How do I get started with hardware?

[NobodyIsHere]

N8VEM Sounds interesting if I can keep the cost low so I'll try scrounging as much parts as I can
I'll have around $160 or so to play with but I'm hoping to still keep the costs well below that.

The cost of the 4MBit SRAM amazes me, though I doubt I'll find one kicking around.

Hi! $6 is too high? Jameco has a 32 pin DIP part that's known good. Search around for deals and they get even cheaper. I've seen other places with ~$3 SRAMs.

http://www.jameco.com/webapp/wcs/st...oreId=10001&catalogId=10001&productId=1927617

Thanks and have a nice day!

Andrew Lynch

 

[Chuck(G)]

The traditional way to salvage old through-hole components was to take the PCB and turn it component-side down and then toast the wiring side with propane torch (keep it moving!), then periodically rap the board against something and the components would just fall out. It's surprisingly effective in getting components out cleanly with little damage, as the components themselves weren't directly heated. You could also use a heat gun.

A toaster oven set to about 350F works with smaller boards, but is harder on the components. On the other hand, it's not nearly as smelly.

Generally speaking, this works to salvage ICs, but tends to damage connectors, capacitors and resistors (or at least affect their values).

When I was young, I used to gut the chassis of old radios and TVs. With scarcely much more than a pair of wire cutters, a screwdriver and a pair of pliers, you had a goldmine of components.

 

[NobodyIsHere]

The traditional way to salvage old through-hole components was to take the PCB and turn it component-side down and then toast the wiring side with propane torch (keep it moving!), then periodically rap the board against something and the components would just fall out. It's surprisingly effective in getting components out cleanly with little damage, as the components themselves weren't directly heated. You could also use a heat gun.

A toaster oven set to about 350F works with smaller boards, but is harder on the components. On the other hand, it's not nearly as smelly.

Generally speaking, this works to salvage ICs, but tends to damage connectors, capacitors and resistors (or at least affect their values).

When I was young, I used to gut the chassis of old radios and TVs. With scarcely much more than a pair of wire cutters, a screwdriver and a pair of pliers, you had a goldmine of components.

Hi Chuck! Exactly! The only thing I would add is to be sure to use safety gear like gloves and goggles. Only do your component recovery outside and away from any structure. Using the heat means you need LOTS of ventilation. Preferrably on a windy day out on the concrete driveway. Certainly never heat circuit boards in doors! Think safety first and you can recover a lot of useful components for low cost.

Thanks and have a nice day!

Andrew Lynch

 

[TheLazy1]

Would it be better to de-solder the sockets/ics I need or just go the heatgun route?
I would hope nothing gets damaged in the process though.

 

[Chuck(G)]

Would it be better to de-solder the sockets/ics I need or just go the heatgun route?
I would hope nothing gets damaged in the process though.

In my experience, sockets are generally too fragile to survive removal without damage, no matter the method. They're inexpensive enough as it is.

Hi Chuck! Exactly! The only thing I would add is to be sure to use safety gear like gloves and goggles. Only do your component recovery outside and away from any structure. Using the heat means you need LOTS of ventilation. Preferably on a windy day out on the concrete driveway. Certainly never heat circuit boards in doors! Think safety first and you can recover a lot of useful components for low cost.

Goggles for certain--all you need is a blob of hot solder to hit you. Long-sleeved shirt, of course. And most certainly outdoors, with a breeze. The resin vapors from PCBs stink something awful and are best not inhaled.

The Chinese outfits that advertise on the web for obsolete ICs apparently get their stock from people who extract the ICs by toasting the boards over charcoal braziers...

 

[TheLazy1]

I see, I won't harvest the sockets then

A little/sort of off topic but does N8VEM have an IRC channel or is it just the google groups thing?
I have many (noobish) questions but posting them all in this thread is probably the right way to go.

 

[saundby]

Start simple

Start simple

I get sockets all the time. Insert a"sacrificial" chip of the right size to hold the socket in shape and add some mass to help get it out of the board, then heat the underside of the board with a torch until you can shake or knock it out. Re-use your sacrificial chips--I keep a jar of "dead bugs" in the garage for different socket sizes. This works best as a two-person operation, but I di it solo all the time and get a good socket 9 times out of 10. Machine pin sockets are well worth the trouble. I save over $100 a year on parts just on the sockets I pull. Overall, better than half the parts I use in my electronic projects are pulls.

I originally got into electronics for the sole reason that it was a cheap hobby. I couldn't afford model railroading, and I didn't know it was possible to make your own telescope when I was a kid. I repaired radios for people, usually finding broken wires or cracked traces. The terms were usually that they'd give me the broken equipment, if I fixed it they'd pay me and get it back, if not I got to keep it. After a while I'd accumulated a bunch of broken radios, and figured I'd get more money if I learned how they worked so that I could repair more of the ones people brought me.

