[QUOTE=Zero-Point;44532747]This is sort of electronics related, so I guess I'll ask here.
I've had some idea for a prop I'd like to make someday, though it would involve having to basically blow a custom glass assembly for a plasma display, but not like a plasma globe where the plasma is flying around all over the inside of the globe, but "sticking" to the inner surface like this:
[IMG]http://i.imgur.com/Zkcb3EO.jpg[/IMG]
Any documentation on how to achieve this effect?[/QUOTE]
I'm thinking it would involve some metallic/conductive paint?
The plasma 'sticks' to the surface wherever your hands touch it because your hands have a lower potential than the plasma in the globe. I guess you could try having an earthed metal mesh on the opposite side of the glass, but the voltage of plasma globes is generally really high so that could be dangerous :v:
[QUOTE=Tw34k;44530636]What did you do to ruin a tip?
Something a small file can't fix?[/QUOTE]
NEVER use a file on a soldering iron tip.
Using a file is fine if you just want a little extra life out of a seriously worn tip, but you should never need to use it on a new'ish tip, hell I've had the same tip on my soldering station since I bought it nearly 2 years ago and it still works just fine.
If you're having problems with frequently worn tips then your probably running it too hot, not tinning often enough, using a solder with poor flux content or abusing the tip by applying too much force.
Spots of heavy oxide can be fixed with a tip cleaner or a gentle rub with wire wool, do it straight away or it will become more difficult to remove.
[QUOTE=Subby;44533036]I'm thinking it would involve some metallic/conductive paint?[/QUOTE]
A very bad idea, the induced RF current will cause it to become quite hot.
My systems teacher used a a bench grinder on a soldering iron tip, managed to tin it after making sure it was quite hot.
[QUOTE=ddrl46;44533092]NEVER use a file on a soldering iron tip.[/QUOTE]
That may be so a new one but one that is already potentially "ruined" couldn't hurt. I've saved damaged tips before using a file and they lasted for years afterwards with proper maintenance.
[QUOTE=Falcqn;44533038]The plasma 'sticks' to the surface wherever your hands touch it because your hands have a lower potential than the plasma in the globe. I guess you could try having an earthed metal mesh on the opposite side of the glass, but the voltage of plasma globes is generally really high so that could be dangerous :v:[/QUOTE]
No no, it sticks to the inner surface of the glass even if you're not touching it.
[QUOTE=Zero-Point;44534890]No no, it sticks to the inner surface of the glass even if you're not touching it.[/QUOTE]
The glass acts as a capacitor between the inside and the surrounding air, since the human body has a much higher capacitance the discharge will be attracted to your finger, you could probably simulate such with a small metal plate connected through a 1k to 10k resistor and 100pF cap to earth.
Done properly it will not generate heat or present a shock hazard since the induced current is low and as we all know V = IR.
[QUOTE=Chryseus;44536068]The glass acts as a capacitor between the inside and the surrounding air, since the human body has a much higher capacitance the discharge will be attracted to your finger, you could probably simulate such with a small metal plate connected through a 1k to 10k resistor and 100pF cap to earth.
Done properly it will not generate heat or present a shock hazard since the induced current is low and as we all know V = IR.[/QUOTE]
You surely mean that the glass acts as a dielectric.
[QUOTE=Chryseus;44536068]The glass acts as a capacitor between the inside and the surrounding air, since the human body has a much higher capacitance the discharge will be attracted to your finger, you could probably simulate such with a small metal plate connected through a 1k to 10k resistor and 100pF cap to earth.
Done properly it will not generate heat or present a shock hazard since the induced current is low and as we all know V = IR.[/QUOTE]
Okay, let's try this.
This is how a typical plasma globe behaves:
[media]http://www.youtube.com/watch?v=RCi5rOy0Xnc[/media]
See how it just kinda floats around inside?
This is the effect I want:
[media]http://www.youtube.com/watch?v=5IL1raReJpA[/media]
See how it only travels along the surface of the glass?
[QUOTE=Zero-Point;44536502]See how it only travels along the surface of the glass?[/QUOTE]
The shape of the envelope, gas, pressure and operating current all changes how the arc behaves, in that case (assuming the glass is not colored) there will be three or perhaps more separate gas chambers giving it a rather complicated internal layout.
It's not really possible to do something that complicated yourself unless you're handy with glass working and have a vacuum pump.
[QUOTE=Chryseus;44536814]The shape of the envelope, gas, pressure and operating current all changes how the arc behaves, in that case (assuming the glass is not colored) there will be three or perhaps more separate gas chambers giving it a rather complicated internal layout.
