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scholzie
Mar 30, 2003

If I had a daughter, she'd probably be pregnant by the time she turned 12.

It pains me to see how much of a moron you actually are. Sorry, but anyone who figures out what resistances to use by mixing and matching until they hit the right one has no right correcting anything anyone says.

But ok, let's go.

SkunkDuster posted:

Here we are talking about using a 12V supply to light up LEDs (first mention of 12V).
I was referring to the OP's original post on "Project #1," wherein a 5V source is used to power a 2.1V LED at 50mA. Please see the massive loving post at the top of this page for further details.

SkunkDuster posted:

Here is a 1/4W (250mW) resistor failing miserably in Scholzie's scenario (second mention of 12V):

Ahem,

SkunkDuster posted:

You're right that at 12V and below in the 20-25mA range that a .25W resistor should be fine for whatever you are doing. When I mentioned using a higher wattage resistor or multiple lower wattage resistors, I was getting another project where I had to do that mixed up with some of the LED stuff I've worked on.

I guess it's my fault that I replied to something you admittedly hosed up on. Let's flame scholzie! My original point still stands, considering most LEDs (go ahead and try to prove me wrong) run around 25mA at ~3V. I've personally never seen any normal LED running at 50mA within spec. This is clearly a special case. I've wired up hundreds of LEDs in my lifetime and have never needed higher than a 1/4W resistor. Since you said only care about hobbyists wiring blooooo LEDs into their PS2 controllers, you should be in agreement that 1/4W will be fine for everything you'll ever need. Sorry I didn't add a catchall clause for every situation using every voltage and every power supply ever. Ever. Yes, if you run a 3V LED on a 12V supply, dropping 9V across a resistor at 50mA, you will need a half watt resistor. (Btw, instead of running the circuit for 5 minutes and feeling it with my hands, which really can't tell if a resistor is too hot or not, I could do a 5 second calculation P = 9V*50mA = 450mW and know right away)

SkunkDuster posted:



And finally, we have Scholzie giving out some information that is flat out wrong:


With your vast experience in semiconductors, didn't you look at your post and think "drat, 70mA is awfully high, really loving high, for a regular LED. Maybe I should take another look at that data sheet to see if maybe I missed the word "peak" in there"?

Then you completely contradict yourself in the very next sentence and give out information that is absolutely correct. High five, buddy!
What I said still stands, idiot. Frankly, 50mA is also really freaking high for an LED as well. That diode can handle currents of 50mA sustained and peak forward currents of 70mA. What I said was that 55mA isn't going to kill the LED, but surpassing the max current will fry the LED. How that's flat out wrong is a mystery, because it's 100% correct.

SkunkDuster posted:

And some more poo poo that is dead wrong:


I've plotted the "strange I-V" characteristics for a few of the LEDs I commonly use and I wouldn't call a 358% variation in internal resistance an "almost perfect ohmic device". The 14K mcd red LEDs I have drop 1.9V at 10mA giving them an internal resistance of 190 ohms. If you push them up to 40mA, the voltage drop increases to 2.13V with an internal resistance of 53 ohms. I had planned on plotting the curves for all of the various LEDs I have to use as reference sheets, but I stopped after plotting red, orange, and ultraviolet because I realized that...
Jesus loving Christ take Electronics 101. Diodes operate as a non-ohmic device up to and just past their threshold voltages. Then they can easily be modeled as pure ohmic devices with low-to-no resistance. I'm not even going to argue with you on this point because you're a moron who needs to crack open a textbook before cracking open your mouth.

Most people don't sit in front of their DC LED circuit and loving crank a variable resistor to change current. Once you pick a voltage drop and stick to it, the math falls in place. If you're going to sit here and try to argue semantics then you've got way too much time on your hands. We (real engineers, not pretend ones like you) model diodes as ohmic devices all the time and no one has died from it.

Incidentally, you didn't supply plots, just a bunch of numbers. This is a true diode IV characteristic:


See that nice straight line after the curvy bit? That's I/V. That slope is equal to 1/R (= S [edit: I means S as in Siemens, not S as in the graph's "S=10-4"). If you set your voltage well past the threshold, you do NOT have to worry about changing resistance.

