Electronics and Embedded Programming V2

[LoneWolf_Recon]

Chryseus, I've made an interesting discovery/theory. My current modulator wasn't able to fully oscillate in theory. Essentially the series LC circuit shouldn't be able to oscillate as the transistor shorts out the capacitor, not allowing it to charge and hence begin oscillation.
[IMG]https://sites.google.com/site/lonewolfscircuits/sitefiles/SingleTransistorFMTransmitter_DEMO.JPG[/IMG]

Yet on the breadboard in my demo of the modulator it oscillates as well as a video of a friend who made my circuit:
[video=youtube;WhChQUnLBTs]http://www.youtube.com/watch?v=WhChQUnLBTs[/video]

My theory is that the breadboard in my video and some other stray capacitance in the other video became an invisible capacitor across the inductor creating a true LC tank circuit or it became a Colpitts, allowing oscillation. My hunch was further supported by the frequency calculations I made
didn't match those I found while on my radio, for example:

I did my inductor coil calculations and combined that with the capacitors I had. I also compensated for transistor junction capacitance with a +/- 4pF across the C & E junction. The calculated frequency was say 92MHz. What I found instead the signal being transmitted on a lower frequency say 87.5MHz, other times it wouldn't even show up on the FM band at all, instead showing in the lower VHF band around 60-70MHz. :P

Can you verify my theory, or correct me if I'm wrong?
(I apologize for the large post)

Thanks

[Chryseus]

The single transistor FM modulator circuit is not very stable, the antenna will act as an additional inductance lowering the frequency and the stay capacitance and inductance from the various components will shift it also.
Calculations are a good starting point but when it comes to RF your going in mostly blind unless you happen to have some nice RF equipment.

[LoneWolf_Recon]

Right, thank you. Yeah I really do need an O-Scope, unfortunately the ones my Physics teacher have are only running at 20MHz... :/
Would a SWR meter aid well?

I'll continue work, and fortunately my audio pre-amp is working accordingly. I have two designs on the table, although I'm probably going to stick with the 10K one though to ease the impedance transition on then emitter follower.

[MIPS]

:v: :v: :v:
I was programming a universal remote today and didn't know while I ahd the power button pressed my Sharp Aquos was madly turning on and off until I tried to turn it back on....and the power light was blinking.
Looks like I burned out one or more of the switching transistors (hopefully).

[IMG]http://i11.photobucket.com/albums/a166/ballsandy/100_2463.jpg[/IMG]

I have forgotten, you had to take them out of circuit to test (like diodes), right?

[Lapsus]

[img]http://imgkk.com/i/bpo7.jpg[/img]

My DE-2 arrived today! :dance:

[chimitos]

I just found this in our basement. ...It belonged to a family member.

It's brand new. (I took the plastic wrap bag to take pictures.)
It has two probes, a power chord and fuses.
Also there's a magazine sized instruction book.

[img_thumb]http://img267.imageshack.us/img267/5715/p1010004hj.jpg[/img_thumb] [img_thumb]http://img846.imageshack.us/img846/8092/p1010005y.jpg[/img_thumb]
[img_thumb]http://img268.imageshack.us/img268/4002/p1010017ai.jpg[/img_thumb] [img_thumb]http://img444.imageshack.us/img444/1917/p1010019dg.jpg[/img_thumb] [img_thumb]http://img190.imageshack.us/img190/6973/instructionh.jpg[/img_thumb]

(all thumbed)

Anybody want a new scope? :v:

[Lapsus]

Oh you lucky bastard you.

I'd be interested if shipping that thing wouldn't end up raping my wallet.

[ROBO_DONUT]

Building another audio amp with two input sources. Not for any kind of signal gain, just so I get audio from two computers with my headphones. This time I'm using differential inputs because I was having grounding issues with the other one I built (which was single-ended).

[img_thumb]http://img94.imageshack.us/img94/9914/schematics.png[/img_thumb]

[img_thumb]http://img688.imageshack.us/img688/1306/ampq.jpg[/img_thumb]
If all the values and parts seem odd, its because I'm building with whatever I could find. That's about $20 in op-amps. I'd've used cheaper ones, like NE5532/NE5534s, if I had enough, but I didn't. :(
The input caps are also going to have to be electrolytic, which kinda sucks :\

Taking a Skyrim break because the solder fumes are giving me a splitting headache.

