View Full Version : Components
02-14-2005, 09:11 PM
I've aquired two stepping motors for my wire winder project. I'm going to pickup a darlington array this weekend. While I am at RAE I would like to pick up anything else I need. For example I'll probably buy 50 or so 470 omh resistors, what other common items should I pickup? My project is to finally include two stepper motors, a 5 button control panel, and an LCD. I guess mainly I'm just thinking caps and resistors and other odds and ends. Trying to stock up on my parts.
02-14-2005, 10:40 PM
220 resistors are nice for pin-protection.
Four to eight LED's make nice debug indicators.
A 470 Ohm resistor array is nice. These are SIP or DIP chips with multiple resistors in them.
A few small 0.1 uF capacitors for decoupling are good.
10 Kohm resistors are nice for pull-ups and pull-downs.
Look at the "Analog and Digital Interfacing" book, or the BS2 manual, for how to debounce a button. You'll need some small parts for that.
02-14-2005, 10:42 PM
Just as a supplier(no offense, Parallax)go to www.goldmine-elec.com (http://www.goldmine-elec.com) and check out
their prices. BTW, there is a minimum order-$10.00.
I think I know what I'm doing...
Post Edited (bugg) : 2/16/2005 1:06:26 AM GMT
02-15-2005, 01:39 AM
You might want to get a resistor and capacitor variety pack (you never know when you'll need a specific·resistor or cap).· Alligator clips are handy too.
02-15-2005, 02:04 AM
The resistor variety pack is a good idea.·
I've picked up a couple capacitor packs and have no use for them.· There never seems to be an oft used value in there.
If you see a cap pack with all electrolytics...grab them.· Don't bother with it if it uses some old ceramic disc types...only my opinion.
those are what I'd shoot for.· You probably·won't need anything in the meg range...but maybe pick up a couple 100kohm·and remember, you can put 2 (or more) resistors in series to get the value you want (adding them) and same goes for putting them in parallel (parallel resistor math applies--quick tip, the total parallel value of more than 1 resistor is never larger than the smallest single resistor value in the parallel cct.).
Pick up some pots too.· 1k 5k 10k and maybe a couple 10-turn pots for more resolution.
0.001uF/0.01uF/0.1uF/1uF/10uF are the more common caps you'd need (electrolytic).· The voltage rating need only be more than what you're cct supplies....so go for 50V caps unless you want a small design and are only using 5Volts in your cct.
Some 12V/5V relays (automotive relays are cheap)....some opto's and LEDs.
I could go on....:p
What you don't get this trip, you can get next trip....cuz you can NEVER make enough trips to an electronic shop!
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
02-15-2005, 02:48 AM
Although not real important, you should consider your actual "wiring" method. Nothing worse than having to work around a mess of wires that have poor contact or can become loose, that can potentially cause damage or cause you utter frustration due to an unknown intermitent connection. I prefer the ribbon cable / connectors and using .01 male headers for the pins off the board. Anyway, something to check out while you are there.
02-15-2005, 03:00 AM
For small-quantity items it's tough to beat www.glitchbuster.com (http://www.glitchbuster.com)
02-15-2005, 03:19 AM
kelvin james said...
I prefer the ribbon cable / connectors and using .01 male headers for the pins off the board.
I assume you mean 0.1", .01 inch or mm is really small for headers, the smallest Im aware of is .02" which are smt board to board connectors, which are a specialty item and tricky to solder.
02-15-2005, 05:58 AM
You should also read this topic as this was discussed in the Sandbox area a while ago http://forums.parallax.com/images/smilies/smile.gif
02-15-2005, 09:05 AM
thanks for the input people, this should get me started.
02-15-2005, 02:50 PM
Nice catch Paul. Yeah i meant .1 inch, must learn to proof-read my posts !
02-15-2005, 09:44 PM
Where do you guys get the 0.1" ribbon cables with pins.
The only place i've seen them was on Digikey.
"Flat Flex Cable Assemblies" Page 45-46 from the May-Aug 2004 Catalog. But they are somewhat pricey there.
02-16-2005, 12:12 AM
How many pins are you looking for and what configuration for each end are you looking for (female,male,bare) to (female,male,bare)?