SkunkDuster posted:



...I was wasting my time plotting all these graphs when it was a hell of a lot quicker to just stick the LEDs on the breadboard with my multimeter hooked up in series to measure current, and then


It's not that I don't know the formulas, I just don't think that working them out on paper is always the most efficient way to build a circuit to light up some LEDs. If you just want to make a few LEDs light up, it is a lot quicker to just go straight to the breadboard and measure the results firsthand. Your posts seem geared towards people who want to become electronic engineers and think about substrates and whatnot. Mine are geared towards the average goon who wants to add an LED to his PS3 controller to make the Playstation logo button light up without setting anything on fire.
Interesting, I never make plots before putting an LED in, and I'm still alive to talk about it. It takes me, literally, less than 20 seconds to work out ohm's law. That's assuming my calculator is in my bag and I have to go get it. I'll bet you spend quite a bit of time mucking around and double checking your line voltages and currents with a multimeter, especially considering you have to unplug everything to get your current reading. And then do it all over again when you need to swap out parts.

SkunkDuster posted:

I'd have to consult Schrödinger on that one.
Delta-Wye circuits are neither parallel, nor series. Believe it or not, it's possible. Most circuits can be rearranged into equivalent circuits containing nothing but series and parallel connections, but some cannot and must be analyzed with a different method. Of course you'd know that if you knew what you were talking about.

SkunkDuster posted:


If I was going to light up 50 LEDs, I would start by ignoring the number 50 and look at how many LEDs I could light up in series with my supply voltage. If I had a 12V supply, and I ballparked each LED to have a 3V drop at 25mA...
A perfectly valid way of doing it, if that's all the circuit had in it. Real world circuits have more than just LEDs and resistors. They include active networks like op-amps and flip flops. You can't just string up the LEDs and swap some resistors. You've got no choice but to figure out what voltages you're going to have at what nodes (or what currents you're going to have in which meshes) and decide the best course of action. This is why it pays off to do it the right way from the start. Once you know how to do 1 LED the right way, you know how to do 50 without breaking a sweat.

SkunkDuster posted:

Your math and formulas are dead on correct, but some of the stuff you have posted in this thread ranges from unclear to completely wrong. This is a great thread and I agree that
Gee, thanks for the pat on the back, teach. Shucks. And you haven't actually proved me wrong on anything. All you've proven is that there was a miscommunication earlier when we were both talking about two different scenarios. Whew, I guess my teachers didn't give me good grades to be nice after all. I'd hate for a hobbyist on the internet to invalidate my secondary education.

SkunkDuster posted:

so please take a couple minutes to look over your replies to make sure you are talking about the same thing the person you are replying to is (12V vs 5V) and your facts are correct (75mA PEAK voltage).
Same goes for you. I wasn't even referring to your example. I was talking about the OP's. Perhaps I could have made that more clear when talking about power ratings, but if you took as much time checking over the last page of the thread as you did trying to prove me wrong, you might have picked up the (relatively minor) error.

SkunkDuster posted:

I'm also looking forward to this:
It's called a joke, you fatuous gasbag. When you spend hours upon hours behind a soldering iron, you're bound to tag your own skin once in a while. Are you an Aspie? I can't think of any other reason you wouldn't have realized that I was kidding.



Can we move on now? Christ Almighty.

scholzie fucked around with this message at 08:26 on Jan 11, 2008

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SnoPuppy
Jun 15, 2005


Top Cop

Chalupa Joe posted:

In my experience, 99.99% of the time where the Auto-router is used, you end up with a board that won't work properly (i.e. susceptible to EMI), as they're all variations on "Drunkard dragging a wet bit of string around".

this page: http://www.alternatezone.com/electronics/pcbdesign.htm has a good tutorial including examples of what, and what not to do when laying out boards.

This is very, very true. Especially if you have switching power supplies, high speed traces or sensitive analog areas, your layout becomes as important as the actual schematic.

I know some people might be put off at the complexity of doing a hand layout using free tools, but realize that even expensive software packages will probably still suck enough to make you do it by hand as well (I'm looking at you Mentor Graphics).

Mill Town
Apr 17, 2006



Hillridge posted:

A good thing to do to keep your iron tips fresh and shiny is to "tin" them before turning the iron off. Basically cover the whole tip with a big glob of solder and let it cool on there. When you need to use the iron again, just let it heat up and wipe off the solder on the sponge.