[editline]_[/editline]
Bah. Found a mistake and don't really have the board space to fix it :\

[Ddrl46]

[QUOTE=MIPS;33973524]:v: :v: :v:
I was programming a universal remote today and didn't know while I ahd the power button pressed my Sharp Aquos was madly turning on and off until I tried to turn it back on....and the power light was blinking.
Looks like I burned out one or more of the switching transistors (hopefully).

[IMG]http://i11.photobucket.com/albums/a166/ballsandy/100_2463.jpg[/IMG]

I have forgotten, you had to take them out of circuit to test (like diodes), right?[/QUOTE]

I would first check if you get anything out of the power supply (under load).

[yngndrw]

[QUOTE=MIPS;33973524]:v: :v: :v:
I was programming a universal remote today and didn't know while I ahd the power button pressed my Sharp Aquos was madly turning on and off until I tried to turn it back on....and the power light was blinking.
Looks like I burned out one or more of the switching transistors (hopefully).

[IMG]http://i11.photobucket.com/albums/a166/ballsandy/100_2463.jpg[/IMG]

I have forgotten, you had to take them out of circuit to test (like diodes), right?[/QUOTE]
Is it not still under warranty ? Just tell them that you came to it and one day it didn't switch on. (I think its pretty shitty that a TV can break itself if switched on and off too quickly, but I guess that's what happens when companies start maximising profits with no regard for anything else.)

[DrLuke]

They probably saved 2 cents on a protective diode or shit like that that ends up with some inductive load frying the transistor when it's turned off too fast.

[MIPS]

[QUOTE=ddrl46;33978219]I would first check if you get anything out of the power supply (under load).[/QUOTE]

I can get it into standby mode and it seems to behave. The moment you actually turn it on from the power button or remote however it throws itself inth "PSU FAULT" blink mode on the power light until you press the power button again. I'm assuming that something's failing to come up as expected by the firmware (probably one or both of the inverters) and that's what is throwing the fault.

[quote]Is it not still under warranty ?[/quote]
Haha. I bought it a recycler for $40. It's missing a box called the AVR which has the tuner and shit in it (so nothing on the remote works besides the power button) but because it has a DVI input I turned it into a 720p LCD monitor with amplified speakers.

[ROBO_DONUT]

Progress!
[img_thumb]http://img85.imageshack.us/img85/8858/progressyw.jpg[/img_thumb]

[Lapsus]

Finally got something running on my FPGA, it only took a few hours of tearing out my hair too.

[video=youtube;UjigMSPnz8Q]http://www.youtube.com/watch?v=UjigMSPnz8Q[/video]

Code is in SystemVerilog, 'cause regular Verilog doesn't let me assign arrays to other arrays.

module switches(SW, LEDR, HEX7, HEX6, HEX5, HEX4, HEX3, HEX2, HEX1, HEX0);
	input SW[17:0];		// The Toggle Switches
	
	output LEDR[17:0];	// The Red LEDs
	output HEX0[6:0];	// The Seven-Segment Displays
	output HEX1[6:0];
	output HEX2[6:0];
	output HEX3[6:0];
	output HEX4[6:0];
	output HEX5[6:0];
	output HEX6[6:0];
	output HEX7[6:0];
	
	assign LEDR = SW;		// Have the LEDs show the states of the switches, easy

	ShutUp Seg0(HEX0);	// Turn off the unused displays
	ShutUp Seg1(HEX1);
	ShutUp Seg2(HEX2);
	ShutUp Seg3(HEX3);
	
