Well, I was more referring to the Tesla coils but its good to know the price of an IGBT too.
I've been wanting to build a raman spectrometer, but I don't want to spend the $500 on a visible-light notch filter.
[QUOTE=DrDevil;45413798]The easiest way to do that is using a linear regulator like the LM317 in this configuration:
[img]http://upload.wikimedia.org/wikipedia/commons/4/4f/LM317_1A_ConstCurrent.svg[/img]
The linear regulator tries everything to keep the voltage on the Adj pin at 1.25V below the output voltage.
If the voltage dips below that, it increases the output voltage. If it grows larger than that, it lowers the output voltage.
Now we cleverly use Ohm's law ( R = U/I ). As the current flows through the resistor, a voltage drops over it.
The voltage drop is proportional to the current, so you can calculate the resistance you need to make it output 1.7A.
Given the equation R = U/I, you pluck in both U and I. U is 1.25V, since ADJ has to be 1.25 below the output. I is 1.7A, since that is the current you want to set.
You need a resistor of 0.735 Ohm.[/QUOTE]
Okay, I think I got that for the most part.
One thing, though. The voltage drop of 1.25V is part of the functionality of the LM317's functionality, correct?
Also, that resistance is quite small. Not surprising when working with this high of current.
[QUOTE=Cakebatyr;45421812]Well, I was more referring to the Tesla coils but its good to know the price of an IGBT too.
I've been wanting to build a raman spectrometer, but I don't want to spend the $500 on a visible-light notch filter.[/QUOTE]
Probably terrible but at least you can see something: [url]http://publiclab.org/wiki/spectrometer[/url]
[QUOTE=Splash Attack;45421924]Okay, I think I got that for the most part.
One thing, though. The voltage drop of 1.25V is part of the functionality of the LM317's functionality, correct?
Also, that resistance is quite small. Not surprising when working with this high of current.[/QUOTE]
Yes the 1.25V drop is part of the LM317. Sadly nothing is 100℅ efficient.
[QUOTE=Cakebatyr;45421812]Well, I was more referring to the Tesla coils but its good to know the price of an IGBT too.[/QUOTE]
Well, when it comes to a tesla coil, a lot of factors come in. usually the most expensive parts to the coiler are:
-Copper wire.
-Copper plate
-IGBTs
-MMC Capacitors
Small DRSSTCs can cost around £100 or so if you do it right while the largest could cost over £10,000
[QUOTE=ddrl46;45421956]Probably terrible but at least you can see something: [url]http://publiclab.org/wiki/spectrometer[/url][/QUOTE]
I've already built one of those. Gave it to an ex actually.
But that deals mostly with transmission of light through a dissolved compound.
Raman techniques involve bouncing a single wavelength of light off an object and analyzing the spectrum that comes off it.
Here's a good explanation of what I want to do: Intro to DIY Raman Spectroscopy: [url]http://youtu.be/tRrOdKW06sk[/url]
[QUOTE=Splash Attack;45421924]Okay, I think I got that for the most part.
One thing, though. The voltage drop of 1.25V is part of the functionality of the LM317's functionality, correct?
Also, that resistance is quite small. Not surprising when working with this high of current.[/QUOTE]
Yes, you're correct. The 1.25V is a reference voltage that is generated inside the LM317.
Broke the light button on my new Chronos.. by taking it apart to program it. Not exactly the most durable :v:
I'll get pictures of it later but I'm working on a gift for a friend in which there is a glass jar containing magic cards in a shoebox wrapped with wire and a switch on the outside. turn the switch, and a brushless motor with a match spins, lighting itself and the dryer lint and paper inside the shoebox! :O
Not sure this falls under electrical engineering or electrical terrorism but eh!
Shit I'm an idiot, I taped up the shit out of the box and thought "man, I need a picture of this!"
Sorry. D:
I'm integrating my USB-powered bluetooth audio receiver into a pair of old portable speakers at the moment. I looked up the datasheet for the amplifier and since it uses 5v (Rather than the 6v the speakers are powered by), I piggypacked the dongle off it. I also grabbed a nearby ground that worked. Everything works, though there's a weird, occasional clicking sound. Could this be a bad ground or something?
