Recent Posts

1

Test Equipment / Rigol DP2031 web password?

« Last post by Per Westermark on Today at 02:48:47 pm »

Anyone know what the password is to access the web pages on the Rigol DP2031 power supply?

The manual claims user: admin and password rigol. Doesn't work.
Some other documentation claims password is RIGOL - uppercase. Doesn't work.
I seem some other Rigol power supply claims password 2012. Doesn't work.

I have a support ticket to Rigol about another issue - and that one has been zero-answer for over a week...

More interesting. My instrument has the web pages.

The most recent manual from August this year have removed the text about any web interface. So no way to check if any password correction has been incorporated.

2

Beginners / Re: High frequency (50kHz) 16 bit PWM

« Last post by pcprogrammer on Today at 02:48:08 pm »

stmH7, stmG4 have HRTIM. G4 equivalent clock is >4 GHz, so 16-bits at 83 kHz PWM.
Nucleo-G474re is at mouser about $23 CAD.

This HRTIM is also mentioned in this thread but it comes with a lot of constraints, and is not a true high speed clock, but something with delay lines, so read the manual carefully before you decide to buy. A G474 board from weactstudio is ~7 euro on Aliexpress.

3

Projects, Designs, and Technical Stuff / Re: Energizer Ultimate Lithium: sudden failure of only some cells

« Last post by voltsandjolts on Today at 02:47:32 pm »

Well, you're not alone!
https://www.eevblog.com/forum/renewable-energy/sudden-death-problems-with-energizer-ultimate-lithium/

4

Test Equipment / Re: Zoyi ZT-MD1 - new LCR Tweezers

« Last post by indman on Today at 02:41:47 pm »

May I remind you that I didn't even pay $20 for this little device (including replacement heads, bag and delivery) and that it is quite useful and convenient for many cases?
No one questions that a more expensive device measures more accurately, especially in borderline cases.

These cheap tweezers will certainly find their buyers and supporters, primarily due to their low price and fast speed of work in determining the main values ​​of LCR components in a fairly wide range. Nobody argues with this. But comparing them in terms of capabilities with more serious competitors in the form factor of smart tweezers is also pointless.

5

Test Equipment / Re: Zoyi ZT-MD1 - new LCR Tweezers

« Last post by mawyatt on Today at 02:40:52 pm »

May I remind you that I didn't even pay $20 for this little device (including replacement heads, bag and delivery) and that it is quite useful and convenient for many cases?
No one questions that a more expensive device measures more accurately, especially in borderline cases.

Of course that's the intended purpose in evaluating a particular component with limited accuracy, it's only when folks start to look to these tweezers for precision measurements that brings up the question of measurement validity

We might even get these for quick and easy SMD Component evaluations, but never for any type component comparisons and details measurements

Even with expensive bench type LCR meters as shown above, one needs to pay close attention and understand the test setup and details if one expects repeatable precision results with low Z components

BTW where did you get your Tweezers for $20 from?

Best,

6

Repair / Re: Agilent 34401A Bubble on PCB ... can it be saved ?

« Last post by Dr. Frank on Today at 02:37:46 pm »

sorry to reply so late.
The current source still might have a problem gor the high Ohm ranges. That should be the 500nA source current, affecting both highest ranges.
Please apply a 1M or 10M resistor in 2W autorange  mode, and fill out the diagram, which shows the crucial voltages in this circuit, once with the correct ones as measured by me.
Most suspect is this dual OpAmp with very low bias current, which fails quite often.

Frank

7

Projects, Designs, and Technical Stuff / Re: Energizer Ultimate Lithium: sudden failure of only some cells

« Last post by 6SN7WGTB on Today at 02:34:31 pm »

The batteries are all in series with no taps.

I have the factory schematics plus a fairly deep knowledge of the unit as I have done the full SMD re-cap...

8

Projects, Designs, and Technical Stuff / Re: Question about real time clock - M48T12-150PC1

« Last post by Peabody on Today at 02:33:55 pm »

Can you clarify what you mean by "power cycle"?  Is this a power failure, or is power deliberately switched off every day?  If the former, perhaps you could just get a small UPS that would keep everything running when the power goes out.

Is the MT48T12 in a socket?  Could you possibly post pictures of the top and bottom of the circuit board?

Would you be replacing the whole board, or just the MT48T12?  Digikey carries the MT48T12 for $25.

9

Test Equipment / Re: Zoyi ZT-MD1 - new LCR Tweezers

« Last post by mawyatt on Today at 02:31:37 pm »

So with a 1.0 mill Ω DUT one could expect ~8.5 microvolts peak across the DUT, this will be a difficult level to resolve accurately and repeatability for the tweezers due to the limited level of test current which questions the validity of such low Z measurements with these tweezers.

Absolutely right, with such a low signal(current) there can be no talk of any more or less reliable measurement(Z) of low milliohm resistances. Therefore, there is no need to show us fantastic photographs where 0.5 mOhm is measured with these tweezers. 
These results will change randomly with each new measurement and depend on the pressing force of the tips. Moreover, the 4-wire circuit turns into a 2-wire circuit on the measuring tips of the tweezers.

We've had difficulty even with Lab Grade LCR Meters like the Tonghui TH2830 and Hioki IM3536 which can deliver ~150ma peak making low Z measurements with the quality Tonghui TH26009B Tweezer Fixtures (also with Standard Type SMD Fixtures). This is because of the uncertainty in contact details as you mention.

WRT the 4-wire to 2-wire transition at the tweezers tips, this is why we developed the Split-Kelvin Type measurement fixture for LCR meters for low Z SMD components.

Here the Force and Sense (4-wire to 2-wire transition) connections are made by the SMD component end terminals, thus considerably reducing measurement uncertainty due contact variations. We can state this technique works very well indeed

https://www.eevblog.com/forum/projects/different-type-lcr-smd-fixture/msg5061028/#msg5061028

https://www.eevblog.com/forum/testgear/sensitive-lcr-meter-measurements/msg5582175/#msg5582175

Best,

10

Test Equipment / Re: Zoyi ZT-MD1 - new LCR Tweezers

« Last post by Aldo22 on Today at 02:30:35 pm »

May I remind you that I didn't even pay $20 for this little device (including replacement heads, bag and delivery) and that it is quite useful and convenient for many cases?
No one questions that a more expensive device measures more accurately, especially in borderline cases.