I borrowed a 100-in-1 electronics lab from school (the teacher was overjoyed to see the thing come out of the closet) and started playing around. Pretty soon I realized I could make the noise-maker circuits from the lab out of parts from my broken radios. I started cannibalizing parts. Since I didn't solder yet, I'd connect parts by wrapping magnet wire around the leads really tight then putting tape over that. My usual enclosure was an old flashlight. Dad got them free with a fill-up back then, they'd rust out over winter and I'd get them when he filled up again to get new unrusted ones. I'd sand the contacts, then have a power switch and battery holder for my latest circuit. The circuit would go in in place of the light with a mass of electrical tape holding it on top of the flashlight body.

Anyway, to learn electronics, I don't recommend starting with a computer kit. Building one is fine, just don't expect to learn electronics that way.

If you want to start with digital electronics, as said before get a solderless breadboard and jumper wires, and some chips. I make my jumper wires from 24ga solid aluminum wire (like this presently: http://www.bgmicro.com/index.asp?PageAction=VIEWPROD&ProdID=11265) rather than buying jumper wire packs since many of the jumper wires sold presently don't hold properly in newer solderless breadboards even when they are sold together.

For a book, you can get the old Bugbooks online for free now. To download them, click on the navbar link for the desired book, e.g. BBI for Bugbook I. Then left-click on the chapter link, e.g. Unit 1 Bugbook I PDF. Then, in the window that appears, right click on the PDF link and do a "save link as..." (or whatever your browser says for the save option.) BB0, BBI, and BBII will be of interest to you for getting started.

If you want to learn analog electronics, the best route is probably to find some of the old hobby manuals from RCA and Motorola as mentioned above. I used to get these for a dime or quarter at our local TV/Radio repair shop. Nowadays you can get them from used booksellers that stock technical books like Powells.com or by searching on abebooks.com. The old hobby magazine annuals like "101 Transistor Projects" and "99 IC Projects" used to appear on newsstands about this time every year, but that stopped some years ago. They may also be available used. There are still decent old-fashioned style 100-in-1 type lab sets available, though the market has been flooded with useless plastic techy-looking toys that have displaced the old ones that actually worked in most mass-market outlets. Perhaps someone here can recommend a source for the good ones, I see them on the pages for chinese wholesalers, so I know they're still made, but I don't know where to get them retail.

At some point I'll be posting some projects in the vein of the old "99 IC Projects" ones on my web site, presently I'm working to finish posting all the details of a build-it-from-scratch 8085 microprocessor trainer (writing up and posting takes at least 3 times as long as actually building.) I'm hoping to wrap up the hardware construction posts by the end of this year.

Good luck, and I'll be glad to help more through pm, email, or forum post if you like.

-Mark

 

[NobodyIsHere]

I see, I won't harvest the sockets then

A little/sort of off topic but does N8VEM have an IRC channel or is it just the google groups thing?
I have many (noobish) questions but posting them all in this thread is probably the right way to go.

Hi! Right now, it is just the Google Groups mailing list/web forum thingy but hopefully that will change to something quite a bit better. Please don't feel any hesitation posting new builder questions though. The whole point of the N8VEM project is to help advocate homebrew computing so new builders are highly valued and get help they need to get going.

I consider it top priority to help new builders get their systems working -- especially those with problems. There are a lot of experienced builders and developers in the project who go on their personal projects and interests. I can barely keep up with all the stuff they are doing and for the most part they are on their own which is probably how they like it anyway. It is likely there are projects underway I haven't even heard about. However, its from the ranks of the new builders that the project contributors arrise so I spend most of my project time with them. Its mostly sending out PCBs and some email correspondence though.

Almost all builders get their systems working on the first try or with minor tweaks. Sometimes there are glitches along the way but everyone who has tried has gotten a working system AFAIK. I have a standing offer that if anyone gets a PCB and cannot make it work after a good faith effort and with the help on the mailing list to debug it myself. No one has taken up the offer yet though which I find rather surprising.

I hope this helps! Thanks and have a nice day!

Andrew Lynch

 

[Crawford]

Some more ideas

Some more ideas

TheLazy1,

To learn digital electronics, I'd get the following books:

The TTL Cookbook by Don Lancaster
Bebop to the Boolean Boogie by Clive Maxfield

To scavenge electronics, I use a large coffee can with a high-wattage incandescent spotlight bolted to the inside. Boards are set on the top and the light from the spotlight melts the solder. You can lift chips or sockets while it's heating up. Or you can flip the board and whack it on a solid corner for mass evacuation of components. Use eye protection PLEASE! Use with adequate ventilation! (This is marginally safer than the blowtorch method).

