Author Topic: $20 LCR ESR Transistor checker project  (Read 1384412 times)

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Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #75 on: April 21, 2013, 01:43:07 am »
I've never played with these AT projects. A quick google tells me there are a variety of ways to upload programming to these chips.  The Chinese board seems to have a 10 pin unpopulated header that might be the interface for the soldered processor. Can anyone confirm this?

The 6 or 10 pin header is the ISP interface supported by ATtiny and ATmega MCUs. The drawback of the ISP interface is that it can't be used if the fuses are messed up badly. In that case you'll need a so called HV parallel programmer. AFAIK the Dragon board supports both methods.

Quote
Supplementary question: does this look like a suitable programmer: http://www.ebay.com/itm/USB-ISP-Programmer-for-ATMEL-AVR-51-ATMega-ATTiny-/200460739146 ?

Make sure the progammer is supported by avrdude or is compatible with STK-500.
 

Offline torch

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Re: $20 LCR ESR Transistor checker project
« Reply #76 on: April 21, 2013, 07:13:13 am »
Well, according to Mr. Karl-Heinz Kübbeler (in his excellent documentation referenced on page 1 of this thread) when he tested one of the Chinese versions:

Quote
The lock fuses of the ATmega were set, so no readout was possible. But I could install the software version 1.05k without any problems.

He doesn't specify exactly what method he used to install the software, but I will guess he used the ISP header interface since he mentions it earlier in the section, and I think he would have said something if it didn't work.

The unit I found on fleabay indicates it is is "based on Thomas Fischl's USBasp design". I found a tutorial on using USBasp with Avrdude, so my guess is that it is compatible. However, that particular unit comes with Chinese language software/manual only, so I think I'll keep looking for something with English support. I will have enough trouble understanding the English...  :-DD
 

Offline hunter

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Re: $20 LCR ESR Transistor checker project
« Reply #77 on: April 22, 2013, 01:40:42 pm »
I would like to know if it is possible to reflash/update the firmware on the chip with Arduino board. They seem to use ATmega chip as well. Is it same procedure as with normal Arduino code ?

The old one uses removable chip , while the new one has a tiny chip soldered. So I am sure the new one is not update able.  ???

Old one: /ebay


New one: /ebay
 

Offline ecat

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Re: $20 LCR ESR Transistor checker project
« Reply #78 on: April 22, 2013, 07:41:40 pm »
@hunter

See the 10 holes (5x2) on the left side of the new board?
High probability these are for a programming header :)

 

Offline torch

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Re: $20 LCR ESR Transistor checker project
« Reply #79 on: April 22, 2013, 07:46:14 pm »
That's the one I have. I believe the 10 unpopulated holes on the left side are the ISP programming header. I'm going to try upgrading to V1.07 with this Usbasp programmer: http://www.ebay.com/itm/300695243866. It specifically mentions it is compatible with the avrdude software as recommended by madires.

I'll let you know if it works once the programmer arrives and I have time to figure this out.
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #80 on: April 22, 2013, 09:42:52 pm »
See the 10 holes (5x2) on the left side of the new board?
High probability these are for a programming header :)

Good guess! :-)  Please see http://www.batsocks.co.uk/readme/isp_headers.htm for the 6 and 10pin ISP headers.
 

Offline kubi48

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Re: $20 LCR ESR Transistor checker project
« Reply #81 on: April 23, 2013, 12:18:10 am »
Here is my early version of the new Tester with some modifications.
The 10-pin ISP header is soldered, but one side of the frame must be cut out
to match the room left for the header.
The original potentiometer has been replaced to a exemplar with higher resistance
(10k) to save power.
Two blocking capacitors of 100nF each are additionally mounted near the ATmega.
The D1 zener diode is replaced by a precision voltage reference like LM4040AIZ2.5 .
If you don't have a precision voltage reference, you should remove the zener diode at least.
I had also replaced the original 78L05 regulator by my preferred MCP1702-5002 regulator,
because this regulator can also save quiescent current.
Regards, Karl-Heinz
 

Offline moemoe

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Re: $20 LCR ESR Transistor checker project
« Reply #82 on: July 15, 2013, 04:21:48 pm »
Karl-Heinz (the current main developer of the software) started to implement an enhanced software for the 328 in the current trunk http://www.mikrocontroller.net/svnbrowser/transistortester/Software/trunk/mega328/

This version uses the additional space to measures the current amplification in emitter and collector configuration (don't know the correct english term here, perhaps I should visit english for engineers next semester).