	SevenSegment Seg4(SW[3:0], HEX4);	// Display the state of the switches in hex
	SevenSegment Seg5(SW[7:4], HEX5);
	SevenSegment Seg6(SW[11:8], HEX6);
	SevenSegment Seg7(SW[15:12], HEX7);	
endmodule

module ShutUp(Display);	// Turn shit off
	output Display[6:0];
	
	assign Display[0] = 1;
	assign Display[1] = 1;
	assign Display[2] = 1;
	assign Display[3] = 1;
	assign Display[4] = 1;
	assign Display[5] = 1;
	assign Display[6] = 1;
endmodule

module SevenSegment(Data, Display);	// Convert from Binary to Seven-Segment
	input Data[3:0];
	output Display[6:0];
	
	reg [6:0]SevenSeg;
	always @(*) begin
		case(Data[3:0])
			4'h0:    SevenSeg = 7'b1000000;
			4'h1:    SevenSeg = 7'b1111001;
			4'h2:    SevenSeg = 7'b0100100;
			4'h3:    SevenSeg = 7'b0110000;
			4'h4:    SevenSeg = 7'b0011001;
			4'h5:    SevenSeg = 7'b0010010;
			4'h6:    SevenSeg = 7'b0000010;
			4'h7:    SevenSeg = 7'b1111000;
			4'h8:    SevenSeg = 7'b0000000;
			4'h9:    SevenSeg = 7'b0010000;
			4'ha:    SevenSeg = 7'b0001000;
			4'hb:    SevenSeg = 7'b0000011;
			4'hc:    SevenSeg = 7'b1000110;
			4'hd:    SevenSeg = 7'b0100001;
			4'he:    SevenSeg = 7'b0000110;
			4'hf:    SevenSeg = 7'b0001110;
			default: SevenSeg = 7'b1111111;
		endcase
	end
	
	assign Display[0] = SevenSeg[0]; // This fuckery is necessary
	assign Display[1] = SevenSeg[1]; // thanks to SystemVerilog's
	assign Display[2] = SevenSeg[2]; // packed arrays conflicting
	assign Display[3] = SevenSeg[3]; // with Altera's unpacked pin
	assign Display[4] = SevenSeg[4]; // assignments for this board
	assign Display[5] = SevenSeg[5]; // Had a fun 2 hours figuring
	assign Display[6] = SevenSeg[6]; // that out.
endmodule

[Electroholic]

I have a question. I read somewhere the Zilog Z80 doesn't need a fast refresh rate because the internal memory doesn't need refreshing and you could run the CPU at 1hz. First of all, is this true?

Secondly, I ordered a Z80 thats says 8Mhz. Does that mean this specific cpu must be ran at 8Mhz?

I wanted to be able to run it very slowly so I could look at the address and data pins in slow motion :v:

[URL]http://search.digikey.com/scripts/DkSearch/dksus.dll?WT.z_header=search_go&lang=en&site=ca&keywords=269-3895-ND&x=0&y=0[/URL]

[ROBO_DONUT]

-snip-

[DrLuke]

All I know is that the first time I programmed my AVR, I basically had code running that toggled PORTB without any delay. When I accidentally fucked up the fuses and set it to some ridiculous settings. Well, I was really frustrated and just left it there, turned on.
After 4 hours, suddenly the LED hooked up to PORTB lit up.

[Chryseus]

[QUOTE=DrLuke;34000468]All I know is that the first time I programmed my AVR, I basically had code running that toggled PORTB without any delay. When I accidentally fucked up the fuses and set it to some ridiculous settings. Well, I was really frustrated and just left it there, turned on.
After 4 hours, suddenly the LED hooked up to PORTB lit up.[/QUOTE]

Are you trying to say it worked fine with a very slow clock?
But yes to answer your question thisBrad microcontrollers and microprocessors should work at any clock rate regardless of memory, SRAM does not require refreshing and DRAM is refreshed by an internal clock.
Of course what you can do with the processor may be limited at lower clock rates, particularly systems that derive their clock from the master clock such as UART or SPI.

[howling techie]

Well I got my Arduino Uno at Christmas, been having some fun with it, some extra components came a few days later (mostly LEDs) and made a minecraft day counter thing:
[img_thumb]http://i.imgur.com/29FYg.jpg[/img_thumb]
During the day, the green LED stays on, each bar represents 1 minute of time left.
Then the green LED starts to flash for dusk, and each bar represents 10 seconds.
Night and dawn work the same way, except with the red LED.
However this morning I got the LCD I ordered, so I was able to condense it.
[img_thumb]http://i.imgur.com/dkBDe.jpg[/img_thumb]
For night and day, each block is 30 seconds (6s a pixel across), and for dawn and dusk, each bock is worth 5 seconds (1s a pixel across).
I know this is all probably really simple stuff, and I've probably broken some important rules, but I have to say it's all rather fun, and nothing has exploded yet.

