We’ve recently seen a couple reviews of a particularly cheap oscilloscope that, among other things, doesn’t meet its advertised specs. Actually, it’s not even close. It claims to be a 100 MHz scope, and it’s got around 30 MHz of bandwidth instead. If you bought it for higher frequency work, you’d have every right to be angry. But it’s also cheap enough that, if you were on a very tight budget, and you knew its limitations beforehand, you might be tempted to buy it anyway. Or so goes one rationale.
In principle, I’m of the “buy cheap, buy twice” mindset. Some tools, especially ones that you’re liable to use a lot, make it worth your while to save up for the good stuff. (And for myself, I would absolutely put an oscilloscope in that category.) The chances that you’ll outgrow or outlive the cheaper tool and end up buying the better one eventually makes the money spent on the cheaper tool simply wasted.
But that’s not always the case either, and that’s where you have to know yourself. If you’re only going to use it a couple times, and it’s not super critical, maybe it’s fine to get the cheap stuff. Or if you know you’re going to break it in the process of learning anyway, maybe it’s a shame to put the gold-plated version into your noob hands. Or maybe you simply don’t know if an oscilloscope is for you. It’s possible!
And you can mix and match. I just recently bought tools for changing our car’s tires. It included a dirt-cheap pneumatic jack and an expensive torque wrench. My logic? The jack is relatively easy to make functional, and the specs are so wildly in excess of what I need that even if it’s all lies, it’ll probably suffice. The torque wrench, on the other hand, is a bit of a precision instrument, and it’s pretty important that the bolts are socked up tight enough. I don’t want the wheels rolling off as I drive down the road.
Point is, I can see both sides of the argument. And in the specific case of the ’scope, the cheapo one can also be battery powered, which gives it a bit of a niche functionality when probing live-ground circuits. Still, if you’re marginally ’scope-curious, I’d say save up your pennies for something at least mid-market. (Rigol? Used Agilent or Tek?)
But isn’t it cool that we have so many choices? Where do you buy cheap? Where won’t you?
Eliot are you mad, using an unearthed scope or a live mains circuit is asking to die!
Wear an all-rubber suit and you’ll be fine. Just dont forget to post the video.
Next up on shark channel…
I’m getting sarcastic vibes here, but I’ll bite anyway. :)
I’m pretty careful to check power is off, set probes/clamps up, pull my hands off, and only then turn the power back on. Hell, sometimes I even unplug instead of just flipping a switch, b/c then you’re _really_ sure.
And when it’s off in the basement on the breaker, I’ll still test it with the meter before I put my fingers anywhere. I live in 230 V AC land now, and I have a wife and kid. :)
On lifting grounds: https://hackaday.com/2017/03/01/the-importance-of-electrical-safety/ and the articles linked therein.
(thumbs up!)
No sarcasm just brown stuff in my boots!
Have a look at the video from the “Learn Electronics repair” channel. @35:40 he connects the GND lead of the fnirsi to mains voltage, and @36:50 he is adjusting the scope knobs about 10mm away from the other (now live) BNC connectors without the slightest concern.
With floating scope, there is a big chance to float straight into Valhalla.
If you’re going to do a lot of that, an isolation transformer would help.
Some variacs also have isolation, and have the advantage that after you replace the blown fuse you can run up the voltage slowly while measuring things and potentially see where the problems are.
I’m a big fan of getting damaged and/or non-working electronics on eBay, hamfests, and dumpsters and simply trying to fix them. The amount of knowledge you get from looking up the specs, circuits, and datasheets for the ICs can be considerable.
(I grabbed a broken HP3577A VNA from eBay and fixed the broken fan and it’s fine, grabbed a non-working 50″ plasma TV from craigslist and replaced the $0.50 fuse and have been using it daily for years.)
Just taking things apart can teach you a lot about how things work.
“Just taking things apart can teach you a lot about how things work.”
Doctors can relate.
(chuckle!)
Paging Dr. Vivian Section, Dr. Vivi Section please report to the Scream Room…
Some variacs are isolated? That seems like something I could use. Especially since it probably has a larger core, and it of course must have an independent primary winding – so if it took the opportunity to put in a step up or down, you could combine a lot of functions into a smaller space and weight. Can you link an example, or was it actually two transformers in a trench coat?
