Electrical Engineering V3

[Fourier]

IRF530N. I think it's quite fried as it is, because previously when I touched gate with my finger, it would randomly switch on/off, now no more.

[Chryseus]

Your power supply may have blown it if it's shocking you, it doesn't take significant current to damage a low voltage MOSFET gate.
Use a good reliable switching supply not a cheap one and make sure it's properly earthed, you should also avoid touching the gate since MOSFETs are very static sensitive.

[paindoc]

Anyone have any good reading on building digital synths or audio generation in general? Me and Halofreak are going to collaborate on a synthesizer project and I'm sorta dealing with the more mechanical side at this point since he's better at all-analog circuits. I'd like to try a digital analog emulation synth though, since they can be made for so cheap it seems.

Also, can I get neopixels anywhere for really really cheap? Still thinking of my crazy daft punk helmet project and now that there is a pcb mill on campus and I have my lipo battery stash here i may be able to actually make a board capable of powering a massive array of those LED's and a few fans.

[Fourier]

[QUOTE=Chryseus;48526773]Your power supply may have blown it if it's shocking you, it doesn't take significant current to damage a low voltage MOSFET gate.
Use a good reliable switching supply not a cheap one and make sure it's properly earthed, you should also avoid touching the gate since MOSFETs are very static sensitive.[/QUOTE]

My power supply might really be culprit but it's all I have. Maybe I really should earth/ground it.

In fact, my whole room 220V is not earthed/grounded properly.

[nikomo]

My room doesn't have protective earth available either, it's just one of the annoying things about living in an old building.

[Cakebatyr]

I was considering installing an earth grounding rod outside my apartment in a bush (under the cover of night) and running a wire from my room (2nd floor) to it myself...

[Van-man]

[QUOTE=Cakebatyr;48536181]I was considering installing an earth grounding rod outside my apartment in a bush (under the cover of night) and running a wire from my room (2nd floor) to it myself...[/QUOTE]

If you're ghetto, then bolting it to bare betal of the water plumbing works.
Disconnect it when there's thunder and lightning though

[LoneWolf_Recon]

[QUOTE=paindoc;48528678]Anyone have any good reading on building digital synths or audio generation in general? Me and Halofreak are going to collaborate on a synthesizer project and I'm sorta dealing with the more mechanical side at this point since he's better at all-analog circuits. I'd like to try a digital analog emulation synth though, since they can be made for so cheap it seems.

Also, can I get neopixels anywhere for really really cheap? Still thinking of my crazy daft punk helmet project and now that there is a pcb mill on campus and I have my lipo battery stash here i may be able to actually make a board capable of powering a massive array of those LED's and a few fans.[/QUOTE]

Here's what I could dig up with an [URL="http://users.ece.gatech.edu/lanterma/ece4803/"]actual class[/URL] on the topic and some random reference material ([URL="http://hackaday.com/2008/05/01/how-to-make-a-digital-synthesizer/"]DIY Synth with Pitch/Freq/LFO/Duty adjustments[/URL]), [URL="https://www.youtube.com/watch?v=QsSKh7Z2EVs"]7400 Logic Based Synth/Drum Machine[/URL] (With Schematics).

Mostly there's alot of useful digital synth chips you can find readily (Like the [URL="http://pdf1.alldatasheet.com/datasheet-pdf/view/84281/YAMAHA/YM3812.html"]YM3812[/URL], [URL="http://pdf1.alldatasheet.com/datasheet-pdf/view/103366/ETC/YM2149.html"]YM2149[/URL] ([URL="https://www.youtube.com/watch?v=3TLg3MAHWCg"]Example[/URL]), or other Yamaha chips, etc) they're operated via parallel logic or serial interface.

In terms of NeoPixels, as far as I know only [URL="http://www.adafruit.com/category/168"]Adafruit[/URL] & [URL="https://www.sparkfun.com/products/11821"]Sparkfun[/URL] carry the equivalent RGB modules & strips (And generally the cheapest), from the major distributors there isn't much in terms of lower powered RGB modules (Especially for the cost) from what Adafruit/Sparkfun have.

