http://www.opencircuits.com/api.php?action=feedcontributions&user=Ratmandu&feedformat=atomOpenCircuits - User contributions [en]2024-03-29T13:25:10ZUser contributionsMediaWiki 1.34.2http://www.opencircuits.com/index.php?title=Integrated_Circuits&diff=11334Integrated Circuits2007-11-24T04:06:14Z<p>Ratmandu: /* RF ICs/Modules */</p>
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<div>== Digital Potentiometers ==<br />
[[Digital Potentiometers|Digital Potentiometers(AD5204)]]<br />
The digital Potentiometers made by analog devices (AD5204) has 255 positions can be adjusted by the microcomputer that can receive commands from the computer. This is a great way for analog circuitry to have digital control. This is a chip with 4 digitally controlled POTs and the pots can be daisy chained to have multiple chips controled by a single SPI interface.<br />
<br />
<br />
<br />
== Voltage Regulators ==<br />
{|<br />
! colspan="2" align="left"| Linear Regulators<br />
|-<br />
| align="center"|[[Image:Main-LT1528.jpg|69px|LT1528]]<br>[[LT1528]]<br />
| High current, Variable Voltage Regulator<br />
|-<br />
| align="center"|[[Image:TPS-V-Reg.jpg|69px|TPS V-Reg]]<br>[[TPS V-Regs]]<br />
| These are 3.3V and 5V LDO, Low-Noise Voltage Regulators. Very small SOT-23 SMD package. 150mA max current. Best used in battery applications.<br />
|-<br />
| align="center"|[[Image:Main-LM7805.jpg|69px]]<br>[[Basic Voltage Regulators]]<br />
| Variable voltage regulators, set output regulators, we give you the whole breakdown. Perfect for use with an external wall-wart power supply.<br />
|-<br />
| align="center"| [[Image:UA723CN_Symbol.gif]]<br>[[The 723 Voltage Regulator]]<br />
| Precision Voltage Regulator. Can be used as fixed or floating, variable, linear or switching. <br />
'''NOTE:''' Only the DIP-14 version (image) has the Vz pin, which is used for negative regulators. The Metal Can and the Flat-Pack do not have enough pins so exclude the Vz.<br />
|-<br />
| &nbsp;<br />
|-<br />
! colspan="2" align="left"| Switching Regulators<br />
|-<br />
| align="center"| [[Image:MCP1253-ADJ.png|69px]]<br>[[MCP1252/3]]<br />
| Extremely Efficient, 120mA Flyback Switching Regulators.<br />
|-<br />
|}<br />
<br />
== Microcontrollers ==<br />
<br />
* [[Image:lpc2103.jpg|69px|LPC2103]] [http://www.k9spud.com/arm/lpc2103/ LPC2103] Low cost 70MHz ARM7TDMI-S FLASH Microcontroller from Philips. The [http://coridiumcorp.com/arm7/ "$49" "Coridium ARMmite"] does use this chip.<br />
* [[Atmel]] AVR 8 bit FLASH microcontrollers<br />
* [[Microchip]] PIC 8 bit FLASH microcontrollers<br />
* Microchip dsPIC 16 bit FLASH microcontrollers ( [[DsPIC30F 5011 Development Board]] )<br />
* Cypress PSoC 8 bit FLASH microcontrollers<br />
<br />
''I've written a little about the various kinds of microcontrollers at [http://en.wikibooks.org/wiki/Embedded_Systems/Particular_Microprocessors Wikibooks: Embedded Systems]. --[[User:DavidCary|DavidCary]] 06:15, 10 March 2007 (PST)''<br />
<br />
== Op Amps ==<br />
<br />
Op amps and instrumentation amps.<br />
<br />
[[op amp]]s: great for amplifying weak signals from [[sensors]] to a more useful level. Also used in filters, integrators, etc. <br />
* [[LT1168|LT1168 Programmable-Gain Precision Instrumentation Amplifier]] - Low Power, Single Resistor Gain Programmable, Precision Instrumentation Amplifier<br />
* [[LT1114|LT1114 Low Power Precision OP-Amps]] are used for amplification and filtering of the signal - Dual/Quad Low Power Precision, Picoamp Input Op Amps<br />
* [http://en.wikibooks.org/wiki/Electronics/Op-Amps Wikibooks:Op-Amps] has a "quick design process" using Daisy's theorem: ''"The sum of the gains = +1 in a properly-designed op amp circuit."''<br />
* [http://ciphersbyritter.com/RADELECT/PREOPAMP/OPAMPDSN.HTM "Some Op Amp Audio Design Issues"] by Terry Ritter<br />
<br />
== logic gates ==<br />
<br />
* NAND gate: [http://www.coprolite.com/art48.html "Using a NAND Gate for a Set/Reset Latch"] (the 74HC132 Schmitt-trigger quad NAND is better than the 74HC00 quad NAND).<br />
* [http://people.freenet.de/dieter.02/alu_4.htm "Multiplexers: the tactical Nuke of Logic Design"] by Dieter Mueller 2004 (74153)<br />
<br />
There are hundreds of other specialized logic gates. Here we only list the ones we actually use in some Open Circuit [[Projects|Project]]:<br />
<br />
* 74HC595 eight bit shift register with output latch (used for POV display)<br />
<br />
== RF ICs/Modules ==<br />
<br />