I have an isolation xfrmr that I attached to a variable xfrmr around 40 years ago.
But I haven’t used it for decades, partly because it might only handle 100 Watts max.
My understanding is that isolation transformers are essentially “two transformers in a trench coat” but with extra precautions to make sure there’s no capacitive coupling between the two sides as well.
I’ve always wanted one, never actually needed one. But when I do finally need one, or if I see one at a surplus shop….
If I don’t have a scope with an (expensive) differential input, floating is sometimes the only option. Other times floating is necessary to avoid problems with a noisy ground or a ground loop. I’ve never had to float a scope to mains voltage, and I don’t think I’d ever try.
The majority of two channel scopes have an option to show you the sun/difference between the two channels, no need to float. I accept however that you can’t then see a second channel, a small price to pay for safety. I absolutely agree with you it is not often that you should consider floating scope and to be clear, for my sins, I have done it!
good luck using that to see <1V ripple over mains with 8 bit scope
Buy once, cry once. Words to live by.
Don’t get too carried away though. No need to buy the best if you’re only going to use it once, eg you buy the big set of cheap drill bits knowing you’ll never use most of them (but nice to have just in case), and spend your money once you figure out what you do actually use.
Generally I’m a fan of cheap tools and not-so-cheap sharp bits rather than vice-versa.
A friend on mine had an very wise motto.
It wasn’t just the classic “buy cheap, buy twice” but “I’m too poor for bad tools!”
Which means that said friends can’t afford bad tools. The income depends on the work, which is impossible if the tools don’t cut it.
I think that’s something to consider.
Some people think they’re so smart because they save a few cents.
But in reality, it’s not very smart to rely on something that’s not reliable.
Just think of a hiker who’s not willing to invest in a quality equipment..
Okay, to be fair, there’s nothing wrong by buying inferior things just for fun. It’s often interesting to find out how far you can get with “a toy”.
One approach I’ve seen is to buy the cheapest to see it it’s useful / you like it etc and then go and get the best you can.
If you look at what people like Project Farm do, there are always a bunch of “best value” tools, sitting neatly between the absolute cheapest and the vastly overpriced. Occasionally there’s not much of a gap between cheapest & best.
Project Fzrm product reviews are the best!
Ever trash a screw head because you used a cheap screwdriver? Then got an expensive screwdriver to do the job properly, only to realise trashing the screw head in the first place significantly reduced your chances of ever getting it out…. Then comes the left-handed drill bits and screw extractor.
I’ve done it (although I was lucky and my left-hand drill bit grabbed and removed the screw, so I didn’t have to go the extractor route). Would have been hard to do seeing as I was left-hand drilling a 1mm hole…
And that’s why when you buy the cheap stuff, you need to use it carefully any time something might break, or be prepared for what happens if it does. Let the people with the expensive stuff be careless and let their tools do the work for them.
Not every hobbyist mucking around with Arduinos needs a $5k Tek scope though… even a really crappy one will do for a bit of basic development & debug.
Much like not everyone changing a tyre or doing their own oil filter needs a $200 Snap-On wrench.
I tend to do as Bob says below – buy a cheap-ish version of something, see if it’s useful and upgrade if/when it breaks or a job demands it.
I also factor in the cost of the alternative – if I have to buy a tool for $100 to do a job, but I would be charged $250 by a professional to do that job, that’s still a good deal even if it’s a “one time” sort of tool.
Reciprocating saw, for rough work, not a precision tool. I expect to use it only occaisonally. Harbor Freight!
Dovetail saw, precision work, I want to make a lot of dovetailed boxes: Lie-Nielsen!
I once bought a Chinese crowbar from Harbor Freight. It looked beefy … maybe 5/8″ diameter and about 18″ long. I was using it to remove some fairly large nails that wouldn’t budge, and I literally bent the crowbar with only the force of my arms. On another occasion I bought a worm gear winch from them rated for 2,000 pounds. While trying to lift a 300 pound load the worm gear immediately started eating away at the toothed gear. I greased the toothed gear every turn and by the time I had raised the load a few feet fully half the width of each tooth was gone.
Harbor Freight…for tools you only intend to use once.
