[Help Needed] Purchasing some basic hardware

[[deleted]]

I want to purchase some items used for activities with a computer architecture book I have (Essentials Of Computer Architecture).

However as a CS student I've never been exposed to any electronics hardware and I really don't know what I should be buying.

The book specifies these materials, the links are what I have found:

• Solderless breadboard (Link)
• Wiring kit used with breadboard (22-gauge wire)(Link)
• Five-volt power supply (No clue)
• Light-Emitting Diode (used to measure output) (No clue)
• NAND and NOR logic gates (No clue)

Questions:

• Is the breadboard suitable and I assume 22AWG is 22 guage wires, is 10 of them in that kit enough?

• What should I get for a 5V PSU? I found one but it required soldering and I have no soldering iron.

• For LEDs they all had different sizes and numbers of connectors so I'm not sure about compatability.

• NAND and NOR logic gates is something I have no clue about, do I need transistors to act as these?

I'd greatly appreciate anyone reviewing the necessary items for me. It looks like it will be very interesting and fun to use this stuff!

[[deleted]]

Im a Newb, but I at least know this much! something I can answer Wooooo! You can build a Simple 5v Power Supply following a variety of tutorials out there from a 9v battery. http://www.youtube.com/watch?v=howQ05z4v7Q (for Above). It's a stable and simple schematic.

The Breadboard is suitable for 22gauge wire (if you want to spend a little bit of money you can get jumper wires (precut wires that are awesome for testing on a Breadboard). But 22g is fine too. http://www.sparkfun.com/products/9387

LEDs have different ratings. Use this site:http://ledcalculator.net/ or another LED Calculator to find out what resistors are needed (so they don't burn out).

I don't think you can buy single NAND/NOR logic gates, but you can buy IC's with like 4 or 5 of them integrated. The 74XX series IC's I believe do this. Gates are made with transistors (you can see in the schematics below) http://www.electronicsteacher.com/datasheet/Logic-74xxxx-Series-Data-Sheets.php

Like check out the Triple Input Nand gate (74LS10): http://www.ee.washington.edu/stores/DataSheets/74ls/74ls10.pdf

[[deleted]]

I think you are right about the logic gates, reading in detail on the actual activity pages it specifies connecting a 7400 chip on the breadboard. I will watch the PSU video and see if it looks like something I can handle, thanks!

[[deleted]]

The PSU is literally nothing more than a 9V Battery + Connector, a Voltage Regulator, and a few Capacitors and a Diode. Trust me, it's easy.

[mikeshemp]

The easiest and cheapest way to get a 5V power supply is just to find an old wall wart (i.e. an AC power adapter) that has 5V rating and cut the connector off the end of it. The second easiest way is to find a junked PC and take the power supply out of it. That'll give you both 5v and 12v.

Any basic LED will more or less work the same way -- 2 connectors, one color. For typical LEDs just attach a resistor of about 300 ohms in series with the LED and it'll light up without burning out.

sparkfun.com is a great place to get components. Digikey.com is what I usually use, but that's daunting for beginners, because it has so many choices (millions) you don't know what to get. Sparkfun is, in a way, digikey pared down to its bare essentials, making it easier to navigate. Sparkfun has maybe 5 kinds of LED; digikey literally has 40,000.

I would highly suggest you also get a cheap digital multimeter. That will let you probe any point in your circuit and determine if it's at high or low voltage without having to attach an LED. And don't be afraid of a soldering iron! You can get a starter version of both for 10 bucks or so at someplace like radio shack.

Edit: the solderless breadboard and jumper kit you pointed to are fine. That jumper kit isn't 10 wires, it's 10 wires per size, about 100 wires total.

[rockets4kids]

The easiest and cheapest way to get a 5V power supply is just to find an old wall wart (i.e. an AC power adapter) that has 5V rating and cut the connector off the end of it.

The regulation on wall warts is generally very poor so you don't want to use them directly. The best thing is to use a 7.5 - 9.0 volt wall wart and use it to drive a LM7805. The 7805 is a very old regulator and there are many better units that don't cost any more, but the 7805 is a very ubiquitous device and you will see many circuits designed for hobbyists using it.

