Recent Posts

1

Mechanical & Automation Engineering / Re: Paint Bubbles On Snowblower

« Last post by T3sl4co1l on Today at 03:09:11 pm »

Not wasted, it might've done this, or much worse, sooner, without cleaning and all that.  But I understand the disappointment.  Unfortunate, but that's just reality, everything gets older, steel rusts, bodies creak, there is no escape from the inevitable embrace of entropy.

Tim

2

General Technical Chat / Re: How does this stuff work?

« Last post by Andy Watson on Today at 03:08:07 pm »

My guess would be that the 62nF disc is the piezo "speaker" - producing sound. The coil is probably there to be used with hearing-aids which have an induction coupling option.

3

Beginners / Re: Help understanding Kirchoff's Voltage Law/Current Law

« Last post by Terry Bites on Today at 03:06:59 pm »

This page is very informative. An introduction to network analysis.
www.allaboutcircuits.com/textbook/direct-current/chpt-10/what-is-network-analysis/

4

Test Equipment / Re: Rigol DHO800/900 Oscilloscope Bug Reports + Firmware

« Last post by Fungus on Today at 03:05:34 pm »

So how about scenario 4: change scale, wait a couple of minutes, then pull the power cord?
If it still remembers the settings change, then saving them is purely timeout-based.

Yes that's exactly what happens. It does not need the power button to be pressed for the settings to get saved, but it appears to need some time to pass after a change is made.

It's a very short time, certainly much less than "a couple of minutes".

I'd also be very surprised if the settings aren't checksummed against corruption.

5

Mechanical & Automation Engineering / Re: Paint Bubbles On Snowblower

« Last post by bostonman on Today at 03:04:17 pm »

wait, we went over this before, with your allthread question, didn't we?

Are you referring to the discussion about threaded rod?

Ariens has been around for decades, so I remain shocked they managed to mess up the paint. Then again, I had a Buick that had paint literally coming off like sheets of paper. Turned out GM did something wrong at the factory (I think it was a recall) that made the paint not adhere to the metal.

The sad part about the snowblower is that I devote a solid three-hours prepping it for summer storage including cleaning the body with regular household spray cleaner, keep the wheels off the ground, and even shine the tires.

The paint bubbling and knowing it will eventually flake off is that now it feels all that time was wasted.

6

Beginners / Re: Help understanding Kirchoff's Voltage Law/Current Law

« Last post by tggzzz on Today at 03:03:54 pm »

Do you understand how to formulate and solve simultaneous equations?

Assign names to all the components (e.g. R1, R2 etc), and denote the current through Rn as In. Similarly denote the voltage at each node.

Then use KCL on each node, and KVL on each loop, e.g. I1=I2+I3, V3=V1+V5, and add Ohms' law e.g. I1=(V5-V3)/R1.

Solve the resulting equations. Once you have done that a few times, you will develop an understanding for the patterns, and then be in a position to take "short cuts".

I note the OP is good at starting threads, but poor at following up to indicate whether or not they have understood: 10 threads, 3 followups. Doesn't look good.

7

Other Equipment & Products / Re: Which 3M static shielded bag

« Last post by Shock on Today at 03:03:09 pm »

bump

8

Test Equipment / Re: Choosing between entry-level 12-bit DSOs

« Last post by Fungus on Today at 03:02:41 pm »

Discussion is going in wrong direction. Beginner that wants entry level scope has no knowledge to understand all DSP stuff being discussed. They need device to simply work. User will bring in enough of it's own confusion into the process.

Rigol UI is better for a beginner so that's probably bad advice. Better to have the stuff they do 99% of the time easy to do than to make life life difficult for some theoretical thing that they might never do.

A "beginner that wants entry level 'scope" probably has no 200Mhz signals lying around anyway.

(I'm not even sure I do...)

Rigol (unlocked to to 250 MHz) and applied 200 MHz signal to all enabled channels

Where's it written that people must do that?

(Be honest, do YOU do that...?)

9

Microcontrollers / Re: SD Card reliability in SPI mode

« Last post by peter-h on Today at 03:01:59 pm »

I may be missing something simple, but surely talking to an SD card via the serial interface is no different to using say FatFS and talking to an SPI flash memory chip.

You will be limited by the flash endurance; typically 100k writes to the same block, plus other limitations like adjacent line interference which needs blocks to be periodically refreshed.

If you want a FAT file system (and you do if you also want it to look like a removable drive to windoze, via USB MSC device profile) then auto wear levelling in the flash media is the only way.

10

Repair / Re: APC Smart-UPS 1500 (SMT1500)

« Last post by Bretterson on Today at 02:58:52 pm »

You're right, I definitely should've cleaned it up before posting. I agree that it likely appears worse than it is since I was able to wipe soot off that big yellow capacitor.

I thought that very charred/melty bit might be a varistor. I'm pretty sure there's also a missing component that fell out right below that and to the right of the yellow cap. I think it might be another varistor based on pictures of a board that sold on eBay a few months ago: eBay auction: #204631885269.

I didn't mean to suggest the batteries measured high, if it sounded that way. Reading it again I can see how it might be a little unclear.

I'll clean it up this week, maybe tonight, and post a new pic.