[cartman300]

Okay, so my dad and me are building a CNC machine. We already completed the frame and put on the motors. We're using car door glass DC motors for the X, Y and Z axes. I'm going to do the controller electronics and programming for it.

I'm using a custom power supply (220V -> ~18V), the motors work fine with that. I thought of building a H bridge for each of them with MOSFET transistors. 20V, 10A at least. These are gonna be triggered with digital logic 5V, the goal is to be able to move them forwards and backwards (and also stop them).

Any part recommendations? I've got nothing so far.

[Fourier]

[QUOTE=cartman300;48539092]Okay, so my dad and me are building a CNC machine. We already completed the frame and put on the motors. We're using car door glass DC motors for the X, Y and Z axes. I'm going to do the controller electronics and programming for it.

I'm using a custom power supply (220V -> ~18V), the motors work fine with that. I thought of building a H bridge for each of them with MOSFET transistors. 20V, 10A at least. These are gonna be triggered with digital logic 5V, the goal is to be able to move them forwards and backwards (and also stop them).

Any part recommendations? I've got nothing so far.[/QUOTE]

Yeah, I was once building H-Bridge. Don't fuck up like me:

- Don't just make it out of N-channel. You need to use 2x N-channel and 2x P-channel MOSFETs
- 5V logic means you need to add driver transistors for MOSFET.
- Choose MOSFETs with protection diode, will simplify circuit
- Have fatter PCB copper connections, less resistance I think.

IRF5X0 MOSFETs are cool, replace X with number.

[Van-man]

[QUOTE=cartman300;48539092]Okay, so my dad and me are building a CNC machine. We already completed the frame and put on the motors. We're using car door glass DC motors for the X, Y and Z axes. I'm going to do the controller electronics and programming for it.

I'm using a custom power supply (220V -> ~18V), the motors work fine with that. I thought of building a H bridge for each of them with MOSFET transistors. 20V, 10A at least. These are gonna be triggered with digital logic 5V, the goal is to be able to move them forwards and backwards (and also stop them).

Any part recommendations? I've got nothing so far.[/QUOTE]

You'd either need to smack on a rotary encoder on the end of each motor or swap them out for steppers.

[LoneWolf_Recon]

This [URL="http://www.mouser.com/ProductDetail/Infineon-Technologies/IPP042N03L-G/?qs=sGAEpiMZZMshyDBzk1%2fWi9Xn%2fBYY8cyR2dBMsqT%252blMo%3d"]n-channel[/URL] & this [URL="http://www.mouser.com/ProductDetail/International-Rectifier/AUIRF4905/?qs=sGAEpiMZZMshyDBzk1%2fWi4%252be7FLSKd%2fq%252bNcj7CDSo%2fU%3d"]p-channel[/URL] look pretty good/cost effective for what you'll be using them for. Plus their Rds-on is low enough that you *shouldn't* need heat sinks for them (You might be able to get away with just their tabs), but it couldn't hurt to have them.

[pentium]

[img]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_1004.jpg[/img]
[img]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_1005.jpg[/img]
[img]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_1001.jpg[/img]
[img]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_1006.jpg[/img]

[i]What on earth am I assembling form a kit now??[/i]

[LoneWolf_Recon]

Front panel to an old programmable kit computer like an Altair? I see some Single Step/Address/Data/Halt switches.

[pentium]

[QUOTE=LoneWolf_Recon;48539594]Front panel to an old programmable kit computer like an Altair? I see some Single Step/Address/Data/Halt switches.[/QUOTE]

[url=http://obsolescence.wix.com/obsolescence#!pidp-8/cbie]We have a winner![/url]

[Fourier]

It's Bass line or sequencer of some sort!?

[editline]25th August 2015[/editline]

Meh

[cartman300]

[QUOTE=Van-man;48539418]You'd either need to smack on a rotary encoder on the end of each motor or swap them out for steppers.[/QUOTE]

I don't need a rotary encoder. A simple switch that actuates once (or multiple times) each turn is enough as i already know the direction the motor is rotating in.