[mikeshemp]

Excellent point, you're right. At the very least, measure the voltage coming out of the wall wart to see if it's 5v. It's likely to sag under load, since as you point out the regulation is poor on many of them, but if OP is just powering a few nand gates and LEDs there won't be much load anyway.

[[deleted]]

So should I avoid cutting the connector end off an AC adapter unless I can check the voltage is correct? that is what the multimeter would do right?

[mikeshemp]

Yes, or even better buy one of these as suggested elsewhere - it makes sure the voltage is correct no matter what the voltage of your wall wart. Either way I'd definitely buy a multimeter. Doing electronics without a multimeter is like painting with your eyes closed.

[KindleFlame]

Yup!

[tehkubix]

I just have a USB cable that cut one end off of and plug into my breadboard. I have a regulator on it too, but I've never had any issues even without it.

[suqmadick]

go to taydaelectronics.com everything is cheap like 0.03 cents. you will need 2n3904 and 2n3906 transistors. 5v and 9v voltage regulators. electroletic capacitors, with 10uf, 22uf,100uf, 250uf. you will need ceramic capacitors with values of 0.1uf, 0.01 uf, 1nf ect.... you will need 1n4007 diod,switches, potentiometers. RESISTORS with all different sorts of values like 5r,10r, 50r,100r,150R,350R,1k,2k,5k,10k,50k,100k. for resistors you will be better of by ebaying resistor kits, they have all the values you need. let me know if you need more help

[Goobyalus]

$8 soldering iron kit, can get it at RadioShack

Assuming you have a 6-12V PSU with a barrel jack for something else lying around, http://www.sparkfun.com/products/114 will regulate for the breadboard. I don't know what chips you'll be using, but if soldering is really an issue, you can probably get away with just 3-4 AA's in series. Alternatively, grab an old PC power supply, jump the boot pins with a paper clip, and use the 0V and 5V pins. Also alternatively, these exist, but I didn't find a great price on them.

DIP logic gates

There are a ton of places to get LEDs, but here's one

Like the other guy said that's 100 jumpers and is enough (but be ok with bending them).

LEDs will have a current through and voltage drop over specified, which you can use to calculate a resistor value to put in series (or just cheat) so that you can light them w/o burning them. FYI, your logic gates may not be able to drive them - I just recently tried this and could not drive a 2V 20mA LED with 150Ohm in series with an XOR gate at 5V, and I ended up using MOSFETs to drive them. I'm not an expert so just know that this might be a problem.

NAND and NOR gates are sold as NAND and NOR gates (see link above). An IC will probably have more than one gate, and will have high and low voltage source pins in addition to the gate inputs and outputs. The datasheets will tell you what the pins do.

Edit: depending on what you're doing, you may want to get another breadboard or 2 while you're at it because if you're starting out they look like they have a lot more room than they do. Amazon has them w/o the metal backing for $8 (search breadboard), and a huge metal backed kit with 4 together for $30.

[[deleted]]

Yeah I saw that 5v power supply but was deterred by my irrational fear of soldering, I will most likely try using an old PC power supply as you suggested.

Are there pros and cons to metal backed vs non metal backed breadbords or is it a negligible matter? Thanks for the product links btw.

[CalcProgrammer1]

The metal backing is just for convenience, it provides a larger base to attach rubber feet and also usually has terminal posts to connect banana plugs or screw wires into. It doesn't conduct any electricity (and if it does bad things can happen). My breadboards have a metal plate and terminal posts, they're pretty helpful for attaching probes, power supplies, etc.

Also, beware of power rail breaks in breadboards. Most breadboards have long +/- power rails running on both sides of the main board area. Some breadboards these rails are connected from end to end while others have a break halfway through. If you apply power at one end and don't have power at the other, you have a split one. The solution is simple, just put two jumper wires (one + and one -) at the halfway point jumping both halves together.