[http://www.linxtechnologies.com/ Linx Technologies] makes several low power RF transmitter/receiver chips. Their range is around 500' - 1000'. They are geared for one way communication only, like keyless entry systems. They also make several serial encoding chips that make the wireless communication more secure/crack proof. Their latest chip, the HS series, is based upon the SkipJack algorithm developed by the NSA. <br />
<br />
[http://www.cypress.com/ Cypress Semiconductor] makes several 2.4ghz transceiver modules, which are available for sampling, and are fully assembled with PCB antennas. They use SPI to be configured and to communicate with the microcontroller. The CYWM6934 (10 meter range) and CYWM6935 (50 meter range) are both very easy to interface with. [[User:Ratmandu|ratmandu]] 20:06, 23 November 2007 (PST)<br />
[[Category:Components]]<br />
<br />
== ADC analog to digital converter ==<br />
<br />
There are a huge variety of ADCs available.<br />
<br />
If you need 10 bits or less of resolution,<br />
counter-intuitively,<br />
it costs less to buy an ADC plus a microcontroller on one chip<br />
than to buy a stand-alone ADC.<br />
<br />
* ATTINY13V -- lowest-price chip I know of with at least one 10 bit ADC<br />
* ATTINY261 -- lowest $/ADC chip I know of<br />
* LPC2101FBD48 -- lowest-price 32-bit microcontroller I know of with at least one internal 10 bit ADC<br />
<br />
Many people (*) do EKGs with only 10 bit converters.<br />
<br />
The [[Programmable Chip EEG]] might need more bits of resolution.<br />
<br />
What low-cost ADC are available with at least 12 bits? <br />
* $2.50 MCP3301 has 1 ADC input (13 bits) <br />
* $3.50 MCP3302 has 2 ADC input (13 bits) <br />
* $3.50 MCP3204 has 4 ADC input (12 bits) <br />
* $4 MCP3208 has 8 ADC input (12 bits) <br />
* $8 dsPIC30F 2011 microcontroller has 8 ADC inputs (12 bits). See [[dsPIC30F 5011 Development Board]] for details. <br />
* $6 CY8C27443 Cypress PSoC microcontroller has 4 ADC inputs (14 bits) -- but what is the sampling rate? Also has 4 DAC outputs (9 bits). <br />
<br />
* $56 biosemi used analog devices AD7716: four independent, simultaneous 22 bit ADCs. <br />
* [http://www.maxim-ic.com/appnotes.cfm/an_pk/885 the Maxim MAX1460 includes a 16-bit ADC, 12-bit DAC], a programmable gain amp (PGA), temp sensor, and 16-bit processor. (Alas, its program is in unchangeable ROM). <br />
* Analog Devices AduC812: 200kHz 12-bit ADC, 12-bit DAC, and flash-based 8051 MCU core. <br />
<br />
''I am astonished to discover that (a few) microcontrollers include 12 bit or more ADCs. Are there others? --[[User:DavidCary|DavidCary]] 18:48, 28 August 2007 (PDT)''</div>Ratmanduhttp://www.opencircuits.com/index.php?title=Amiga_floppy_project&diff=9512Amiga floppy project2007-10-08T21:31:10Z<p>Ratmandu: yet more spam</p>
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<div>== Amiga Floppy Project ==<br />
<br />
This project is the building of an external USB amiga floppy drive controller. It sits between the USB port on a Windows PC, and a regular PC floppy drive. It will allow the PC to create .ADF images from an amiga floppy disk. This device is based on a Parallax SX28 microcontroller, uses Ramtron FRAM memory for temporary track storage, and uses another Parallax component for the USB interface.<br />
<br />
<br />
[[Image:AFPimage.jpg]]<br />
<br />
== related projects ==<br />
<br />
* [[Minimig]], an open source exact FPGA re-implementation of an Amiga 500.<br />
<br />
== External links ==<br />
<br />
[http://www.techtravels.org/amiga/amigablog Amiga Floppy Project Blog]<br />
<br />
[http://www.parallax.com/sx/index.asp Parallax SX Microcontroller]<br />
<br />
[http://www.ramtron.com/doc/Products/Nonvolatile/Detail.asp?ID=30&gr=5 Ramtron Serial FRAM]<br />
<br />
[[Category:Projects]]</div>Ratmanduhttp://www.opencircuits.com/index.php?title=Op_amp&diff=9511Op amp2007-10-08T21:24:43Z<p>Ratmandu: removed link spam</p>
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<div>An op amp ("operational amplifier") is ...<br />
<br />
Great for amplifying weak signals from sensors to a more useful level. Also used in filters, integrators, etc.<br />
<br />
== quick summary ==<br />
<br />
* Many sensors need an amplifier to "buffer" their output signal. Often a single op amp is adequate. For very weak signals, you may want a "difference amplifier" or "instrumentation amplifier".<br />
* All ADCs need an anti-aliasing filter on their input. Often a single op amp, 2 caps and 4 resistors is adequate.<br />
