$20 LCR ESR Transistor checker project

[madires]

Why changing to EUPL? Weekday about license compatibility?

Actually it's not a change. There was no license before. And EUPL is pretty simple and straight forward.

[timofonic]

Why changing to EUPL? Weekday about license compatibility?

Actually it's not a change. There was no license before. And EUPL is pretty simple and straight forward.

Severe license incompatibilities, especially the GPL variants.


https://joinup.ec.europa.eu/software/page/eupl/eupl-compatible-open-source-licences
https://joinup.ec.europa.eu/community/eupl/news/eupl-or-gplv3-comparison-table-main-characteristics-and-differences
http://www.gnu.org/licenses/license-list.en.html#EUPL

You can go "the french way" and relicense to CeCILL v2, then you can relicense to GPLv2 and then you can relicense  it to GPLv3. To me as long time wannabe geek and bureaucracy hater, this seems like in the Brazil movie!

I think this license is quite problematic if someone wants to do a fork and add some functionality, like SCPI support (crazy idea, but I'm sure there are saner ones to do in more complex AVR chips).

Why did you choose that license? It seems done to make wet dreams to bureaucrats and politicians, but not so practical in the FLOSS community.

I don't want to offend you. I'm an expert at nothing, but I had to deal with license violations in the Free Software and reported some of them. In fact, I just reported one a few hours ago.

[upsss]

Hi, I am brand new to this forum but an old EE.  I finally decided to order one of these testers.  I would like to use a rechargeable battery instead of the 9V one.  I am planing on using an 18650 Li-Ion with one of these cheap USB PowerBank (<$1 on eBay and I have plenty of these batteries).  These PowerBanks have a small charger for the Li-Ion and a step-up PWM for the 5V output.  My idea is to use the circuit to charge the battery and to replace the linear 5V regulator on the tester.  A fully charged battery will probably last me over a year if it wouldn't self discharge before that.

My question is, the tester monitors the battery voltage on PC5, does it do anything with that information, like shutting down everything if it thinks that the battery voltage is low (Li-Ion is ~3.7V)?  Would I need to reprogram the AVR, or the battery voltage monitoring is just for the user information.

[tom666]

@upsss
Before compiling the new firmware you have to make the necessary changes in the "Makefile":
# To adjust the warning-level and poor-level of battery check to the capability of a
# low drop voltage regulator, you can specify the Option BAT_POOR=5400 .
# The unit for this option value is 1mV , 5400 means a poor level of 5.4V.
# The warning level is 0.8V higher than the specified poor level (>5.3V).
# The warning level is 0.4V higher than the specified poor level (>2.9V, <=5.3V).
# The warning level is 0.2V higher than the specified poor level (>1.3V, <=2.9V).
# The warning level is 0.1V higher than the specified poor level (<=1.3V).
# Setting the poor level to low values is not recommended for rechargeable Batteries,
# because this increase the danger for deep discharge!!
CFLAGS += -DBAT_POOR=2800

[upsss]

@tom666, so what exactly happens when the battery reaches the "poor level", does the system shuts down?

[bianchifan]

I am planing on using an 18650 Li-Ion with one of these cheap USB PowerBank (<$1 on eBay and I have plenty of these batteries).  These PowerBanks have a small charger for the Li-Ion and a step-up PWM for the 5V output.  My idea is to use the circuit to charge the battery and to replace with it the linear 5V regulator on the tester.

Yes, you can.

what exactly happens when the battery reaches the "poor level", does the system shuts down?

No, but it doesn't start

All what you need is to get familiar with the makefile options.
Hardware specific there are three point for voltage monitoring:
- voltage divider
- battery/input voltage
- regulator output voltage/VCC

If you connect the LiIon with battery input and the booster output to VCC there is no need for a seperated protection board.

