[QUOTE=false prophet;42047504]What is the difference between a 1/4 and 1/2 watt resistor?[/QUOTE]
1/4 of a watt
[QUOTE=false prophet;42047504]What is the difference between a 1/4 and 1/2 watt resistor?[/QUOTE]
the 1/4th watt resistor can only dissipate 1/4th of a watt of power before the magic smoke containment field collapses, while the 1/2 watt resistor can take 1/2 of a watt. The 1/2 watt resistor will of course be bigger though.
[QUOTE=DrDevil;42048641]the 1/4th watt resistor can only dissipate 1/4th of a watt of power before the magic smoke containment field collapses, while the 1/2 watt resistor can take 1/2 of a watt. [b]The 1/2 watt resistor will of course be bigger though.[/b][/QUOTE]
It depends on the materials used in the construction, I've seen some tiny ass 1W resistors smaller than your average 1/4W.
I guess I should have asked what does it mean and how is it applied.
Also, what type of solder would you guys suggest for a tiny generic pcb? I have a roll of some huge solder but it's far too big for my project and can cover up more than 1 hole.
[QUOTE=false prophet;42052077]I guess I should have asked what does it mean and how is it applied.
Also, what type of solder would you guys suggest for a tiny generic pcb? I have a roll of some huge solder but it's far too big for my project and can cover up more than 1 hole.[/QUOTE]
The resistor needs to be able to handle the power dissipated in it which is almost entirely converted to heat, any resistance dissipates a certain amount of power depending on the voltage dropped across it and the current flowing through it hence P = V*I, if the power dissipated is greater than the resistor is rated to handle it will overheat and fail.
As Ohm's Law states the voltage dropped across a resistor is V = I*R and the current through it is I = V/R.
As for solder I suggest you use 0.5mm 60/40 or 63/37 with a rosin core flux.
[QUOTE=Chryseus;42052146]The resistor needs to be able to handle the power dissipated in it which is almost entirely converted to heat, any resistance dissipates a certain amount of power depending on the voltage dropped across it and the current flowing through it hence P = V*I, if the power dissipated is greater than the resistor is rated to handle it will overheat and fail.
As Ohm's Law states the voltage dropped across a resistor is V = I*R and the current through it is I = V/R.
As for solder I suggest you use 0.5mm 60/40 or 63/37 with a rosin core flux.[/QUOTE]
And in case you didn't notice if you bosh ohms law into the power equation to get a nicer one for when you only know current or voltage. P=Rx(I^2) or P=(V^2)/R
Bah! Why must the beautiful [URL="http://sigma.octopart.com/184533/image/Bud-Industries-EX-4500.jpg"]extruded aluminium chassis[/URL] be to short to fit a transformer? Just as soon as I finish my panel design for my upcoming bench psu, I found out that my transformer is to tall to fit..
Anybody know of a extruded aluminum chassis that is taller than 3 inches? 7"x4"x3+".
I don't want to design for these [URL="http://www.mouser.com/images/hammond/lrg/1411v5b.jpg"]peasant level enclosures[/URL].
Restuffing capacitors is hard work!
[t]https://lh6.googleusercontent.com/-Je2gt8nCMFQ/UiTc1sQTKRI/AAAAAAAABPE/ePZyimTBW98/s0-I/DSCF1057.JPG[/t]
[t]http://u.cubeupload.com/Chryseus/ZTnwTB.jpg[/t]
That looks really gross.
[QUOTE=Map in a box;42057866]That looks really gross.[/QUOTE]
50 years of old dirt, dust and wax will do that.
At least it was not a smokers set, now that is something really gross.
Eugh. I hate it when wax caps explode.
Yay, my scope came...
[t]https://dl.dropboxusercontent.com/u/286964/wbench/IMG_2228.JPG[/t]
[t]https://dl.dropboxusercontent.com/u/286964/wbench/IMG_2221.JPG[/t]
But the probes didn't... Egh, it works though, the trace rotation was way off but I tweaked that and it picks up mains noise and the line trigger works - Ill check the calibration when my probes arrive, not that I need it to be super-duper accurate.
I built a simple triangle wave generator but it failed, woops.
That's a pretty neat setup with those part bins.
[b]Edit[/b]
So I had an idea for a sweep generator since my current function gen sucks when it comes to sweep, I could of course use a DDS chip but there is no fun in that, so my idea is to have a fixed oscillator at say 10MHz and another VCO from 9-10MHz, then mix the two signals together and low pass filter out the sum F1 + F2 so all I'm left with is the difference F1 - F2 which will give 0 to 1MHz, all I need to do then is drive the VCO with a sawtooth and all being well it should put out a swept 0-1MHz sine, if you managed to understand what I just said what do you guys think ?
