$20 LCR ESR Transistor checker project

[vinceroger]

yes sorry about the confusion (was one of those days yesterday nothing went rite) i misscounted the ebay picture now just re checked the kit all again yes there are 24 spots on my pcb and also 24 resistors fitted too the pcb on the ebay picture  just re counted my resistors again 23 plus 1 zero ohm (which isnt shown in any ebay pictures) but without a scmematic to show what value resitor goes where and where also too fit the zero ohm one on the pcb im a bit stuck.

[bitseeker]

No worries. I was having a rough day yesterday, too. It happens. Glad to hear things are coming together.

[stj]

GM328r stuffing list.
-------------------------------
r1 - 680r sensing circuit
r2 - 470k sensing circuit
r3 - 680r sensing circuit
r4 - 470k sensing circuit
r5 - 680r sensing circuit
r6 - 470k sensing circuit
r7 - 10k reset pullup
r8 - 33k power control
r9 - 3k3 power control
r10 - 27k
r11 - 100k (says r1 but is next to r10)
r12 - 10k voltage divider for battery sense
r13 - 3k3 voltage divider for battery sense
r14 - 560r display related - led current limit
r15 - 27k
r16 - 0r jumper for AVCC
r17 - 2k2 from tl431 to vcc
r18 - 1k rotary encoder current limit
r19 - 1k rotary encoder current limit
r20 - 10k rotary encoder pullup
r21 - 10k rotary encoder pullup
r22 - 470r frequency input dropper
r23 - 10k frequency input voltage divider
r24 - 10k frequency input voltage divider

rv1 - 10k preset frequency input voltage divider

u3 = tl431

q1 - 4673 (bc557c)
q2 - c945 (bc547)
q3 - c945 (bc547)

c1 - 22pf for crystal
c2 - 22pf for crystal
c3 - 100nf
c4 - 10nf
c5 - 100uf 25v
c6 - 100uf 25v
c7 - 100nf
c8 - 100nf
c9 - 100nf frequency input DC blocker
---------------------------------------------------
 

[vinceroger]

Thanks again stj i will try to build this up probably monday/tuesday as not back home untill then thanks again for your time working this all out i will update the thread when built.

[ogara]

Looks like for the Chinese tester, upgrading from the 78L05 regulator is highly recommended.

MCP1702 is often mentioned but if I read the datasheet correctly, its load regulation @ 1% is quite poor if you compared to the xxx1117 @ 0.2% or the LP2950 @ 0.05%! 

Seeing how bad the display flickers with the default 78L05, should more focus be on picking a LDO replacement with better load regulation?

[stj]

it already uses a 1117 for the 5v.

[hapless]

Seeing how bad the display flickers[...]

It should not be doing that. Are you providing enough power for the regulator to start doing its job?

[belzrebuth]

Okay,I'm seriously considering getting one of these and I'm between these two:

http://www.ebay.com/itm/2016-EZM328-GM328-transistor-tester-ESR-frequency-meter-square-wave-genera-/322041933144?hash=item4afb31ed58:g:eIQAAOSwYlJW6Tg8

http://www.ebay.com/itm/Digital-LCD-GM328A-Transistor-Tester-Capacitance-LCR-ESR-Meter-MOS-PNP-NPN-V2PO-/221960020347?hash=item33add9217b:g:~bYAAOSwHQ9WYnAG

I like the EZM ones ,they seem nicely assembled and I don't mind not having a case.

Of these two I posted ? prefer the thru-hole build.
It also states that it has the new 1.12 firmware.("official firmware"?) but the cheaper build(2nd link) is a newer board revision.
I'm not really sure of the differences between these two.(I admit I didn't read the whole thread )

Which of these two should I be going with?
(other options are welcome)

Thanks:)

[hansibull]

I got my TC1 component tester with color LCD in the mail today, and I'll have to say I'm impressed! It got a step-up circuit for measuring zener diodes with a higher breakdown voltage of 4.7v. The battery is a rechargeable 3.7v Litium ion battery, that can be charged with a micro USB cable. Here are some pictures of it! (Open the pics in a new tab for even higher resolution)

[madires]

Don't worry about the firmware! You can update it anytime with the current k or m firmware. Which clone to buy isn't a simple decision. The EZM328 is through-hole and got a rotary encoder. The GM328A has an unpopulated ISP header and the SRV05-4 based input protection. If you're going to use the extra features, the rotary encoder would be very handy.

[belzrebuth]

Okay,so I should go with the GM328R.

Will I need to update the firmware once I get it?

[madires]

No, you don't need to update the firmware, but you can if you wish

[belzrebuth]

I obviously have no clue about how to do that but I think I'll have to buy a build first,start using it and go from there..
I believe I also need to start reading this thread from the start..