And, as there are many problems in the thread at http://www.mikrocontroller.net/topic/248078 due to sleep mode and wrong oscillator, just a little hint:
When using sleep modes and the internal RC oscillator, you have to set 'RESTART_DELAY_TICS=6' because the wake up is faster and therefore timing is calculated wrong so that you will get wrong capacitor values.
https://github.com/maugsburger/
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Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #83 on: July 18, 2013, 02:38:02 am »
1.09m is released:
- fixed a pin assignment bug for MOSFETs
- leakage current is considered for hFE now
- detection of IGBTs (if the tester is able to exceed the gate threshold voltage)

http://www.mikrocontroller.net/svnbrowser/transistortester/Software/Markus/
 

Offline firewalker

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Re: $20 LCR ESR Transistor checker project
« Reply #84 on: July 18, 2013, 03:14:41 am »
Nice!!!  :-+ :-+ :-+

Alexander.
Become a realist, stay a dreamer.

 

Offline A Hellene

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Re: $20 LCR ESR Transistor checker project
« Reply #85 on: July 19, 2013, 01:18:31 am »
Damn it, Markus and Karl-Heinz!
You made me succumb to the temptation of ignoring your project and, finally, to build that relentless spare-time killing device*! :)

Kidding aside, please let me contribute a little something to this fine project, and feel free to use it at will. This will be a surprisingly accurate version of the Sleep_5ms/MilliSleep time delay functions you already make use of.

The following version of the sleep-time delay breaks down the total requested sleep-time to three partial and very accurate TC2 wait times of 16.00 ms, 3.00 ms and 1.00 ms. Additionally, it utilises the Extended Standby Sleep Mode instead of the Idle Sleep Mode (that introduces timing errors for reasons currently unknown to me). Trying to keep the function spartan, the resulting timing error is a couple (or three or four in the worst case!) microseconds only, regardless of the total requested time delay, which is in the range of 1.00 ms to 65535.00 ms!

There are two problems, though:
The obvious one is that this function has to be ported to C, in order to be utilised in the current project --which is a trivial task.
The second one is that, in its current form, the function does only support the crystal oscillator option at 8.0 MHz (that I use in my implementation), since the RC oscillator needs very different start-up times and makes the redefinition of the partial delays an absolute requirement. Of course, the function can be rewritten to support the 16.0 MHz crystal oscillator or the 8 MHz RC oscillator option.

This is the assembly code:

Code: [Select]
;-------------------------------------------------------------------------------
; Registers definitions
;-------------------------------------------------------------------------------
;.def = r0 ; Temp / Product of the MULx instructions: [r1:r0]
;.def = r1 ;
.def C0 = r2 ; Temp / Math registers: [C7:C0]
.def C1 = r3 ;
.def C2 = r4 ;
.def C3 = r5 ;
.def C4 = r6 ;
.def C5 = r7 ;
.def C6 = r8 ;
.def C7 = r9 ;
.def D0 = r10 ; Temp / Math registers: [D3:D0]
.def D1 = r11 ;
.def D2 = r12 ;
.def D3 = r13 ;
;.def = r14 ; Ct. = 0xFF
.def Zero = r15 ; Ct. = 0x00
.def A0 = r16 ; Temp / Math registers: [A3:A0]
.def A1 = r17 ;
.def A2 = r18 ;
.def A3 = r19 ;
.def B0 = r20 ; Temp / Math registers: [B3:B0]
.def B1 = r21 ;
.def B2 = r22 ;
.def B3 = r23 ;
.def T0 = r24 ; 16-bit temp: [T1:T0]
.def T1 = r25 ;
;.def XL = r26 ; X pointer: [XH:XL]
;.def XH = r27 ;
;.def YL = r28 ; Y pointer: [YH:YL]
;.def YH = r29 ;
;.def ZL = r30 ; Z pointer: [ZH:ZL]
;.def ZH = r31 ;


