discover there are shortcomings to those designs.
I’ve worked with some nice PicoScopes but even then there are things you’ll notice if you have experience that might make you think twice. PicoScope can be found here: https://www.picotech.com/oscilloscope/2000/picoscope-2000-overview
Common issues appear such as issues capturing non-periodic events using triggers.
There are often questionable analog front ends on these devices that impact the performance of inputs.
Some of them do not have input impedances that are accurately rated and that can screw up current probe measurements in particular.
Many use sampling tricks and can’t capture raw sample data in discrete time steps such that they aren’t useful as data collectors (and this can apply to cheap dedicated DSO hardware as well - but the introduction of the USB2 limits increases the risks there’s some tricks going on in there).

Personally a concern I have with students and DSO is that students fail to learn how to operate an analog scope.
The measurement cursors and ability to get waveform shots without film is a nice feature, but you can snap a picture of an analog oscilloscope screen with a cell phone in a mount and get an image.

I’ve been very impressed with my Hantek DSO5072P for the month I’ve owned it. Tough to beat for $250.


I’ll take another vote for the Rigol DS2072A scope as well. It is amazing! Really great for price.

Also the Rigol DSA815-TG is a great spectrum analyzer as well for the price.

I was going to advocate for a Tek 465B, but in retrospect they’re heavy and the CRT is fragile. They are nonetheless awesome and can be had for under $200 in perfect condition.
At work we use PicoScopes, but they are not inexpensive.

*Here’s a weird coincidence. The day after I started this thread a friend stopped by for a visit. During the conversation, and without my asking, he said he was going to have an auction to clean out the basement, and he had an oscilloscope he had inherited. That really piqued my interest so I asked him what brand and model. He didn’t know, but he texted me a picture later that afternoon.

Delightfully nostalgic, but not quite what I had in mind :frowning:

Tis a thing of beauty, all valves as well. Would most likely need the caps replacing, but she could run again.

I hope it ends up in a good home.

I found a scan of the original manual if anyone is interested: http://bama.edebris.com/manuals/eico/460/

If you happen to find out what he would ask for it (shipping to VA included), please PM the answer to me.

Oh boy, those are the kind of scopes most guys give away for free or very cheap at ham radio flea markets (hamfests). Actually I’ve seen that exact one before. It WILL need caps replaced on it. I can guarantee that. That would make a nice boat anchor scope to add to your collection.

Another very portable nice scope I have is a Hitachi V-209. That is my portable test scope, it is definitely older but you may be able to find a very good deal on it if you look in the right places.