Author Topic: $20 LCR ESR Transistor checker project  (Read 3397107 times)

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Offline b0hoon

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Re: $20 LCR ESR Transistor checker project
« Reply #6850 on: March 07, 2021, 09:10:12 pm »
Fair enough. I guess there will be no support for my super tester in next version ;) That's ok. I got it running.
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #6851 on: March 10, 2021, 06:20:59 pm »
FYI, the next m-firmware version will include a driver for b0hoon's ST7735 semi-compatible display. I assume that more users have (or will get) a GM328A with that special LCD module.
 
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Offline klimm

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Re: $20 LCR ESR Transistor checker project
« Reply #6852 on: March 16, 2021, 09:53:04 am »
Interesting. It looks like you can use a junction FET as a low gain transistor - I had never thought of trying that.



I think I stumbled into this problem of detecting the PN4117A as a NPN BJT with my multitester.
I tested also  a 2N4416  and it is recognised as a FET but it has a much higher IDSS. 
Is there a way to simple tell a FET from a BJT?
I did the usual BJT DMM test and the PN4117 behaves like a BJT  with pin2 as base
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #6853 on: March 16, 2021, 11:17:50 am »
You can check JFETs also by measuring the resistance across drain and source (gate and source shorted!). Typical values are around 100 Ohms. Do you run a current k-firmware? If that doesn't help you could try the m-firmware which comes with some additional checks to cope with JFETs with a low I_DSS.
 

Offline klimm

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Re: $20 LCR ESR Transistor checker project
« Reply #6854 on: March 16, 2021, 12:21:03 pm »
Thank you Madires,
I remember  I have the 1.13. I actually  bought the tester 2-3 years ago from a local builder. Don't know how to check the version.

Thanks for the other hints. I did that resistance check with GS shorted; it gives infinite resistance both ways, which it should not. I actually bought the PN4117s to be used as low leakage diodes on a null meter   
I'll build a simple BJT multivibrator to be sure.
 

Online indman

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Re: $20 LCR ESR Transistor checker project
« Reply #6855 on: March 16, 2021, 12:40:53 pm »
Don't know how to check the version.
You have k-firmware running. M-firmware is really better at identifying such JFETs. :)
 

Offline klimm

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Re: $20 LCR ESR Transistor checker project
« Reply #6856 on: March 16, 2021, 12:53:11 pm »
Thanks indman, I will need to find out if I can upload the m firmware.
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #6857 on: March 16, 2021, 01:21:05 pm »
Thanks for the other hints. I did that resistance check with GS shorted; it gives infinite resistance both ways, which it should not. I actually bought the PN4117s to be used as low leakage diodes on a null meter   

If you bought them via eBay or aliexpress and not from a reputable distributor there's the possibility that they could be fakes, e.g. cheap NPNs with changed markings.
 

Offline klimm

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Re: $20 LCR ESR Transistor checker project
« Reply #6858 on: March 17, 2021, 08:09:01 am »
It looks the seller knew what he sent. To my inquiry he immediately commited to refund.
Well, at least I learned the fact that I need a new firmware  :)   
Thank you all for your help.
 

Online indman

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Re: $20 LCR ESR Transistor checker project
« Reply #6859 on: April 10, 2021, 06:23:18 pm »
Hi! I updated the comparative table clones. Added modifications of clone T7, the number of connecting pins LCD to the base board.  ;)
« Last Edit: April 11, 2021, 01:55:09 pm by indman »
 
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Offline pierreraymondrondelle

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Re: $20 LCR ESR Transistor checker project
« Reply #6860 on: April 11, 2021, 10:40:10 am »
Hi, thanks for the update, My tester is a GM328 TR tester, as displayed on the LCD. The board is labelled GM328A V1.11. It's very similar to the GM328A+ of your table but with a TQFP instead of the DIL-28. If you need more for your information, I have to dismount the board from its cabinet to shoot it. Let me know.
Regards
 