[Van-man]

[QUOTE=cartman300;48539770]I don't need a rotary encoder. A simple switch that actuates once (or multiple times) each turn is enough as i already know the direction the motor is rotating in.[/QUOTE]

it's not gonna be very precise at all, those switches are used for car door windows to tell the controller it's near the top so it'll limit the current to the motors, and also to start sensing the current both for things blocking, and for when it's rolled all the way up.

[cartman300]

[QUOTE=Van-man;48540286]it's not gonna be very precise at all, those switches are used for car door windows to tell the controller it's near the top so it'll limit the current to the motors, and also to start sensing the current both for things blocking, and for when it's rolled all the way up.[/QUOTE]

Oh god guys stop assuming stuff. I'm talking literally just the motor from the car windows, with NOTHING from the pre-built electronics on it (and even then, there's no switch on it).

I'm talking about literally ducttaping a bulge to the screw that pushes the axis that actuates a switch on each turn. Each screw turn doesn't even move the axis by more than 0.1 mm. It's gonna be precise enough.

[editline]25th August 2015[/editline]

And besides, i asked about the MOSFETs not about measuring the distance (about which i didn't give any info btw)

[paindoc]

[QUOTE=cartman300;48540968]Oh god guys stop assuming stuff. I'm talking literally just the motor from the car windows, with NOTHING from the pre-built electronics on it (and even then, there's no switch on it).

I'm talking about literally ducttaping a bulge to the screw that pushes the axis that actuates a switch on each turn. Each screw turn doesn't even move the axis by more than 0.1 mm. It's gonna be precise enough.

[editline]25th August 2015[/editline]

And besides, i asked about the MOSFETs not about measuring the distance (about which i didn't give any info btw)[/QUOTE]

Then be more specific when you ask for advice, they were just going off what they could interpret in what you said

Thx for links by the way. Good reading so far. Want to make analog/digital crossover synth like Roland's JD Xi and XA

[cartman300]

[QUOTE=paindoc;48541791]Then be more specific when you ask for advice, they were just going off what they could interpret in what you said[/QUOTE]

[QUOTE=cartman300;48539092]I'm using a custom power supply (220V -> ~18V), the motors work fine with that. I thought of building a H bridge for each of them with MOSFET transistors. 20V, 10A at least. These are gonna be triggered with digital logic 5V, the goal is to be able to move them forwards and backwards (and also stop them).

Any part recommendations? I've got nothing so far.[/QUOTE]

[Cakebatyr]

[QUOTE=Van-man;48536380]If you're ghetto, then bolting it to bare betal of the water plumbing works.
Disconnect it when there's thunder and lightning though[/QUOTE]

This is going to be a ground point for an RF system, the shorter the distance to ground the better (also tidier) because it will act as an antenna in its own right.

[gamerpaddy]

Fitted a new laser into my cheap ass cutter:
1.8W M140 diode, 445nm controlled via PWM in grbl 0.9j and a G2 lens

thath zigzag pattern comes from my newly installed x axis, which i have to fix and apply oil. also the lens in the 12mm aixiz housing wobbles around, have to fix that using something...
[video=youtube;3DVBjE6aczs]http://www.youtube.com/watch?v=3DVBjE6aczs[/video]
[video=youtube;9U13EqPq7Fc]http://www.youtube.com/watch?v=9U13EqPq7Fc[/video]

Can cut white paper up to 900mm/min
4mm cardboard 150mm/min
and probably thin wood

[URL=http://www.directupload.net/file/d/4091/kb82dcci_jpg.htm][IMG]http://fs1.directupload.net/images/150826/temp/kb82dcci.jpg[/IMG][/URL]

[Chryseus]

[QUOTE=cartman300;48540968]Oh god guys stop assuming stuff.[/QUOTE]

We're not assuming anything, it's a fact that without an encoder you'll get poor positional accuracy, the accuracy of a CNC is fundamentally determined by the number of steps per revolution, now it might be fine for some things but it's no good for machining or 3D printing where something like 0.1mm matters a lot, particularly when it comes to hitting the same spot multiple times.

