Electrical Engineering V2

[No_Excuses]

[QUOTE=Angus725;42625746]First thing that came to mind...

Damn your simulations, I have to do that all by hand right now...All of it.

2nd thing:

you can have a AC input into an OP-AMP?[/QUOTE]

Ah don't worry I've done my fair share of hand calculations.

And yes, an op amp is well, an amplifier. As in say an audio amplifier. AC signals galore.

[Angus725]

[QUOTE=No_Excuses;42625805]Ah don't worry I've done my fair share of hand calculations.

And yes, an op amp is well, an amplifier. As in say an audio amplifier. AC signals galore.[/QUOTE]

I guess I meant AC input into the +-VCC.

[No_Excuses]

[QUOTE=Angus725;42625974]I guess I meant AC input into the +-VCC.[/QUOTE]
Oh sorry. Well the AC signal just sees the input as a 10k || 30k = 7.5k ohm resistance to ground. The op-amp's VCC doesn't see it.

To elaborate, it has to do with AC and DC equivalent circuits. The second example on this page is pretty much the same as what's happening here:

[url]http://electronicslab.eu/en/analog-electronics/349-dc-and-ac-equivalent-circuits.html[/url]

[Chryseus]

You did not include a DC blocking capacitor in the feedback network, the op-amp will saturate to the negative rail due to the high open loop DC gain which can cause significant problems, you want the DC gain to be limited to unity.

[Tamschi]

[QUOTE=Agent766;42625256]Would anyone happen to know about 3DSs? It'd be really cool to figure out how to make my own capture card rather than spending tons of money on one.[/QUOTE]

The 3DS is almost completely encrypted afaik, you'd have to hook onto the speakers and display directly.

[TCWilliamson]

Ooohhhh~ look at my new line filter for my Fullbridge
96A 3 phase~

[img]http://i.imgur.com/7cFWban.jpg[/img]

Also, got the heatsink for the Full-bridge, its currently at a machine shop, the top of it will be milled flat and then 8 holes drilled in it for mounting the brick :D

[img]http://i.imgur.com/DWHjRGp.jpg[/img]

[S31-Syntax]

Soooooo I contacted the manufacturers, turns out the bridged pins are intentional, so thats not the problem. Right now I'm communicating with a design engineer over there in Japan and he's helping me troubleshoot the display.

I'm real close to buying a cheap monocrome display off of adafruit just so I can prove I can drive a display and proceed to the radio, MP3, amplifier, and audio spectrum analyzers...

[Ddrl46]

[QUOTE=S31-Syntax;42551820][url]http://www.noritake-elec.com/evalkit-sample.php[/url]

Its this guy right here.

Package came with the screen, a 6 pin cable with connectors, 6 headers, the data sheet, info packets, all that jazz.

Here's what I know:
I know its getting 5v at somewhere between 250 to 500mA
I have the serial baud rate set at 38400, this is what the example code shows plus this is what the datasheet shows is supported.
I know the pins are in the right spots [I]and[/I] I have the pins on the arduino board activated and set to either input or output, depending on what the data sheet shows.
This is the example code provided by the manufacturer, built for arduino boards.
The code also came with the complete code libraries for all the GU7000 VFDs from their company, which I have loaded and it compiles without error.

#include <GU7000_Interface.h>
#include <GU7000_Parallel.h>
#include <GU7000_Serial_Async.h>
#include <GU7000_Serial_SPI.h>
#include <GU7000_Serial_Sync.h>
#include <Noritake_VFD_GU7000.h>

// ****************************************************
// ****************************************************
// Uncomment one of the communication interfaces below.
//
//GU7000_Serial_Async interface(38400,3, 5, 7); // BAUD RATE,SIN,BUSY,RESET
//GU7000_Serial_Sync interface(3, 5, 6, 7); // SIN,BUSY,SCK,RESET
//GU7000_Serial_SPI interface(3, 5, 6, 7, 8); // SIN,BUSY,SCK,RESET,CS
//GU7000_Parallel interface('R', 8,9,10,11, 0,1,2,3,4,5,6,7); // Module Pin#3=RESET; BUSY,RESET,WR,RD,D0-D7
//GU7000_Parallel interface('B', 8,9,10,11, 0,1,2,3,4,5,6,7); // Module Pin#3=BUSY; BUSY,RESET,WR,RD,D0-D7
//GU7000_Parallel interface('N', 8,9,10,11, 0,1,2,3,4,5,6,7); // Module Pin#3=nothing; BUSY,RESET,WR,RD,D0-D7