[DrLuke]

So I heard you guys like sine waves:

[img]http://i56.tinypic.com/21c8q38.png[/img]

[Electroholic]

[QUOTE=howling techie;34003776]<snip>
[img_thumb]http://i.imgur.com/29FYg.jpg[/img_thumb]
<snip>
[/QUOTE]

Nice. What IC is that on the left?

You inspired me to pull out my Arduino again and play around. I ordered a bunch of parts last week so hopefully they come sometime this week.

I made a driver for this 4 Digit display. Not sure what Im gunna do with it now :p
[IMG]http://img217.imageshack.us/img217/9841/screenshot2012010120524.png[/IMG]

[ROBO_DONUT]

I finished my amp!
And I didn't forget anything!
And there was no magic smoke!
And it actually sounds good!

Final schematic (without power supply):
[IMG_THUMB]http://img10.imageshack.us/img10/5861/schematicw.png[/IMG_THUMB]

I didn't take a picture of the actual board before shoving it all into the enclosure, but you can get a good idea of what it looked like by doing a google image search for 'spaghetti'

[howling techie]

[QUOTE=thisBrad;34006208]Nice. What IC is that on the left?
[/QUOTE]

It is an 8-Bit Shift Register (74HC595). All the components I used are from the [url=http://oomlout.co.uk/starter-kit-for-arduino-ardx-p-183.html]ARDX arduino starter kit[/url]. The LED bar is from bitsbox, and the LCD is from [url=http://www.topsellings.com/en/hd44780-2004-20x4-lcd-controller-module-blue-blacklight-p11611.html]top sellings[/url].

[Ddrl46]

High voltage capacitors are fun.
[img_thumb]http://i.imgur.com/giL7o.jpg[/img_thumb]

Charged it to 158v with a little switchmode I built.

[DrLuke]

[QUOTE=ddrl46;34018048]High voltage capacitors are fun.
[img_thumb]http://i.imgur.com/giL7o.jpg[/img_thumb]

Charged it to 158v with a little switchmode I built.[/QUOTE]

[img]http://i51.tinypic.com/23qxyxu.png[/img]

I dare you to short it

[VistaPOWA]

I always wanted to program microcontrollers and stuff, so I've decided to buy an Arduino.

I've checked a few hungarian webshops and all of them only listed AVR-Duino boards. Are those cheap copies or is that the full name of Arduino boards?

[OogalaBoogal]

[QUOTE=VistaPOWA;34034521]I always wanted to program microcontrollers and stuff, so I've decided to buy an Arduino.

I've checked a few hungarian webshops and all of them only listed AVR-Duino boards. Are those cheap copies or is that the full name of Arduino boards?[/QUOTE]

They are not officially made by Arduino, although they probably are not cheap copies. This one is basically a part for part copy of an Arduino Mega.

[Lapsus]

Definitely some sort of copy, though that doesn't necessarily mean they won't work.

[img]http://avr.tavir.hu/modules/Asers_Shop/images/productimages/avrduino-uno.jpg[/img]

[ROBO_DONUT]

It [i]is[/i] open hardware...

[MIPS]

Huh.
So the surge monitoring among other things in my TV is monitored by the firmware. If a spike is detected it flips a bit in the service menu and will not allow the customer to regularly use the set. You can only "fix" it by going into service mode and resetting the error condition.

Also, finding support for electronics such as TV's (ad we are not even talking about trying to find the service manual) reminds me of an XKCD comic:

[img]http://imgs.xkcd.com/comics/wisdom_of_the_ancients.png[/img]

[editline]3rd January 2012[/editline]

[QUOTE=Lapsus;34034860][img]http://avr.tavir.hu/modules/Asers_Shop/images/productimages/avrduino-uno.jpg[/img][/QUOTE]

Just looking at that fills my nostrils with the scent of cheap chinese circuit boards.