Oh, that's cool, I had thought you were supposed to tin the iron about a minute after turning it on, which doesn't work so well when it's been sitting around for a while and is oxidized. That makes more sense.

quote:

By heat gun I actually meant one of these guys:


This thing is essential in reworking surface mount parts since it allows you to heat up the whole part at once. You can pop off a chip with dozens of pins in a matter of seconds, whereas I don't think you'd ever get it off with an iron. They also have a tip that fits over the end of the wand to reduce the airflow to a small tube rather than the big 1" or so opening, which is ideal for resistors and other small parts.


This works, but I solder parts almost exclusively with an iron, even the fine pitch stuff (there is a neat trick that involves dragging the iron along the pins). Have you ever looked at solder paste under a microscope? It's tons of tiny solder balls suspended in flux and looks really cool:


(Click for huge)

I have never needed a vacuum rework station for anything, but they are neat. You can save your money and buy a small manual solder sucker and a package of solder wick instead.:



I do use desoldering braid and a solder sucker, and I find they work great on single-sided boards, but take forever on double-sided boards and sometimes don't work at all. They both seem to get the solder that's on the bottom of the board, but any that's left in the hole will keep holding the component in place. I figured a powered vacuum rework station that would suck continuously would be able to get it all out. Maybe I'm just doing it wrong.

quote:


Flux is your friend. It makes everything solder related easier. The type I use around the lab is Kester 959 low residue no-clean flux. It's designed for wave soldering machines, but it works great for doing stuff by hand too. I've gotten it all over my hands when I'm working and it has yet to hurt me. I just wash up when I'm done. Don't inhale when the iron vaporizes it though.

Edit - From their site:
959
No-Clean Alcohol-Based | Fluxes

Kester 959 is a no-clean, non-corrosive, halogen free liquid flux that is designed for the wave soldering of conventional and surface mount circuit board assemblies. Kester 959 was developed to minimize the formation of micro-solderballs during wave soldering operations. This flux contains a small percentage of rosin (1%), which improves solderability, heat stability and surface insulation resistance. Kester 959 offers the best wetting and the shiniest solder joints of any no-clean, solvent-based chemistry. Kester 959 leaves evenly distributed residues for the best cosmetic appearance.


This may be a lot for someone just getting started. I went for years using a soldering gun (huge compared to an iron) on through hole projects.

Well, I definitely need to upgrade something. Desoldering a single part can take me half an hour or more if it's stubborn and has a lot of leads.

Thanks for the informative post!

Mill Town fucked around with this message at 00:15 on Jan 10, 2008

scholzie
Mar 30, 2003

If I had a daughter, she'd probably be pregnant by the time she turned 12.

Circumcision Hater posted:

Well, I definitely need to upgrade something. Desoldering a single part can take me half an hour or more if it's stubborn and has a lot of leads.

Thanks for the informative post!
Not sure if you meant to make that comment when quoting the flux post, but flux will only make a very minor difference with desoldering. Its primary purpose is to strengthen the joint by cleaning the metal pre-flow. Cleaner joints are easier to desolder because there isn't crap sandwiched between the pad and the solder.

If you're having problems desoldering standard parts (meaning the cheap throwaway ones), I'd go ahead and solder them in with a bit more lead on the device side next time. That way, if you need to take them out you can just snip the part off (try to save as much as you can so you can use it again down the line). Then you can hold the board with some Helping Hands (see an earlier post), hold the lead with some pliers, and then heat the joint with the iron. The lead will pull right out, and you can then press some desoldering braid on the joint to clean up the excess solder.

For more expensive or limited supply parts, you might considering using sockets rather than hardwiring the device in. This is especially useful with ICs and hard to find special order transistors (like new old stock germanium ones from the 60s). This has the added benefit of protecting the more sensitive devices from too much heat when soldering since you can just install them after you're finished applying heat.

Lastly, if you find yourself doing a lot of prototyping, you'd be smart to pick up a Wire Wrap Gun. These will allow you to make some very strong connections with a perfboard, without making them permanent. You'll be able to fully test the device, then unwrap if necessary to fix anything. Bonus: once you've verified it's all working, you can solder right over the wire wrap if you don't care about it being messy. Now you won't lose anything in the translation from wrap to solder.

clredwolf
Aug 12, 2006


Ok, tomorrow's moving day and unfortunately Time Warner is playing games with me and I might be without internet for a bit. Oh joy. I'll do updates when I return.