It's not really possible to do something that complicated yourself unless you're handy with glass working and have a vacuum pump.[/QUOTE]
I have a friend who blows glass, and I can borrow a vacuum pump from work. It's not something I'm gonna do any time soon, just curious as to how I could make something like that.
I also think the glass is somehow colored internally, as I've seen them up-close and while the glass is thick, I don't see anything that would suggest multiple gas chambers. (that and the final project would be single-color anyway)
In other news, after digging through all of those old boards and finding OTP PIC16s, I found a PIC18f! According to the data-sheets it SHOULD be re-usable for-
[t]http://i.imgur.com/UKw4aSK.jpg[/t]
Oh. :C
Wonder if it's OK. :v:
I got my Hakko FX-888D today, it's fantastic compared to the crap I've used before. I also got some decent multicore 0.39mm solder. I still need to buy some helping hands and a desoldering pump, but just having a decent iron is helping a ton.
[QUOTE=Zero-Point;44537109]I have a friend who blows glass, and I can borrow a vacuum pump from work. It's not something I'm gonna do any time soon, just curious as to how I could make something like that.
I also think the glass is somehow colored internally, as I've seen them up-close and while the glass is thick, I don't see anything that would suggest multiple gas chambers. (that and the final project would be single-color anyway)
In other news, after digging through all of those old boards and finding OTP PIC16s, I found a PIC18f! According to the data-sheets it SHOULD be re-usable for-
[t]http://i.imgur.com/UKw4aSK.jpg[/t]
Oh. :C
Wonder if it's OK. :v:[/QUOTE]
Is that some kind of polyurethane coating on the board? To me it looks like the relay had a fatal blowout and sputtered its crud all over the board. Power it up and check if anything works at all
[QUOTE=DrDevil;44567406]Is that some kind of polyurethane coating on the board? To me it looks like the relay had a fatal blowout and sputtered its crud all over the board. Power it up and check if anything works at all[/QUOTE]
Nah, the black shit is usually soot. The relay might have just caught fire and the board was mounted vertically. Although in this case the fire was hot enough to reflow that D-PAK.
Had a similar case myself. From the first glance it looks like the cap or rectifier went haywire, but it was actually a jumper that vaporized.
[thumb]http://i.imgur.com/M0zHTuc.jpg[/thumb]
Nah, what happened was a metal-oxide varistor asploded. But yeah, there is a coating on the board, seems more like silicone oddly enough. This is a board designed to handle the elements so it's basically just a water-proofing layer. Can't remember for the life of me what it went to though, possibly a motor controller.
I found this ragged box in the loft, and had no clue what was in it
[t]https://dl.dropboxusercontent.com/u/43645231/photos/electro/2014-04-18%2016.16.43.jpg[/t]
After opening it up
[t]https://dl.dropboxusercontent.com/u/43645231/photos/electro/2014-04-18%2016.18.28.jpg[/t]
Turns out to be some kind of pocket multimeter! Comes with two cables, two fuses and a manual leaflet. I tested it and it still works.
here's a closeup of the scales
[t]https://dl.dropboxusercontent.com/u/43645231/photos/electro/2014-04-18%2016.19.35.jpg[/t]
I want to try to build my own simplistic 8-bit CPU. I'm not too worried about the "electronic details", but rather about the sequential logic. For example, how would one decide what operations to support in the ALU? How do I generally decide my instruction set for an educational CPU? What kind of memory model can I use? I think I should use registers, but I'm not sure how they are separate from other kinds of memory per se.
[QUOTE=ArgvCompany;44596395]I want to try to build my own simplistic 8-bit CPU. I'm not too worried about the "electronic details", but rather about the sequential logic. For example, how would one decide what operations to support in the ALU? How do I generally decide my instruction set for an educational CPU? What kind of memory model can I use? I think I should use registers, but I'm not sure how they are separate from other kinds of memory per se.[/QUOTE]
Its honestly what you want your CPU to do as well as how your instruction set is supported by the Memory Model/ISA. If you want it to be educational, I suggest going with the usual suspects of instructions (i.e. AND, OR, XOR, ADD, SUB) along with the facilities to view/debug the contents of memory before and after (7-Seg/Hex Viewer). Don't forget to have support for basic flow control and potentially have a Hex Viewer on the Program Counter.
For the memory, you can simplify your registers to the basics: Accumulator, Index Registers (X/Y), Misc General Purpose Registers, CPU Flags (i.e. Zero, Negative, Overflow, etc), Program Counter, Link Register (For Storing Addresses To Return From Subroutines). All which can be done with D-Flip Flops arrays. For the program counter, you can do what I did with my [URL="https://www.youtube.com/watch?v=t5b_OnCjymw"]4-Bit CPU[/URL], and utilize two 4-Bit counters to store the current location in memory, and parallel load a new address in for flow control.