I wouldn’t trust anything they sell, but sometimes you just need something that will do enough of the job to get you moving, and that’s what you get at HF
People buy HF small engines that are clones of Honda and other brands because they run just as well, all the hop up parts for the name brands either just fit or need very minor modifications – and the price for the engine is far less so if it blows up on the track it’s much less of a loss.
That sub-brand is one of the few things I’ve bought that moves at harbor freight, and even then they’re so well thought of on the basis of the 200cc engines, not necessarily all the others in the lineup. Other products at HF that aren’t dead simple and are among the cheapest available are basic power tools like their angle grinders. When I looked, their cheap ones were something like 60% of the power of the same price amazon one, which also looked better made and had a three position handle. Or for brick and mortar, sometimes walmart is close. That general impression is what I have for most of their products – they’re paradoxically expensive, because even if you buy the cheapest one, you might not save any money versus the cheapest option elsewhere or versus a worn out version bought secondhand, but it won’t work as well so you might need to buy something else to finish the job.
My HF crowbars are going strong at decades old. It’s a good example of the kind of thing to buy there.
If you bent 5/8” of something with 18” of lever is wasn’t steal. Was it magnetic?
It may be whatever came out of that portion of the scrap melting furnace load that day. It seems to me that it takes expensive furnace time and power to get a good consistent melt, and good quality, consistent materials in to get consistent top quality materials out.
You can often pass the cheap tool off to a friend who either doesn’t need a good tool, or isn’t sure if it’s for them yet. In which case no loss.
Hm, yes. As long as it’s not deathly cheap. Otherwise, the “loss” might be said friend. I’m thinking of China products here, some are lethal. Like cheap power supplies without any regulation and fuses.
PS: There’s the ethical point, too. Do you tell saud friend that you give him/her a low-quality product? I mean, if you don’t, what kind of friend does that make you?
I established the oposite theory. I’d rather pass a pro tool that my friends can’t break rather than a chep one that they will (god’s know how, everytime) break.
I also only pass on when they work in my house :)
Yeah nah.
So you think a $500 will survive being loaned out while a $20 won’t.
I can see an attitude change in your future.
I aim to get something OK, but not get too carried away. Doesn’t always happen :)
Things that need to be study or will get abused (like a bench vise), get something decently sized and name brand. You can usually sell it easily if needed too.
Something that just needs to be functional like a set of spanners, avoid the junk but don’t get mad with it either.
Stuff that will get destroyed or lost no matter what you do, just by whatever. Brushes, cold chisels, a cheap set of screwdrivers you can destroy.
However if there are tasks that constantly annoy the crap out of you, or can make or break a project, then get the right tool. Two things that come to mind for me are a decent tape measure (Stanley FatMax), and a proper finish nailer.
It’s very easy to overspend of tools, so keep it real
Oh, please not again.
This is now the third hackaday article in a row about this fnirsi scam, and it really does not deserve this attention.
And yes, I call it a scam because it it blatantly lying about it’s spec’s and pretends to be what it isn’t.
It looks good, has a big TFT, nice buttons, and it looks like a decent scope on the outside, but inside there is just barely enough electronics to not be recognised as the scam it is by inexperienced people.
Both hantek and Instek have handheld DSO’s that are safe to use on mains voltages and for the same price as the fnirsi scam. Disadvantages are the small TFT and more cumbersome operation with push buttons. but at least they do not lie in their specifications, have the mains isolation and are decent products.
If you want an oscilloscope in a “big” form factor, then save up a bit more and buy something decent.
I would even recommend the Jye Teck DSO150 over the fnirsi. It is also a toy, but for EUR30 the price is right, and although it is very limitited in capability, you can use it to show some PWM signals from your adruino. I would even have liked this thing if the triggering was better. And as a last resort, you can always repurpose it as a generic STM32 development platform with TFT.
Things tend to get better over time, so sometimes it is better to get what you need now and upgrade later. There is little point paying extra for what you might need, when chances are a few years down the line, something better will be available that you would like but you already spent so much on the kit you have you can’t justify the new purchase. I’d rather buy a cheap scope that I can work with and then buy a better one a few years later than be stuck with a 10 year old model because I paid thousands for it.