Note:
I've built two testers from DIY M12864 Tester, the 7550 has a drop of 0.1 V only.
I selected a booster for 5.135 V output, connected to BatIn and VCC is 4.99 V, when testing it drops to 4.89 V

[madires]

@tom666, so what exactly happens when the battery reaches the "poor level", does the system shuts down?

The tester displays a "battery low" message and powers off. For a Li-Ion battery you would have to change/remove the voltage divider (just a single resistor I assume) and the code for the battery check. Simple job.

[upsss]

Thanks guys, that is exactly what I needed to know.  In the meantime I will probably cheat (I am a hardware guy) and change proportionally the PC5 voltage divider while I order a programmer and learn how to reprogram this thing.

[tom666]

For a Li-Ion battery you would have to change/remove the voltage divider (just a single resistor I assume) and the code for the battery check.

I do not understand why? How then will test the voltage of the Li-Ion battery?
The voltage divider is needed and there is no reason to change the values of the divider (resistors 10k and 3k3). Attached picture is only for inspiration (power from 2xAA battery or from the USB port).

[upsss]

@tom666, you are right if you are going to reprogram the AVR then the sensing voltage divider should stay the same.  What I will do temporarily until I reprogram it, I will change the lower resistor from 3.3k to 15k and that will "fool" the AVR to think that the 3.7V battery is actually 9V.

[timofonic]

@madires

Sorry if I'm stubborn and boring with that.

Did you read my message about the license?

[Macbeth]

@madires

Sorry if I'm stubborn and boring with that.

Did you read my message about the license?

I would prefer he doesn't waste his time on utterly shit banal bureaucratic legalese crap and get on with just doing what all hobbyists and enthusiasts have done forevermore. Especially as we already know the fucking Chinese are not in the least bothered with this shit for a $10 transistor tester.

Stop harassing people with your version of what you think is the correct version of open source - go and make something fucking interesting and useful instead, maybe? Then apply your own preferred license to it. 

[madires]

For a Li-Ion battery you would have to change/remove the voltage divider (just a single resistor I assume) and the code for the battery check.

I do not understand why? How then will test the voltage of the Li-Ion battery?
The voltage divider is needed and there is no reason to change the values of the divider (resistors 10k and 3k3). Attached picture is only for inspiration (power from 2xAA battery or from the USB port).

The Li-Ion battery got 3.7V which is less than 5V. So you can monitor the battery directly (just protected by a series resistor). Also I would change the ok/weak/low levels to match the Li-Ion battery.

The circuit you've attached doesn't have the MCU controlled power management. If you take the original circuit, adjust some resistor values and insert the boost converter behind the power switching PNP you'll get a nice Li-Ion powered unit.

[madires]

@madires

Sorry if I'm stubborn and boring with that.

Did you read my message about the license?

Yes, I have. And I'll stay with the EUPL, because that license is exactly what I want.

[AlessandroAU]

Anyone buy one of these from eBay?

http://www.ebay.com.au/itm/381439312402?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

[tom666]

The Li-Ion battery got 3.7V which is less than 5V. So you can monitor the battery directly (just protected by a series resistor). Also I would change the ok/weak/low levels to match the Li-Ion battery.

I agree. However, it should make a small modifications in the source code. Otherwise (if used standard voltage divider), just only make the appropriate adjustments in the Makefile.

[tom666]

I would like to use a rechargeable battery instead of the 9V one.  I am planing on using an 18650 Li-Ion with one of these cheap USB PowerBank (<$1 on eBay and I have plenty of these batteries).  These PowerBanks have a small charger for the Li-Ion and a step-up PWM for the 5V output.  My idea is to use the circuit to charge the battery and to replace the linear 5V regulator on the tester.

Attached pictures (inspired with the Fish8840 tester) contain two possible solutions for the supply with the Li-Ion battery and adjustable voltage boost module. This circuits could be supplemented with a charging module.

[upsss]

With my idea, the Power Bank circuit for <$1 incorporates the charger and the 5v output into one tiny circuit.