;-------------------------------------------------------------------------------
Sleep_1ms_Init: ; <Sleep_1ms> function initialisation
;-------------------------------------------------------------------------------
;     Initialisation of the <Sleep_1ms> function
;
; Syntax:
; call Sleep_1ms_Init ; Initialise the <Sleep_1ms> function
;
; <Sleep_1ms_Init> Parameters:
;   None!
; <Sleep_1ms_Init> Returns:
;   None!
;
; Registers used:
;   Zero;  Non-destructive use of <Zero> that can be any CPU register loaded with the constant value of 0x00
;   A0;    Non-destructive use of <A0> that can be any of the CPU high-registers (r16..r31)
;
push A0 ; Preserve the <A0> temp
; Stop and disable TC2 and TC2 ISRs
sts TCCR2B,Zero ; [FOC2A,FOC2B,-,-,WGM22,CS22,CS21,CS20]
sts TIMSK2,Zero ; [-,-,-,-,-,OCIE2B,OCIE2A,TOIE2]
sts TCNT2,Zero ; Reset TC2
; Set TC2 mode to CTC (WGM22:20 = 0b010)
ldi A0,1<<WGM21 ; Mode 2 (CTC): WGM22:20 = 0b010
sts TCCR2A,A0 ; [COM2A1,COM2A0,COM2B1,COM2B0,-,-,WGM21,WGM20]
sts ASSR,Zero ; [-,EXCLK,AS2,TCN2UB,OCR2AUB,OCR2BUB,TCR2AUB,TCR2BUB]
; Avoid any TIM2_COMPA ISR firing caused by possible low values loaded to OCR2A
ldi A0,-1 ;
out TIFR2,A0 ; [-,-,-,-,-,OCF2B,OCF2A,TOV2]
sts OCR2A,A0
; Done!
; cbi PORTC,3 ; ########  D E B U G G I N G  ########
; cbi PORTC,4 ; ########  D E B U G G I N G  ########
; sbi DDRC,3 ; ########  D E B U G G I N G  ########
; sbi DDRC,4 ; ########  D E B U G G I N G  ########
pop A0 ; Restore the <A0> temp
ret


;-------------------------------------------------------------------------------
Sleep_1ms: ; Sleep for <T1:T0> * 1 ms time
;-------------------------------------------------------------------------------
;     Set the CPU to sleep for <T1:T0> times 1ms
;
; Syntax:
; ldi T0,Byte1(Delay) ; <Delay> is the requested sleep-time delay
; ldi T1,Byte2(Delay) ;  in 1 ms steps. Range: Delay = 1..65535
; call Sleep_1ms ; Sleep for <T1:T0> * 1 ms time
;
; <Sleep_1ms> Parameters:
;   T1:T0 = 1..65535, in 1 ms steps
; <Sleep_1ms> Returns:
;   None!
;
; Registers used:
;   Zero;  Non-destructive use of <Zero> that can be any CPU register loaded with the constant value of 0x00
;   A0;    Non-destructive use of <A0> temp that can be any of the CPU high-registers (r16..r31)
;   T1:T0; Destructive use of <T1:T0> that should be any of the 16-bit addressing capable register pairs (r25:r24, X, Y or Z)
;
.equ Restart_Delay_Tics = 16384                            ; CPU restart delay, in Clk cycles
.equ Restart_Delay = Restart_Delay_Tics*1000000/F_CPU ; 2048 ms for 8 MHz clock
.equ T2_Period_004 =    32 * 1000000/F_CPU            ;    4 µs for 8 MHz clock
.equ T2_Period_128 =  1024 * 1000000/F_CPU            ;  128 µs for 8 MHz clock
; Preamble
; sbi PORTC,3 ; ########  D E B U G G I N G  ########
push A0 ; Preserve the <A0> temp
ldi A0,1<<OCIE2A ; Enable the TC2 Output Compare Match A interrupt
out TIFR2,A0 ; [-,-,-,-,-,OCF2B,OCF2A,TOV2]
sts TIMSK2,A0 ; [-,-,-,-,-,OCIE2B,OCIE2A,TOIE2]
sei ; Now, we can safely enable global interrupts

