[QUOTE=DrDevil;42075477]Complex numbers aren't the same 2-dimensional numbers (also known as vectors). All it really is, is a number that consists out of a real number part (1,2,3,...) and an imaginary number part (i, 1*i, 2*i, ...).[/QUOTE]
I thought complex numbers (and hypercomplex numbers like quaternions) were used to represent points before vector analysis became popular?
[URL]http://en.wikipedia.org/wiki/Quaternion[/URL]
Someone on eBay was feeling creative...
[img]http://puu.sh/4iYhk.jpg[/img]
[img]http://puu.sh/4iYhW.jpg[/img]
[url]http://www.ebay.nl/itm/Philips-Fluke-PM-6666-Programmable-Timer-Counter-120MHz-Fully-Tested-/271256767652?pt=LH_DefaultDomain_0&hash=item3f2829cca4&_uhb=1[/url]
Does anyone know where to get decent quality photo resist coated boards from? I get my 200mm x 150mm dual sided ones 5 euros each locally, so I figure there should be cheaper options ordering online.
[QUOTE=ddrl46;42077438]Someone on eBay was feeling creative...
[img]http://puu.sh/4iYhk.jpg[/img]
[img]http://puu.sh/4iYhW.jpg[/img]
[url]http://www.ebay.nl/itm/Philips-Fluke-PM-6666-Programmable-Timer-Counter-120MHz-Fully-Tested-/271256767652?pt=LH_DefaultDomain_0&hash=item3f2829cca4&_uhb=1[/url][/QUOTE]
How could someone Deface such useful equipment....
New scope arrived today!
[t]http://i.imgur.com/KAGwAGj.jpg[/t]
£60 off of ebay - that's £1 per MHz!
Got a really good deal (and took a gamble on my troubleshooting abilities) because the seller said that he could only get one trace, but it seems like he actually just couldn't find the dual trace button and was a bit embarrassed to say :v:
So I'm pretty pissed that CircuitLab went down the toilet with them now charging money for a half finished simulator, certainly it isn't the best but it was very convenient particularly for drawing schematics, there are some alternatives around like PartSim but they're just not as good.
I've done some work on my own simulator which can so far parse a spice netlist and display the result, the general idea is pretty simple, generate a netlist, run it through a simulator (ngspice for example) and display the data, however it's pretty slow going as I'm no expert at PHP or javascript so help would be much appreciated if any of you guys are interested, I'm quite willing to pay for hosting and a domain for it and it will of course always remain free.
I make a living doing web development on PHP and JS but I know I wouldn't have the time to commit to the project :( - Already juggling 2 businesses, a Band, a Degree, A software project and a Job.
It does interest me though.
Was looking forward to removing some components from this PCB. Why is there icky yellow-ish glue everywhere?
[QUOTE=Kirth;42109995]Was looking forward to removing some components from this PCB. Why is there icky yellow-ish glue everywhere?[/QUOTE]
If you have a big device that is just standing on few pins (like a capacitor, or any TO-220 etc. device) you will get problems due to fatigue. Basically the pins will weaken and the device could break off. The glue prevents vibrations and reduces the mechanical stress to the pins.
I assumed as much, doesn't really excuse the sloppy work, though :p
[QUOTE=Kirth;42110509]I assumed as much, doesn't really excuse the sloppy work, though :p[/QUOTE]
What does it matter? Why should they spend money, time and effort on something that the customer won't get to see under normal circumstances?
I'm embarrassed to ask this because I just can't seem to 'get it' from the articles I've read.
Can someone explain Ohm's law and what an amp is? My definition isn't clear... About the only thing that I think I understand is resistance.
[QUOTE=false prophet;42116456]I'm embarrassed to ask this because I just can't seem to 'get it' from the articles I've read.
Can someone explain Ohm's law and what an amp is? My definition isn't clear... About the only thing that I think I understand is resistance.[/QUOTE]
An ampere is simply coulombs per second, simply the amount of charges (electrons or holes) moving per second.
An electron has a charge of -1.602x10^-19 Coulombs (Hole is the opposite charge).
Resistance/Impedance is the opposition/limitation of how many charges can flow per second. The product of these brings about the kinetic potential of these charges as voltage (Joules per Coulomb).
[QUOTE=false prophet;42116456]I'm embarrassed to ask this because I just can't seem to 'get it' from the articles I've read.
Can someone explain Ohm's law and what an amp is? My definition isn't clear... About the only thing that I think I understand is resistance.[/QUOTE]
One ampere is a coulomb per second, meaning that in one second that much charges pass a certain point/slice/whatever.
A mass of electrons isn't arbitrarily compressible in a conductor (mostly due to the charge imbalance that pushes them away from or towards an area with many/few of them), so if something is obstructing their flow they get backed up on one side and held back on the other. This is the voltage you can measure across a resistor with current and the relative absence of it along the rest of the cable.
This imbalance pushes the charges through the resistor, so that you get a certain throughput/current based on the properties of the resistor and voltage/charge imbalance.
Electrons are accelerated proportionally to the electric displacement field (the field from the outer voltage weakened by the polarization of the material) which is proportional to the outer field. This means that they will drift with a speed proportional to the voltage, on average, and you get for a given resistor a certain current per applied voltage. The resistance is simply the inverse of that value and gives you the voltage you have to apply for a certain amount of current:
1Ohm = 1V / 1A
In practice not many resistors are perfect enough to keep the same resistance over a wider range of voltages, so this law can only be used in specific cases where the resistors are used within their specifications.