Jailbrekr
Apr 8, 2002
A TOWN LEVELED BY AN EXPLOSION? DOZENS LIKELY KILLED? OH GOD LET ME SEE THAT SWEET VIDEO OH MY GOD I'M CUMMING


Does this make me a bad person?

Skycks
Jan 6, 2008


No Jailbrekr, these make you a great person.

poo poo, we could have a mspaint your favorite electronics principles thread in GBS and not get stuff as good as this.

spencer for hire
Jan 27, 2006

we just want to dance here, someone stole the stage
they call us irresponsible, write us off the page


franc0ph0bic posted:

Im just gonna throw this in - if anybody out there plays any for of amplified instrument (ie. electric guitar/bass, electric violin...) making simple circuits to modify the sound is very popular. I have made many different guitar effects, including distortions, delays, and modulation effects. There are many good beginner projects that are also very useful, and its a great way to learn electronics.

This is the main reason why I'm interested. I've found numerous sites online that have board layouts for different effects but I have yet to find a source for the reason behind placement of resistors and capacitors. Obviously designing my own pedal would be a project for the extreme future but I'd like to at least know the theory behind the design and how each part affects the sound. Do you have tips or know of any resources to how they shape sound? Like how would you go about designing a delay from scratch?

Locker Room Zubaz
Aug 8, 2006


~*~THE SECRET OF THE MAGICAL CRYSTALS IS THAT I'M FUCKING TERRIBLE~*~




spencer for hire posted:

This is the main reason why I'm interested. I've found numerous sites online that have board layouts for different effects but I have yet to find a source for the reason behind placement of resistors and capacitors. Obviously designing my own pedal would be a project for the extreme future but I'd like to at least know the theory behind the design and how each part affects the sound. Do you have tips or know of any resources to how they shape sound? Like how would you go about designing a delay from scratch?

If you provide me with a schematic I might be able to analyze it over the weekend and do my best to describe it in stages with SPICE simulations and

async1ronous
May 23, 2003

I flopped the nuts straight

Jairbrekr posted:

Does this make me a bad person?


Needs more sex and explanation.

franc0ph0bic
Oct 26, 2007


Kahlua Bomb posted:

Do you have any good resources for plans/parts/kits?

Yes, but only for guitar/bass related stuff. A good place for kits is Build Your Own Clone (http://www.buildyourownclone.com/) which sells a few overpriced kits which are clones of commercial effects. http://runoffgroove.com is a great site for more original schematics, but they do not sell kits. http://www.tonepad.com is another great site like this. The absolute best resource is http://www.diystompboxes.com/ which has the most active and productive effects building forum available.

Jailbrekr
Apr 8, 2002
A TOWN LEVELED BY AN EXPLOSION? DOZENS LIKELY KILLED? OH GOD LET ME SEE THAT SWEET VIDEO OH MY GOD I'M CUMMING


async1ronous posted:

Needs more sex and explanation.

Ya, it was a real quick job and I wish I had put more effort like throwing in an xy graph that relates graph usage with faggotry.

Powdered Toast Man
Jan 25, 2005

TOAST-A-RIFIC!!!

You need to write a book and put all these great diagrams in it, Jairbrekr. It could be called ELECTRONICS FOR FAGGOTS: HOLY TAPDANCING CHRIST LOOK AT THESE ELECTRONS.

Zenaida
Nov 13, 2004


A lot of companies will give you free samples of parts. I have a bunch of PICs and a MEMS accelerometer at home that I got just by asking. Some sites even have a sample parts form you can fill out. As a hobbyist, you generally only need one-off parts, so it's a great way to keep your costs down, especially for more expensive bits like sensors and MCUs.

The Radiskull
Feb 23, 2007
I like my coffee boiling hot

Zenaida posted:

A lot of companies will give you free samples of parts. I have a bunch of PICs and a MEMS accelerometer at home that I got just by asking. Some sites even have a sample parts form you can fill out. As a hobbyist, you generally only need one-off parts, so it's a great way to keep your costs down, especially for more expensive bits like sensors and MCUs.

This is a good point. There are alot of free sample sites lined from this one= http://www.dutchforce.com/~eforum/i...showtopic=13348

Follow the rules and you will get alot of free stuff.