02-16-2005, 12:26 AM
I was looking for a couple different configurations, lets just say:
3 or 4 pin Female to "Solder Tab" (thats what digikey refers to them as, tabs are small enough to be inserted into breadboards, but still dont bend.
digikey product #s A9BAG-0404F-ND for example.
02-16-2005, 01:05 AM
Ok, now I know why. Your looking at flat flex cable which is more expensive. Traditionally what is used is standard ribbon cable 0.05" pitch and using crimp connectors for the ends (just like the cables used for you floppy drive and older hard drive cables).
But your requirements of .1" spacing, bread board insertability I can understand you not wanting to use this. One thing to keep in mind is that the solder tails have a width of .026" (.66mm), I dont know what gauge wire this corresponds to but they may be too wide to fit into a standard breadboard (someone else would be able to better help you with this aspect).
I'll explain what I do: I still use standard ribbon cable for breadboarding when the situation warrants. I strip 1/4-1/2" off the end, take a razor and carefully split the individual wires. I then tightly twist the ends. If I'm in a rush, I just carefully insert them into the board at this point. If I have extra time, I solder each exposed wire with just enough for the end to act like a solid wire for easier insertability. By doing this I can crimp an appropriate connector on the other end for plugging into another board or do the same to the other end if plugging into another breadboard. The advantage of this method is that when you move from prototype to a pcb layout you can simply cut off the ends which have been split attach a crimp connector and use the same cable in your final version.
Alternatively you can use 0.1" pitch ribbon cable like the molex/woldom cable on page 49 of the digikey catalog, those would also require solder to stiffen the ends, but wouldn't require spliting the cable out to fit the breadboard. But you cannot use standard crimp connectors on them.
If you only need 4 wires and you dont plan on moving past prototype, I would consider just sticking with individual solid wires
Post Edited (Paul Baker) : 2/15/2005 5:10:05 PM GMT
02-16-2005, 01:18 AM
Also the female ends of flat flex cables can be difficult to interface with. I have a 640x400 military surplus LCD whose connection is a female flat flex cable (26 pin .1" pitch) which like you I found getting a matching flat flex cable too expensive for my taste (it would have cost more than the LCD itself). So I bought a very thin, single sided copper clad board and hand drew/etched a matching male connector and soldered a standard ribbon cable to provide a breakout of the connector. (This is as far as I have gotten with the project becasue I am having issues with the inverting flyback power supply which provides -19V for the LCD bias, so the project has been set aside for the moment)
02-16-2005, 04:15 PM
I made up a couple of pics to show what i do, explains it better than words. The .1 in. pins are in a breakaway package as shown in the first pic, i think the the standard length are 7/16 in., but there are ones that are 17/32 in. shown here, that give a nice solid connection. Just a little extra length for insertion. You see the pins are offset to one side, they can be pushed through the plastic spacer so they are equal lengths on each side and then the proper amount of pins can be broken off for the size of connector, as shown in pic 2. The next pic shows the pins in the ribbon cable connector, perfectly spaced to be inserted into the breadboard.
This is only an example, there are many ways to use this, as if you don't need all the pins, some can simply be pulled out. And there are different sizes of connectors. Just wish a straight 5 or 8, etc. connector was made instead of the double configuration, but i can live with it.
When you are wiring the ribbon cable into the compression fitting, be aware of what side of the connector you want contact with. There is a small arrow one side of the connector that points to the first pin. Anyway, works for me and saves playing around with stripping, soldering and twisting the ends of wires, and provides a nice connection that won't come out by itself. And best of all, the cost is small.
02-17-2005, 01:15 AM
Nice Kelvin, much more straight forward and cleaner than my method. I typically follow the hacker's creed "don't buy it till you really need it", so I frequently make do with what I have on hand and typically don't buy headers till its time to pcb. Plus I have two component boxs stuffed with items accumulated through the years and have been holding off on getting a third box (amazing all the various components and devices college makes you buy which I probably will never use again, but why throw away a perfectly working component?), therefore I try to minimize adding anything else. But the average hobbyist should keep a couple full-length breakaway headers lying around.