$20 LCR ESR Transistor checker project

[djQUAN]

I bought this a few months back and works well (didn't come with the li ion cell) and just stumbled upon this thread. Still back reading now at P24.

Works pretty well. I chose this over the large LCD types as I can replace the LCD if necessary.
Usb charging with onboard 14500 li ion cell
Uses the 328 uC 1.11k FW and a TL431 voltage reference with an option for trimming but not used.

There appears to be a 6p inline ISP header but I currently don't have an AVR programmer so I'm sticking with the old FW for now.

edit: menu is enabled in mine so the additional functions can be used

[Kalvin]

@Circuiteromalaguito, Kalvin, et al:

This, of course, is just my opinion, but...

Every now and then someone comes who wants to add lots of bells and whistles to the existing schematic. The charm of the original tester was in the simplicity of its hardware. Take that away, and you are left with something other than the transistor tester that we are all discussing in this thread. Sure, you can do everything that you suggest, but what reason is there not to do it as a separate project? Then you can use, say, ARM and a voltage converter, and do many other interesting things... but I believe you're trying to horseshoe this particular project into something that it's not.

I am great admirer of the minimalist design. No need to make things too complicated. And if the 1284-based version is available, then my suggestion is obsolete of course.

[ralphd]

You could use my asm SPI code.
http://nerdralph.blogspot.ca/2015/03/fastest-avr-software-spi-in-west.html

I'll have a look. Thanks for the hint!

If your firmware has serial output on PC3, my soft uart is the smallest around, and the only one with no jitter (difference between the timing of 1 vs 0 bits)
https://github.com/nerdralph/nerdralph/tree/master/avr/libs/bbuart

[Macbeth]

You could use my asm SPI code.
http://nerdralph.blogspot.ca/2015/03/fastest-avr-software-spi-in-west.html

I'll have a look. Thanks for the hint!

If your firmware has serial output on PC3, my soft uart is the smallest around, and the only one with no jitter (difference between the timing of 1 vs 0 bits)
https://github.com/nerdralph/nerdralph/tree/master/avr/libs/bbuart

You've developed some pretty cool stuff. That soft UART is something I could use on a tiny85  Bookmarked

[djQUAN]

After reading stuff around here, a good reference is said to be beneficial so I checked my unit.

It was using a TL431 which measured 4.9xx volts on the Vref pin. Swapped it out for a LM336-2.5 and added a trimmer on the unpopulated space so I could set it to exactly 2.500V.

Redid a self cal test and I'm not sure which measurements it helped. But it still worked. Oh well 

[GnatGoSplat]

Macbeth, indman, and tom666, thanks very much for the help, it makes sense now and I got it going.

Hi GnatGoSplat,
the recommended setting of the fuses for ATmega8 (Int. RC 8MHz) by software author (KHK) is:
lfuse:0x24 hfuse:0xd9

I used the firmware you attached and also set the fuses exactly as shown.  It now seems to work perfectly with one slight issue is the display of the result goes away very quickly before it shuts off.  Is there a way to increase this delay?

[MLXXXp]

In case it's of use to anyone, here are some photos of how I replaced the test switch with a rotary encoder on my tester.

My unit is one of the popular 2 x 16 character display designs with through-hole components and a socketed 328p processor. The board is marked EZM Electronics Studio, M328_9V_V3.1, 2013.09.25

I removed the original test switch, drilled holes and cut lands out of the ground plane. The resistors are size 0603. I also rotated the LED and moved the + terminal so it would be further from the encoder and visible when I added a 20mm knob.

The orange capacitors on the processor pins aren't part of the encoder circuit. They are the recommended 1nF capacitor on AREF, plus additional 100nF capacitors on Vcc and AVcc.

[tom666]

I used the firmware you attached and also set the fuses exactly as shown.  It now seems to work perfectly with one slight issue is the display of the result goes away very quickly before it shuts off.  Is there a way to increase this delay?

Delays can be adjusted by modifying the file "config.h".

