$20 LCR ESR Transistor checker project

[Richard Crowley]

To be fair the use of the term "function generator" was introduced by a user, and none of the Ebay sellers appear to claim any sort of "function generator" feature.  The latest firmware revision appears to have frequency-controllable square wave generation, and @madires speculated about using an additional (external) low-pass filter to generate other wave shapes.

[paulie]

Yea, its unfortunate that bad terminology catches on so easily.

And it's true the Ebay sellers are more honest in their description of this particular product. What I was referring to was them calling NE555 boards and the like "function generators". Makes it very difficult to locate actual function generators which may not show up for many pages later. Also really aggravating when they call things like cheap OOK rx "super-heterodyne". Totally fraudulent and again makes it impossible to tell what is what.

BTW unlikely a square wave can be converted into anything useable with a filter. At least not over any useful range or circuit less complicated than an op amp or dds based generator. Speaking of which I think dedicating a few pins to general purpose SPI bus would make it very easy to implement a high performance AD9850 or AD9833 generator (12mhz!) for couple dollars with very few parts.

It would also be nice to add an LM311 for nanohenry and pf capability. Kinda like those Ebay cheapo testers that have extreme accuracy. Specially considering the comparator circuit is also very simple and costs pennies.

[Richard Crowley]

But description "inflation" and misrepresentation is a time-honored tradition on Ebay.  It happens in all categories, not just electronics.  One must develop a high degree of "Ebay-fu" to find what you are really looking for, and filter out the "commercial puffery" and downright misinformation from the sellers.  And, of course many of the sellers having a tenuous grasp of the English language doesn't help, either.

And remember that just as there is the "$20 LCR/diode/transistor tester", there are similar products which actually ARE function generators.  For example...

"2014 Newest DDS Function Signal Generator Module Board Sine Square Sawtooth"
http://www.ebay.com/itm/2014-Newest-DDS-Function-Signal-Generator-Module-Board-Sine-Square-Sawtooth-/221636591065


And many others........

[madires]

Thanks. Although unable to get latest versions working I am very happy with the original firmware and greatly appreciate the effort you put into this. But a little disappointed to see the term "function generator" used here which at the least would generally include triangle or sine.. This kind of stretching might be expected from Ebay chinese liars but IMO better to refer to it as "square wave generator" or "signal generator" to not get peoples hopes up. Anyway, thanks again for the wonderful design. It proved to be an invaluable tool here.

I was referencing another user, but I understand you. Just to make things clear, the k-firmware uses the term "Frequency Generator" and the m-firmware uses "Signal Generator". But I'll change it to "Square Wave Signal Generator" in the m-firmware to be absolutely clear.

[madires]

BTW unlikely a square wave can be converted into anything useable with a filter. At least not over any useful range or circuit less complicated than an op amp or dds based generator. Speaking of which I think dedicating a few pins to general purpose SPI bus would make it very easy to implement a high performance AD9850 or AD9833 generator (125mhz!) for couple dollars with very few parts.

No, the idea is to use some math plus PWM to create the signal. The purpose of the low-pass filter should be obvious by now

[paulie]

Oh yes, that makes much more sense. I was thrown off by Richards mention of "external filter". And IMO "Frequency Generator" and "Signal Generator" are perfectly accurate for square wave so no need to change that. I was just hoping we posters could avoid the "f" word (LOL) for square only.

And BTW in addition to the LC meter posted I do have one of those Atmega16 based function generators in Richards link. It's hard to believe you can actually buy those units fully assembled for 10 bucks or so. And can attest from experience they both perform even better than expected. Along with the semiconductor tester here it's hard to believe anything else would be needed by the average hobbyist or even most professionals. Modern marvels, specially considering what these things cost!

I will however continue to pine away for all these in one compact hand held unit. Maybe DMM type case. I know this can be done because a lot of the circuitry is common all 3 devices and source is available for many different platforms.  Maybe one day (or year) I will roll up my sleeves and give it a try.