For some people it’s difference between having tool and not having it at all. In second case you can’t do anything and having a tool is infinitely better.
In general, yes, but not always.
Let’s imagine a knife, for example.
Having none is better than having a cheap one.
A quality, sharp knife causes clean cuts, lays safely in the hand and won’t break off.
If you hurt yourself with such a knife, you may cut yourself or loose a finger at worst.
However, since the cut is clean, the finger is still intact and could be re-attached in a hospital
In sane situation, with a cheak knife, you may also cut a finger, but the cut won’t be clean, maybe, rather looking as if it was ripped of. Then your chances of a successful operation in hospital are much lower.
Well, no, you’ll still try to cut something if you don’t have a knife. You might try using a box cutter, or scissors, or something, and that may not go well either.
Sure, a Rigol isn’t a Tek or HP scope from yesteryear, but consider that you get trace storage, portability, flash cards instead of a Polaroid camera for screen shots, 4 traces, and even if none of it’s perfect, the plusses start to add up pretty fast.
Something in the power supply of my trusty Tek 465 let off some smoke, and I bought a 4-channel 200 MHz Rigol to replace it. I’m happy with my decision.
Oh, and I paid $2k for the 465 in 1978. The Rigol cost me about 1/2 that.
$2000 from ’78 is $9,305.61 today money, Rigol DS7024 is $3700 (4ch,200MHz,10Gs)
hence you paid 39.76%, for double the specs.
How is current market price of 45years experience of actual using the scope?
Even in the last 5 years I’ve watched the price of scopes stay the same but the features go up and up.
What I used to spend on a basic 100 MHz B&W Tek gets me a 200 MHz Keysight with colour screen and mixed-signal analysis
For me personally I decided some time ago : If I use a tool every day – it should be a good quality to allow me working reliably. That’s why I have an official JLINK (yeh, but to be fair I haven’t bought it – I insisted that company bought it for developers) and good multimeter. But for the tools that I use 2/3 times a year – a cheap thing will do just fine.
As for isolation on this scope – I’m fairly sure I’ve used higher priced models where I needed to connect oscilloscope to socket without ground to work on some PCBs.
Or you could have, you know, bought a cheap, simple beam torque wrench and had excellent accuracy and repeatability with some practice.
They can also convey more information in use. For example you have a 30ftlb torque spec, tighten it up a bit, 15lb, nother quarter turn, 20lb, nother quarter, 25lb, nother quarter 25lb, what? something hinky… Sometimes you can find out you’ve stretched or about to snap the head off your faster before it breaks off flush and you do the 4 hour rigmarole of drilling it, breaking off an ez-out, drilling that out…
*fastener
“dirt-cheap pneumatic jack and an expensive torque wrench…”
Respectfully, in your use case I would have recommended going with the opposite – a decent jack and a cheap torque wrench (or none). I’ve going on 3 decades of working on pretty much anything that with wheels – everything from simple tire changes and brake jobs to transmission swaps and engine rebuilds. I’m not a professional mechanic but I’ve done enough to know what equipment you really need to have and which tools are niceties best borrowed or doing without on jobs you’re not likely to be doing frequently.
The hydraulic jack, well that’s a safety issue and you can’t really put a price on that. I’m not saying you should get a nice low profile, aluminum unit but I wouldn’t trust my life to the cheapest HF model either. Remember, it wasn’t that long ago that HF issued a recall and free replacement for millions of jack stands that were collapsing when supporting the weight of a vehicle.
The torque wrench is honestly overkill for simple wheel and tire swap. Yes, I know lug nuts have a specified torque rating but if you simply use a standard lug wrench like the one included with your vehicle in a criss cross torque pattern and get the lug nuts “tight” then your wheels aren’t going to fall off and you won’t snap off any wheel studs. If you just an impact wrench or a cheater bar then ya, you can get them too tight and damage things. But that’s not going to happen if you’re using just the standard lug wrench and not going crazy with it. While I can appreciate the attention to accuracy and adherence to factory specifications, changing a wheel isn’t rebuilding an engine. Precision isn’t vital here. If a torque wrench was necessary to change a tire and using a standard lug wrench presented a safety issue then vehicle manufacturers would include a torque wrench in their tire change kits or not include any tools and tell owners they needed to tow their vehicle to a service center in case of a flat tire. Also, the vast majority of tire centers don’t use torque wrenches (even if they claim to). Most of the time they’re using impact wrenches and torque sticks which, as other commenters have pointed out, are notoriously inaccurate.
