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.