Electrical Engineering V3

[LoneWolf_Recon]

[QUOTE=DrDevil;48752807]You're using SMA connectors for DC connectors?
Why not BNC?[/QUOTE]

The SMA connectors are for DC to 2MHz connection which in retrospect, BNC could handle easily. But the [URL="http://www.ettus.com/product/details/USRPPKG"]USRP/SDR[/URL] that me and my partner are using has SMA connectors for TxA & RxA.

[IMG]http://www.ettus.com/content/images/prod_usrp-pkg_01_md.jpg[/IMG]

[TCWilliamson]

Got 140g of sodium... what can I do with that (beside put it in water, already done that)

anything interesting I can do with it electrically?

NaK pump?
[media]http://www.youtube.com/watch?v=9EGAXOWpGy8[/media]

Electromagnetic pump, really quite a cool idea, works with mercury as well.

[pentium]

Fucking design problems. I'm so damn close to finishing this project finally. Ffffs

So if you might remember, I learned that the dialing system in my teletype would not work in tandem with the modem because pulse dialing devices require they be the only devices off hook. DTMF gets around this by emitting tones that the exchange will recognize as numbers instead, thereby meaning that so long as the line is quiet you can have as many devices off hook as you want. Pulse to DTMF adapters exist already to modify rotary phones to work on newer telephone systems that do not support pulse dialing anymore. The phone circuit was redesigned, sans the bell for now, on a breadboard.

[img]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/IMG_1084.jpg[/img]

It works...but it doesn't.

Putting just it off hook and dialing (you do it blindly as there's no voice circuit) works fine. Dialing with any other device off hook (IE: the modem), does not. It will not even emit a tone.
No documentation exists on how exactly the adapter works, or if it is wired correctly.

[LoneWolf_Recon]

What about a more custom [URL="http://boris0.blogspot.com/2013/09/rotary-dial-for-digital-age.html"]Pulse-DTMF[/URL] converter?

[pentium]

[QUOTE=LoneWolf_Recon;48754315]What about a more custom [URL="http://boris0.blogspot.com/2013/09/rotary-dial-for-digital-age.html"]Pulse-DTMF[/URL] converter?[/QUOTE]

That's what the adapter does. The two contacts on the dial are inputs to a microcontroller which use a DTMF generator to create the tones. The whole thing is powered through the 48V DC of the telephone line, which are what that large number of diodes and transistors are for.

[IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_1091.jpg[/IMG]
[IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_1092.jpg[/IMG]

In fact, his video is what I should be hearing. It would be really nice if they shipped the fucking thing with at least a schematic or some sort of fucking instructions, even if they were all in chinese.

[pentium]

I've been fucking looking at this thing for six hours now. I don't fucking get it.
I feel like I'm missing something here but I'm so far outside my comfort zone that I really don't know what I should be fucking looking for.

[Zero-Point]

Decided to have a walk down to one of the local Radioshacks. Heard that since the bankruptcy thing they were getting rid of a bunch of stuff for cheap so I thought I'd have a gander.
I made the mistake of walking to the closest one (located in the mall), as they usually don't have much good shit at all, but this one had less good shit than usual. On top of that they had a 12AH lead-acid cell "on clearance" for $34.99, but it's always been at that price since for the past few years. :v:
Got some of those Parallax two-axis joysticks for $4 each, though. I guess it's not bad considering they were charging upwards of $10 for them before. :unimpressed:

[pentium]

[IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_1093.jpg[/IMG]

One side of this cable took two minutes to crimp. The other took an agonizing four hours.

[Zero-Point]

Well? Don't leave us in suspense, which end is which?!

[Papkee]

Anybody know where you can get the silver version of the Hakko FX888D? They show it on their website but apparently nobody actually carries it.

[Nightrazr]

Can anyone help me figure out what kind of component the brown one labeled PC306 is?
It's connected between the positive and negative sides of the power jack on this Dell Inspiron N5010 I'm trying to repair.

[thumb]http://i.imgur.com/D6Um1Sy.jpg[/thumb]

[DrLuke]

[QUOTE=Nightrazr;48782655]Can anyone help me figure out what kind of component the brown one labeled PC306 is?
It's connected between the positive and negative sides of the power jack on this Dell Inspiron N5010 I'm trying to repair.
[/QUOTE]

That's a ceramic capacitor. Based on the size I'd guess the value to be something between 0.1uF to 1uF.

[Nightrazr]

Whelp, it's not the board, the power supply for the laptop I'm trying to fix squeals like a hog.