//
// ****************************************************
// ****************************************************
Noritake_VFD_GU7000 vfd;

void setup() {
  _delay_ms(500);           // wait for device to power up
  vfd.begin(140, 16);       // 140x16 module
  // Enter the 4-digit model class number
  // E.g. 7040 for GU140X16G-7040A
  vfd.isModelClass(7000);
  //vfd.isGeneration('B');    // Uncomment this for B generation
  vfd.interface(interface); // select which interface to use
  vfd.GU7000_reset();       // reset module
  vfd.GU7000_init();        // initialize module
  
  
  // Print Noritake on screen.
  vfd.print("Noritake");
}

void loop() {
}

Uncommenting the first serial interface, I have all the pins in place, the board and the VFD are both getting power, I compile the code, send it to the board, board shows it got the code, display stays dark.[/QUOTE]

You are initializing the display at 140 * 16 while the display is 140 * 32 (I assume you are using a 140 * 32 display since you linked to one)?

[S31-Syntax]

[QUOTE=ddrl46;42633244]You are initializing the display at 140 * 16 while the display is 140 * 32 (I assume you are using a 140 * 32 display since you linked to one)?[/QUOTE]

Tried changing that originally, no effect.

[Ddrl46]

[QUOTE=S31-Syntax;42633293]Tried changing that originally, no effect.[/QUOTE]

Have you also looked at page 29 in the datasheet about the jumpers to select the baud rate etc?

[S31-Syntax]

Thats just a copypaste directly from the code libraries they shipped with the device.

[editline]24th October 2013[/editline]

I did, it implied that 38400 baud is selected by leaving J0 and J1 open, so I did.

[editline]24th October 2013[/editline]

Am I interpreting that incorrectly?

[demoguy08]

I'm doing some experimenting with a RF transmitter hooked up to an Arduino (GND, VCC, DATA, not much more complicated than that) but it's quite noisy and just touching the USB cable makes the signal jump all over the place. Is there anything to be done except enclosing the whole thing in a metal box?

[LoneWolf_Recon]

[QUOTE=demoguy08;42634555]I'm doing some experimenting with a RF transmitter hooked up to an Arduino (GND, VCC, DATA, not much more complicated than that) but it's quite noisy and just touching the USB cable makes the signal jump all over the place. Is there anything to be done except enclosing the whole thing in a metal box?[/QUOTE]

Decoupling capacitors across the voltage lines and a stable enclosure is your best bet along side of a well-designed antenna. What sort of xmitter are you using? Xbee?

Also, if its a commercial transmitter and its drifting this badly, chances are its a bad unit.

Unless its your own DIY xmitter to which we need a schematic.

[No_Excuses]

[QUOTE=Chryseus;42630065]You did not include a DC blocking capacitor in the feedback network, the op-amp will saturate to the negative rail due to the high open loop DC gain which can cause significant problems, you want the DC gain to be limited to unity.[/QUOTE]
I actually wanted to achieve this the whole time but I'm having trouble coming up with a circuit that will do it. Maybe you can help? I'm still fairly green when it comes to actual circuit design.

[Chryseus]

[QUOTE=No_Excuses;42635643]I actually wanted to achieve this the whole time but I'm having trouble coming up with a circuit that will do it. Maybe you can help? I'm still fairly green when it comes to actual circuit design.[/QUOTE]

Put a capacitor in series with the resistor going to ground (R7 in your schematic), this blocks DC current through it so at DC the feedback network only consists of R6 making it a voltage follower (gain = 1)

[url=http://www.falstad.com/circuit/#%24+1+1.0E-6+38.696464541249114+50+5.0+50%0Aa+320+176+416+176+1+12.0+0.0+1000000.0%0Ar+240+160+240+96+0+10000.0%0Ar+240+160+240+208+0+10000.0%0Ar+544+176+544+240+0+10000.0%0Ar+416+240+352+240+0+1500.0%0Ar+320+240+320+304+0+1000.0%0Ac+208+160+128+160+0+1.0E-6+5.9824602401857465%0Ac+464+176+512+176+0+4.7E-6+6.0035076613150515%0Aw+320+160+240+160+0%0Aw+240+160+208+160+0%0Aw+320+192+320+240+0%0Aw+320+240+352+240+0%0Aw+416+240+416+176+0%0Aw+416+176+464+176+0%0Aw+512+176+544+176+0%0Ac+320+304+320+352+0+4.7E-6+6.017622424717909%0Ag+320+352+320+368+0%0Ag+240+208+240+224+0%0Ag+544+240+544+256+0%0AR+240+96+240+64+0+0+40.0+12.0+0.0+0.0+0.5%0Av+128+160+128+240+0+1+1000.0+1.0+0.0+0.0+0.5%0Ag+128+240+128+256+0%0Ao+3+64+0+34+4.676805239458889+1.8268770466636287E-4+0+-1%0A]example.[/url]

[demoguy08]

[QUOTE=LoneWolf_Recon;42634656]Decoupling capacitors across the voltage lines and a stable enclosure is your best bet along side of a well-designed antenna. What sort of xmitter are you using? Xbee?