[pmsr]

Does anyone know if the LCR-T5 version on Ebay is the same as the LCR-T4, just with a case? Are there other differences? Thinking of ordering this one and having a go at Tom666's v1.12k r453 EN firmware on it.

/Pedro

[Gyro]

No it's certainly a different PCB as it has the Lipo charger circuit and boost regulator on the back - there's a photo of the PCB somewhere. It looks as if the LCD aspect ratio is different too, which would be a s/w compatibility issue if so.

The T4 in a case is this one (not sure if there are any others):

http://www.ebay.co.uk/itm/Pocketable-12864-Transistor-Tester-Capacitance-ESR-Diode-Triode-Triac-MOS-Meter-/261548717202?pt=LH_DefaultDomain_3&hash=item3ce584b492

[Electro Fan]

Gixy you can find all the acronyms with diagrams here
http://www.onsemi.com/pub_link/Collateral/AN1628-D.PDF

+1 for the article. Thx!

[pmsr]

The T4 in a case is this one (not sure if there are any others):

http://www.ebay.co.uk/itm/Pocketable-12864-Transistor-Tester-Capacitance-ESR-Diode-Triode-Triac-MOS-Meter-/261548717202?pt=LH_DefaultDomain_3&hash=item3ce584b492

Thanks, Gyro. I can see now it is the same as the one on 91make.taobao.com, right down to the "multifuction" spelling error. Ordering it and will post pictures when I receive it.

/Pedro

[Gyro]

@pmsr  You're welcome it seems you can tell a lot from the spellings  for instance the Fish888 based ones have "unknow component".

@Tom666  Many thanks for posting the V1.12k software for the T4. Any chance that you have a backup of the original T4 V2.07 in case I need to go back for the easier (read LARGE  ) graphics?

[tom666]

@Tom666  Many thanks for posting the V1.12k software for the T4. Any chance that you have a backup of the original T4 V2.07 in case I need to go back for the easier (read LARGE  ) graphics?

I like to help A backup of the original firmware found in the posts by "samnmax".

[Gyro]

Great, thanks, I missed that one. 

[yo0]

hello, a bit offtopic, anybody have the lcr-t4 with plastic case?, can share the parts and measures of the plastic case needed for replicate it? i have no see the case alone for sale on the net.

thank you in advance.

best regards.

Pio

[tom666]

Although it is not a Chinese box for LCR-T4, but can serve as inspiration
- Case for LCR-T4 Component Tester
- Case for LCR-T4 Component Tester
- Case for LCR-T3 Component Tester
&
- Others

[Gyro]

Wow, nice case design! - 3d printed I assume 

Yes, I took the easy route of buying a T4 in the plastic (plexiglass?) case. I don't think I'd try to replicate it as it's all held together with tabs and slots - quite a precision job, even the display window is flush fitted with no visible glue line. No machining marks visible. Also the side panels taper with bottom thinner than the top. Top, bottom and T4 pcb are held by threaded brass spacers, again close tolerance. Not sure how much the tooling would have cost considering so few listings on ebay.

Anyway, photo attached. You can just see the small input protection relay below the zif socket (Needs 'the battery at bottom variant' to allow space - 2 types are listed on ebay). I have also added a small Off button top left of the yellow one to turn off immediately without waiting for the timeout - useful in 1-3 C/esr and R/L continuous measuring modes.

@tom666 As you can see, new 1.12k s/w loaded, nice bold text and added functions. No need to worry about the old backup now.  Thanks

[yo0]

Thank you very much for the very interesting responses

Best regards.

Pio

[eas]

Wow, nice case design! - 3d printed I assume 

Yes, I took the easy route of buying a T4 in the plastic (plexiglass?) case. I don't think I'd try to replicate it as it's all held together with tabs and slots - quite a precision job, even the display window is flush fitted with no visible glue line. No machining marks visible. Also the side panels taper with bottom thinner than the top. Top, bottom and T4 pcb are held by threaded brass spacers, again close tolerance. Not sure how much the tooling would have cost considering so few listings on ebay.

