[QUOTE=Chezburger;39792392]Why not just make pcb's by taking a piece of wood, hammer in some nails and mount the parts between the nails? Yes, I actually did this to make my crystal receiver back in tha day.[/QUOTE]
try that with a 40 pin dip and a few SMD components.
I've done it myself, but it's only good for large components with few legs
[img]http://i.imgur.com/2CzAnjz.png[/img]
Why doesn't the second scheme work while the first one does?
[QUOTE=alexaz;39793142]
Why doesn't the second scheme work while the first one does?[/QUOTE]
I don't believe you can allow the output transistor of a darlington to fully saturate or else you'll have negative feedback developing on its emitter, causing the input transistor to shut off.
[QUOTE=alexaz;39793142]Why doesn't the second scheme work while the first one does?[/QUOTE]
In the second circuit (emitter follower) the output current is:
VE / RLoad
Where VE = VB - 1.4
As a result IB must be:
(VE / RLoad) / (β1 * β2)
R2 in particular can cause an increase in IB & IE due to positive feedback but this is not usually significant enough to worry about so can be in practice ignored, the purpose of R1 and R2 is simply to reduce the base charge storage time giving a faster turn-off.
The first circuit works much better for switching applications since IC = IB * (β1 * β2)
IB is then of course roughly (VB - 1.4) / Re
Re being the intrinsic emitter resistance which at high current should be << 0.2 ohm which is why you need a base resistor.
[quote]I don't believe you can allow the output transistor of a darlington to fully saturate or else you'll have negative feedback developing on its emitter, causing the input transistor to shut off.[/quote]
The emitter is in phase with the base so it's positive feedback, now if it was from the collector to base it would be negative due to the 180 degree phase difference.
I assume your confusing it because the emitter degeneration acts rather like negative feedback.
[QUOTE=MIPS;39789886]Is there a cheaper alternative to carbon paint?
The contacts on a rubber dome keyboard died and I need something I can paint on the old contacts to restore them.
Carbon paint sound sliek it would work but it's super expensive.[/QUOTE]
[url]http://store.caig.com/s.nl/sc.2/category.181/.f[/url]
[QUOTE=voodooattack;39801331]Fucking I2C..[/QUOTE]
Setting up I2C on the Pi is a pain, but the interface and protocol itself is easy to learn.
[QUOTE=MIPS;39801356][quote]Price: $1,175.00[/quote][/QUOTE]
[quote]226 grams[/quote]
[editline]5th March 2013[/editline]
[QUOTE=LoneWolf_Recon;39801389]Setting up I2C on the Pi is a pain, but the interface and protocol itself is easy to learn.[/QUOTE]
Yeah, I just got it to work. Turns out I wired it with the wrong resistors on the VDD line.
Now my chip can read humidity/temperature from a HYT-271. Next step is plotting the graphs on the LCD screens.
I fucking love i2c.
[I]SPEAKING[/I] of I[SUP]2[/SUP]C, where the hell can I snatch up a [URL="http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en545865"]MCP3428[/URL] for cheap? (including a DIP adapter would be great)
[QUOTE=Van-man;39805221][I]SPEAKING[/I] of I[SUP]2[/SUP]C, where the hell can I snatch up a [URL="http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en545865"]MCP3428[/URL] for cheap? (including a DIP adapter would be great)[/QUOTE]
Farnell has them. And you can get adapters on ebay.
[QUOTE=DrLuckyLuke;39805482]Farnell has them. And you can get adapters on ebay.[/QUOTE]
Farnell either requires me to place a fuckhuge order in return for free shipping, or pay a extremely expensive shipping fee.
But what would you need such a high precision adc for?
~automerge~
Places like Farnell usually are the only places where you can get those for relatively cheap, unless some chinese sellers sell them on ebay or a store like sparkfun carries them for 10 times the price.
[editline]5th March 2013[/editline]
Also, if you're a bad boy you could try to sample them.
[QUOTE=DrLuckyLuke;39805502]But what would you need such a high precision adc for?[/QUOTE]
The 10 bit ADC in a Arduino is a little bit on the weak side for measuring, not to mention the reference voltage isn't really that precise.
