New (toy?) DSO+LCR meter - Fnirsi DSO-TC2 (june 2022)

[tunk]

Yet another small DSO, this time with a twist:
- 2.5MSPS, 200kHz bandwidth
- 2.4" screen
- 80kHz/5V PWM test signal
- LCR+transistor tester

More info e.g. here:
https://www.alibaba.com/product-detail/FNIRSI-digital-handheld-Oscilloscope-LCR-Transistor_1600516268209.html?spm=a2700.shop_plgr.89.4.3912463d8ik5w4

[ledtester]

You can also find it on aliexpress -- search for "DSO-TC2".

I wonder if they just added an atmega328p along with the stm32 mcu they use for their scope. Or if they translated the transistor tester code to run on the stm32 -- like perhaps this project:

https://github.com/mean00/stm32ComponentTester

[tautech]

Just like many of their earlier products.....capability severely hampered by its very limited sensitivity.
10mV/div = 100mV/div when using a 10x probe. 

[thm_w]

You can also find it on aliexpress -- search for "DSO-TC2".
I wonder if they just added an atmega328p along with the stm32 mcu they use for their scope. Or if they translated the transistor tester code to run on the stm32 -- like perhaps this project:

https://github.com/mean00/stm32ComponentTester

That would be hilarious, but considering its only $50, I'm thinking they cut every corner, and kept it all in the one MCU.

Ali link: https://www.aliexpress.com/item/3256804119843938.html

Transistor detector introduction:

    Automatically identify and measure various transistors, including NPN and PNP transistors, N-channel and P-channel FETs, junction FETs, diodes, dual diodes, thyristors, etc., as well as passive components such as resistors, inductors, and capacitors
    Automatic detection of pin definitions
    Automatically parse the infrared code of NEC protocol
    Other functional modes: including circuit continuity test, 0~16V input voltage measurement, PWM output, 0~24V Zener diode measurement, DS18B20 temperature sensor measurement, DHT11 temperature and humidity sensor measurement, etc.

24V zener is not available in the regular testers right?
They must have a 24V boost inside at least.

[ledtester]

24V zener is not available in the regular testers right?
They must have a 24V boost inside at least.

The TransistorTester firmware has the option for utilizing a DC-DC converter to test Zener voltages of up to 50V but a lot of hardware implementations do not include this option.

More details available on numbered page 12 of:

https://github.com/kubi48/TransistorTester-documentation/blob/main/pdftex/english/ttester.pdf

That would be hilarious, but considering its only $50, I'm thinking they cut every corner, and kept it all in the one MCU.

I'm really curious to see what's inside one of these things. They could very well be using the LGT8F328P clone chip since they seem to be available for a lot less than a real 328p. Then they would just have to figure out a way for the two MCUs to share the display.

[tunk]

A long review by TechCornerTV:
- nice case, good screen
- clunky user interface (only five buttons)
- usable bandwidth 50-100kHz
- fast component tester, no ESR measurement

[ledtester]

Towards the end of the review there is this shot of the internals:



Note the two crystals -- good evidence that there are two MCUs. The top QFP has 12 pins per side and the bottom one 16 pins per side.

[indman]

Note the two crystals -- good evidence that there are two MCUs. The top QFP has 12 pins per side and the bottom one 16 pins per side.

I'm not 100% sure, but it looks like Chinese friends ported Karl-Heinz's original code to the STM platform. This explains the high speed of the transistor tester. The big disadvantage is that the device was not taught how to measure ESR!

[Evi]

Does anybody knows what is done by long press OK in scope mode?
>> appeared in left top corner.

Manual says Fast move and nothing more.

[ledtester]

In this youtube video I found a hi-res shot of the board at 14:31:

Тестер компонентов + осциллограф FNIRSI DSO-TC2 -- ElEnBlog - блог об электронике
https://youtu.be/9ttlPFrPENE?t=14m31s



The two processor chips are:

ARM MM32F103 RET6
WCH CH32F103 C8T6

It would be interesting to know what responsibilities each MCU has.

