If they're red LEDs, just cool them with liquid nitrogen. That will shift down the frequency.
[QUOTE=DrDevil;41614491]If they're red LEDs, just cool them with liquid nitrogen. That will shift down the [del]frequency[/del] [b]wave length[/b].[/QUOTE]
Fixed.
(I had no idea this happened before, but your post made me curious so I googled it. The cooling widens the band gap and thereby increases the energy of the transition.)
[QUOTE=Tamschi;41614767]Fixed.
(I had no idea this happened before, but your post made me curious so I googled it. The cooling widens the band gap and thereby increses the energy of the transition.)[/QUOTE]
Correct me if I'm wrong, but doesn't it increase the wave length and therefore shift down the frequency? So your stripe doesn't make sense at all
Anyone has a nand programmer schematics?
[QUOTE=nuttyboffin;41612523]What are you making with it?[/QUOTE]
ASR33 teletype machines on top of being able to output strings of data in the form of paper tape can also act as readers for the host computer for loading programs (I don't own one of these because they're several hundred dollars). My much later LA-120 DecWriter has zero support for paper tape however it has a knockout beside the keyboard for an optional keypad so I'll build a reader to fit in the knockout and add a switch so I can toggle the serial line between the terminal and the reader.
[QUOTE=Asgard;41614937]Correct me if I'm wrong, but doesn't it increase the wave length and therefore shift down the frequency? So your stripe doesn't make sense at all[/QUOTE]
No, it widens the energy gap that the electron "fall" when emitting light, so there is more energy released per photon and a red LED shifts towards yellow and maybe green.
[media]http://www.youtube.com/watch?v=3e0qcYlKPws[/media]
It may be possible to shift a red LED out of the visible range by heating it, if it doesn't fail ahead of time.
[QUOTE=Tamschi;41614767]Fixed.
(I had no idea this happened before, but your post made me curious so I googled it. The cooling widens the band gap and thereby increases the energy of the transition.)[/QUOTE]
But you do know that wavelength and frequency are directly dependent of each other? (Meaning higher frequency = shorter wavelength)
[QUOTE=DrDevil;41616709]But you do know that wavelength and frequency are directly dependent of each other? (Meaning higher frequency = shorter wavelength)[/QUOTE]
I [I]think[/I] he was correcting the guy, saying that the wavelength would actually decrease if you cooled it, not the frequency (which implies the frequency would increase)
My three tube radios arrived today, a 1949 Cossor 494AC, 1955 Ekco U245 and a 1958 Marconi T73DAB portable battery / mains radio.
The Marconi has a smashed tube which is rather annoying so I've put that on hold for the moment, currently I'm working on the Cossor and so far it looks quite good, none of the tubes appear gassy and it appear no one else has ever worked on it, so I'm going to try power the tube filaments tomorrow and finish cleaning *fingers crossed*.
I've not got around to opening the Ekco yet but from the sellers picture I suspect at least one gassy tube.
Here's the Cossor after shifting a [b]lot[/b] of dust (thankfully it's not a smokers set, urgh).
[t]http://u.cubeupload.com/Chryseus/Lejgjo.jpg[/t]
[QUOTE=DrDevil;41616709]But you do know that wavelength and frequency are directly dependent of each other? (Meaning higher frequency = shorter wavelength)[/QUOTE]
However there are some semiconductors that have indirect bandgaps, which typically is more dependent upon phonons (temperature of the semiconductor, etc, thus achieve different bandgaps from temperature)
--
Also, managed a simple design using a Raspberry Pi, DC-DC converter, Fuel Level Sensor and a few other odd & in parts for a [URL="http://www.mouser.com/500challenge_2013_c1/"]pit crew camera.[/URL]
[QUOTE=LoneWolf_Recon;41620206]However there are some semiconductors that have indirect bandgaps, which typically is more dependent upon phonons (temperature of the semiconductor, etc, thus achieve different bandgaps from temperature)
[/QUOTE]
Yes, that's all true. I was just referring to the fact that he corrected my frequency to wavelength.
