Recent Posts

Pages: [1] 2 3 4 5 6 ... 10 Next
1
Test Equipment / Re: No love for the Rigol DM3058E DMM ?
« Last post by netdudeuk on Today at 08:28:11 PM »
How about the B&K Precision models 2831E ?

http://www.farnell.com/datasheets/1858092.pdf

KEYSIGHT TECHNOLOGIES  U3401A ?

http://www.farnell.com/datasheets/1864167.pdf
2
Running the numbers on the maximum possible surface power density in the laser spot, I get 1.59KW/sq m, which is only about 50% more than the power density of tropical noon desert sunlight.  This makes the observed discharged vanishingly unlikely to be a electrooptical effect as unless its highly frequency sensitive or requires a coherent light source, such behaviour would be common knowledge, and a known design issue for above ground HV electrical distribution systems.

Except for some important differences...

We are talking about a beam of light not randomly scattered wide area lighting (day light)
a beam provides a conduit for the effect (if it does exist) ie: if particles can become trapped in this beam, they're all in a line and can interact and behave very differently than a mass amount of randomly scattered particles, it doesn't matter how bright that light is.. just the shape of this light.

Could also have something to do with the monochromatic nature of the laser?

Cheer
Simon



3
Beginners / Re: USB cable power testing
« Last post by Balaur on Today at 08:25:42 PM »
4
Beginners / Choosing power resistor for inrush limiter
« Last post by Stefan on Today at 08:24:59 PM »
I'm using a 1000VA transformer I happen to have around to build an isolation transformer. Right now it is only a rather heavy fuse killer  |O

The idea is to use a series resistor as a current limiter and then bypass the resistor with a time-delay relay or something.

A reply on http://www.eevblog.com/forum/beginners/ntc-heat-disspipaion/ suggests to use a power resistor instead of an NTC, which makes a lot of sense to me.

But which one to choose? If I'd like to limit the current to 2A @ 230V, the resistor dissipates a wooping 460W. A resistor that can handle this continuously that would be a bit of a beast. This seems overkill as the resistor will only be in use for a short time.

I think I need a power resistor that has a high termal mass, but I don't find much information in the data sheets about that.

P.S.
Is a 2A limit for 100ms realistic for a 1000VA toroidal on 230V?

5
Microcontrollers & FPGA's / Re: Abysmal Microchip experience
« Last post by NANDBlog on Today at 08:23:32 PM »
Really? I'm the *first* to discover that the channel 9 ADC input wasn't actually hooked up internally to the ADC input mux? How could this not have been caught in testing??
Quite possible. There are many PIC24 and dsPIC33 and all the other chips which I guess never used by anyone. There are some well documented parts, like the 16F and the 32MX bigger, but if you step down from that road, it is like no mans land.
It's not that the chips aren't used, but that most users only use a small proportion of the functionality.
I've never had any issues with undocumented silicon bugs on PICs, but tend to stick to a fairly small subset of chips in each range. More common are errors in header files etc. which can appear like silicon bugs until you figure out what's going on.
I had problems with PIC32MX (not MZ). Like UART libraries only existed for uart 1-4 if you tried using 5/6 thent you are on your own. It was a copy paste and some register modification to make it work.
Other time, I worked with a dsPIC33. I've choose one which had a better ADC than others, well because the application needed one. No library. And in the end, the same part, I found out that one of the port pins did absolutely nothing. After days of frustration I've connected 6V to it on one of the boards, and there was absolutely no current going into it because the pin wasn't even connected to the die.
I'm not saying they are the worst, I've seen Infineon MCUs. It is just a little bit too much that every project I did with a PIC, I ended up having Errata/Library/Silicon bugs.
The PIC32MX is a nice chip, and the ecosystem was nice some 5 years ago. But if they are not changing the picture that they are presenting to everyone, they are going to loose markets left and right.
6
Besides, this soldering station is designed so that you can extract the live soldering tip and replace it with another (that comes to temp within 7 seconds) to fit whatever job is needed.

You need to power-cycle the supply unit, however. Once the tip is removed, it with latch into a fault mode (that's what the yellow LED will then indicate), and only power-cycling clears that.

Also, the 7 seconds is true only for a few tips at a certain temperature. Larger tips, or higher temp cartridges, will require a few more seconds. Althoght it's still very fast.

Greetings,

Chris
7
Hello,

Did any one buy an Asscon Q300? How much did you pay? Are any used available?

I want to buy one but I am looking for a less expensive occasion.

I asked Asscon and they offered one for 7200€ to me which seems a little expensive to me.

Any ideas where to get one for less money?
8
General Chat / Re: We just don't get lightning like this in little old NZ
« Last post by Psi on Today at 08:18:00 PM »
We do get lightning on some occasions. The Auckland skytower gets hit quite often.
But it's never fork lighting

9
Beginners / Re: Analogue V digital scope trace question
« Last post by Chris Wilson on Today at 08:16:53 PM »
Curious that the spikes only appear on positive signals - it's almost as if a power-supply was dropping out.


Hmm, I should have posted the other screen shot Andy. I presume this is showing that when i change the span of the SA the spikes change to appearing on negative signals?
10
The last paragraph on the harmony page leads here: http://www.microchip.com/SoftwareLib.aspx for non-harmony development, or is that something different?
Pages: [1] 2 3 4 5 6 ... 10 Next