To answer your question most MOSFETs will do the job, it's hard to recommend any specific one since it depends on your supplier, something like IRF9530PBF and IPP50R299CP will work.

[No_Excuses]

I have a bit of a question here about caps. I'm rebuilding a vintage mixer made by some company called Ross. In general they cut corners in a lot of places. Really unmodular and unfriendly compared to my Peavey Mixer built in the same era (early 1980s). The mains filter caps are rated for 63WV so possibly naively I ordered replacements of the same voltage rating. Now to my surprise I'm actually getting about 64.5V across each cap. About 90V rms out the transformers, so it makes sense.

Upon further inspection, the old caps were rated at 63WV and 79SV. Does anyone know what SV stands for?

I'm wondering if this is a bad situation. When a capacitor is rated to some voltage there must be some overhead in that number I'm thinking. I know its terrible practice but the caps were about $20 each and I don't want to keep them or really go through the hassle of sending them back.

[Chryseus]

[QUOTE=No_Excuses;48545591]I have a bit of a question here about caps. I'm rebuilding a vintage mixer made by some company called Ross. In general they cut corners in a lot of places. Really unmodular and unfriendly compared to my Peavey Mixer built in the same era (early 1980s). The mains filter caps are rated for 63WV so possibly naively I ordered replacements of the same voltage rating. Now to my surprise I'm actually getting about 64.5V across each cap. About 90V rms out the transformers, so it makes sense.

Upon further inspection, the old caps were rated at 63WV and 79SV. Does anyone know what SV stands for?

I'm wondering if this is a bad situation. When a capacitor is rated to some voltage there must be some overhead in that number I'm thinking. I know its terrible practice but the caps were about $20 each and I don't want to keep them or really go through the hassle of sending them back.[/QUOTE]

How on earth did they cost 20bux each?
Unless you bought a matching vintage replacement which is generally a terrible idea, if you want to keep the vintage look stuff the modern caps inside the old ones since they are smaller.
A few volts over should be fine.

[Fuxed]

[QUOTE=paindoc;48528678]Anyone have any good reading on building digital synths or audio generation in general? Me and Halofreak are going to collaborate on a synthesizer project and I'm sorta dealing with the more mechanical side at this point since he's better at all-analog circuits. I'd like to try a digital analog emulation synth though, since they can be made for so cheap it seems.
.[/QUOTE]

Ask and ye shall receive.

[URL]http://electro-music.com/wiki/pmwiki.php?n=Schematics.Schematics[/URL]

The whole site is a goldmine but that page right there is the good stuff. In particular the various envelope generator schems saved me weeks of time.

For digital, a good resource to look at how it's done in terms of raw bits, bytes and connects is to pour over this guys stuff.

[url]http://www.fpga.synth.net/pmwiki/pmwiki.php[/url]

Some of it's a little messy but the HDL files he provides are good reading.

[No_Excuses]

[QUOTE=Chryseus;48545777]How on earth did they cost 20bux each?
Unless you bought a matching vintage replacement which is generally a terrible idea, if you want to keep the vintage look stuff the modern caps inside the old ones since they are smaller.
A few volts over should be fine.[/QUOTE]

Cool, thanks. I've always found 10000uF+ filter caps to be pretty expensive, at least actual name brand ones not from ebay or other places. But yeah same size and shape as the old ones, with screw lugs that even have the same thread pitch.

[pentium]

Finished.

[img]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/IMG_0763.jpg[/img]

The bamboo cabinet the thing came with is really shit though. I wanna see if I can make it rackmountable.

[Van-man]

[QUOTE=pentium;48547924]Finished.

[img]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/IMG_0763.jpg[/img]

The bamboo cabinet the thing came with is really shit though. I wanna see if I can make it rackmountable.[/QUOTE]

So are you gonna mod the rPI (removing pullups from i2c lines?) so you have that sweet low-level serial port for accessories?