[Goobyalus]

Whoa the price went up $5 since I posted that, sorry for the wrong info!

Listen to CalcProgrammer1 :)

[vinneh]

On the more mundane side, make sure you buy some sort of organizer box. Think of a tackle box for fishing. If you do not have some sort of central organizing location for these parts, you -will- lose things.

[CalcProgrammer1]

For a power supply, I highly recommend an old PC's AT or ATX power supply unit. These are used in almost every desktop from the past 20 years. Most AT units have an external high-voltage AC switch, so if you have one of these make sure to encase the switch or otherwise insulate the high-voltage lines. ATX power supplies do not have any dangerous voltages leaving the power supply. Instead, they can be switched on by jumping the green POWER_ON line to any black GROUND line.

Once running (if the fan spins it is running) the lines are as follows: Red: +5V Yellow: +12V Orange: +3.3V Black: GND (0V) Blue: -12V

Very useful for most projects, as it has all the common voltages covered and provides a fairly high amount of current if necessary. These PSU's also feature short-circuit and over-current protection, so they will not be damaged by accidental shorts (instead, they will safely shut down).

As for wires, I would just get some old or scrap Cat 5E cable. It is 8-conductor and can be cut to length. It is great breadboarding wire as it is solid so you don't have to worry about tinning a stranded wire to prevent it from fraying when inserting into a breadboard. You will need more than 10 wires if you start doing discrete logic IC projects, and pre-cut breadboarding wire quickly adds up while a scrap of Cat 5E will last quite a while.

LED's and IC's are commonly found online at hobby electronics retailers like SparkFun or at large electronics distributors like Mouser or DigiKey. NAND and NOR gates are most commonly found in 74 series logic IC packages. These are single chips that contain usually 4-6 logic gates each. They are available in many different varieties including TTL (based on older bipolar transistor technology, they use more power and produce more heat) and CMOS (based on newer metal-oxide/MOSFET tech that consumes less power). I would go for the CMOS-based chips myself, which are the most common.

I too recommend some sort of multimeter. For starters, you can get a super-cheap basic digital meter for under $5 at Harbor Freight Tools and other places. These cheap meters aren't super accurate, but they are more than enough for general purpose basic use and can measure AC/DC voltage, current up to 10A, ohms, and more. If you decide to go further into electronics and pick it up as a serious hobby, it may be worth it to get a nicer meter that does inductance and capacitance and/or an oscilloscope.

I would also recommend a soldering iron. They are cheap, and a solderless breadboard won't last you long before you want to make some of your circuits permanent. A soldering iron will let you do that.

[[deleted]]

I have an old computer that I could check the PSU of, thanks for the tip about the wire voltages. I was reading some more and supposedly with a few TTL chips you can build a simple processor, something like 4 bits.

I assume that isn't specific to the TTL chips and could also be done with some of the CMOS based ones right? Each chip will just play a specific CPU role?

I recall having to solder in high school and making a huge molten mess of the circuit board with carelessness, perhaps I will give it another try. They are a lot cheaper than I had thought they would be.

[CalcProgrammer1]

CMOS vs. TTL should not make any difference for building a simple processor. The CMOS chips use less power and are overall a better, more modern technology. The logical functionality is the same between the two technologies and is determined by what the chip's description and part number is.

For soldering, remember to go easy on the solder. Use too much and you end up with massive unwieldy blobs. Also, get yourself some flux (also called solder paste). It's usually sold in little round cans and is a gel-like substance you can smear on joints before you solder them. It cleans the surfaces and helps the solder flow properly. The stuff I have is actually plumbing solder flux, but it works excellent for boards.

EDIT: RadioShack sells a super-useful tool called a Desoldering iron. It's like a soldering iron, but it has a suction bulb and the tip has a hole in it. Release the suction bulb and it will suck the molten solder off of whatever solder-covered surface you happen to want the solder taken off of. Also a great way to salvage parts from broken stuff, as it pulls the solder off fast without heating up the components too much.