* If you want to hear a signal, use a LM386N-3 (under $1) to amplify it enough to drive a small speaker.<br />
* If you want to drive heavy loads (big speakers, big antennas, electric motors, etc.), too heavy for typical op amps to drive, use op amps to amplify the signal to the desired voltage, followed by power transistors to drive the load [Veselinovic].<br />
<br />
== details ==<br />
<br />
[[Suppliers]] such as Jameco, Digikey, and Newark each have pages and pages of fine print listing hundreds of op-amps, from "low-cost" quad op amps for under $0.40 each to "hi speed precision" op amps for well over $10 each.<br />
That doesn't include more complex devices (such as [[Integrated Circuits|voltage regulator]]s and RS-485 transcievers ) that combine op amps and other components on a single IC.<br />
Each one of those op amps has a data sheet several pages long packed with lots of details, which you can freely download from the [[manufacturers|manufacturer]]'s web site.<br />
<br />
"But in reality, there are only two important specifications that you should initially consider when selecting an op amp for your active, low-pass filter. ... Gain Bandwidth Product and Slew Rate." [Baker 2003]<br />
<br />
=== designing the circuit around the op amp ===<br />
<br />
* [http://david.carybros.com/html/schematic.html#op_amp_design Daisy's theorem: standard op-amp design]<br />
<br />
* [http://www.maxim-ic.com/appnotes.cfm/appnote_number/738 "APPLICATION NOTE 738: Minimizing Component-Variation Sensitivity in Single Op Amp Filters"]<br />
<br />
=== selecting the appropriate op amp out of the hundreds (thousands?) available ===<br />
<br />
* [http://ww1.microchip.com/downloads/en/DeviceDoc/adn003.pdf "Select the Right Operational Amplifier for your Filtering Circuits"] by Bonnie Baker 2003<br />
<br />
* [http://www.edn.com/archives/1995/052595/11dfcov.htm "Choosing an op amp: it's no longer a trying task"] by Bill Schweber 1995<br />
<br />
* [http://www.epanorama.net/links/components.html Basic electronics components list] lists 10 of the most common op-amps.<br />
<br />
* [http://zero-distortion.com/tests/tweaking.htm "Tweaking" by Dejan V. Veselinovic]<br />
<br />
* [http://www.embedded.com/showArticle.jhtml?articleID=175400254 "How to choose the right bipolar op amp"] by J. Scott Elder 2005-12-23<br />
<br />
----<br />
<br />
[[Category:components]]</div>Ratmanduhttp://www.opencircuits.com/index.php?title=Chemical_Etchants&diff=9510Chemical Etchants2007-10-08T21:12:16Z<p>Ratmandu: reverted to last good page</p>
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<div>{{stub}}<br />
<br />
After masking off the parts of the copper-clad board you want to keep, you need to remove the parts you don't want to keep. This is usually done by chemically etching away the copper. There are a lot of different chemical techniques for doing this, each with its own advantages and drawbacks.<br />
<br />
None of these chemicals is incredibly dangerous, but they can all be toxic or caustic, and should be treated with care. Eye protection and gloves are a very good idea. Before you start, make sure you know how dangerous each chemical is, and figure out what you will need to do if you spill it or get it on yourself. Washing with plenty of water is usually a good start. For some chemicals you may want to keep a neutralizing agent handy. An MSDS (Materials Safety Data Sheet) for the chemical will give you some basic information.<br />
<br />
== Ferric Chloride ==<br />
This is the most common hobbyist etchant. Ferric chloride, FeCl<sub>3</sub>, is a brownish substance. It's usually sold in a bottle (dissolved in water, perhaps with a little acid or peroxide) or as a powder (which you have to dissolve in water).<br />
<br />
When in solution, ferric chloride is a ferric ion (Fe<sup>3+</sup>) and a chloride ion (Cl<sup>-</sup>). The ferric ion reacts with the metallic copper on the circuit board in a redox reaction, producing a ferrous ion (Fe<sup>2+</sup>) and cuprous or cupric (Cu<sup>1+</sup> or Cu<sup>2+</sup>) copper. The chlorine is just along for the ride. The copper ion, unlike the metallic copper, is soluble, so it leaves the circuit board and goes into solution. The reaction products form a black sludge which settles to the bottom of the etching tank. After etching enough copper, all your Fe<sup>3+</sup> is used up and your solution is full of Cu<sup>1+</sup>, and you need to get more etchant.<br />
<br />