WilfBerT
May 28, 2007
I'm just a soul whose intensions are good

Has anyone has an experience with these relatively cheap (~$200US) USB digital storage oscilloscopes?

http://www.beigly.com/catalog/hante...scope-p-96.html

I am thinking of getting one off eBay, however I would like to get some feedback from some people before I drop $200 bucks. I would be using this oscilloscope mainly for audio circuitry so the 40MHz bandwidth is more than enough!

Thanks

Locker Room Zubaz
Aug 8, 2006


~*~THE SECRET OF THE MAGICAL CRYSTALS IS THAT I'M FUCKING TERRIBLE~*~




WilfBerT posted:

Has anyone has an experience with these relatively cheap (~$200US) USB digital storage oscilloscopes?

http://www.beigly.com/catalog/hante...scope-p-96.html

I am thinking of getting one off eBay, however I would like to get some feedback from some people before I drop $200 bucks. I would be using this oscilloscope mainly for audio circuitry so the 40MHz bandwidth is more than enough!

Thanks

It can't do an FFT which probably can't be expected from any $200 scope but I really wouldn't buy a scope that couldn't do it. It's really nice to be able to see harmonic content of your output waveform especially in audio circuits.

Cyril Sneer
Aug 8, 2004

Life would be simple in the forest except for Cyril Sneer. And his life would be simple except for The Raccoons.

I love watching engineers engaged in debate

ValhallaSmith
Aug 16, 2005


WilfBerT posted:

Has anyone has an experience with these relatively cheap (~$200US) USB digital storage oscilloscopes?

http://www.beigly.com/catalog/hante...scope-p-96.html

I am thinking of getting one off eBay, however I would like to get some feedback from some people before I drop $200 bucks. I would be using this oscilloscope mainly for audio circuitry so the 40MHz bandwidth is more than enough!

Thanks

I hate these things. They tend to be laggy and poorly featured. They work ok if you are just trying to automatically log some waveforms. But for interactive work they are kind of a pain.

Really, you would be best served by getting a real scope off of ebay. An analog tek 7000 series mainframe scope can work pretty well. Or just save up 1000$ for a small tek scope. Or hit ebay every day and learn which scope are worthwhile and which are not.

Instek can sometimes have cheap equipment as well. I kind of wish there was more of a market, an opensource scope kit would be nice.

Locker Room Zubaz
Aug 8, 2006


~*~THE SECRET OF THE MAGICAL CRYSTALS IS THAT I'M FUCKING TERRIBLE~*~




ValhallaSmith posted:

I hate these things. They tend to be laggy and poorly featured. They work ok if you are just trying to automatically log some waveforms. But for interactive work they are kind of a pain.

Really, you would be best served by getting a real scope off of ebay. An analog tek 7000 series mainframe scope can work pretty well. Or just save up 1000$ for a small tek scope. Or hit ebay every day and learn which scope are worthwhile and which are not.

Instek can sometimes have cheap equipment as well. I kind of wish there was more of a market, an opensource scope kit would be nice.

That is not entirely sure. We have some usb scopes in my labs that have no lag and have a slew of features present in more expensive in only the more expensive Tektronix. Things like FFT are a bit slower than an entire DSP based system like those in a good high end scope but still it functions well enough for basic measurements. Also the ability to dump data directly to excel is oh so nice, although you can do that with some of the newer cheap scopes anyway so it is a moot point.

If you have an engineering school near you I recommend you check out their salvage store, whatever the hell they call it, mine had http://www.tek.com/products/oscillo...2000/index.html these for sale for like $50 a piece or something, of course they probably had the insides gutted about 30 times because of the silly freshman EEs killing them somehow(still not sure how to kill a scope but I've seen it done). Deals can also be had on craigslist pretty regularly if you live in a big city.

I just started a class on DSP's and I can honestly say these are by far the most interesting things I have touched upon in any class ever. We are only a week into lecture and have already learned how to implelement relatively complex high order filters really easily. Digital ROCKS!

ANIME AKBAR
Jan 25, 2007

afu~


Can anyone tell me where I can get lead free solder paste? Like a few hundred milliliters of the stuff.

And REAL MEN drive their LEDs with current sources.

slackingest
Dec 9, 2006

mosfet.swf


mtwieg posted:

Can anyone tell me where I can get lead free solder paste? Like a few hundred milliliters of the stuff.

And REAL MEN drive their LEDs with current sources.

digikey.com or mouser.com should be able to hook you up.