It is this part of the code (the time is specified in milliseconds):
// LONG_WAIT_TIME is the time for displaying the successfull test result
#ifndef LONG_WAIT_TIME
#define LONG_WAIT_TIME 28000
#endif

// MIDDLE_WAIT_TIME is used for display the next parameter for Show data menu function
#define MIDDLE_WAIT_TIME 15000

// SHORT_WAIT_TIME is the time for displaying a unknown component message
#ifndef SHORT_WAIT_TIME
#define SHORT_WAIT_TIME 8000
#endif

[eas]

MLXXXp: Thanks for showing your mod!  I have the graphical version of that tester and it would be nice to upgrade it.

I mostly built my bangood kit (with case and rotary encoder) over the weekend. I prepared by doing a 4-wire measurement of the provided 0.1% 470K and 680 Ohm resistors. All were within spec, but I still paired them up so each was as close to the ideal ratio as possible. The value of this exercise is questionable, but I did it for fun.

I've paused to consider what I'm going to do about the test socket and leads. My current plan is to modify the case to shoehorn in three 2mm banana jacks rather than 2 4mm. Then I'm going to mount the DIP ZIF socket on a piece of protoboard and bolt/solder three 2mm banana plugs to the other side along one edge. It will be similar to the MK168/MK328. If I like the result, I'll probably have a small PCB made with some SMD test pads.

Parts are on order from China. At least some of them will be here within a week or so. I'll share details of my success (or failure!) once they arrive.

The other alternative I'm considering is to use some IC sockets as a riser to mount the ZIF socket onboard as giovannirat did and cut the case for it. Then, I'd make up an adapter that will allow 3 test leads.

Question: What, if any, downsides are there to replacing the 8MHz crystal with a 16MHz (and reflashing the MCU appropriately)? I figured the extra clock speed could help with UI responsiveness/refresh. Battery life might suffer, but I'd be ok with that.

[madires]

Question: What, if any, downsides are there to replacing the 8MHz crystal with a 16MHz (and reflashing the MCU appropriately)? I figured the extra clock speed could help with UI responsiveness/refresh. Battery life might suffer, but I'd be ok with that.

A 16MHz crystal increases the accuracy and measurement range of some measurements, and also increases the top frequency of the squarewave generator. The only downside is that you have to build a new firmware with the MCU frequency set to 16MHz

[9a4wy]

I have this one from ebay....
It has  1.07 FW
Could I flash it with new FW and what version please??
tnx...Kristian

[madires]

I have this one from ebay....
It has  1.07 FW
Could I flash it with new FW and what version please??

Yes, 1.12k or 1.19m classic edition. Please see http://www.mikrocontroller.net/svnbrowser/transistortester/Software/ and go to "trunk" for the current k-firmware or "Markus" for the m-firmware.

[tom666]

I have this one from ebay....
It has  1.07 FW
Could I flash it with new FW and what version please??

Specifically, in the case of using the k-version you can use directly the contents (files "TransistorTester.hex" and "TransistorTester.eep") of these folders:
http://www.mikrocontroller.net/svnbrowser/transistortester/Software/trunk/mega328/?view=tar
or
http://www.mikrocontroller.net/svnbrowser/transistortester/Software/trunk/mega328_2X16_menu/?view=tar

Setting of fuses for ATmega328:
lfuse:0xf7 hfuse:0xd9 efuse:0x04 (0xfc)

[klaus11]

I need a reliable fish8840 scheme, you can help me

[CustomEngineerer]

I've paused to consider what I'm going to do about the test socket and leads. My current plan is to modify the case to shoehorn in three 2mm banana jacks rather than 2 4mm. Then I'm going to mount the DIP ZIF socket on a piece of protoboard and bolt/solder three 2mm banana plugs to the other side along one edge. It will be similar to the MK168/MK328. If I like the result, I'll probably have a small PCB made with some SMD test pads.

If you are successful please post pictures when you are done. Anything has to be better than the crappy socket supplied with the case. I installed my first tester into the case last week and had all kinds of problems with the supplied 5 hole socket. I was was trying to join the socket to the 2 mini banana terminals to the PCB (like the pictures on banggood for the case) and one of the socket's gold colored leads snapped right off. After some effort I was able to MacGuyver it back together and as soon as I got that one fixed one of the leads on the other side snapped off. I managed to get that one fixed and the whole thing assembled, but I went ahead and ordered one of the replacement sockets listed a couple of pages back because I really don't expect my fixes to hold for too long. While waiting for that to arrive I decided its not worth trying to even install. Due to a screw up on my initial order I got a second tester and case and had been planning to just not even use the case but I saw some pictures of a user that modified a different version of the tester/case to use the ZIF socket and think it would be worth trying. If I am ever successful in doing something similar I will probably disassemble the first one and just use it without the case. I was thinking it might be nice to have just the PCB mounted to my desk near all my parts for quick checking.