For main memory, you have options, SRAM, DRAM, etc. Or go stupidly simple and use [URL="https://www.youtube.com/watch?v=Af-wx5k0jwo"]DIP switches[/URL] for program memory like I did :v:
Thumbnails would be pretty nice...
Just scored a Propeller board from Radioshack for $20. Not the "Altoids Tin Arduino" I was looking for, but hey.
Also trying to make a reflow oven. It's insane how hard it is to find a toaster oven that isn't super expensive or so small it barely makes two slices of toast in this town.
[QUOTE=Zero-Point;44598885]Just scored a Propeller board from Radioshack for $20. Not the "Altoids Tin Arduino" I was looking for, but hey.
Also trying to make a reflow oven. It's insane how hard it is to find a toaster oven that isn't super expensive or so small it barely makes two slices of toast in this town.[/QUOTE]
You'd be amazed how hard it is to find a toaster oven here at all. No one even knows what that is.
Try searching for a pizza oven instead
Make your own out of nichrome wire.
[QUOTE=Leestons;44597864]Thumbnails would be pretty nice...[/QUOTE]
Here my kind sir :) Didn't knew before how to do it and googled a bit just to find tags
[editline]21st April 2014[/editline]
[QUOTE=Zero-Point;44598885]Just scored a Propeller board from Radioshack for $20. Not the "Altoids Tin Arduino" I was looking for, but hey.
Also trying to make a reflow oven. It's insane how hard it is to find a toaster oven that isn't super expensive or so small it barely makes two slices of toast in this town.[/QUOTE]
Same for refrigerators, once I was crazy about chemicals and I wanted to store them efficiently but family refrigerator was kinda dangerous to store in..
[QUOTE=DrDevil;44603374]Try searching for a pizza oven instead[/QUOTE]
Big Lots had some that would cook a 12" pizza, which is large-ish, but I'm gonna check Goodwill first before I make a purchase, they were closed yesterday because of Easter. (the NERVE of those people!)
Sorry for barging in here asking HEY ANSWER MY QUESTION
buuuut Im having some problems with figuring out how to dissipate an amp and a half from a circuit.
What we have going is a regulated wall wart power supply outputting 12v 6A into a circuit, with two 12v 1A fans receiving first power priority then a few resistors finished with a 12v 5A peltier.
Thing is the peltier runs wayyy too hot at 5A and I'd like to step it down to closer to 3.5A, which is a safer level based on our tests.
I just cannot for the life of me figure out the best way to do this and its really getting on my nerves, since we've already had to ditch our arduino control system due to power problems (and me popping the nano...)
thanks!
[QUOTE=paindoc;44609200]Sorry for barging in here asking HEY ANSWER MY QUESTION
buuuut Im having some problems with figuring out how to dissipate an amp and a half from a circuit.
What we have going is a regulated wall wart power supply outputting 12v 6A into a circuit, with two 12v 1A fans receiving first power priority then a few resistors finished with a 12v 5A peltier.
Thing is the peltier runs wayyy too hot at 5A and I'd like to step it down to closer to 3.5A, which is a safer level based on our tests.
I just cannot for the life of me figure out the best way to do this and its really getting on my nerves, since we've already had to ditch our arduino control system due to power problems (and me popping the nano...)
thanks![/QUOTE]
You could utilize a [URL="http://www.spaennare.se/PWMDIG/mosfet.gif"]PWM setup[/URL] (Just replac the Motor/Diode with the Peltier plate, also look for a *very* low Rds Mosfet) to limit the amount of power going to the Peltier plate, that would be the smartest way to limit current. Mess around with the PWM frequency as you do [U]not[/U] want to put the frequency to high to inadvertently give the plate thermal shock (~10kHz is a good starting frequency).
Alternatively, you could setup a semi-hysteresis system with a [URL="http://en.wikipedia.org/wiki/Resettable_fuse"]PPTC[/URL], to limit current through the plate, while applying thermal contact between the PPTC and the plate (PPTCs work on temperature changes akin to thermistors). Depending upon the coefficient of the PPTC (Usually positive), you can apply it to the hot side to begin to trip when the plate becomes too hot.
Also no worries about barging in, we're pretty relaxed with support questions in the EE thread.
Toaster oven acquired. What's super neat-o is it has a fan to circulate the air, creating an evenly tempered environment inside. The real question is how quickly does it heat up/cool down? If it's too slow then I'm a sad nerd.
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