Cyril Sneer
Aug 8, 2004

Life would be simple in the forest except for Cyril Sneer. And his life would be simple except for The Raccoons.

Cuw posted:

Digital ROCKS!

*sigh*

ah well, maybe with everyone focusing on digital subjects these days, there'll be more jobs for us RF people.

Thumposaurus
Jul 24, 2007



franc0ph0bic posted:

Yes, but only for guitar/bass related stuff. A good place for kits is Build Your Own Clone (http://www.buildyourownclone.com/) which sells a few overpriced kits which are clones of commercial effects. http://runoffgroove.com is a great site for more original schematics, but they do not sell kits. http://www.tonepad.com is another great site like this. The absolute best resource is http://www.diystompboxes.com/ which has the most active and productive effects building forum available.

I would like to add these sites too:
http://www.commonsound.com/ mostly guitar/bass related but alot of the projects are able self oscillate and can be used with out either and the Tri-Wave Picogenerator is a great noisemaker.

http://www.generalguitargadgets.com/ kits, layouts, schematics

http://olcircuits.com/ sells kits of RunOffGrooves projects

http://www.home-wrecker.com/ a sister site to RunOffGroove focusing on clones

http://www.geofex.com/ One of the best sites that explain the theory behind what makes effects "tick" schematics, and project ideas too.

http://www.smallbearelec.com/StoreFront.bok electronics supplier dedicated to the parts needed to build effects pedals with carrys some specialized parts that are hard to track down via other sites.

I probably have more I need to sort through my bookmarks.

ANIME AKBAR
Jan 25, 2007

afu~


slackingest posted:

digikey.com or mouser.com should be able to hook you up.
That was the first place I checked, but they don't have it (in reasonable quantities, at least).

Also I dig the new mosfet av.

ValhallaSmith
Aug 16, 2005


What do you guys think beginning electronics hobbyists would want in a power supply? I was thinking of offering free schematic and a kit. Is it better to just keep it as cheap as possible (under 10$) or give it some features that drive up the cost?

I was thinking of something with a bare minimum of features right now. Also I want to keep the size down so it can fit in an altoids tin. I would ditch any display or controls in favor of a USB pic uC. This keeps costs down since you can get a PIC sample free from microchip. The power supply would be able to do 0-~15v depending on what type of DC wall wart you plug into it. Current limiting, but I think I will forgo remote sense to start with. Not sure how many outputs. Probably just 1.

I figure the PIC, Op amps, regulator and transistors can be had for free. You can eat the altoids, so you just need to get a small kit of passive components and some connectors (banana posts, USB, wall wart power). So yea, 0-15v@1A, PC controlled, variable current limit. Think that would be a good hobby power supply?

mtwieg posted:

That was the first place I checked, but they don't have it (in reasonable quantities, at least).

Also I dig the new mosfet av.

These guys have free 250g paste samples: http://www.smtsolderpaste.com/free_solder_paste.php

ValhallaSmith fucked around with this message at 21:44 on Jan 12, 2008

Kudosx
Jun 6, 2006

it's raining zerglings!


Thumposaurus posted:

I would like to add these sites too:
http://www.commonsound.com/ mostly guitar/bass related but alot of the projects are able self oscillate and can be used with out either and the Tri-Wave Picogenerator is a great noisemaker.

http://www.generalguitargadgets.com/ kits, layouts, schematics

http://olcircuits.com/ sells kits of RunOffGrooves projects

http://www.home-wrecker.com/ a sister site to RunOffGroove focusing on clones

http://www.geofex.com/ One of the best sites that explain the theory behind what makes effects "tick" schematics, and project ideas too.

http://www.smallbearelec.com/StoreFront.bok electronics supplier dedicated to the parts needed to build effects pedals with carrys some specialized parts that are hard to track down via other sites.

I probably have more I need to sort through my bookmarks.

Thanks for posting these! I have been interested in getting back into making electronics stuff, and I think this is exactly what I'd like to make. Tremolo effect stompbox incoming.....

Edit: I'm pretty sure but I just want to make sure.... will most of these effect pedals while being designed for a guitar, still sound alright on a bass?

Thumposaurus
Jul 24, 2007



They will be fine for bass, the only change you might want to make is the input/output capacitors. I forget which it is right now but increasing/decreasing them changes the amount of low end frequencies that get through. That is what is great about building them yourself you can tweak and tweak until it sounds perfect to you.