[indman]

ARM MM32F103 RET6 - component tester
WCH CH32F103 C8T6 - oscilloscope

[ledtester]

ARM MM32F103 RET6 - component tester
WCH CH32F103 C8T6 - oscilloscope

I couldn't tell if you were serious, but it appears you are correct.

At the 3:00 mark this Russian language video asserts that the MM32F103 is responsible for the component tester and the WCH chip for the oscilloscope:

FNIRSI DSO-TC2 - осциллограф + транзистор-тестер
https://youtu.be/PXzY-pvd7OM?t=3m

At that point there is a close-up of the PCB and you can see the triple pair of 680R and 470K resistors near the top and they are connected to the MM32F103:



I'm curious what that chip in between the two MCUs is.

[indman]

I couldn't tell if you were serious, but it appears you are correct.

This became clear immediately after it was possible to read the marking of the chips.Because the CH32F103 C8T6 FNIRSI is also used in other pocket oscilloscopes.

I'm curious what that chip in between the two MCUs is.

RS2227-Analog switch
https://datasheet.lcsc.com/lcsc/2202251530_Jiangsu-RUNIC-Tech-RS2227XUTQK10_C783419.pdf

[CChin254]

Here are the chips used on the FNIRSI Digital Oscilloscope & Transistor Tester:


(Image was from Dave Jones' Flickr account.)

[snapper]

the replacement TC3 only has a 100-pin µC from which unfortunately the labeling has been removed   
But with the TC3, the designer must have run away with it. Why do you need almost 40 transistors in the measurement circuit?

[coromonadalix]

must be like an universal programmer,  switching and level shifters if there is any ??

[KungFuJosh]

I just received a DSO-TC3 today. I'm looking forward to playing with this new toy.

[Rado123]

Any clues on what MCU is actually used?

We are looking for LQFP-100, at least 512k FLASH (the firmware update file is roughly 360k), USB and at least one fast ADC and a DAC.
Most likely an ARM Cortex  or maybe much less likely a RISC V.

Today I stumbled across a Chinese company I never heard about before (https://www.nationstech.com/). Their products are available at LCSC.
Line card (https://www.nationstech.com/uploadfile/file/20220407/1649311413763814.pdf)

N32G452VEL7 (2x ADC, no OPAMP)
N32G455VEL7 (4x ADC, 4x OPAMP)
N32G457VEL7 (4x ADC, 4x OPAMP, Ethernet)

My guess would be on that one : N32G455VEL7

datasheet: (https://www.nationstech.com/uploadfile/file/20220906/1662453066413965.pdf)
manual: (https://www.nationstech.com/uploadfile/file/20220906/1662453133922816.pdf)

[KungFuJosh]

I bought the TC3 because I liked the TC1 transistor tester, and thought the extra toys were cute. Definitely a toy though.

I connected it to my scope and dmm, and the TC3 RMS is typically ~0.5V low. Sometimes only 30mV off, but usually closer to the .5V.

What I find goofy is the displayed values and the waveform don't make sense unless they're displaying it upside down. 🤷

The source is the AWG on the SDS2X04XP. 4Vpp set, 1kHz.

[snapper]

We are looking for LQFP-100

if the manufacturer has remained true to his chip supplier i suspect something like this
(see DSO-TC2) but in the end only the price will be decisive!
https://www.mindmotion.com.cn/products/mm32mcu/mm32f/

[Aldo22]

These gadgets are kind of cute, but somehow they don't make much sense imo.
Can the DSO-TC3 still not measure ESR?

I bought a DSO-TC2 a while ago and wouldn't do it again.
Well, it's relatively fast in tester mode, that's about the only advantage.

Comparing the oscilloscope part, a $62 DSO1511G is a Rolls Royce, if only for the ease of use.
An LCR-TC2 for $15, which can also measure ESR, fits in with this.
OK, that costs a bit more overall, but not that much.

Add an AN8008 and you have your first cheapo "lab" for less than $100. 