; <T1:T0>: Delay register, in 1.0 ms units step
 _Slp1ms_Dly: wdr ; Prevent a WD timeout event
; sbi PORTC,4 ; ########  D E B U G G I N G  ########
; Fast Clk (4 µs / 250 kHz)
ldi A0,1<<CS21|1<<CS20 ; T2_Period = Clk/32 = 4 µs
sts TCCR2B,A0 ; [FOC2A,FOC2B,-,-,WGM22,CS22,CS21,CS20]
ldi A0,1<<PSRASY ; TC2 prescaller reset
out GTCCR,A0 ; [TSM,-,-,-,-,-,PSRASY,PSRSYNC]
sts TCNT2,Zero ; Reset TC2
; Delay module (1/3/16 ms)
cpi T0,Byte1(3)
cpc T1,Zero
brlo _Slp1ms_01m ; Delay < 3 ms
cpi T0,Byte1(16)
cpc T1,Zero
brlo _Slp1ms_03m ; Delay < 16 ms
; Slow Clk (128 µs / 7812.5 Hz)
ldi A0,1<<CS22|1<<CS21|1<<CS20 ; T2_Period = Clk/1024 = 128 µs
sts TCCR2B,A0 ; [FOC2A,FOC2B,-,-,WGM22,CS22,CS21,CS20]
ldi A0,1<<PSRASY ; TC2 prescaller reset
out GTCCR,A0 ; [TSM,-,-,-,-,-,PSRASY,PSRSYNC]
sts TCNT2,Zero ; Reset TC2

; 16.00 ms to sleep: Use the Power Save Sleep Mode
;  OCR2A = ((16000µs-2048µs)/128µs)-1 = (13952µs/128µµs)-1 = 109-1
 _Slp1ms_16m: ldi A0,((16000-Restart_Delay)/T2_Period_128)-1
sts OCR2A,A0
; Set the Sleep Mode to Power Save (SM2:0 = 0b011)
ldi A0,1<<SM1|1<<SM0|1<<SE
out SMCR,A0 ; [-,-,-,-,SM2,SM1,SM0,SE]
sleep
; Update the Delay register
sbiw T0,16 ; Delay register timed-out?
; cbi PORTC,4 ; ########  D E B U G G I N G  ########
brne _Slp1ms_Dly ;  Not yet. Else:
rjmp __Slp1ms_X

; 3.00 ms to sleep: Use the Power Save Sleep Mode
;  OCR2A = ((3000µs-2048µs)/4µs)-1 = (952µs/4µs)-1 = 238-1
 _Slp1ms_03m: ldi A0,((3000-Restart_Delay)/T2_Period_004)-1
sts OCR2A,A0
; Set the Sleep Mode to Power Save (SM2:0 = 0b011)
ldi A0,1<<SM1|1<<SM0|1<<SE
out SMCR,A0 ; [-,-,-,-,SM2,SM1,SM0,SE]
sleep
; Update the Delay register
sbiw T0,3 ; Delay register timed-out?
; cbi PORTC,4 ; ########  D E B U G G I N G  ########
brne _Slp1ms_Dly ;  Not yet. Else:
rjmp __Slp1ms_X

; 1.00 ms to sleep: Use the Extended Standby Sleep Mode (no Restart Delay)
;  OCR2A = (1000µs/4µs)-1 = 250-1
 _Slp1ms_01m: ldi A0,(1000/T2_Period_004)-1
sts OCR2A,A0
; Set the Sleep Mode to Extended Standby (SM2:0 = 0b111)
ldi A0,1<<SM2|1<<SM1|1<<SM0|1<<SE
out SMCR,A0 ; [-,-,-,-,SM2,SM1,SM0,SE]
sleep
; Update the Delay register
sbiw T0,1 ; Delay register timed-out?
; cbi PORTC,4 ; ########  D E B U G G I N G  ########
brne _Slp1ms_Dly ;  Not yet. Else:

; Done! Stop TCNT2 and disable OCIE2A and the Sleep Modes
 __Slp1ms_X: sts TCCR2B,Zero ; [FOC2A,FOC2B,-,-,WGM22,CS22,CS21,CS20]
sts TIMSK2,Zero ; [-,-,-,-,-,OCIE2B,OCIE2A,TOIE2]
out SMCR,Zero ; [-,-,-,-,SM2,SM1,SM0,SE]
pop A0 ; Restore the <A0> temp
; cbi PORTC,3 ; ########  D E B U G G I N G  ########
ret

-George


EDIT:
Corrections of the premature and incomplete assembler code that was mistakenly posted.