Looks like it may be a case from "100MHz." They seem to specialize in those tabbed acrylic cases.

[caius]

I have some confusion about what is the best model of this component tester to buy among all.Which is you advice?Thanks.

[eas]

I have some confusion about what is the best model of this component tester to buy among all.Which is you advice?Thanks.

"Best" is relative to your requirements, as best as you can articulate them.

A few questions:

• Are you willing to tinker with the device at all?
• If yes, how much? Once to install a recent version of the firmware, or on an ongoing basis?
• Do you want it to come wrapped in a case, with test leads, etc?
• How important is testing surface mount components?

My favorite is the GM328 from EZM electronics studios because: It seems to use recent versions of the mainline firmware with minimal modifications, and good through-hole components, so it is ready to use without modification. On the other hand it has a socketed MCU, allowing you to try different firmwares easily, and through-hole components make it easier to modify if you so desire.  The main downside is that the configuration is a little awkward for putting in a case and the pads for testing SMD devices don't accommodate a lot of different orientations.

My next favorite is probably the versions from 91Make (T-4, etc). In their favor is that their custom firmware version makes the better use of graphical displays than the mainline firmware, and other proprietary forks. It also doesn't suffer from the battery-wasting power supply design of the Fish8840 variants. The single board should be easier to mount in an enclosure, and, people have managed to reprogram it without much trouble, but this comes at the expense of the nice UI design of the original firmware. The SMD pads also allow for more flexibility in component positioning than the GM328 (but not as much as the Fish8840). The main downside for use as-is is that the firmware doesn't have the mainline firmware's full set of features enabled.

Other people probably have their own take, and we may be able to give a better recommendation if you can clarify your requirements a bit.

[caius]

A few questions:

• Are you willing to tinker with the device at all?

Sure, I'm a geek...

 

• If yes, how much? Once to install a recent version of the firmware, or on an ongoing basis?

I want to experiment different versions

• Do you want it to come wrapped in a case, with test leads, etc?

I can add case later  as well test leads

• How important is testing surface mount components?

Not really, I can always use my tweezer.
 

My favorite is the GM328 from EZM electronics studios because: It seems to use recent versions of the mainline firmware with minimal modifications, and good through-hole components, so it is ready to use without modification. On the other hand it has a socketed MCU, allowing you to try different firmwares easily, and through-hole components make it easier to modify if you so desire.  The main downside is that the configuration is a little awkward for putting in a case and the pads for testing SMD devices don't accommodate a lot of different orientations.

Yes, a PCB with though-hole component would be fine even if I could program the MCU in-circuit.Do you mean this?

eBay auction: #251653350287

My next favorite is probably the versions from 91Make (T-4, etc). In their favor is that their custom firmware version makes the better use of graphical displays than the mainline firmware, and other proprietary forks. It also doesn't suffer from the battery-wasting power supply design of the Fish8840 variants. The single board should be easier to mount in an enclosure, and, people have managed to reprogram it without much trouble, but this comes at the expense of the nice UI design of the original firmware. The SMD pads also allow for more flexibility in component positioning than the GM328 (but not as much as the Fish8840). The main downside for use as-is is that the firmware doesn't have the mainline firmware's full set of features enabled.

Could you post link of both, please?
Anyway some years ago I bought this version, it came with firmware 1.05k onboard.It works quite well but it as some nasty bugs, for example ESR measurements are totally wrong compared to the right ones of my Bob Parker Blue tester.I see on Markus F. repository that newer firmwares have been released.So, it would be possible to upgrade it and , if yes, to which version?[/list]

[eas]

My favorite is the GM328 from EZM electronics studios because: It seems to use recent versions of the mainline firmware with minimal modifications, and good through-hole components, so it is ready to use without modification. On the other hand it has a socketed MCU, allowing you to try different firmwares easily, and through-hole components make it easier to modify if you so desire.  The main downside is that the configuration is a little awkward for putting in a case and the pads for testing SMD devices don't accommodate a lot of different orientations.