Online indman

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Re: $20 LCR ESR Transistor checker project
« Reply #6861 on: April 11, 2021, 12:50:51 pm »
pierreraymondrondelle,thanks! Information in the table, which I compiled, cannot be considered reliable by 100%, since there are a large number of options and modifications of the same clones manufactured by the Chinese. With all my desire, I can not put all these options in the table. Although in most cases, even sellers cannot answer your questions with sufficient confidence. :)
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #6862 on: April 11, 2021, 01:08:48 pm »
Please enjoy the new v1.43m:
- Added R&D display driver for identifying display controllers.
- LCD_RD control signal is now optional for ILI9341, ILI9481, ILI9486 and ILI9488.
- Added modified driver for ST7735 semi-compatible displays (suggested by b0hoon4@gmail.com).
- Option to run Zener check during normal probing (HW_PROBE_ZENER, suggested by indman@EEVblog). Requires  ZENER_UNSWITCHED. Also added corresponding remote control command (V_Z).
- Added option to specify a custom voltage divider for the Zener check (ZENER_DIVIDER_CUSTOM, ZENER_R1 and ZENER_R2).
- Removed option for low resolution in Zener check and also the ZENER_HIGH_RES configuration switch.
- Updated Russian texts (thanks to indman@EEVblog).
- Optional display of pulse duration for PWM generators (PWM_SHOW_DURATION, suggested by guest "hamburger" @mikrocontroller.net).
- Source archive includes "dep" directory to make some IDEs happy (suggested by DAIRVINE@EEVblog).
- Renamed configuration switch SW_PROBE_COLORS to UI_PROBE_COLORS.
- New feature to color titles differently (UI_COLORED_TITLES) and also cursor and key hints (UI_COLORED_CURSOR).
- Updated Romanian texts (thanks to Dumidan@EEVblog).
- Updated alternative Polish texts (thanks to Jacon@EEVblog).
- Updated Spanish texts (thanks to pepe10000@EEVblog).

Available at:
- https://github.com/madires/Transistortester-Warehouse/tree/master/Firmware/m-firmware
- https://github.com/Mikrocontroller-net/transistortester/tree/master/Software/Markus
« Last Edit: April 11, 2021, 08:33:26 pm by madires »
 
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Online indman

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Re: $20 LCR ESR Transistor checker project
« Reply #6863 on: April 11, 2021, 01:58:11 pm »
Hi! I updated the comparative table clones. Added modifications of clone T7, the number of connecting pins LCD to the base board.  ;)
Sorry, I discovered small errors in the table as well as added additional information on the clone GM328A+.
I replaced the old file to a new one.
 
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Offline pierreraymondrondelle

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Re: $20 LCR ESR Transistor checker project
« Reply #6864 on: April 12, 2021, 10:25:15 am »
Hi Indman, I understand. Great work anyway.
kind regards
 

Offline g.costanza

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Re: $20 LCR ESR Transistor checker project
« Reply #6865 on: April 14, 2021, 03:43:07 pm »
When measuring a used 50v 33uf electrolytic capacitor that was removed from a circuit, why would this meter only display a capacitance reading and no ESR reading? I'm doing a recap project and it only showed capacitance on all three of the caps. It didn't show an esr reading at all. I measured several NEW caps I have that are close to those used caps in size/capacitance and the meter DID show ESR readings on those caps. Any ideas? Thanks!
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #6866 on: April 14, 2021, 04:40:23 pm »
I don't know which firmware you're using, but in general a missing ESR value indicates a problem with the measurement, e.g. out of range.
 

Offline Andrey

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Re: $20 LCR ESR Transistor checker project
« Reply #6867 on: April 15, 2021, 12:09:44 pm »
Hi friends! I have a GM328A tester, like the one in the photo from b0hoon. The microcontroller is installed Mega328PU-TH. I have compiled firmware 1.43M, it works, but esr is overstated by 30-40 times. With firmware 1.13K, there is no such effect, everything is correct within normal limits. This tester can only work with 8 MHz quartz, if quartz 16 - artifacts on the display ... on both firmwares. Wrt such a sadness ...  :-\
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #6868 on: April 15, 2021, 01:14:51 pm »
Do you have the ESR issue also with 1.42m and 1.40m? The broken display output can be caused by a slow level shifter or a slow display controller. You could try to slow down the display driver by adding some delay between sending bits (wait1us() or similar).
« Last Edit: April 15, 2021, 01:26:14 pm by madires »
 