(*) Here are a few ideas that might be of some use for the project.
This is my hardware version of a single layer PCB, an easy one to be built at home, with the following modifications:
- Additional PCB space to host a 9V battery, for an autonomous and completely floating testing device.
- The use of the more accurate and flexible LP2950-5.0 LDO/reference, which eliminates the need for an external voltage reference diode.
- The addition of R2 in series to the push-button, in order for the FW to be able to use the LED indicator independently of the  push-button state (because without R2, when the push-button is ON the Q3 B-E junction limits the LED anode voltage to ~0.7V only).
- The omission of the LCD backlight current limiting resistor and the LCD Vee bias trimmer, since both those LCD module requirements are handled internally by elements (resistors) added directly to the LCD module PCB.
- Finally, the addition of a BootLoader header port (J3) for faster and less hassle FW updates, for those who really enjoy messing with the firmware!

Here are the schematics and the PCB top and bottom layout views of my Component Tester implementation:
« Last Edit: July 19, 2013, 10:18:33 pm by A Hellene »
Hi! This is George; and I am three and a half years old!
(This was one of my latest realisations, now in my early fifties!...)
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #86 on: July 19, 2013, 03:00:55 am »
You made me succumb to the temptation of ignoring your project and, finally, to build that relentless spare-time killing device*! :)

It's part of our secret world domination plan :-)

Quote
Kidding aside, please let me contribute a little something to this fine project, and feel free to use it at will. This will be a surprisingly accurate version of the Sleep_5ms/MilliSleep time delay functions you already make use of.

Thanks! The sleep function doesn't has to be very accurate at the moment, it's just used to wait for uncritical stuff and saving power. But in case we need a more accurate version I got some nice code now :-)

Quote
(*) Here are a few ideas that might be of some use for the project.
This is my hardware version of a single layer PCB, an easy one to be built at home, with the following modifications:
- Additional PCB space to host a 9V battery, for an autonomous and completely floating testing device.
- The use of the more accurate and flexible LP2950-5.0 LDO/reference, which eliminates the need for an external voltage reference diode.
- The addition of R2 in series to the push-button, in order for the FW to be able to use the LED indicator independently of the  push-button state (because without R2, when the push-button is ON the Q3 B-E junction limits the LED anode voltage to ~0.7V only).
- The omission of the LCD backlight current limiting resistor and the LCD Vee bias trimmer, since both those LCD module requirements are handled internally by elements (resistors) added directly to the LCD module PCB.
- Finally, the addition of a BootLoader header port (J3) for faster and less hassle FW updates, for those who really enjoy messing with the firmware!

I wouldn't choose the 7805/78L05 either, the MCP1702 works also really great (0,4%). We're very careful with changes to keep everything compatible. But you could create a zip file with the layout and some documentation for the SVN if you like.
 

Offline A Hellene

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Re: $20 LCR ESR Transistor checker project
« Reply #87 on: July 19, 2013, 03:16:24 am »
It's part of our secret world domination plan :-)

Oh, please my dear friend, do not force me to reveal my own agenda by changing my avatar to this, below... :-)


-George
Hi! This is George; and I am three and a half years old!
(This was one of my latest realisations, now in my early fifties!...)
 

Offline vehf277

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Re: $20 LCR ESR Transistor checker project
« Reply #88 on: August 19, 2013, 05:31:21 am »
Hello,
Can this tester be used as in-circuit ESR meter?
Excuse me for my English:)
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #89 on: August 19, 2013, 09:31:58 pm »
Can this tester be used as in-circuit ESR meter?

No, because the voltage used is higher than 0.7V.
 

Offline Radio Tech

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Re: $20 LCR ESR Transistor checker project
« Reply #90 on: August 19, 2013, 10:00:25 pm »
Few months ago I was working  on a monitor and checking some caps. I replace some bad caps and powered it up and then decided I needed to check the main cap on the power supply. Remove cap connected the tester and nothing, no power on.  I realized I did not short the cap before testing.