Yes, a PCB with though-hole component would be fine even if I could program the MCU in-circuit.Do you mean this?

eBay auction: #251653350287

Yeah, that's the one.

My next favorite is probably the versions from 91Make (T-4, etc). In their favor is that their custom firmware version makes the better use of graphical displays than the mainline firmware, and other proprietary forks. It also doesn't suffer from the battery-wasting power supply design of the Fish8840 variants. The single board should be easier to mount in an enclosure, and, people have managed to reprogram it without much trouble, but this comes at the expense of the nice UI design of the original firmware. The SMD pads also allow for more flexibility in component positioning than the GM328 (but not as much as the Fish8840). The main downside for use as-is is that the firmware doesn't have the mainline firmware's full set of features enabled.

Could you post link of both, please?
[/quote]
Kind of a hassle for me to find links right now on my mobile. I think other people have described and linked to both of these in the last few pages.

[tom666]

My next favorite is probably the versions from 91Make (T-4, etc). ...

Could you post link of both, please? ...

for example:
Update firmware for LCR-T3 & LCR-T4 Tester by 91make
Correction to my original post:
G-LCD are identical but PCBs have slightly different dimensions.

eBay auction: #371301439496 - LCR-T3 Tester by 91make
eBay auction: #311331001449 - LCR-T4 Tester by 91make

Anyway some years ago I bought this version, it came with firmware 1.05k onboard. It works quite well but it as some nasty bugs, for example ESR measurements are totally wrong compared to the right ones of my Bob Parker Blue tester. I see on Markus F. repository that newer firmwares have been released.So, it would be possible to upgrade it and , if yes, to which version?

I recommend to update the firmware through the ISP connector. Setting the fuses for M168 you have in the attached image. File contains firmware (final v1.09k for M168) will work without recommended hardware changes (see the official manual). Is set so as not by trouble with the message "CELL".

[caius]

for example:
Update firmware for LCR-T3 & LCR-T4 Tester by 91make
Correction to my original post:
G-LCD are identical but PCBs have slightly different dimensions.

eBay auction: #371301439496 - LCR-T3 Tester by 91make
eBay auction: #311331001449 - LCR-T4 Tester by 91make

Thanks you Tom for your explanations.So, at the end your advice is to get an LCR-T3 or LCR-T4 instead of the GM328 with though-hole components?

I recommend to update the firmware through the ISP connector. Setting the fuses for M168 you have in the attached image. File contains firmware (final v1.09k for M168) will work without recommended hardware changes (see the official manual). Is set so as not by trouble with the message "CELL".

OK, I will upgrade it to v1.09k.Regarding the hardware changes, I guess you refer to the ones mentioned in this manual:

http://radioskot.ru/_fr/6/ttester_eng105k.pdf

I'll figure out if my PCB need these changes by comparing its layout with the one showed in the manual.

 

[caius]

So, at the end your advice is to get an LCR-T3 or LCR-T4 instead of the GM328 with though-hole components?

It is difficult to decide - it's all a matter of taste In the case of damage MCU I think will be easier maintainable GM328 - but it has a slightly larger PCB size. The advantage GM328 is also the possibility of using classical character LCD.]

OK, I will think about and decide.

 

You do not need to make any correction of hardware. Use only firmware which I uploaded here

I'm just trying it.Since I'm using a TL866CS programmer, the  configuration of efuse is a bit different, I can change only three bits.Is 0xF9 the same of 0x01?
I could use my Arduino Mega2550 and AVRdude to program the ATmega168 but I'm bit lazy now
Besides, I can't see how to program the EEPROM of the MCU with my TL866CS.