[timofonic]

Is the Transistor/Component Tester code easy to port to other similar platforms?

There are interesting chips from Silicon Labs that are 8051 based, too. I causally got for free a C8051F063 one.

I have no clue about programming, but it seems to provide nice ADC and DAC features.

[eas]

Is the Transistor/Component Tester code easy to port to other similar platforms?

There are interesting chips from Silicon Labs that are 8051 based, too. I causally got for free a C8051F063 one.

I have no clue about programming, but it seems to provide nice ADC and DAC features.

I have only a slight clue about programming, but I'm guessing that, no, it isn't easy to port, since it takes advantage of particulars of AVR hardware. On the other hand, the documentation is quite detailed. A port sounds like a good way to learn something about embedded programming...

[timofonic]

@Macbeth
@madires

I'm sorry, I didn't want to annoy at all. The real issue is that mixing codes from different licenses is a real mess, that's all. I didn't want to annoy people, just provide feedback.

Is the Transistor/Component Tester code easy to port to other similar platforms?

There are interesting chips from Silicon Labs that are 8051 based, too. I causally got for free a C8051F063 one.

I have no clue about programming, but it seems to provide nice ADC and DAC features.

I have only a slight clue about programming, but I'm guessing that, no, it isn't easy to port, since it takes advantage of particulars of AVR hardware. On the other hand, the documentation is quite detailed. A port sounds like a good way to learn something about embedded programming...

Thanks for the info!

I had a very wrong idea about AVR and 8051. I did think this would be a lot simpler, just like porting an x86 OS to another x86 machine. But thinking about that, there should be "drivers" for the peripherals and such.

I can get more of those chips. If anyone is interested in research about that, he'll get them for free

[timelessbeing]

I want to add a relay to the tester to protect it from charged capacitors. Should I include a series resistor to limit the discharge current?
I know that when the "screwdriver method" is used with high energy caps, there is a visible arc, and then damage to the surface of the piece of metal used. Maybe the arcing would eventually destroy the relay contacts, or possibly weld them shut. I think a 1R3 resistor would do the trick.

[madires]

I want to add a relay to the tester to protect it from charged capacitors. Should I include a series resistor to limit the discharge current?
I know that when the "screwdriver method" is used with high energy caps, there is a visible arc, and then damage to the surface of the piece of metal used. Maybe the arcing would eventually destroy the relay contacts, or possibly weld them shut. I think a 1R3 resistor would do the trick.

The relay is just a crude protection. A series resistor limits the current but increases the discharge time, and the delay might be long enough to destroy the MCU. The question is more likely to be whether the MCU or the relay is cheaper. I'd suggest to have a simple process in place to measure the voltage with a DMM and discharge the cap with a resistor before using the Transistortester. This is a good advice anyway when repairing a device.

[timelessbeing]

How can the rotary encoder be connected to the same pins as the display (PD1/3) without interfering with it?

[all_repair]

I want to add a relay to the tester to protect it from charged capacitors. Should I include a series resistor to limit the discharge current?
I know that when the "screwdriver method" is used with high energy caps, there is a visible arc, and then damage to the surface of the piece of metal used. Maybe the arcing would eventually destroy the relay contacts, or possibly weld them shut. I think a 1R3 resistor would do the trick.

The relay is just a crude protection. A series resistor limits the current but increases the discharge time, and the delay might be long enough to destroy the MCU. The question is more likely to be whether the MCU or the relay is cheaper. I'd suggest to have a simple process in place to measure the voltage with a DMM and discharge the cap with a resistor before using the Transistortester. This is a good advice anyway when repairing a device.

+1 , without protection an ESR meter would not last long in a real repair scene.  I have burnt a Russian cute tiny ESR 4 times and last time it became non-repairable.  Same to my capacitance meter.  Make it able to withstand 600V, even at 50V, I can retire my Bob Parker ESR.