[KungFuJosh]

These gadgets are kind of cute, but somehow they don't make much sense imo.
Can the DSO-TC3 still not measure ESR?

Does accuracy matter? It's not an LCR meter, but it does show ESR. Is the number real? Great question.

I tested a UKZ2A220MPM 22uF 100V electrolytic cap.

TC3 said: 21.3uF, ESR=0.11 ohm
DE5000 said: 19.08uF, ESR=1.09 ohm
Shannon tweezers said: 19.97uF, ESR=2.7 ohm
3055X-E said 20.5uF (no ESR capability)

[KungFuJosh]

I was just messing around with the signal generator on the TC3, and it's surprisingly not that bad. The 1k 3Vpp sine wave came up clean on my SDS2504XP with 3.017Vpp, and 1.023K for the frequency. All the other forms were pretty clean, but the top of the square wave was a little goofy. The signal generator also keeps a square wave running when you're in DSO mode for probe calibration. Overall, pretty awesome for a $50 toy.

[indman]

It's not an LCR meter, but it does show ESR. Is the number real?

https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg4785317/#msg4785317
No, this figure shows the weather on Mars or something similar, but not the real ESR of the capacitor.
So far, DSO-TC3 in terms of measuring the secondary parameters of capacitors is more like a beautiful toy.

[Aldo22]

Hi KungFuJosh

Does accuracy matter? It's not an LCR meter, but it does show ESR. Is the number real? Great question.

OK, I see.
Can we say that the DSO-TC2 was at least honest by not displaying the ESR at all? 

I was just messing around with the signal generator on the TC3, and it's surprisingly not that bad. The 1k 3Vpp sine wave came up clean on my SDS2504XP with 3.017Vpp, and 1.023K for the frequency. All the other forms were pretty clean, but the top of the square wave was a little goofy. The signal generator also keeps a square wave running when you're in DSO mode for probe calibration. Overall, pretty awesome for a $50 toy.

I also have some sympathy for this little device because it looks cute, but if we're honest, it's not really good at anything.
Max 100kHz? A $3.90 DIY SG can do 1 MHz with adjustable amplitude.

A $62 DSO1511G has a 2MHz Signal Generator.

[KungFuJosh]

No, this figure shows the weather on Mars or something similar

The weather is only 0.11 ohm on Mars?? No wonder them billionaires can't resist going there.

I also have some sympathy for this little device because it looks cute, but if we're honest, it's not really good at anything.
Max 100kHz? A $3.90 DIY SG can do 1 MHz with adjustable amplitude.

A $62 DSO1511G has a 2MHz Signal Generator.

Range doesn't make a thing good or bad. The question is what is it good for. I test audio equipment, and that's almost always a 1K sine wave. So it would be perfectly acceptable for that. I don't expect it to compare with my SDG2122X, and I don't expect the scope to compare with my Siglent scope either. But as toys go for $50, it's pretty cool.

I'd say it's okay at a few things. The AWG is okay for the range I actually need. I'll probably almost never use it for that anyway. The DSO is okay for basic uses or screwing around, also won't likely use it much. I mostly bought the thing because I like the transistor tester, which appears to be at least as good or better than the TC1. The rest is just extra fun stuff.

Two things I like better about the TC3 than the TC1: 1. nicer screen, 2. last test persists on the screen instead of the device shutting itself off. That's useful if you need to record data for comparison.

My curiosity will make me try the TC3's DSO when I find something with a parasitic oscillation, just to see how it performs on something useful. Maybe won't even be able to see the PO based on the frequency range, but that won't make trying less fun. 😉

[Aldo22]

@KungFuJosh

If it helps you, then good for you.
If you have better equipment and it's just a toy for you, then good for you.

I just don't think that $50 for the TC3 is a very good investment for someone who wants cheap basic equipment, because in the end it just doesn't do enough for that money.
I wouldn't recommend it to anyone who wants basic equipment for less than $100.