EDIT: I played around with it more and the clicking / popping only happens when I'm going through the bluetooth dongle. I took some measurements and when the bluetooth dongle is disconnected, the 5v line reads 5.12v, when it's connected and in use I get about 5.08. Still within spec (5.00±0.25), though I might try looking around for a larger capacitor I can use to smooth things out. Another option would be to find out where the 6v is being stepped down to 5v and throw on a regulator that I have laying around.
Either way, my multimeter probe slipped between the leads of a small capacitor on the dongle and it no longer works, so I bought three more for $10.
I've found a few old PC PSUs in the 200 to 300 Watt range. I tested 2 of them by grounding the PS_ON wire and hooking up a case fan. I want to use them to power a DIY 2.0(1?) audio amp. I'll have one unmodified supplying the power, and scrap the other ones for parts. Would the transistors/MOSFETs in the PSUs work good for audio amplification, or are they strictly for driving the power supply?
[QUOTE=Sombrero;45449445]I've found a few old PC PSUs in the 200 to 300 Watt range. I tested 2 of them by grounding the PS_ON wire and hooking up a case fan. I want to use them to power a DIY 2.0(1?) audio amp. I'll have one unmodified supplying the power, and scrap the other ones for parts. Would the transistors/MOSFETs in the PSUs work good for audio amplification, or are they strictly for driving the power supply?[/QUOTE]
You really do not want to use one of those supplies in any amplifier application due to the large amount of noise that can't be removed without significant filtering.
Most or all of the transistors that are not surface mount are designed for high power / high voltage use, in addition MOSFETs are frowned upon for use with audio due to significantly higher distortion products compared with BJTs.
The only possible use I can think of would be to power a class B or D power stage, but really you're limited by the supply voltage to 36W into 4 Ohms so your not getting any benefit from a high power and physically bulky PSU.
[QUOTE=Chryseus;45451142]You really do not want to use one of those supplies in any amplifier application due to the large amount of noise that can't be removed without significant filtering.
Most or all of the transistors that are not surface mount are designed for high power / high voltage use, in addition MOSFETs are frowned upon for use with audio due to significantly higher distortion products compared with BJTs.
The only possible use I can think of would be to power a class B or D power stage, but really you're limited by the supply voltage to 36W into 4 Ohms so your not getting any benefit from a high power and physically bulky PSU.[/QUOTE]
In short, You're a lot better off with a transformer.
Also, just ruined my dreams of a peltier mini fridge
[url]http://en.wikipedia.org/wiki/Heat_pump#Thermoelectric[/url]
" Thermoelectric (Peltier) heat pumps are generally only around 10-15% as efficient as the ideal [URL="http://en.wikipedia.org/wiki/Refrigerator"]refrigerator[/URL] ([URL="http://en.wikipedia.org/wiki/Carnot_cycle"]Carnot cycle[/URL]), compared with 40–60% achieved by conventional compression cycle systems (reverse [URL="http://en.wikipedia.org/wiki/Rankine_cycle"]Rankine[/URL] systems using compression/expansion);[SUP][URL="http://en.wikipedia.org/wiki/Heat_pump#cite_note-17"][17][/URL][/SUP] however, this area of technology is currently the subject of active research in materials science."
[QUOTE=pentium;45462782][url]http://www.ebay.ca/itm/Commodore-64-128-SID-MIDI-synth-chip-6581-custom-made-key-ring-Unique-/291194275994?pt=LH_DefaultDomain_0&hash=item43cc88089a[/url]
:([/QUOTE]
Unless it was already a dead chip, if not then this guy is inline with audiophiles.
[QUOTE=pentium;45462782][url]http://www.ebay.ca/itm/Commodore-64-128-SID-MIDI-synth-chip-6581-custom-made-key-ring-Unique-/291194275994?pt=LH_DefaultDomain_0&hash=item43cc88089a[/url]
:([/QUOTE]
He didn't even drill the hole in line with the spot on the package
:suicide:
[QUOTE=LoneWolf_Recon;45463040]Unless it was already a dead chip, if not then this guy is inline with audiophiles.[/QUOTE]
*7 available*
We could be lucky. He could be one of those people who tried to buy SID chips bulk from china for 10 cents each so he could flip for $30 each and got burned by buying a pile of plastic slugs with legs.
I'm amazed there's actually a market for counterfeiting SID chips.