[QUOTE=Van-man;39805562]The 10 bit ADC in a Arduino is a little bit on the weak side for measuring, not to mention the reference voltage isn't really that precise.[/QUOTE]
You can provide an external reference voltage.
Just got my Pi.
Out of interest, what compilers/tools do you guys use to program your MCUs?
[QUOTE=voodooattack;39806236]Just got my Pi.
Out of interest, what compilers/tools do you guys use to program your MCUs?[/QUOTE]
I typically use AVRStudio 6 and the WinAVR library for my megas/tinys.
(Quick tip: When you install your distro onto your Pi, I recommend Debian, there is a package for CodeBlocks and a G++ compiler on the Pi store)
[QUOTE=LoneWolf_Recon;39806944]I typically use [b]AVRStudio 6[/b] and the WinAVR library for my megas/tinys.[/QUOTE]
*vomit*
I use winavr or avrdude with notepad++
Not that I use it often I'm an analog guy.
[QUOTE=Chryseus;39807061]*vomit*
I use winavr or avrdude with notepad++
Not that I use it often I'm an analog guy.[/QUOTE]
What's your problem with AVRStudio? It's pretty awesome.
[QUOTE=DrLuckyLuke;39805912]You can provide an external reference voltage.[/QUOTE]
I'd still have to deal with a ADC that doesn't have a high enough resolution.
[editline]5th March 2013[/editline]
[QUOTE=DrLuckyLuke;39807243]What's your problem with AVRStudio? It's pretty awesome.[/QUOTE]
Windows only
In retrospect, I've noticed that CodeBlocks IDE (That I typically use for coding C++ for Windows) has an option to code for AVRs (Probably involves setting up the WinAVR toolchain)
[QUOTE=Van-man;39807289]I'd still have to deal with a ADC that doesn't have a high enough resolution.
[/QUOTE]
Well, what are you trying to do?
[QUOTE=DrLuckyLuke;39807343]Well, what are you trying to do?[/QUOTE]
Measure voltages & currents precisely.
Although ADC's can be used for more than just that, so it's because i'd like a precise addition to pretty much any microcontroller.
Should probably also look for a accurate (non audio) DAC while I'm at it, even though PWM can do (somewhat) the same
[QUOTE=voodooattack;39806236]Just got my Pi.
Out of interest, what compilers/tools do you guys use to program your MCUs?[/QUOTE]
Aha, enjoy, it makes for a nice little web-box.
AVR-GCC/Binutils/LibC for AVR (Obviously!); CodeSourcery, Linaro or YAGARTO for ARM usually with the Vendor libraries, depends on the project and Eclipse/C2H for NIOS II. Nano or Leafpad for text editor, Notepad++ if on Windows.
Been working on the USB programmer for my computer!
Still a couple parts to go on, but it's mostly populated, and all the parts for talking over USB are on there:
[t]http://i.imgur.com/08vBQ4q.jpg[/t]
Power and USB is hooked up, mostly just point-to-point for the data and control bus now:
[t]http://i.imgur.com/vcW53Rg.jpg[/t]
Kinda surprised by how neat it's turned out, but there are still some dodgy bits...
Sending commands with libusb to turn the LED on and off:
[t]http://i.imgur.com/7k7h5em.jpg[/t]
Works! (The arduino is just a programmer)
Which avr are you using?
atmega8-16pu, got a bunch off of deal extreme a while ago :) it's got no PCINT though, just INT0 and INT1, so the pin layout's a little bit funky. (Because I need an interrupt pin for USB)
This is what I did a while back :) toy car controlled by Wifi via PC or Android
[video=youtube;BBWMjAR1V6k]http://www.youtube.com/watch?v=BBWMjAR1V6k[/video]
Wow, AVR kicks PIC's butt. No more random freezing douche-baggery.
[IMG]https://dl.dropbox.com/u/27714141/Screenshot%20from%202013-03-06%2006%3A42%3A02.png[/IMG]
Just finished migrating my code to AVR.. Now I'll be adding the rest of the circuit (Pump and heater control with a configurable threshold, and a USB serial interface for calibration)
It also looks like I'll have to use a touch-screen LCD instead of that one. It's the only part available at our retailer right now.
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