$20 LCR ESR Transistor checker project

[texaspyro]

It's not long enough or high enough of a voltage/current to do any damage.

But wouldn't it be safer to limit the test voltage to something under a capacitors reverse breakdown voltage of 1.5v?

You can't do that with a processor/circuit that is using 5V digital I/O pins.

[Alex1]

You can't do that with a processor/circuit that is using 5V digital I/O pins.

What about if one lead of the tester was designated as positive so that it could always be connected to the positive side of the capacitor by the user, or would the way the test works break that?

[SeanB]

LONG term reverse voltage will damage an electrolytic, but a short term ( less than 1 second) non repetitive pulse will have no effect. Repetitive reverse pulses will destroy it, asa they average out as a long term reverse voltage. Remember a non polarised electrolytic is subjected to a reverse voltage on each foil, and they last decades in service.

[Alex1]

Fair enough then if its just long term reverse polarity that does damage.

I was just having a moment thinking that I might have just done something stupid on an appliance I am repairing for a friend.

[madires]

@madires Looking on a scope during a capacitance test it seems that this tester will apply a high reverse voltage directly across the capacitor during one half of the cycle, which for an electrolytic is bad.

Should it be placing such a reverse voltage across the capacitor?

Below shows my scope which is DC coupled to the output of the tester with a 1200uF capacitor connected across it. Shouldn't this cause the capacitor to break down during one half of the test cycle?

What you saw seems to be some test for another component. During the capacitance measurement the polarity of an electrolytic cap might be reversed, but the current is limited to 7mA and 10ms pulses for the first phase (high capacitance) and is limited to 10µA for the second phase (low capacitance). During the first phase a voltage of more than 300mV across the cap will end the test. The test for small capacitance limits the voltage to the internal bandgap reference (ATmega168/328: 1.1V). The ESR measurement creates pulsed forward and reverse voltages for a few µs each, also limited to 7mA. If you're concerned about running the other tests you could run the tester's in-circuit ESR measurement via the menu.

[Alex1]

What you saw seems to be some test for another component.

During the first phase a voltage of more than 300mV across the cap will end the test.

So it shouldn't be doing the test displayed on the waveform? The atmega328 has version 1.11k according to the end of the self calibration routine.

If you're concerned about running the other tests you could run the tester's in-circuit ESR measurement via the menu.

What is the procedure to access this menu?

Thanks.

[con-f-use]

The atmega328 has version 1.11k according to the end of the self calibration routine.

Latest version should be 1.10k.

[Alex1]

The atmega328 has version 1.11k according to the end of the self calibration routine.

Latest version should be 1.10k.

It definitely says 1.11k.

What you saw seems to be some test for another component. During the capacitance measurement the polarity of an electrolytic cap might be reversed, but the current is limited to 7mA and 10ms pulses.

During the first phase a voltage of more than 300mV across the cap will end the test. The test for small capacitance limits the voltage to the internal bandgap reference (ATmega168/328: 1.1V).

[/b]

This definitely doesn't look right then.

Some waveforms taken during a capacitor test, all 2 volts and 1 second a division.
From top to bottom is 10uF, 1500uF (reads 1222uF) and then 2200uF.

[madires]

So it shouldn't be doing the test displayed on the waveform? The atmega328 has version 1.11k according to the end of the self calibration routine.

The tester runs several checks to detect the component type and the capacitor check is done at the end. What you saw isn't probably part of the capacitance measurement but some other test done before the capacitance check.

What is the procedure to access this menu?

For the k-firmware it's a long key press (>500ms).

[Alex1]

The tester runs several checks to detect the component type and the capacitor check is done at the end. What you saw isn't probably part of the capacitance measurement but some other test done before the capacitance check.

Would your "m" firmware 1.15m act any differently?

For the k-firmware it's a long key press (>500ms).

I can't seem to access it at all and holding down the button for too long gives a timeout error. Maybe the Chinese have started to disable that menu by modifying the code before flashing the uC.

[madires]

Would your "m" firmware 1.15m act any differently?

A little bit different, but mostly the same.

I can't seem to access it at all and holding down the button for too long gives a timeout error. Maybe the Chinese have started to disable that menu by modifying the code before flashing the uC.

The menu was added in 1.10k and is enabled with the WITH_MENU option in the Makefile.