I upgraded my soldering iron, I picked up an older JBC station, and it's amazing. From a mains iron to this makes me see what all the fuss is about. Also got my MSP reading my sensors and spitting the data over an NRF24L01+ radio. All I need now is to log the data and make pretty graphs.
[CODE]0 0xf0 0 0x1 0x87 0xd1 0 0xf0 0x2 0x6c 0xd 0xd4 0xcb
22:53:56: T1: 24.000000 C, T2 24.000000 C, P 100.305000 kPa, H 62.000000 %, V 3540 mV
0 0xf0 0 0x1 0x87 0xd4 0 0xf0 0x2 0x6c 0xd 0xdd 0x5e
22:53:57: T1: 24.000000 C, T2 24.000000 C, P 100.307999 kPa, H 62.000000 %, V 3549 mV
0 0xf0 0 0x1 0x87 0xd1 0 0xf0 0x2 0x6c 0xd 0xdd 0xf4
22:53:58: T1: 24.000000 C, T2 24.000000 C, P 100.305000 kPa, H 62.000000 %, V 3549 mV
0 0xf0 0 0x1 0x87 0xd0 0 0xf0 0x2 0x6c 0xd 0xd8 0x30
22:54:00: T1: 24.000000 C, T2 24.000000 C, P 100.304001 kPa, H 62.000000 %, V 3544 mV
0 0xf0 0 0x1 0x87 0xd5 0 0xef 0x2 0x6c 0xd 0xdd 0x83
22:54:01: T1: 24.000000 C, T2 23.900000 C, P 100.308998 kPa, H 62.000000 %, V 3549 mV[/CODE]
Got a neat little power supply and fixed it up a bit. It had a blown selenium rectifier stopping the entire thing from working, quite an easy fix.
[url=http://i.imgur.com/2b8mnYf.jpg][img]http://i.imgur.com/2b8mnYfl.jpg[/img][/url]
Oltronix C15-2
That's a neat photo. Did you take it?
[QUOTE=mrmr;45475154]That's a neat photo. Did you take it?[/QUOTE]
Yes, two pieces of leftover mdf from a crappy closet and a flash does wonders.
[QUOTE=Chryseus;45451142]You really do not want to use one of those supplies in any amplifier application due to the large amount of noise that can't be removed without significant filtering.
Most or all of the transistors that are not surface mount are designed for high power / high voltage use, in addition MOSFETs are frowned upon for use with audio due to significantly higher distortion products compared with BJTs.
The only possible use I can think of would be to power a class B or D power stage, but really you're limited by the supply voltage to 36W into 4 Ohms so your not getting any benefit from a high power and physically bulky PSU.[/QUOTE]
Wouldn't you be limited to more like 4W? Your AC signal would be +-6V at best so that's 4.1V rms across 4 ohms.
[QUOTE=No_Excuses;45476749]Wouldn't you be limited to more like 4W? Your AC signal would be +-6V at best so that's 4.1V rms across 4 ohms.[/QUOTE]
Ah yes of course your right, which really makes an ATX supply useless for power audio, unless you have a boost converter but that's not going to help the noise at all.
Could someone tell me what this tall, white thing is?
[T]http://i.imgur.com/rVt8WuD.jpg[/t]
[QUOTE=Sombrero;45483267]Could someone tell me what this tall, white thing is?
[T]http://i.imgur.com/rVt8WuD.jpg[/t][/QUOTE]
A Resistor
[QUOTE=nuttyboffin;45483323]A Resistor[/QUOTE]
More precisely a heatsink around a resistor.
[QUOTE=DrDevil;45484194]More precisely a heatsink around a resistor.[/QUOTE]
What? It's just a radial lead ceramic resistor by the looks of it.
[thumb]http://m4.sourcingmap.com/photo_new/20120316/g/ux_a12031600ux0081_ux_g03.jpg[/thumb]
[QUOTE=ddrl46;45484288]What? It's just a radial lead ceramic resistor by the looks of it.
[thumb]http://m4.sourcingmap.com/photo_new/20120316/g/ux_a12031600ux0081_ux_g03.jpg[/thumb][/QUOTE]
Ah, I thought it would be one of those normal resistors that just get shoved into a ceramic block.
I bought 20 16 MHz crystals from eBay over 1 month ago. Today I got 20 6 MHz crystals.
They should probably put the kids with good eyesight sorting the small items :v:
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