Never even checked for that... :goodjob:

[Zero-Point]

Well that figures. Some months ago I grabbed a couple of ultrasonic sensors for cheap on eBay, and yesterday I came up with an idea/exercise to make a "radar" system using one of the sensors, a servo (for sweep) and some LEDs (brightness determined by distance measured), and lo and behold, I've succeeded in finding everything I could need for the project (choice of Propellor Quickstart or Arduino, a small servo, breadboard, wires, etc).
...Except the fucking sensors. I've turned this place damn-near upside down and can't find them anywhere. :hairpull:

[paindoc]

I missed what I think was a great deal on a vintage synth today- someone was selling a Roland jx-3p that used to work but got dropped and stopped working, plus broke a few keys and sliders.

Most of the time the power board or transformer just breaks slightly, and the rest I an easy fix. You can buy spare keys online and I could have 3d printed any of the broken knobs and faders.

Final bid was $75, and I could have bid on it if I hadn't fallen for a mediocre deal on another synth :/

[editline]28th September 2015[/editline]

[QUOTE=Zero-Point;48782899]Well that figures. Some months ago I grabbed a couple of ultrasonic sensors for cheap on eBay, and yesterday I came up with an idea/exercise to make a "radar" system using one of the sensors, a servo (for sweep) and some LEDs (brightness determined by distance measured), and lo and behold, I've succeeded in finding everything I could need for the project (choice of Propellor Quickstart or Arduino, a small servo, breadboard, wires, etc).
...Except the fucking sensors. I've turned this place damn-near upside down and can't find them anywhere. :hairpull:[/QUOTE]

I had a bundle of infrared leds from when I rigged up a track ir system, and told a friend I had these leds and that he could have them. I've searched my entire box of parts and my entire room and can't find the things

[Zero-Point]

[QUOTE=paindoc;48782909]I had a bundle of infrared leds from when I rigged up a track ir system, and told a friend I had these leds and that he could have them. I've searched my entire box of parts and my entire room and can't find the things[/QUOTE]

I'm worried that I might have accidentally thrown them away at this point, the very thought of it makes me feel sick.
Might as well fuckin' buy some more, I guess. Found 10 for about $15 including shipping, so not bad.
It just sucks because this is the first time in a REALLY long time that I've had the urge/energy to tinker like this, and it's stopped dead in its tracks because I can't find the one integral part to it, which only serves to discourage me. Can't fucking stand it.

[pentium]

[QUOTE=Zero-Point;48770385]Well? Don't leave us in suspense, which end is which?![/QUOTE]

[IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_1094.jpg[/IMG]

[Chryseus]

You have more patience than me, I'd toss that straight in the bin.

[KmartSqrl]

Yo! I recently started putting together a eurorack system. I'm interested in diving in to a bit of EE so I can start making my own modules. Do you guys have any recommendations for good books to dig in to as a starting point? Preferably with an emphasis on audio and synthesis if there's good entry level books that lean that way, but that's not a requirement. If there's a general book that really stands out above the rest I'd prefer to go that route and supplement with something else on synthesis.

Thanks in advance!

[Chryseus]

[QUOTE=KmartSqrl;48788283]Yo! I recently started putting together a eurorack system. I'm interested in diving in to a bit of EE so I can start making my own modules. Do you guys have any recommendations for good books to dig in to as a starting point? Preferably with an emphasis on audio and synthesis if there's good entry level books that lean that way, but that's not a requirement. If there's a general book that really stands out above the rest I'd prefer to go that route and supplement with something else on synthesis.

Thanks in advance![/QUOTE]

[url]http://www.allaboutcircuits.com/textbook/[/url]
Once you've learned basic electronics you can move on to more audio related stuff.
In particular you need to learn the basics of amplifiers both discrete (transistor) as well as op-amps, active and passive filters and oscillators.

Other books and resources are in the op.

[paindoc]

[QUOTE=KmartSqrl;48788283]Yo! I recently started putting together a eurorack system. I'm interested in diving in to a bit of EE so I can start making my own modules. Do you guys have any recommendations for good books to dig in to as a starting point? Preferably with an emphasis on audio and synthesis if there's good entry level books that lean that way, but that's not a requirement. If there's a general book that really stands out above the rest I'd prefer to go that route and supplement with something else on synthesis.

Thanks in advance![/QUOTE]

Make: Analog Synthesizers! Literally takes you through designing a modular synth. Its great, and he has tons of good info and later in the book goes over some neat circuits using Op-Amps and comparators and such. Covers ADSR, waveshapers, amps, etc. Its an excellent book.

I will also stand by Getting Started In Electronics by Forrest M. Mimm's or something like that. Its really good, one of my favorite books I've read. Drawn in a really neat handwritten style too, and can be had for pretty cheap.