I'm a bit worried about that input protection the -A model has and the -R hasn't but I think it will be just a matter of caution before testing.(properly discharge caps etc)

I think the thru hole EZM seems a nice starting point regardless..

[hansibull]

No, you don't need to update the firmware, but you can if you wish

The tester with the color LCD (the one I posted a few posts ago); is it possible to refresh it with your firmware without any major code modifications? Do the tester need a rotary encoder in order to be able to navigate in a menu, or can I use long/short press?

[madires]

The m-firmware supports ILI9341/9342 compatible color displays. If the TC1 got one of those, it should work. I assume that the IR receiver module is connected to a dedicated pin, but it's easy to modify the code for that (could become a hardware option). The user interface works fine with a simple push button or a rotary encoder, besides one feature. The squarewave generator is only enabled if a rotary encoder is available, because you don't select a preset frequency in a short list, like in the k-firmware. The frequency is tuned with the rotary encoder, also considering how fast you turn it, for an easy access to the full frequency range.

@all: If you want more displays to be supported, please send me the display or tester clone with a hint about the display controller and I'll try to write a driver.

[KD0CAC John]

I am interested in one , but I see there is no provision for surface mount components ?
I find the need for testing with SMD , because of learning repair still and the difficulty of IDing these parts .
Looks good .

[madires]

I've seen several clones with test pads for different SMD packages. And if you don't find one suitable for your needs, make one yourself The circuit is quite simple.

[hansibull]

@all: If you want more displays to be supported, please send me the display or tester clone with a hint about the display controller and I'll try to write a driver.

The LCD in the transistor tester looks identically to my ST7735S LCD module, which is a typical 128x160 TFT LCD. I think many users would like the code to support the Nokia 5110 LCD, even if the screen is a bit small. It's neat and dirt cheap at Ebay or AliExpress!

Oh, while you're here; why don't you host your code at Github instead? It makes it much easier to get in touch with the users, fix bugs, get help (by pull requests) 

[upsss]

I am interested in one , but I see there is no provision for surface mount components ?
I find the need for testing with SMD , because of learning repair still and the difficulty of IDing these parts .
Looks good .

For 2 pin SMD parts you much better off with one of these.  You can get them on eBay (tweezer probe ~$2.5) and of course you can use them in circuit testing.

[madires]

The LCD in the transistor tester looks identically to my ST7735S LCD module, which is a typical 128x160 TFT LCD. I think many users would like the code to support the Nokia 5110 LCD, even if the screen is a bit small. It's neat and dirt cheap at Ebay or AliExpress!

I've had a quick look at the ST7735 datasheet. Looks familiar And the PCD8544 seems to be quite simple. I just need some samples

Oh, while you're here; why don't you host your code at Github instead? It makes it much easier to get in touch with the users, fix bugs, get help (by pull requests) 

There's a mirror at Github ( https://github.com/svn2github/transistortester ) and the two forums (this one and mikrocontroller.net) work fine for user interaction and support.

[madires]

For 2 pin SMD parts you much better off with one of these.  You can get them on eBay (tweezer probe ~$2.5) and of course you can use them in circuit testing.

Those SMD tweezers are really handy. The only drawback is when you press them too hard. It's amazing how far a 0603 resistor can fly. More food for the vacuum cleaner

Just an example for SMD test pads (and a nice enclosure):

[bitseeker]

Wow, that's quite the variety of test pads. I hadn't seen an enclosure like that before.

[stryker]

Just an example for SMD test pads (and a nice enclosure):

Have you seen anything similar to that SMT enclosure elsewhere?  Their US distributor doesn't list the product on their site, and they have nobody nearer to Australia for their particular product. 

Thanx, Geoff

[Radio Tech]

A big thanks to the fine folks of this thread.

My tester from Banggood come up with some strange characters on the display. After reading a lot in this thread and direct help from mauroh and reading Mardires post and Tom666 I was able to get mine reprogrammed and back up and running.

I made a video of the reprogramming on my YouTube channel and posted it here in the forums:
https://www.eevblog.com/forum/other-blog-specific/55-lcr-esr-transistor-checker-error-and-reprogram/new/#new

Attached is a pic of the problem.

Many thanks again to the wonderful folks of this forum.
I learned a little today.

[madires]

Have you seen anything similar to that SMT enclosure elsewhere?  Their US distributor doesn't list the product on their site, and they have nobody nearer to Australia for their particular product. 

Unfortunately not, just PCBs with a few SMD test pads. Have you asked the US distributor? Maybe they'll add the testers to their stock if there's demand. It's a nice design, not copied yet by the Chinese clone manufactures.