Just my 2 cents. Now watch my wheels fall off tomorrow.
Fair enough. My guess is that if the jack fails, it’s super unlikely to get me. I’m not under the car, just changing the wheels. But I get it, and it might trash the brake rotor or something. I have respect for it, still.
The torque wrench has a nice long handle and makes it about 10x more pleasant than using the crap lug wrench that came with the car. I could have saved $40 there, though, and bought a crappier one, and I’m glad that I didn’t just based on how nice it is to use. Even if it’s something I only do 2x / year.
Things that you need repeatability, accuracy, and hopefully long life – buy good ones.
Things that don’t matter much, get cheap but usable.
For example, I buy pretty cheap hand battery electric drills, but have a very good drill press..
When doing tire changes, be aware that the torque sticks made for air impact wrenches should not be used with electric (corded or cordless) impact wrenches.
A torque stick is an extension that’s thin in the middle, designed to twist and rebound to limit the amount of torque the impact wrench can apply to the lug nuts.
They rely on the time between impacts to rebound so they can twist again with the next hit. Electric impact wrenches hit much faster than air impact wrenches, so fast that the torque stick cannot rebound fully, or at all. They “wind up” then act like a normal extension, delivering all the torque the wrench can apply, making the nuts too tight, warping brake rotors, or even snapping off studs.
Thanks!
I was unaware of the difference air v. electric could make on the torque sticks.
Torque sticks aren’t particularly good on air tools, either, because there is no one standard for IPM, hammer mass, anvil mass, etc.. Even on the same air impact wrench, the same stock tends not to be particularly repeatable or accurate.
Erm, stick*
Sometimes you are not sure what you want out of a tool until you’ve spent a bit of time using one for the things you’re going to use one for.
This can result in a waste of money if you either buy top of the line and it has 50 features you do not use, or buy top of the line in quality feature light version and find there are 3 very essential features you should have bought. The bargain basement model could have let you figure this out at minimal cost.
The high-end models do likely have warranty, however and can be given back to the seller in most cases. If you buy from a professional with a reputation, you will be treated much better than, say, as if you were a cheap consumer buying at Walmart.
To each, their own
There’s a lot of snobby attitude here in the comments around tools, and it’s a pretty silly one too. Comparing a <$500 instrument to one costing thousands and yes, unsurprisingly the cheap instrument doesn't perform as well. There's a whole hipsterish attitude around "having to have" expensive tools, it smacks of the coffee nerds that make outrageous claims about being able to tell if the water is off by a couple of degrees and whether you stirred it clockwise or counter-clockwise.
The original video that Richard from Learn Electronics Repair responded to typified it, and the snotty responses to Richard's video do too: Richard didn't say the cheap fnirsi scope outperformed or even equalled the Rigol, what he said was *it was good enough to do basic repair work with*. No more, no less. It can show you if a switching power supply PWM is working, it can tell you if a clock is pulsing. It's not going to analyse your logic signals, it doesn't have a great capture depth and it doesn't have a fantastic resolution, but if you're doing that kind of basic repair, do you need it?
I'm personally just learning about electronics, my background is in software and I thought it would be a good idea to understand how the underlying technology works inside a processor and around the computer in general. A cheap scope will do the job to visualise some signals and get a handle on what's going on. I got myself a cheap Hantek scope. It's a cheap instrument, it cost me under $300 AUD so I know it isn't going to compare to a multiple-thousand-dollar instrument and I don't expect it to. I picked the Hantek because there's a community of people publishing mods for it so I figured it could maybe grow with me as my skills improve.
The haughty, exclusionary attitude, and the frankly unwarranted sense of adequacy on show in the hackaday comments is awful. I'm in a group that's starting up a new maker space in our city which is sorely under-served in that area, and this is absolutely the attitude we don't want to attract.
Your comments are spot on.
I’ve been reading Hackaday for many years, and trolls are scarce, but there are an awful lot of nay-sayers and some who just like to pick on the author’s spelling and grammar. The quality of the articles varies a lot too.