Sat down and looked at what chips I needed. Accurate TTL signalling from the phototransistors comes from two 4093 NAND gates which will feed into a PIC16C for buffering and decoding to ASCII before being sent to a MAX232 via the integrated UART which will give me standard RS-232 to the host terminal.
Problem #3: I have not finished assembling my programming station.
Problem #4: I'm illiterate when it comes to programming microcontrollers. Hell it's been so long since I last coded anything I don't remember much of anything.
Once this is up and running I'll see if I can find a small DC motor that I can use to pull the tape through the reader at the flip of a switch. I'm looking at the eject motor out of a Macintosh floppy drive but some other small low power motor will work.
[QUOTE=pentium;41633723]before being sent to a MAX232 via the integrated UART which will give me standard RS-232 to the host terminal.
[/QUOTE]
It's like I'm really in the 90s again!
[QUOTE=DrDevil;41633881]It's like I'm really in the 90s again![/QUOTE]
-Snip, found what I needed-
Since everyone likes LED lights I decided to put some up.
[t]http://u.cubeupload.com/Chryseus/aLzCc8.jpg[/t]
Has anyone worked with ntc thermistors as inrush current limiters? I'm having a hard time sorting out the criteria for them, I assume they work oppositely to a PPTC (To which I understand Hold, Trip current, etc), however does the resistance specify the lowest resistance given by the ntc at continuous current? (Not surge current?).
Also, somewhat related. Most of the ways of protecting from inrush current seem quite inefficient and temperature dependent. Why not have an inductor in series with quite low resistance, and use its magnetic flux on a deflection plate? So when more current flows through the inductor (Until saturation atleast), more magnetic flux deflects the electrons in the deflection plate, thus increasing resistance and controlling inrush? Maybe something like a Corbino Disc? Just an idea I had.
(Of course, permeability would be a critical issue considering the reaction time of the device)
[QUOTE=LoneWolf_Recon;41650785]Has anyone worked with ntc thermistors as inrush current limiters? I'm having a hard time sorting out the criteria for them, I assume they work oppositely to a PPTC (To which I understand Hold, Trip current, etc), however does the resistance specify the lowest resistance given by the ntc at continuous current? (Not surge current?).[/quote]
NTC Thermistors designed for inrush current limiting specify a cold resistance (at 25c usually), a maximum continuous current and maximum power dissipation.
Generally you want to pick a thermistor that has a continuous current rating greater than your load and a cold resistance high enough to limit the maximum current, half the rectifier maximum peak current should do the job.
Example:
Using a W04M bridge rectifier the maximum peak current is 50A, so assuming a 240V input the cold resistance must be greater than 9.6ohms (R = 240V / 25A), in most cases you don't care what the actual value will drop to when it reaches equilibrium (it will be rather low), if you really do care the value can be calculated by the thermistors beta value.
More reading: [url]http://www.epcos.com/web/generator/Web/Sections/ProductCatalog/Sensors/TemperatureMeasurement/ApplicationNotes/02__InrushCurrrentLimitingAN2/PDF__InrushCurrentLimiting__AN2,property=Data__en.pdf;/PDF_InrushCurrentLimiting_AN2.pdf[/url]
As for your idea the problem with inductors is they have to carry all the current, they have a fairly high series resistance, you would need quite a large inductor also I have no idea what a deflection plate is, you can't deflect electrons in a solid what your talking about sounds more like the operation of a MOSFET in a crude way.
Thanks for the reading, it'll definitely help.