Offline Andrey

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Re: $20 LCR ESR Transistor checker project
« Reply #6869 on: April 15, 2021, 08:30:43 pm »
To make it clear, I took a photo. One tester is Atmega328P-U, the other is Mega328PU-TH. Firmware 1.43m, display unknown model, capacitor 1000uF 6V. In the first variant esr = 0.01, in the second one esr = 0.35 Ohm. I understand that the problem is in the operation of the ADC of the Mega328PU-TH microcontroller. But firmware 1.13k 864 Mega328PU-TH works correctly, esr = 0.00 -0.01 Ohm.
I did not do the calibration, it will not change the readings significantly ... A new clone with an unknown display and a Mega 328PU-TH microcontroller cannot work correctly with firmware 1.43m, this is sad. Perhaps for this microcontroller you need to make additional changes to the firmware ...
The display can only work at a tester frequency of 8 MHz, if the crystal of the tester is 16/20 MHz, there will be debris on the screen.
« Last Edit: April 15, 2021, 08:39:20 pm by Andrey »
 

Online Obelix2007

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Re: $20 LCR ESR Transistor checker project
« Reply #6870 on: April 16, 2021, 07:18:20 am »
... display can only work at a tester frequency of 8 MHz, if the crystal of the tester is 16/20 MHz, there will be debris on the screen.

Hello Andrey,

at the Mikrocontroller.net I have reported on 01.05.2019 20:12 a problem with this kind of display:

https://www.mikrocontroller.net/topic/transistortester-avr?reply_to=5827593#postform

The driver-circuit has no connect to GND. So it works only at 8MHz. I solve this with a wire bitween GND and pin 8 of U1 CD4050B


Regards Horst
« Last Edit: April 16, 2021, 07:59:10 am by Obelix2007 »
 

Offline Andrey

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Re: $20 LCR ESR Transistor checker project
« Reply #6871 on: April 16, 2021, 08:56:45 am »
Thank you Obelix2007!
I have a different display. There is a connection, I checked.
 

Online Obelix2007

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Re: $20 LCR ESR Transistor checker project
« Reply #6872 on: April 16, 2021, 10:40:36 am »
I have a different display.

... in this case, may be help markus new fw 1.43 with the modification Semi_ST7735. Description in clones-file at line 42.

Good luck, Horst
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #6873 on: April 16, 2021, 11:24:40 am »
To make it clear, I took a photo. One tester is Atmega328P-U, the other is Mega328PU-TH. Firmware 1.43m, display unknown model, capacitor 1000uF 6V. In the first variant esr = 0.01, in the second one esr = 0.35 Ohm. I understand that the problem is in the operation of the ADC of the Mega328PU-TH microcontroller. But firmware 1.13k 864 Mega328PU-TH works correctly, esr = 0.00 -0.01 Ohm.
I did not do the calibration, it will not change the readings significantly ... A new clone with an unknown display and a Mega 328PU-TH microcontroller cannot work correctly with firmware 1.43m, this is sad. Perhaps for this microcontroller you need to make additional changes to the firmware ...

Your Mega328PU-TH should be an ATmega328P U made in Thailand. Most of my testers have also the picopower version but not the exact same type (328P AU). To be able to fix the ESR issue I need to reproduce the problem. So I'd need a tester with an ATmega328P U-TH, and which also has the ESR issue.
« Last Edit: April 16, 2021, 11:26:30 am by madires »
 

Offline ko4nrbs

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Re: $20 LCR ESR Transistor checker project
« Reply #6874 on: April 22, 2021, 11:38:45 pm »
Anyone added leads to their M644?  I'd like to use leads with alligator clips so I can test components taken out of equipment.  Concerned about adding errors if I do it.  The components leads are too short after being unsoldered for insertion in the M644.
Bill

 


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