Author Topic: Tooltop ET120M $50 DSO  (Read 2794 times)

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Offline rhbTopic starter

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Tooltop ET120M $50 DSO
« on: November 02, 2023, 11:02:42 pm »
FWIW Out of curiosity I bought one of these:

https://www.aliexpress.us/item/3256805182059777.html

Real BW is 28 MHz both for the square wave source and the scope input measured by rise time for the square wave and adjusting the frequency of a Keysight 33622A until it dropped to the -3 dB point for the scope.

Have Fun!
Reg
 

Offline rsjsouza

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Re: Tooltop ET120M $50 DSO
« Reply #1 on: November 02, 2023, 11:46:23 pm »
Quite interesting for the price.
Vbe - vídeo blog eletrônico http://videos.vbeletronico.com

Oh, the "whys" of the datasheets... The information is there not to be an axiomatic truth, but instead each speck of data must be slowly inhaled while carefully performing a deep search inside oneself to find the true metaphysical sense...
 

Online Aldo22

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Re: Tooltop ET120M $50 DSO
« Reply #2 on: November 03, 2023, 12:20:33 am »
I think it's the same as MDS120M
 

Offline rhbTopic starter

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Re: Tooltop ET120M $50 DSO
« Reply #3 on: November 03, 2023, 04:54:44 pm »
Looks like it's the same as the MDS120M.  For value I think the Owon HDS2xxS series are much better..  I have an HDDS272S and it's really a 70 MHz DSO.  Which foir portable use is plenty of BW.

I also have a Hantek 2D42, but it's not as good.

The 120M is a bit of a puzzle.  Single channel 30 MHz with 1,10,100 & 1000 kHz square waves with a 30 MHz analog output section.  For $50 delivered.  In 1978 I paid $75 for a 5 MHz recurrent sweep Heathkit IO-18.  This is so much better it's no contest.

But consider the following T&M suite:

TT/MDS 120M DSO  $50
nanoVNA   $60
tinySA    $60
BSIDE ESR02  $30
Diode noise source  $35
DMM    $30


That's less than $300 USD for a rather complete RF T&M suite  sufficient to do most HF design tasks.  Not HPAK, but I've got those to compare to and have been quite impressed.  That's a sea change from 30 years ago when $300 wouldn't buy a decent scope.

The 120M  looks to be approximately a single channel Finirsi at less than 1/2 the price.  At  a day's minimum wage take home pay it's pretty attractive for a student/new HS graduate.

I'm busy building a 6 bay lab rack and populating it.  Once that is done I'll post more detailed measurements.

Have Fun!
Reg
 

Online Aldo22

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Re: Tooltop ET120M $50 DSO
« Reply #4 on: November 03, 2023, 05:34:38 pm »
Yes, the et120m is really cheap!
But for not much more money, the single-channel Zeeweii offers much more in every respect. Be it the 10mV vertical sensitivity or the signal generator with different waveforms, freely selectable frequency and duty cycle, video output, exportable screenshots etc.

 

Offline rhbTopic starter

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Re: Tooltop ET120M $50 DSO
« Reply #5 on: November 09, 2023, 11:23:32 pm »
I just took some time for systematic testing using using my Keysight 33622A 120 MHz AWG. 

The Tooltop ET120M is complete utter crap.  Displayed measurement values are spectacularly wrong, changing the timebase setting will make the signal disappear.  In rolling mode on the builtin arb waveforms in the 33622A the waveform will drop in amplitude as it nears the left edge of the display.  It will autoset on 120 MHz sine wave, but tell you the frequency is below 1 kHz.

It is so badly aliased that you can't believe anything on the screen.  Sometime when I'm really bored I'll take it apart and find out what the true sample rate is.

Have Fun!
Reg
 
The following users thanked this post: rsjsouza, Aldo22

Offline rsjsouza

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Re: Tooltop ET120M $50 DSO
« Reply #6 on: November 10, 2023, 03:53:20 am »
Reg, thanks for the insights. The ZT-702S (scope + DMM combo from Zotek) has a lot of aliasing past 5MHz (its specs are up to 10MHz), but at least it gives accurate measurements and waveforms up until that frequency. In comparison, it seems a more finished product: no screen blanking and no edge rolloff.

In practice I have seen myself carrying the ZT-702S more often than a plain meter when I have to do equipment diagnostics in the field - at least I can get a waveform from the various power rails and detect if capacitors are starting to go down, not to mention an easy way to trace audio or otherwise slow signals. Debugging any serial communications protocol is entirely out of the question, but there are other instruments for that. 
Vbe - vídeo blog eletrônico http://videos.vbeletronico.com

Oh, the "whys" of the datasheets... The information is there not to be an axiomatic truth, but instead each speck of data must be slowly inhaled while carefully performing a deep search inside oneself to find the true metaphysical sense...
 


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