[indman]

I need a reliable fish8840 scheme, you can help me

Fish8840 has many options of execution. You can see diagrams for several clones on my resource according to the link https://yadi.sk/d/yW8xa5NJgUo5z

[tom666]

I need a reliable fish8840 scheme ...

This tester (by Fish8840) is consistent with standard electric connection. It is used with the G-LCD display (ST7565 controller). The difference is in the power supply circuit. See picture from the official manual - there you'll find a lot of useful information about this tester.

Connecting (SPI mode) the G-LCD display with the MCU is as follows:
PD0 - LCD-REST
PD1 - LCD-RS
PD2 - LCD-SCLK
PD3 - LCD-SID


Note:
The advantage of this tester is a simple way of adaptation for 16x2 character LCD.

Edit:
I edited and exported the wiring diagram (by indman) to its original state.

[klaus11]

I need a reliable fish8840 scheme ...

This tester (by Fish8840) is consistent with standard electric connection. It is used with the G-LCD display (ST7565 controller). The difference is in the power supply circuit. See picture from the official manual - there you'll find a lot of useful information about this tester.

Connecting (SPI mode) the G-LCD display with the MCU is as follows:
PD0 - LCD-REST
PD1 - LCD-RS
PD2 - LCD-SCLK
PD3 - LCD-SID


Note:
The advantage of this tester is a simple way of adaptation for 16x2 character LCD.

Edit:
I edited and exported the wiring diagram (by indman) to its original state.

If I know him, but without modifying the original circuit   C20 + not to Q1

[tom666]

If I know him, but  C20 + not to Q1

Everything is OK.

[klaus11]

I do not want to be indiscreet, but I only see Q1 to C18 and U5

[tom666]

On the PCB are two positions for C20 (the same is for C18) and it is therefore possible to use either a THT electrolytic capacitor or the tantalum capacitor.
In this case, on the position C20 and C18 is mounted tantalum capacitor.

Edit:
In the wiring diagram is reversed C20 and C18. In the Annex is a corrected circuit diagram

[indman]

tom666, thanks for corrections on the diagram C20 and C18! I upgrade the clone of Fish8840 with the big blue display - changed and added some elements in the diagram for correct operation of new firmwares from the author. Changes are selected in the red color on the diagram. The diagram in high quality can be downloaded at the link https://yadi.sk/d/yW8xa5NJgUo5z

[eas]

I've paused to consider what I'm going to do about the test socket and leads. My current plan is to modify the case to shoehorn in three 2mm banana jacks rather than 2 4mm. Then I'm going to mount the DIP ZIF socket on a piece of protoboard and bolt/solder three 2mm banana plugs to the other side along one edge. It will be similar to the MK168/MK328. If I like the result, I'll probably have a small PCB made with some SMD test pads.

If you are successful please post pictures when you are done. Anything has to be better than the crappy socket supplied with the case.

I plan to. If shipping on the 2mm sockets is as fast as it was on my last order from the same seller, I should have the parts by next weekend.

[CustomEngineerer]

I've paused to consider what I'm going to do about the test socket and leads. My current plan is to modify the case to shoehorn in three 2mm banana jacks rather than 2 4mm. Then I'm going to mount the DIP ZIF socket on a piece of protoboard and bolt/solder three 2mm banana plugs to the other side along one edge. It will be similar to the MK168/MK328. If I like the result, I'll probably have a small PCB made with some SMD test pads.

If you are successful please post pictures when you are done. Anything has to be better than the crappy socket supplied with the case.

I plan to. If shipping on the 2mm sockets is as fast as it was on my last order from the same seller, I should have the parts by next weekend.

I've got some 2mm sockets laying around, really wish I would have thought to do the 3x2mm like you are saying. I will probably do that on the second case/tester I've got. Thanks for the great ideas.

[klaus11]

In this new scheme Fish8840. Already the reference TL431 is not used?