[QUOTE=Tezzanator92;42064475]Yay, my scope came...
[t]https://dl.dropboxusercontent.com/u/286964/wbench/IMG_2228.JPG[/t]
[t]https://dl.dropboxusercontent.com/u/286964/wbench/IMG_2221.JPG[/t]
But the probes didn't... Egh, it works though, the trace rotation was way off but I tweaked that and it picks up mains noise and the line trigger works - Ill check the calibration when my probes arrive, not that I need it to be super-duper accurate.
I built a simple triangle wave generator but it failed, woops.[/QUOTE]
I brought my Scopes off ebay for £80, same brand too, i think it may have been the same guy
([url]http://www.ebay.co.uk/itm/251316262880?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649[/url])
I Brought 2 of them idk why...
Aye, Same guy. Same scope. He's on the EEVBlog forum.
I don't think it's a bad little buy for £80. Does everything I'll need it to do I think, probably better I spend £300 on a half decent scope, power supply and function generator than on a single Rigol digi scope anyway :)
Aye, this scope certainly is amazing for analog stuff, but you won't be able to measure single shot signals. I strongly recommend you invest in an additional digital scope.
I learned how my breadboard works.
Then I made a circuit for my fan. Then I made the fan speed adjustable with a switch and a resistor. Feels so freakin' awesome. Can't wait to get some solder and hookup wire.
Need to find my solder iron though.
Today I learned how to calculate bode diagrams and how to set up a matrix for four-poles. I want to kill myself at this point.
If I have a bunch of LED's that I don't know the mA rating for, but do know that they vary between 15 and 30mA, how would I best guess the mA for choosing a resistor for? Like, should I base the calculation on a lower, higher or medium mA?
[QUOTE=false prophet;42070371]If I have a bunch of LED's that I don't know the mA rating for, but do know that they vary between 15 and 30mA, how would I best guess the mA for choosing a resistor for? Like, should I base the calculation on a lower, higher or medium mA?[/QUOTE]
Depends upon the color of the LED, most manufactures nowadays list optimal brightness at around ~10mA. I tend to go for 5mA as my reference, but then again I'm a stickler for power saving.
Check their age, and consult the manufacture if you know who it is. But stick with 10mA for starters
looks like a gamma
[editline]4th September 2013[/editline]
what do the symbols in your equation represent, DrDevil?
Im pretty sure thats a j as in jwc (where w is actually ohmega)
Looks like he's rearranging the complex impedance of a capacitor. j being the imaginary term, ohmega representing phase and C capacitance
Ahhh the joy of AC math.
Don't be put off by the crazy looking equation, it's really not that hard.
Yeah my handwriting is terrible
[QUOTE=Chryseus;42074239]Ahhh the joy of AC math.
Don't be put off by the crazy looking equation, it's really not that hard.[/QUOTE]
Its mostly complex numbers right? Not too hard, just an extra dimension to account for.
[QUOTE=LoneWolf_Recon;42075445]Its mostly complex numbers right? Not too hard, just an extra dimension to account for.[/QUOTE]
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, ...).
I think it's amazing how complex numbers can be used to describe voltages, currents and impedances in a really nifty way.
[QUOTE=LoneWolf_Recon;42075445]Its mostly complex numbers right? Not too hard, just an extra dimension to account for.[/QUOTE]
Not too hard, but can be a long winded pile of arse if you're doing it entirely by hand for high power AC systems. Continually converting between polar and cartesian isn't a massive deal until you have to keep going back and forth to add and divide about 10 times.
[editline]4th September 2013[/editline]
[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, ...).
I think it's amazing how complex numbers can be used to describe voltages, currents and impedances in a really nifty way.[/QUOTE]
I try not to think too hard about it, I'm worried if I do I might confuse myself :v
Finally fixed my Function Generator, my collage thrown out some broken equipment, pulled it from the skip, replaced the internal output fuse and a burnt out resistor and its as good as new :)
This One:
[img]http://ecx.images-amazon.com/images/I/31Lk4hTY7lL._SX300_.jpg[/img]
(where my collage got it from:
[url]http://www.rapidonline.com/Test-Measurement/GW-Instek-Function-Generator-GFG-8020H-85-2064/?source=googleps&utm_source=googleps&gclid=CL7VmYSCsrkCFfHKtAodCWoAuw[/url])
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