Of course, it's not so expensive that you would seriously regret buying it, but there are better devices out there for just a little more money.
And honestly, I find the worst thing about the TC2/TC3 is not even the very limited bandwidth but the almost-1-button operation of the oscilloscope drives me nuts. 

[KungFuJosh]

Of course, it's not so expensive that you would seriously regret buying it, but there are better devices out there for just a little more money.
And honestly, I find the worst thing about the TC2/TC3 is not even the very limited bandwidth but the almost-1-button operation of the oscilloscope drives me nuts. 

Yeah, it's pretty goofy to operate in scope mode. It's also a little disappointing that you can't control (or I haven't bother to figure out how to control) the signal generator while using the scope mode. In scope mode it just puts out the square wave to calibrate probes.

I think it's hard to recommend many products under $100 that do most of the features. I'd say the TC1 is a much better investment for transistor testing. There are lots of similar signal generators in that price range. But I've never seen a scope I thought was really useful for less than at last $250, but personally nothing I like under $500.

As I said, for me it's just a toy. Good for me. 😉

[Aldo22]

Hi  KungFuJosh

I think it's hard to recommend many products under $100 that do most of the features. I'd say the TC1 is a much better investment for transistor testing. There are lots of similar signal generators in that price range. But I've never seen a scope I thought was really useful for less than at last $250, but personally nothing I like under $500.

Opinions differ on what a "useful" scope is. 
But we're talking about entry level / lowest budget here.

What I can tell you with certainty is that a DSO1511G is at least a 20 times better scope than the TC2/3 in every aspect for only about $10 more.
It has dedicated buttons for time base and vertical sensitivity. That alone is a relief.

Of course, it's not a $200+ scope, and it shouldn't be compared to those, and maybe the specs are a bit "optimistic", but compared to the TC2/3 it's very usable.
Check out the video from "Adrian's Digital Basement".
He simply uses it as a tool to repair the C64. The video is fun to watch.

https://www.eevblog.com/forum/testgear/dso1511e-review/msg4507981/#msg4507981

[ober]

I'm not 100% sure, but it looks like Chinese friends ported Karl-Heinz's original code to the STM platform.

This comment was about the DSO-TC2.  The DSO-TC3 also seems to have some porting effort behind it.
The results, unfortunately, are not pretty.

Here is a "10 µF" ceramic capacitor in a TC1 and in the DSO-TC3.  Note that the TC3 hallucinates an additional pin!
(You get the same hallucination about the third pin independent of where you put the actual pins.)

Apparently the DSO-TC3 measures itself...  (And note the Rds and Cg values :-)

[indman]

Apparently the DSO-TC3 measures itself...  (And note the Rds and Cg values :-)

Dear authors Markus Reschke and Karl-Heinz Kübbeler have been developing, refining and polishing the code for years, but you want the Chinese toy to work as well as the original AVR project. This will not be in the near future, porting successfully code to another platform to take into account all the subtleties and nuances of ARM is a very difficult task.

[Aldo22]

Is it true that the DSO-TC3 no longer has the PWM output up to 10MHz?
This was one of the more useful hidden features of the DSO-TC2.

[slavoy]

TC-3 has 1-100kHz PWM output @3.3V

[Aldo22]

TC-3 has 1-100kHz PWM output @3.3V

Thanks.
The TC3 seems to have a signal generator with different waveforms.
The TC2 has PWM generators in two places:
- One in the oscilloscope context. This is only capable of PWM up to 80 kHz. It works in parallel to the oscilloscope mode.
- One in the tester menu. This one can do PWM up to 10 MHz!

I didn't notice this feature for a long time, but it's quite remarkable as an add-on function for such a toy.
It seems to have been removed from the TC3, right?

Attached is a screenshot of the PWM output at 5MHz/75% duty of the TC2.
The screenshot is of course not from the oscilloscope of the TC2, which can not display this frequency range (It's from my DSO2512G)

[slavoy]

It seems to have been removed from the TC3, right?

Yep, you get only 1kHz square for the probe compensation when in scope mode.