The Commonsound Tremolo is a great one and not too difficult.

ANIME AKBAR
Jan 25, 2007

afu~


ValhallaSmith posted:

These guys have free 250g paste samples: http://www.smtsolderpaste.com/free_solder_paste.php
Well poo poo, that looks great, thanks.

And as for your power supply, you might be best off rolling your own linear regulator. It's fairly simple and there's no need for digital stuff (unless you want a built in meter or something). I can post an example schematic if you want.

ANIME AKBAR fucked around with this message at 01:04 on Jan 13, 2008

Three-Phase
Aug 5, 2006

by zen death robot


mtwieg posted:

Can anyone tell me where I can get lead free solder paste? Like a few hundred milliliters of the stuff.

And REAL MEN drive their LEDs with current sources.

Right on.

Here's a place I bought LEDs from:
http://www.superbrightleds.com/

LEDs of every color.

Be sure to check the datasheet - not every LED has a forward voltage drop of 1.4V, and not all of them have a 10mA draw. This is particularly true of much larger, more powerful LEDs (aka the "1 watt" or "Luxeon" LEDS).

For instance, the RL5-WW7035 (warm white LED) on SBL, it has a 3.2V drop and a continuous forward current rating of 30mA.

If you do get those large LEDs (1 Watt and higher) be sure to attach them to a heatsink - if you don't they can burn out.

SPICE and Circuit Simulation
Find the student version of PSPice. I think I'll make a little tutorial on simulating circuits in PSpice (that doesn't suck).

Three-Phase fucked around with this message at 01:19 on Jan 13, 2008

ANIME AKBAR
Jan 25, 2007

afu~


Jairbrekr would you be mad if I stole your gimmick and did a a minilesson on transistors?

edit: poo poo, you did that already. Maybe I could do some example transistor circuits.

ANIME AKBAR fucked around with this message at 01:57 on Jan 13, 2008

ValhallaSmith
Aug 16, 2005


mtwieg posted:

Well poo poo, that looks great, thanks.

And as for your power supply, you might be best off rolling your own linear regulator. It's fairly simple and there's no need for digital stuff (unless you want a built in meter or something). I can post an example schematic if you want.

I've built tons of those. What I'm trying to come up with is something very cheap for the hobbyist. The reason I would go with a pic or avr is because using one of those over USB is cheaper than adding in everything you need for a display, controls and switches. Plus I want to keep these at a very small form factor (altoid form factor). I've been reading up on synthetic instrumentation for a chunk of the day. I might draw something up that heads in that direction. Instead of a power supply you could basically build a DAC. Then if you want a voltage meter you add a ADC voltage module. If you want power factor correction/metering you add a shunt resistor, amp and another adc. Basically a very generic instrument set that performs most of the measurement on the PC. It would be USB 2.0 based so that would kind of limit things at times. USB has crappy latency.

But 10$ per module isn't that bad I don't think. Most people don't need sampling in the ghz range. I think just making a 1khz DAC and a 1mhz adc would be a good start.

scholzie
Mar 30, 2003

If I had a daughter, she'd probably be pregnant by the time she turned 12.

mtwieg posted:

Jairbrekr would you be mad if I stole your gimmick and did a a minilesson on transistors?

edit: poo poo, you did that already. Maybe I could do some example transistor circuits.

FYI, it's not Jairbrekr's gimmick. His are pretty good though. There was a whole thread dedicated to explaining things with foul language.

I was actually going to post the links that Thumposaurus posted above. They're great resources (especially geofex, if you're actually interested in learning HOW effects work).

I used a fuzz face schematic from General Guitar Gadgets with matching germanium transistors purchased from small bear, and it came out pretty good. It has two volume knobs, though, because I messed up my wiring. I keep putting off the debugging because I've been happy with it as it is, but I guess it's probably a good idea to see what's wrong.

Locker Room Zubaz
Aug 8, 2006


~*~THE SECRET OF THE MAGICAL CRYSTALS IS THAT I'M FUCKING TERRIBLE~*~




Cyril Sneer posted:

*sigh*

ah well, maybe with everyone focusing on digital subjects these days, there'll be more jobs for us RF people.

we can work together to create the greatest things ever. The lines between digital and everything else are shrinking so fast that without a strong digital background I can't see how you really won't sink in the industry.