Also, if its a commercial transmitter and its drifting this badly, chances are its a bad unit.

Unless its your own DIY xmitter to which we need a schematic.[/QUOTE]

Not an Xbee, just a cheapo transmitter:

[IMG]http://snapping.asia/newdximages/sku_148983_1_small/mx-fu1-315mhz-wireless-transmitter-module-superregeneration-for-arduino.jpg[/IMG]

I assume you can't really do anything more advanced than ASK/CW modulation with it, but who knows.

[LoneWolf_Recon]

[QUOTE=demoguy08;42635874]Not an Xbee, just a cheapo transmitter:

[IMG]http://snapping.asia/newdximages/sku_148983_1_small/mx-fu1-315mhz-wireless-transmitter-module-superregeneration-for-arduino.jpg[/IMG]

I assume you can't really do anything more advanced than ASK/CW modulation with it, but who knows.[/QUOTE]

That's probably about the only thing you can due, basic regens like this are tricky when it comes to AM/FM. So yeah you're pretty much limited to ASK/CW without any added circuitry (Buffers, amp).

Another thing I might recommend is a buffer from the regen to the antenna.

Also fool around with the amount of modulation you can do with it. (E.g. if you're doing CW, instead of dropping the voltage by a full 5V, try modulating in a voltage range of 2.5-3.5V. Analoged to Class-A amps, this may see more stability when you aren't pushing its full oscillating voltage swing (0-5V))

I'm not too much an expert so I can't guarantee this will work.

[No_Excuses]

[QUOTE=Chryseus;42635835]Put a capacitor in series with the resistor going to ground (R7 in your schematic), this blocks DC current through it so at DC the feedback network only consists of R6 making it a voltage follower (gain = 1)

[url=http://www.falstad.com/circuit/#%24+1+1.0E-6+38.696464541249114+50+5.0+50%0Aa+320+176+416+176+1+12.0+0.0+1000000.0%0Ar+240+160+240+96+0+10000.0%0Ar+240+160+240+208+0+10000.0%0Ar+544+176+544+240+0+10000.0%0Ar+416+240+352+240+0+1500.0%0Ar+320+240+320+304+0+1000.0%0Ac+208+160+128+160+0+1.0E-6+5.9824602401857465%0Ac+464+176+512+176+0+4.7E-6+6.0035076613150515%0Aw+320+160+240+160+0%0Aw+240+160+208+160+0%0Aw+320+192+320+240+0%0Aw+320+240+352+240+0%0Aw+416+240+416+176+0%0Aw+416+176+464+176+0%0Aw+512+176+544+176+0%0Ac+320+304+320+352+0+4.7E-6+6.017622424717909%0Ag+320+352+320+368+0%0Ag+240+208+240+224+0%0Ag+544+240+544+256+0%0AR+240+96+240+64+0+0+40.0+12.0+0.0+0.0+0.5%0Av+128+160+128+240+0+1+1000.0+1.0+0.0+0.0+0.5%0Ag+128+240+128+256+0%0Ao+3+64+0+34+4.676805239458889+1.8268770466636287E-4+0+-1%0A]example.[/url][/QUOTE]
You are wonderful.

And with some frequency analysis...a 4.7uF cap in series with as 4.7k ohm resistor puts my -3dB at about 7Hz which is perfect.

[DrLuke]

[QUOTE=demoguy08;42635874]Not an Xbee, just a cheapo transmitter:

[IMG]http://snapping.asia/newdximages/sku_148983_1_small/mx-fu1-315mhz-wireless-transmitter-module-superregeneration-for-arduino.jpg[/IMG]

I assume you can't really do anything more advanced than ASK/CW modulation with it, but who knows.[/QUOTE]

Those fucking things, I tossed mine out the window

[demoguy08]

[QUOTE=LoneWolf_Recon;42636272]That's probably about the only thing you can due, basic regens like this are tricky when it comes to AM/FM. So yeah you're pretty much limited to ASK/CW without any added circuitry (Buffers, amp).

Another thing I might recommend is a buffer from the regen to the antenna.