Hackaday has a global audience, and no restrictions on who can comment. I’ve been through phases where I’m all for commenting, and others where my attitude is ‘why even bother’.
Nowdays I skim articles, read them if they look interesting, and if I’m really interested, do my own deeper research. For me, hackaday has more become a “tip line”.
So what you’re saying is “you get what you pay for”…
“I’m in a group that’s starting up a new maker space in our city which is sorely under-served in that area, and this is absolutely the attitude we don’t want to attract.”
Um, if you’re poor, can’t you ask for public funds? Or ask for donations? Maybe there’s second-hand equipment available that you can get from your community/city?
Old, WW2 era oscilloscopes sitting in abandoned/closed school buildings may still be working or could be fixed. Even if they’re old, they may have much better built-quality than those under ~300 AUD models.
It’s just an idea, of course. No idea how bad the local situation really is. 🤷♂️
I can’t remember having regret over buying a cheap tool. I have been disappointed when cheap tools gave out, some years and amount of wear after buying one, but in my perception they have usually done 5 to 10 times their money’s worth in duty. In some cases I have replaced the broken/worn cheap tool with the exact same cheap tool. That’s when the price progression is something like $20 to $500+, kill cheap one every 5 years and I’m gonna have to get 125 years out of the good one to match it.
I can remember being pissed off at the fragility of some more expensive tools, drill bits are a particular minefield… seems like utilitarian packed midrange is usually safer, the super cheap are useless, and some of what seem high end are the super cheap in a pretty box with shiny anodizing or something. I’ve broken precisely two ratchet wrenches, one a made in china budget special after owning it a decade or so with a decent amount of use, the other a Snap-On after owning it months. (In theory the latter is replaceable free, but I don’t have a dealer relationship.)
Though there are cheap tools that are too cheap, like dollar store screwdrivers made out of some grungy grey metal and not even having their heads shaped properly. So you should probably select cheap tools from a store that is actually in the tool business at minimum. When you are in a tool store you can make visual comparisons that guide you some.
When you are inexperienced and clumsy you break tools though. I swear it’s a psychological thing in some people, hatred of their previous noob, green self, that broke tools, associating it with the cheap tools, because they can’t rationalise being that inept before. Tools will sometimes get broken whatever. I say though that you need that experience, break cheap stuff, you get a personal sense of where your money is best spent. Some tools need an action that some people fight, some people flow with it, just the tool style suits one and not another. If it’s the only style in that type of tool, the flow people might only need one cheap one ever, the fight people might break a dozen, going up the price range continually and cursing the cheapness of all previously owned ones.
I have no problem with using cheap tools. If you only use it a couple of hours per year, who cares if the tool’s MTBF is only dozens of hours?
But if these guys are selling a scope and claiming it’s a 100MHz scope when it isn’t then that’s fraud. It’s a lie. Just tell customers the real specs. As we have seen from all these Hackaday stories, plenty of people will still buy one. Personally, I won’t give this arseholes a cent. There are plenty of cool cheap gizmos out there that aren’t sold by liars.
Yeah nah.
So you think a $500 will survive being loaned out while a $20 won’t.
I can see an attitude change in your future.
For HF tools I think in terms of material quality: avoid anything that depends on high quality materials, because they won’t be.
Hard, tough steel is difficult and expensive to make and machine, however it’s cheap to make and form soft mild steel. I toss HF nuts and bolts (the threads strip) and get Grade 3 to 8, depending.
Steel can be hardened easily if you don’t mind it becoming glass brittle: I don’t buy small import drills (1/8″ import in an electric hand drill lasted about 1.5 holes, while I still have most of the bits in a Craftsman 13 piece set bought around 1975), however for e.g. 1″ being used in a fractional horsepower drill press, the material stress is low.
Assume that their steel is whatever came out of that portion of the scrap metal melt that day; I understand that plumbers run into pipe threading die damage from pieces of broken carbide tooling inserts in import steel pipe. It would cost expensive furnace time, power and ore / clean scrap to get a consistent full melt, and (a guess at their perspective) why do that for crazy rich people in another country when there’s money to be made and they’re not too friendly with your country to start with?