Pretty sure it took the controller out. So just bought another.
Question is this, is it worth taking the time to replace the chip and reprogram it?  I have no problem changing the chip. But the programming may be an issue.

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #91 on: August 19, 2013, 10:23:06 pm »
Few months ago I was working  on a monitor and checking some caps. I replace some bad caps and powered it up and then decided I needed to check the main cap on the power supply. Remove cap connected the tester and nothing, no power on.  I realized I did not short the cap before testing.

There's an official mod for discharging caps with higher voltages (based on a relay). IIRC it's in Karl-Heinz' documentation.

Quote
Pretty sure it took the controller out. So just bought another.
Question is this, is it worth taking the time to replace the chip and reprogram it?  I have no problem changing the chip. But the programming may be an issue.

Yes, any ISP capable programmer will do the job. If the tester you bought matches the reference design you don't even need to compile a matching firmware. Please see http://www.mikrocontroller.net/svnbrowser/transistortester/Software/trunk/ for precompiled firmwares and the source code.

BTW: I'd recommend an ATmega328.
 

Offline Radio Tech

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Re: $20 LCR ESR Transistor checker project
« Reply #92 on: August 19, 2013, 11:14:16 pm »
Thanks,
i'll give it a go.

Offline vehf277

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Re: $20 LCR ESR Transistor checker project
« Reply #93 on: August 20, 2013, 02:27:36 am »
Can this tester be used as in-circuit ESR meter?

No, because the voltage used is higher than 0.7V.
Thank you very much.
It would be great if there is is a way to modify the tester as it can be in-circuit ESR meter cos it is abnormally big price for specialized ESR testers.
Excuse me for my English:)
 

Offline torch

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Re: $20 LCR ESR Transistor checker project
« Reply #94 on: August 20, 2013, 03:57:24 am »
You can, provided you are testing a circuit that won't be damaged by voltages over 0.7v
 

Offline firewalker

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Re: $20 LCR ESR Transistor checker project
« Reply #95 on: August 20, 2013, 04:24:31 am »
It is not only damage. Voltage bigger than 0.7 can turn things on and the reading wont be reliable.

Alexander.
Become a realist, stay a dreamer.

 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #96 on: August 20, 2013, 05:21:17 am »
Thank you very much.
It would be great if there is is a way to modify the tester as it can be in-circuit ESR meter cos it is abnormally big price for specialized ESR testers.

You're welcome! An in-circuit ESR meter would require a special design for low voltages and that would break the hardware-software compatibility we have. But there are a some circuits for dedicated ESR meters, please see http://www.eevblog.com/forum/beginners/esr-meter-circuit/.
 

Offline vehf277

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Re: $20 LCR ESR Transistor checker project
« Reply #97 on: August 20, 2013, 07:41:44 am »

You're welcome! An in-circuit ESR meter would require a special design for low voltages and that would break the hardware-software compatibility we have. But there are a some circuits for dedicated ESR meters, please see http://www.eevblog.com/forum/beginners/esr-meter-circuit/.
I know that URL. I spent a lot of time trying to find a good device for small money and I thought I've done but to my surprise I missed. Thank you very much anyway :)
« Last Edit: August 20, 2013, 07:45:59 am by vehf277 »
Excuse me for my English:)
 

Offline Stonent

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Re: $20 LCR ESR Transistor checker project
« Reply #98 on: August 20, 2013, 11:39:34 am »
To prevent damage I wonder if a relay could be installed that shorts the test pins or maybe a button that you must hold down during the test. When you let go, it shorts the pins.

The relay could be normally closed but then goes open when a test is running, then closes again.
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Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #99 on: August 20, 2013, 09:35:45 pm »
To prevent damage I wonder if a relay could be installed that shorts the test pins or maybe a button that you must hold down during the test. When you let go, it shorts the pins.

The relay could be normally closed but then goes open when a test is running, then closes again.

You're not the first one with that idea :-) Currently there are two moifications supported by Karl-Heinz' firmware. The first one is a relay based discharger for caps (voltage > 5V) and a zener test with a higher voltage (DC-DC converter based). Both are described in the documentation IIRC. And the third mod is a PWM driven backlight control (see my schematics in the SVN).
 


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