Also fool around with the amount of modulation you can do with it. (E.g. if you're doing CW, instead of dropping the voltage by a full 5V, try modulating in a voltage range of 2.5-3.5V. Analoged to Class-A amps, this may see more stability when you aren't pushing its full oscillating voltage swing (0-5V))

I'm not too much an expert so I can't guarantee this will work.[/QUOTE]

I'll try this out, thanks for the input.

[editline]25th October 2013[/editline]

[QUOTE=DrDevil;42638453]Those fucking things, I tossed mine out the window[/QUOTE]

Gotta start somewhere :v:

[No_Excuses]

I now understand pole-zero plots thanks to this document:
[url]http://web.mit.edu/2.14/www/Handouts/PoleZero.pdf[/url]

Frequency response of circuits is one of my favorite topics, mostly because of my interest in audio related electronics.

Alright I rebuilt this little bugger.

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

Then when I was testing I noticed something a little weird...those two little notches at the bottom of the waveform. It was on all 4 channels.
[thumb]http://i.imgur.com/mWKhDFN.jpg[/thumb]

Then I increased the frequency to 20kHz and woah, that's not right:
[thumb]http://i.imgur.com/wfJnzuU.jpg[/thumb]

After some messing around it turns out my LM2902 op-amp's aren't up to the job. I tried again with a TI TL084BCN and it worked perfectly. I ordered some TL084BIN's because the BCN's are only rated to a 0 degree celsius operating temp and the winters here drop down to like -40.

[S31-Syntax]

OKay so further discussion with the VFD design engineers in japan suggests that the unit I received was faulty. They've agreed to send me a successfully tested unit for no extra cost. Cost me nothing to get the first one, so I'm good with that.

If I can get this one working, I can finally proceed with the rest of the radio, now that I have a way to get a visible output from the rest of the modules.

[DrLuke]

[QUOTE=S31-Syntax;42675978]OKay so further discussion with the VFD design engineers in japan suggests that the unit I received was faulty. They've agreed to send me a successfully tested unit for no extra cost. Cost me nothing to get the first one, so I'm good with that.

If I can get this one working, I can finally proceed with the rest of the radio, now that I have a way to get a visible output from the rest of the modules.[/QUOTE]

Those are some very nice engineers. What company is it?

[S31-Syntax]

Noritake. One of the only VFD module manufactures I've been able to find.

[woidoi]

My ATtiny programming shield works :smile:

[t]https://dl.dropboxusercontent.com/u/43645231/photos/electro/2013-10-28%2022.22.05.jpg[/t]

It isn't anything besides some sockets and wires, but now I atleast know that I'm decent at soldering, and it will save me the hassle of having lose cables everywhere each time I want to use my ATtiny's

[URL="http://hlt.media.mit.edu/?p=1695"]Here's an article on how to use ATtiny's if you're interested.[/URL]

[Van-man]

The wonky pin spacing on Arduino's bothers me.
Instead of fixing that tiny flaw that caused it, they stuck with it because of some reason that would make philosophy mayors cream themselves.
Ruining the possibility to make shields out of cheap protoboards.

Cue the Analog fetishists taking this as a opportunity to jerk off while pretending superiority and the elitist programming wankers to curse it even though the only real issue for them is the optional use IDE that can be ignored if desired.

[Chryseus]

[QUOTE=Van-man;42679003]Cue the Analog fetishists taking this as a opportunity to jerk off while pretending superiority[/QUOTE]

No need to pretend there, digital is just an abstraction of analog, you can't be an expert at digital without a good knowledge of analog.

[Van-man]

[QUOTE=Chryseus;42679664]No need to pretend there, digital is just an abstraction of analog, you can't be an expert at digital without a good knowledge of analog.[/QUOTE]

Exhibit A, ladies and gentlemen.

[DrLuke]

[QUOTE=Chryseus;42679664]No need to pretend there, digital is just an abstraction of analog, you can't be an expert at digital without a good knowledge of analog.[/QUOTE]

By that logic, doing analog is really just an abstraction of the maxwell equations, and you can't be an expert at electronics without having a good knowledge about them

[Chryseus]

[QUOTE=DrDevil;42680024]By that logic, driving a car really is just an abstraction of thermal energy and expanding gasses and a pinch of rotational physics.[/QUOTE]

Driving a car doesn't require for you to understand how it works, designing circuits on the other hand does, it's just not possible to completely design circuits from the digital viewpoint when you have to deal with analog things like rise-time, bandwidth, impedance, self resonance, coupling and more, this of course gets much more critical at higher frequencies.
Point is digital is fundamentally analog, if you try ignore the analog aspects your circuits are at best going to be of marginal quality.