Electronics > Beginners

Oscilloscopes and cheap

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paulca:
No.  Oscilloscope + cheap = no.

I have ignored everyone telling me to spend money on the OSC and don't buy cheap.

I have ignored them 3 times and bought 3 scopes.  If I had of listened to them, waited, saved and bought a £500 scope, rather than 3 or 4 £100 scopes I still be better off.

Mistake one:
It's cheap, it says 50Mhz, if it does 25Mhz I'm fine.   Reality:  If it says 50Mhz and it's cheap, expect 5Mhz clear, 10Mhz barely usable and 20Mhz+ garbage.

Mistake two:
I only need to look at 1Mhz or 10Mhz I don't need RF non-sense!  A 20Mhz scope is fine.    Reality:  Your very next project needs 24Mhz to look at a high speed SPI interface.

Even if you get that 20Mhz and it is 20Mhz... you will grow out of it.  I now need to "see" 24mbit/s and 48mbit/s SPI communications.  At the current leading edge of the maker space, TFT screens close to HD and mobile screens from 10 years ago are now common on a breadboard.  ESP32s, STM32s are replacing Arduinos.  SPI and I2C coms on our breadboards are no longer running at 500Khz or 1MBit, but 25 or 50Mbit.... or higher.  20Mhz is useless.

The last scope I bought, after giving up electronics and wanting to get back in and not doing research first... was 100Mhz.  Yeapook.  ADS1014D,.  "100Mhz".  Nope.  It will do WS2812 1MHz perfectly.  3Mbit/s SPI fine..   Give it 24MBit/s SPI and it shows glitching offset sine waves and it's triggers and trace positions are messed up with DC offset, phase and attenuation.  Not to mention rendering artefacts due to software bugs.

If you are really new, just don't buy a scope.... or don't spent more than £50 on a "play" scope.

When you aren't "really new" and want to know why certain projects don't work, LISTEN TO WHAT THEY SAY!  Don't go a little higher in ££.  Go for the base, entry level, scope that has been reviewed, tested and does what you need now and what you will probably need soon.   It will save you time and money in the long run.

So even thought I bought a "This will work fine" scope a few months back.... I STILL need to buy a £500 rigol to debug my current project.

Spend the $50 on the "toy scope", play with it, sure. 

Realise the limitations and the problems with those devices.... then save money and wait... save.... wait for a sale/bargain and buy that Rigol or Keysight (etc) entry level scope which claims to be 100Mhz for £500, which will do far, far better than that £250 AliExpress 0.5GHz scope ... in the real word... measuring even 96MHz signals.

Ground_Loop:
Maybe $800 really isn't too much for a hobbyist scope.  ;D

CaptDon:
Maybe don't buy bogus chinesium trash 'looks like the big name brand' garbage!!! Nothing wrong with dirt cheap Tek gear!! Pure analog stuff is o.k., 2215 etc. can be had in working condition with right-of-return warranty cheap enough. The Tek lunchbox scopes are very nice but more pricey. I paid $500.00 for a Tek TDS2004B and I love it!!! It can be hacked (with much effort) out to I believe 200Mhz. I picked up a TDS644B 500Mhz 4 channel color scope from the dumpster at work. The VGA output was working but the internal screen was blank. All it needed was a new crystal. The old one wouldn't oscillate. $5.00 fix for a scope worth over $1000.00  I generally rely on my analog scopes for most projects and repairs. The TDS644B rarely sees use and mainly for very transient signals or glitch detecting which it can do very well. No chinameese shit for my lab!! The reason I selected the TDS2004B was because a local manufacturer had nearly 100 of the similar models in daily use and only one ever failed in years of use!!

bdunham7:

--- Quote from: CaptDon on November 27, 2022, 09:32:53 pm --- No chinameese shit for my lab!!

--- End quote ---

I'm sorry, but I just had to.   >:D

Doctorandus_P:
Aye, indeed.

If you're really on a tight budget, you can get a 2 channel scope for around EUR300, But I consider an oscilloscope a long term investment and would much rather go for the EUR 500 scope (With More channels, More bandwidth, More Memory, Faster acquisition rate, Ethernet, and lots of other stuff...

With a bit of luck it will last you 20 years, but even if it lasts only 50 years, that's still only EUR 50 per year.

I don't agree much with this though:

--- Quote from: paulca on November 24, 2022, 08:26:45 pm ---Spend the $50 on the "toy scope", play with it, sure. 

--- End quote ---
The trouble with that is that a lot of "beginners" are not able to recognize the limitations of their toy, nor interpret the distorted waveforms for what they are. On top of that, the input section of those those toys is often so bad that it's quite easy to damage them. The (quite old) DS1052E I have says on it's front panel that it's rated for 300Vrms, and normally it's used with a 10:1 probe and pretty much the only way to damage it is by putting lots of current through the ground lead.

On a side note:
I always wondered why the GND lead of oscilloscopes do not have built in fuses. You could make one yourself by just inserting a fuse in the "extra" ground wire with crocodile beak that all probes have. This may worsen HF performance, but for lots of measurements it's good enough and it may save your scope.

--------------
A long time ago, when I was young, I tried to measure how much current a wall socket could deliver into my DMM.
It did not work anymore after that, or, at least I thought so. The meter itself was not fused, but after some time I discovered that the copper of the test leads themselves had fused open, and the test leads were only held together by the plastic.

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