[QUOTE=Chryseus;41652174]
As for your idea the problem with inductors is they have to carry all the current, they have a fairly high series resistance, you would need quite a large inductor also I have no idea what a deflection plate is, you can't deflect electrons in a solid what your talking about sounds more like the operation of a MOSFET in a crude way.[/QUOTE]
Well, I suppose a deflection plate is a misphrase. I should just say a designated area that is typically a conductor where the electrons can freely travel from one end to the other (this conductor is in series with the load). When the magnetic flux of the inductor increases, the electrons are deflected from their destination resulting in more resistance. Perhaps using the same materials used in hall effect devices. E.G. A Corbino Disk, [URL="http://en.wikipedia.org/wiki/Magnetoresistance#Geometrical_magnetoresistance"]magnetoresistance[/URL]:
[URL="http://en.wikipedia.org/wiki/Magnetoresistance#Geometrical_magnetoresistance"][IMG]http://upload.wikimedia.org/wikipedia/commons/thumb/a/a5/Corbino_disc.PNG/250px-Corbino_disc.PNG[/IMG][/URL]
Also, don't throw me in the loony-bin on this one, but what about using graphene as the wire on the inductor? Minuscule resistance
Well this was far more obnoxious than it should've been.
[img]http://img89.imageshack.us/img89/854/audj.jpg[/img]
Co-worker said his laptop wouldn't charge unless he wiggled the plug, and eventually it wouldn't charge at all. So I had to crack the bastard open to observe the predicted broken wire on the charging jack, re-strip the ends a teeny-tiny amount (there were two wires going to the negative end), tin them, and re-affix them to where they needed to be.
So now it works, but as predicted the laptop is now missing a couple of screws. Would help if I had an actual table to work on this stuff. :v:
I have the exact same but the thing at the plug's end is broken in two
[IMG]http://wwww.laptop-inverter.net/images/DC_Power_Jack/LDJAS006.jpg[/IMG]
I've 'fixed' it three times now, where it works for roughly a week. I'd rather not replace the whole thing, but I just might. It's too small to affix a wire or even a small piece of copper between the plug and the board.
Add some hot glue as strain relief
[QUOTE=DrDevil;41660614]Add some hot glue as strain relief[/QUOTE]
You'll have to be more specific :v:
Take off the plug.
Attach wires.
Blast it with hot glue.
If you hot glue the connector and the wires in place, the wires won't be stressed as the plug is being inserted exserted (is that even a word?). Instead, the mechanical stress will be transferred to the hot glue (which really is just plastic, and not really glue), which won't break as fast under stress.
How the fuck do you cleanly cut perfboard?
[IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_0111.jpg[/IMG]
[IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_0112.jpg[/IMG]
What a fucking waste.
I've tried both score/snap and a dremel and neither will get me the perfectly cut piece someone else working on the same project as me got.
[t]http://imageshack.us/a/img189/6631/dsc02294ct.jpg[/t]
[QUOTE=pentium;41668410]How the fuck do you cleanly cut perfboard?
[IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_0111.jpg[/IMG]
[IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_0112.jpg[/IMG]
What a fucking waste.
I've tried both score/snap and a dremel and neither will get me the perfectly cut piece someone else working on the same project as me got.
[t]http://imageshack.us/a/img189/6631/dsc02294ct.jpg[/t][/QUOTE]
If you want a clean finished look, cutting and snapping in a row of holes and then filing it down to a smooth edge will probably give you the best result, though with a bit of work. Also I doubt fiberglass filing dust is very healthy to inhale.
Other than that, the keys to clean cuts are larger blades and rigidity. Since cutting perfboard on a table saw is probably a horrible idea, try a band saw or a scroll saw if you can get access to those.
I've gotten a clean cut using a hacksaw while the board is flat
I just snap it off on a table edge. You will always loose a row of holes. After that sand it down or file it down, whatever you prefer.
[img]https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcQ5xIMFIdV6qviWwtUMsVjdw52zSPJwaFDnlE7byqiMoJTargeX0Q[/img]
Get one of these, rather useful for cutting many things in electronics ect.
On a lighter note, my 1600A arrived.
[IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_0113.jpg[/IMG]
Oh baby~
[IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_0114.jpg[/IMG]
Can't stop cumming! HNNNG~
[IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_0115.jpg[/IMG]
Oh fuck. The shelf space I made isn't deep enough to hold it. Looks like it sits on the shelf above.
[IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_0116.jpg[/IMG]
Anyways, now that I have the 1600A connected to my 1607A I can debug data buses 32 bits wide.
Edited:
[IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/CGS_0117.jpg[/IMG]
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