[hapless]

I can't seem to access it at all and holding down the button for too long gives a timeout error. Maybe the Chinese have started to disable that menu by modifying the code before flashing the uC.

Sometimes it's just a matter of timing.

"Timeout!" should probably say "Shutting down..." or something similar instead, by the way. It describes the event perfectly, but not the action that's being taken.

[Alex1]

Yeah its definitely not been enabled on this unit.

I've spent a good 30 minutes finger blasting the test button for different intervals but nothing comes up.

I am wondering since I don't have the correct hardware to program the atmega328, would it be possible to use an arduino uno to do the job of programmer instead?

[hapless]

I don't have an Arduino, but I'd be surprised if you couldn't. Have a look at this: .

[con-f-use]

Yes, every Arduino can be used as an in-system programmer (ISP) for Atmegas. The board of your tester must have a programming header, though. If it doesn't, you need to botch wire directly onto the pins your tester's microcontroller.

[amtpdb]

Hi:
I purchased this meter:http://www.ebay.com/itm/291041497713?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
and purchased a  ATmega328P-PU with Arduino UNO bootloader.
I went through the postings here and found postings as to what to burn on the chip. Not quite up on this as a few mentioned opened several file and options and I have no idea which one to pick and if there is anything else to do? Also there has been mention of the fuses to set. On my pick programmer I knew where to set these.  I downloaded WinAVR and don't quite know where  to set them if I could find them!
Any help would be appreciated.
Don

[Richard Crowley]

You have not explained WHAT you are attempting to do?
The kit comes with a pre-programmed microcontroller, so WHY do think you want to re-blast the firmware?

[amtpdb]

I want to make sure it is updated.
Thanks

[con-f-use]

Connect all three testpoints toghether with a wires, then press the button on your tester. This will start a selftest. Follow the instructions on the LCD (at some point you might have to disconnect the wires again and/or put a capacitor on the test points). At the end of the selftest your unit will display its firmware version, e.g. "1.10k". Then you'll see if it is up to date.

[amtpdb]

Hi:
It's 1.11

I have an atmel328p and trying to use WinAVR with a Sparkfun  Pocket avr programmer. I am new to this and need or would like some help if you can.
Thanks
Don

I pulled out the Make file and loaded it into WinAVR and I think that is the one to use?

[con-f-use]

There's two versions of the software. Latest Markus version would be 1.15m. Karl-Heiz's firmware has the version 1.11k.

I never used winavr, but with Avrdude and GNUmake installed you can do it all from command line. First you need to know your hardware. The most important stuff being:

You have an atmega328p so -> PARTNO=m328p
What type of LCD do you use?
Is there a crystal on your board?
Do you have a bunch of transistors in your battery power circuit?
Is there a voltage divider measuring the battery voltage?
The pocket avr programmer is based on the usbtiny so -> PROGRAMMER=usbtiny and PORT=usb

According to that, you'll need to set the Makefile options. Did you read the Makefile and the documentation? You'll also need to be more specific about your problems. We can't really guide you through what to do, if you just say 'I don't know winavr'. Try it, and then tell us, what did and didn't work. Be very careful with the fuse bits or you risk bricking your controller.

[madires]

Then most likely you have Markus' firmware. Latest version would be 1.15m. Karl-Heiz's firmware has the version 1.10k.

Just a small hint Karl-Heinz' trunk version (current version under development) is 1.11k.

[amtpdb]

Thanks for getting back.
I'll give it a try and see what happens.
Thanks again.
Don

[Alex1]

I don't have an Arduino, but I'd be surprised if you couldn't. Have a look at this: .

Thanks I will have a look into it.

That's a good idea! I always encourage contributors and users to send bug reports, add-ons, modifications and so on.

How about having a buzzer that gives a small chime when the component is done being tested like on the peak atlas series. I'm guessing all it would need is for one of the chips outputs to pulse high once or twice for a couple hundred milliseconds.

http://youtu.be/8EXcN9kUwUc?t=15m28s its from 15:28 if the youtube autotime function doesn't work.

[madires]

How about having a buzzer that gives a small chime when the component is done being tested like on the peak atlas series. I'm guessing all it would need is for one of the chips outputs to pulse high once or twice for a couple hundred milliseconds.

Could be useful for large electrolytic caps when the tester needs some time for the measurement. For all other components the tests are quite fast. If you like to have a buzzer please design an add-on and write the code driving the buzzer. That would be a good way to start with MCUs