[Zero-Point]

Methinks microcontrollers were a bad intro to programming.
Since I couldn't find the ultrasonic sensors I bought, I decided to try and "plot" the X and Y axis of one of those joysticks I got on clearance. Problem is, while I have a very piss-basic understanding of loops and if statements and what-not, I can't wrap my head around this.
The goal was to have 4 LEDs, 2 red for up/down, and 2 green for left/right. They should increase in brightness as you move the stick towards that direction, but I've hit a snag on the up/down axis (and have remained there until I can un-fuck myself and get this shit working properly). For some reason, for the majority of my iterations, the downward sweep would work exactly as I wanted it to, but the upward sweep would cause the top LED to "stick" on a brightness level if I moved the joystick back too quickly. (it would go back to off/nearly off if I eased back on it slowly)
Asked a friend of mine who's quite proficient in programming, but his assistance has been the equivalent of my attempts to make an omelet as he has me try out voodoo. :v:

I would've thought that the easiest way would be to take the dead-zone, subtract that from what it's currently reading and abs() it (so it should return only a positive value), and then convert that into an 8-bit scale for the 0-255 range for lighting the LEDs, but that hasn't worked worth a fuck, either. :hairpull:

[Nightrazr]

My intermediate-level skill at Wiremod made me overestimate my prowess in this field.

I feel like a retard.:boxhide:

[Zero-Point]

[QUOTE=Nightrazr;48798191]My intermediate-level skill at Wiremod made me overestimate my prowess in this field.

I feel like a retard.:boxhide:[/QUOTE]

Digital logic is always easier when you don't have to worry about PSU noise and support components and shit.

Also, do any of you guys happen to know of a good way to translate a 10-bit value to an 8-bit value on an Arduino? I've tried map() but it causes some goofy shit to happen, including outputting numbers that are well outside of the 0-255 range.

[Dolton]

[QUOTE=Zero-Point;48798738]Digital logic is always easier when you don't have to worry about PSU noise and support components and shit.

Also, do any of you guys happen to know of a good way to translate a 10-bit value to an 8-bit value on an Arduino? I've tried map() but it causes some goofy shit to happen, including outputting numbers that are well outside of the 0-255 range.[/QUOTE]

See below, bit shifting works nicer and compiles much cleaner. No branches.

This will work if you know for a fact char will compile down to 1 word. It isn't exactly portable but should work.

If the 10 bit number is signed then add another tertiary expression that truncates any negative numbers to zero.

[DrLuke]

[QUOTE=Dolton;48799399]

unsigned char eightBit = tenBit > 255 ? 255 : tenBit;

This will work if you know for a fact char will compile down to 1 word. It isn't exactly portable but should work.[/QUOTE]

That's why you use uint8 instead of char.

[editline]1st October 2015[/editline]

[QUOTE=Zero-Point;48798738]
Also, do any of you guys happen to know of a good way to translate a 10-bit value to an 8-bit value on an Arduino? I've tried map() but it causes some goofy shit to happen, including outputting numbers that are well outside of the 0-255 range.[/QUOTE]

Depends on what you want from the 10-bit value. If you know it's never going above 255, just cast it to uint8:
[cpp]uint16 bar = 10;
uint8 foo = (uint8)bar; // Foo will be 10
[/cpp]

On the other hand, if your 10-bit value will actually go up to 1024, you want to just get rid of the last two bits like this:
[cpp]
uint16 bar = 1000;
uint8 foo = (uint8)(1000 >> 2); // foo will be 250
[/cpp]

With the first method you keep the same resolution, with the latter method you obviously lose some precision.

[Dolton]

[QUOTE=DrDevil;48799479]That's why you use uint8 instead of char.

[editline]1st October 2015[/editline]

Depends on what you want from the 10-bit value. If you know it's never going above 255, just cast it to uint8:
[cpp]uint16 bar = 10;
uint8 foo = (uint8)bar; // Foo will be 10
[/cpp]

On the other hand, if your 10-bit value will actually go up to 1024, you want to just get rid of the last two bits like this:
[cpp]
uint16 bar = 1000;
uint8 foo = (uint8)(1000 >> 2); // foo will be 250
[/cpp]

With the first method you keep the same resolution, with the latter method you obviously lose some precision.[/QUOTE]

uint_8 is just a typdef of unsigned char

It is nice when using embedded systems to not have to include lots of files especially when you can get the same results.

[nikomo]

uint_8 is unsigned char on systems where that's the right pick.
On other systems, it's not.

[Ddrl46]

Might be able to do some fun stuff soon!

[media]http://www.youtube.com/watch?v=FS52dI3_l8Y[/media]

[pentium]

[IMG]http://i11.photobucket.com/albums/a166/ballsandy/IMG_1168.jpg[/IMG]

I almost don't want to know what the wattage of this load is.