Three-Phase
Aug 5, 2006

by zen death robot


Cyril Sneer posted:

*sigh*

ah well, maybe with everyone focusing on digital subjects these days, there'll be more jobs for us RF people.

From what I've seen, digital and RF go hand in hand. Especially when you're talking about things like CE testing for noise immunity.

I work with bigger stuff, where you need to make sure different cables are separated. (Like not running an unshielded twisted-pair carrying a 4-20mA signal right next to a massive 500kmcm cable that can cary 600 amps. - That's a class-4 versus class-1 if I remember correctly, and without shielding they would need to be a meter or so apart.)

clredwolf
Aug 12, 2006


*phew* finally back. I'll be working on the OP and cleaning up the drat LED project for ya.

Also the reason I said to check the spec sheet in the LED project is that not every LED has the same voltage drop and current draw, esp. not high power LEDs. I could make a current-driven LED next using a BJT...would you enjoy that?

Locker Room Zubaz
Aug 8, 2006


~*~THE SECRET OF THE MAGICAL CRYSTALS IS THAT I'M FUCKING TERRIBLE~*~




Three-Phase posted:

From what I've seen, digital and RF go hand in hand. Especially when you're talking about things like CE testing for noise immunity.

I work with bigger stuff, where you need to make sure different cables are separated. (Like not running an unshielded twisted-pair carrying a 4-20mA signal right next to a massive 500kmcm cable that can cary 600 amps. - That's a class-4 versus class-1 if I remember correctly, and without shielding they would need to be a meter or so apart.)

It is amazing how diverse the field of EE is. It gets even more diverse when you throw the C in there and do ECE. It really surprises me it hasn't broken down further at this point at most major colleges since there really is no way for anyone to be proficient in all of this stuff by the time they graduate.

clredwolf
Aug 12, 2006


Cuw posted:

It is amazing how diverse the field of EE is. It gets even more diverse when you throw the C in there and do ECE. It really surprises me it hasn't broken down further at this point at most major colleges since there really is no way for anyone to be proficient in all of this stuff by the time they graduate.

I think that's the purpose of having CE and EE separate, but it's not a great seperation if you ask me. Digital stuff is absolutely everywhere and everyone in EE needs at least a little exposure to digital technology at this point. From what I count though, here are the EE 'disciplines':

-Power Systems
-Computer Systems
-RF/Analog Systems
-Signal Processing
-Semiconductor Design
-Optoelectronics and Photonics
-Control Systems
-Robotics
-Bioelectronics

And I'm sure I'm missing a few. There's alot of cross-breeding between those fields though, so maybe it's best that EEs not be split up? Cuw is right though, there's no way anyone can master 'Electrical Engineering' as a whole in 4 or even 6 years.

ValhallaSmith
Aug 16, 2005


Another item you guys might be interested in is Proteus VSM: http://www.labcenter.co.uk

Basically in addition to being able to do spice simulation like the other simulators, it can also simulate a microcontroller at the same time. So you can setup complete projects and simulate them software and all before putting iron to solder. Definitely not free though.

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ANIME AKBAR
Jan 25, 2007

afu~


ValhallaSmith posted:

I've built tons of those. What I'm trying to come up with is something very cheap for the hobbyist. The reason I would go with a pic or avr is because using one of those over USB is cheaper than adding in everything you need for a display, controls and switches. Plus I want to keep these at a very small form factor (altoid form factor). I've been reading up on synthetic instrumentation for a chunk of the day. I might draw something up that heads in that direction. Instead of a power supply you could basically build a DAC. Then if you want a voltage meter you add a ADC voltage module. If you want power factor correction/metering you add a shunt resistor, amp and another adc. Basically a very generic instrument set that performs most of the measurement on the PC. It would be USB 2.0 based so that would kind of limit things at times. USB has crappy latency.

But 10$ per module isn't that bad I don't think. Most people don't need sampling in the ghz range. I think just making a 1khz DAC and a 1mhz adc would be a good start.
uh, it's pretty drat hard to get any simpler than a linear regulator. I don't see how one could make a supply out of a DAC, since they have output impedance and ripple and all that. Measuring output parameters with ADCs sounds fine though, but only for display, not as the feedback element. You should make the feedback path completely analog.

The next logical step up from a linear regulator would be a switcher, which is what I think most good bench supplies use. But unless you're very concerned with load and line regulation, it probably wouldn't be worth the added complexity over a linear supply.

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