Good luck, and have fun.

-C

 

[Chuck(G)]

I save over $100 a year on parts just on the sockets I pull. Overall, better than half the parts I use in my electronic projects are pulls.

Most sockets harvested from consumer-grade boards aren't machine-pin and not worth the trouble even when they're new.

If you want to be cheap, buy new non-machine pin sockets--a 14-pin socket in quantity 1 will run you about a nickel. Shop around for distressed inventory sales and you can probably beat that by a wide margin if you're willing to buy in the hundreds or thousands.

A 14-pin machine-tool socket runs about $0.25-$0.45 depending on the vendor, new. Again, the price probably can be brought down much lower with some shopping.

For me, where my time's worth something, it's not worth scavenging sockets. For someone else with more time on their hands, it might be a working proposition.

 

[TheLazy1]

Cool, some great ideas in here which I will definitely check out.

 

[saundby]

Most sockets harvested from consumer-grade boards aren't machine-pin and not worth the trouble even when they're new.

Depends on what you use them for. For a board that you want to just work, yeah, machine pin is the way to go. But for jigs and fixtures, test setups, and so on, leaf spring types are fine.

If you want to be cheap, buy new non-machine pin sockets--a 14-pin socket in quantity 1 will run you about a nickel. Shop around for distressed inventory sales and you can probably beat that by a wide margin if you're willing to buy in the hundreds or thousands.

Yeah, when I buy stuff it's usually by the thousands. Not only do I go through a lot of parts, but frequently a thousand or more of something goes for the same price as a half dozen.

For me, where my time's worth something, it's not worth scavenging sockets. For someone else with more time on their hands, it might be a working proposition.

My time's worth plenty, that's not really the issue. It's not like someone pays me to read a novel or watch TV, but I spend time on those things, too.

I use my scavenging time efficiently, though. For one thing I do pulls using a torch rather than other methods that take longer. I usually save up two or three bushel boxes overflowing with scrapper boards then have one or two big pull sessions per year. In a few hours I recover scads of parts, sort them into boxes. I do inspection and testing of the pulls on a time-available basis, usually during idle time while waiting on something else. I can clear out a box of general logic while waiting on a board under test reaching a cold soak temp, for example, or test a box of processors while monitoring a sequencer's operation. Or run a bunch of logic through test while watching TV.

It all helps make my hobby electronics take less cash. If I'm planning on pulling any of the parts on a board, it's not much extra effort to take everything that's recoverable, including sockets. I'll pull the socketed chips before using the torch, then stick in the dead chips from my jar to hold the pins straight when pulling with the torch. While I'm pulling the unsocketed parts I want, I take the sockets as well.

It can work on a smaller scale for someone with less money and more time, too. Or someone willing to give up a couple of TV shows to get some parts.

As to uses of cheap sockets, one thing I use them for is to put a couple under CMOS as a jig to hold unused inputs high or low while building up a circuit. As I add inputs to the chip I cut away the jumpers on the stacked sockets of the jig. Once the circuit is finished, I toss the cheap sockets with the jumpers on them.

They can also be used for building up resistor arrays and other small sub-circuits, or for test connectors, or other such things where components are soldered into the socket's top.

Machine pin sockets that get distorted when being pulled make a good source of pins. So even the "ruined" sockets in this case have value.

Then there are all the other parts I get at the same time as I'm pulling the sockets. Torch-pulling caps requires that they be tested after pulling since their values can shift pretty significantly, but most other components don't take much effort to verify. A logic tester of some sort pays off quickly.

Anyway, what works for one person may not work for another. Pulling sockets is easily worthwhile for me. Enough so to go to the trouble of sticking chips back in the empty sockets of my scrap boards. I don't think whether someone does or doesn't bother to pull sockets is a good indicator of the value of their time, either way.

-Mark

 

[docred]

GE has a wonderful book on semiconductors and many of
the early data catalogs included internal diagrams of the
transistor and such inside of the chips.
Dwight

I've got several older manuals and books of that type...I work in radio broadcast engineering, and we were cleaning out/up one of our old transmitter buildings. Of course, I rescued whatever I could, both books and equipment

Most of what I know is self-taught as far as computers go. Its a matter of wanting to learn, but also as some people have mentioned finding a focus to help you learn. I have found that just reading is ok, and just tinkering is ok, but if you have specific goals and projects it gives you more purpose and incentive. Don't let anyone tell you that you can't learn and progress though...if you have the will and the time, you can do it.