Complex impedance works because certain elements in circuit with oscillating voltage/current create a second order differential equation that can be conveniently described with complex numbers.
[QUOTE=false prophet;42116456]I'm embarrassed to ask this because I just can't seem to 'get it' from the articles I've read.
Can someone explain Ohm's law and what an amp is? My definition isn't clear... About the only thing that I think I understand is resistance.[/QUOTE]
To simplify 1 Amp is the amount of current you get when putting a voltage (electrical potential) of 1V across a 1 Ohm resistor.
The larger the resistor the less current and inversely the larger the voltage the more current you get for the same resistance hence the amount of current is proportional the the voltage divided by the resistance:
I = V / R
R = V / I
V = I * R
Also 1V across 1 Ohm also produces a power dissipation of 1 Watt giving:
P = V * I
P = I^2 * R
P = V^2 / R
Which one you should use is simply a matter of convenience since when using multiple resistors in series the voltage dropped across each resistor is not equal to the supply voltage, rather each resistor drops a proportional amount of voltage across it which can be found easily enough with V = I * R since the total current through each resistor must be equal.
[img]http://u.cubeupload.com/Chryseus/NAA1BX.png[/img]
The same sort of rules apply to parallel circuits as well, in parallel circuit the total current is the sum of each branch current, for more complex mixed series / parallel circuits simplification is usually done first then you proceed in reverse to find what you need to know, of course you'd be better at that point to shove it in a simulator.
All components can roughly be simplified to a network of voltage sources, current sources, resistors, capacitors, inductors and diodes.
The best way to learn this is just draw some resistor circuits on paper and apply Ohm's Law, eventually you'll get to the point where you can do it in your sleep.
I finally got a soldering station, a Hakko FX-888D, which has buttons and a digital display. I originally thought that was pretty cool but it's actually kind of a pain to use compared to a dial.
[thumb]http://i.imgur.com/UMppD87.jpg[/thumb]
You can certainly set it faster with a dial, but buttons are more precise. (Unless of course you have a rotary encoder as a dial)
[QUOTE=DrDevil;42135693]You can certainly set it faster with a dial, but buttons are more precise. (Unless of course you have a rotary encoder as a dial)[/QUOTE]
Buttons are too much of a pain in the arse even when factoring in to how accurate they are compared to pots.
Unless you work with RHOS certified solder at a job where you hand-solder boards, assembly line fashion.
My scope has issues with automatic triggering, but only until about 10 minutes after it's turned on - it's fine after that (so I'm guessing something temperature related).
Set level triggering and all the other trigger modes work fine, but the level set by the pot varies significantly as it warms up (it needs steady adjustment to maintain the same level).
The only other thing I've noticed is that auto triggering does work immediately if the gain is set so the wave is taller than the display - the manual says it should trigger on ~5mm displacements :v:
I've found this really hard to google, does anyone have any ideas what's going on? I've given the trigger board a quick glance over and there's nothing obviously burnt or heat damaged.
It's not unusual for precision equipment to require a warm-up period before the specs are reached.
[QUOTE=Van-man;42136543]Buttons are too much of a pain in the arse even when factoring in to how accurate they are compared to pots.
Unless you work with RHOS certified solder at a job where you hand-solder boards, assembly line fashion.[/QUOTE]
Coarse-fine pot pairs + a digital readout!
Probably a leaky capacitor.
[QUOTE=DrDevil;42142763]It's not unusual for precision equipment to require a warm-up period before the specs are reached.[/QUOTE]
Okay, thanks, but the automatic triggering completely does not work (or is out by over a decade) until about 5-10 minutes after power on? If that's normal then I'm not worried, it just does seem a little excessive!
[QUOTE=r0b0tsquid;42143058]Okay, thanks, but the automatic triggering completely does not work (or is out by over a decade) until about 5-10 minutes after power on? If that's normal then I'm not worried, it just does seem a little excessive![/QUOTE]
5-10 minutes does seem very excessive for normal warm up time, it sounds more like a leaky capacitor that starts to work properly once it has heated up.
The easiest way to find it would be to wait until it is working normally then go around with a can of air duster to rapidly cool down parts until the problem comes back.
If something doesn't work, 99% of the time it's a bad capacitor.
Wait until it works, turn it off and then turn it on again and see if the problem still exists.
Any suggestions for a, preferably 16 channel, constant current driver. I need to be able to set it to ~15-20mA, and brightness control would be a plus, though not like the TLC5940 since that requires specific timing and that would mean using another timer on my micro which isn't ideal. An I2C device would be nice since then I will be able to save some IO, so I was looking at the TLC59116 but I was wondering if anyone has a better suggestion.
TI has an excellent product pickers, and they have a vide variety of LED drivers available.
Can someone suggest a multimeter for a beginner? I'm wanting to measure amp, voltage and resistance in a number of things that would range from 240v AC to 24v DC. Budget of $25
[QUOTE=false prophet;42158433][B]Budget of $25[/B][/QUOTE]
Good luck
[QUOTE=Leestons;42158488]Good luck[/QUOTE]
[url]http://www.amazon.com/gp/product/B000EVYGZA/[/url]
[url]http://www.amazon.com/Equus-3300-Hands-free-Digital-Multimeter/dp/B001O1X65A/[/url]
[url]http://www.amazon.com/DT830B-Digital-Voltmeter-Ammeter-Multimeter/dp/B005KGCI0Y/[/url]
[url]http://www.amazon.com/Digital-VOLT-Meter-Voltmeter-Multimeter/dp/B005EK3NRS/[/url]
The reason I have a $25 budget is because I only have some amazon gift cards.
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