== Ammonium Persulfate ==<br />
Expensive & hard to control and optimize the process parameters (such as specific gravity & pH value).<br />
<br />
== HydroChloric Acid / Hydrogen Peroxide ==<br />
<br />
Mixing about 1 part HCl (Which can be found at most hardware stores, also known as Muriatic Acid. Ask for concrete cleaner.) into 2 parts Hydrogen peroxide (normally used for cleaning cuts) you can make a fairly powerful etchant. Use gloves and don't breathe the fumes though. This will etch a 3"x5" board in less than 10 minutes. No need to heat it up. I usually like to drill a small hole through the board on a corner and thread a wire or nylon string through to help agitate / remove the board.<br />
<br />
When the board is done etching, the etchant will probably look like green kool-aid, from the copper content in it. This stuff is highly corrosive and will burn skin, which is why you should wear gloves. But it is easy to handle, and fairly easy to dispose of. the etchant is easily deactivated with baking soda. Pour enough baking soda into it slowly (to keep it from boiling and overflowing... remember what happens with baking soda/vinegar? ya...) until it is a solid mass, then leave it in the sun to dry. You should contact your local authorities to find out what you should do with it next. Whatever you do, DO NOT dump the stuff down the drain, it will eat through your pipes just like any of the other etchants.<br />
<br />
== Sodium Persulfate ==<br />
More environmentally friendly than ferric chloride. Can monitor the etching as initially clear new etchant solution turns blue from the copper ions.<br />
<br />
== Acid Cupric Chloride ==<br />
Dead simple etchant made from ordinary, store-bought chemicals (hydrochloric acid and hydrogen peroxide). Has the advantage that it can be regenerated by bubbling oxygen/air through it, or by adding more H<sub>2</sub>O<sub>2</sub>. In addition, it doesn't get used up: the etchant bath simply grows with use (kind of like sourdough starter…)<br />
The used etchant also makes a great algecide/pH reducer for your pool (and a whole lot cheaper than that stuff they sell at the pool store).<br />
<br />
What you need:<br />
* 38% Hydrochloric Acid, HCl (available at finer hardware stores or pool supply stores as Muriatic Acid)<br />
* 3% Hydrogen Peroxide, H<sub>2</sub>O<sub>2</sub> (available from any drug store)<br />
* Plastic or Glass Pans, Jars, and tongs (no metal)<br />
Directions:<br />
<br />
# Mix your HCl and H<sub>2</sub>O<sub>2</sub> 1:1 in a non-metalic container, making sure to add the acid slowly to the H<sub>2</sub>O<sub>2</sub>. DO NOT ADD THE H<sub>2</sub>O<sub>2</sub> TO THE ACID!!! <br />
# After you've masked your board, dip it in the solution and constantly agitate. You should notice a dark green cloud start to come from the board almost immedately which quickly dissapears or turns lighter as it gets further from the surface of the board.<br />
# Etching should take about 10min depending on the temperature and how well you agitated the etchant. When all of the copper is gone, dip in water to wash off any stray etchant and stop the reaction.<br />
# When done etching, save used etchant in a non-metalic container and mark clearly its contents.<br />
# If your etchant has become a dark, murky green color, add a little bit of H<sub>2</sub>O<sub>2</sub> or bubble air/O<sub>2</sub> through the solution to regenerate it back to a light, transparent green color.<br />
See links at bottom for more information on the chemistry and some pictures of the process.<br />
<br />
== Disposal procedures ==<br />
Flushing used etchant down the drain is a bad idea (and usually illegal) because copper ion is toxic. The usual recommended way to dispose of hobbyist amounts of etchant is to convert it to a solid somehow and dispose of the solid in the trash.<br />
* [http://www.kepro.com/fmc4.htm Kepro Circuit Systems] Removal of Copper and Persulfate from Spent Sodium Persulfate Etchant by Precipitation<br />
<br />
== External Links == <br />
* [http://www.k9spud.com/wiki/PCB:Etchants Ferric Chloride vs. Ammonium Persulfate] and other etching chemicals.<br />
* [http://members.optusnet.com.au/~eseychell/PCB/etching_CuCl/index.html Etching with Air Regenerated Acid Cupric Chloride] — an excellent in-depth page on acid cupric chloride etching by Adam Seychell.<br />
* [http://esmonde-white.com/etching_pcb.html Etching a Copper PCB with HCl and H2O2]<br />
<br />
[[Category:Techniques]]</div>Ratmandu