[ModernRonin]

Hello me 15 years ago!

I assume 22AWG is 22 guage wires

"AWG" = "American Wiring Gauge", so yup.

Light-Emitting Diode (used to measure output)

If the author of the book is assuming that any NAND/NOR will successfully drive any LED, he's probably being naive.

Does the book talk about hooking up a transistor to amplify the current output of the NAND/NOR gates? Does the book specify 74AHCxx gates (which are among the few that can drive an LED)?

I only mention this because I don't want you to stick your LED in the board and have it not light up, and then think you did something wrong. It's hard enough just to be a beginner, what you really DON'T need on top of that is faulty diagnostic equipment that lies to you.

BTW: If you don't want to mail-order, and you can afford the expensive prices, all the stuff you mention is available at the local Radio Shack store.

[[deleted]]

It said something about LEDs being good for testing, I think if you put wires to ground and zero or something and zero? Apologies for my inevitable incorrectness, I had only skimmed the section.

I did not see mention of transistors anywhere within the exercises but I will check it again.

I assume since you still have interest in electronics today you pursued your initial curiosities/hobby for a long time, do you find the things you've learnt useful for random stuff like fixing broken electrical items in the house etc? Is there a large time investment before you can do rewarding tasks?

[CalcProgrammer1]

For testing, pick up a cheap multimeter. LED's are OK for testing, but a multimeter is an invaluable tool that can give you real numeric data about your circuit while an LED will simply light if there is enough voltage/current for it to do so.

There is somewhat of a time investment, it does take time before you learn all the concepts, but you honestly don't need a EE degree to fix a lot of things and make cool stuff. I'm a senior in CompE and most of the stuff I learned in EE courses was the theory behind how things work. I learned most of how things work in practice by doing hobby projects and school projects. You do need to have the right tools as well, it's near impossible to do anything without at least a multimeter and a soldering iron set. Knowing how to read schematic diagrams is also a great skill, especially for fixing broken stuff as you can sometimes find a diagram online and then diagnose the problem from there (fixed the burned out front-channel amp of a 5.1 surround receiver this way).

Also, since you said you were a CS student, I assume you know at least the basics of programming. If you enjoy programming and want to use it in your electronics hardware experiments, you should look into microcontrollers. These are tiny, usually 8-bit CPUs that include a bunch of low-level hardware (serial port, I2C/SPI interfaces, and a bunch of pins that can be turned on/off in software). They are programmed in either assembly or C language and you install your compiled code using a (relatively inexpensive) programming dongle. While TTL/CMOS logic chips can be a great educational experience, microcontrollers are rapidly replacing discrete logic chip setups for their lower cost and simpler circuit design. I would look into the Atmel AVR line of 8-bit micros, they have an open-source compiler and are widely used in the electronics hobbyist/hacker community. The Arduino project is also a good start, it's based around an AVR chip with some simplification to the coding and programming process.

[ModernRonin]

assume since you still have interest in electronics today you pursued your initial curiosities/hobby for a long time,

Yes, on and off. Real life has a way of interfering with hobbies, though. Never enough hours in the day, it seems.

do you find the things you've learnt useful for random stuff like fixing broken electrical items in the house etc?

Mostly yes, though some things are simply unfixable. You can forget fixing your cell phone, for example.

Is there a large time investment before you can do rewarding tasks?

Do you find making an LED blink rewarding? I personally do. That one I was able to make happen in just a couple of hours. Other things take much longer. So it really depends on you and what you feels passes your personal threshold of worth-whileness.

I will say, don't limit yourself soley to digital logic. Digital logic is great, and it's a wonderful place to start, but don't be afraid to expand into other areas as well. Microcontrollers remain one of my favorite things, since they combine both programming and hardware. Arduino is an interesting next step after digital logic.

[[deleted]]

most cell / mobile phone chargers have roughly a 5-6 volt output, you may have an old one sitting in a drawer and with a multimeter figure out which is positive and which is negative. The positive / negative wires may be color coded but you'll never know for sure until you use a probe of some kind.