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Topic: Ordering basic stuff - what should I get? (Read 4599 times) previous topic - next topic

cr0sh

#15
Jan 11, 2011, 03:57 am Last Edit: Jan 11, 2011, 03:57 am by keeper63@cox.net Reason: 1
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two L293 or L298 h-bridge ICs seems fairly cheap at e-bay,


From what I've researched, ebay is the cheapest for those two components.

The difficult thing to find/buy though, are multiwatt-15 heatsinks; DigiKey has "something", but they don't show pics, and their part descriptions are none-too-clear. SparkFun has a large heatsink for those devices, but if you are wanting to encase your PCB, you'd need a tall box for that heatsink (or let it stick out).

I managed to find some heatsinks that should work OK at Apache Reclamation here in Phoenix, for only $0.15 USD each - but I have yet to find anyplace or anyone selling the nice thick heatsinks you see mounted on L298 driver PCBs and shields sold on Ebay (not sure why that is, you can get everything else on there).

Does anybody know of a good and cheap source for multiwatt-15 heatsinks?
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

Ran Talbott

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Does anybody know of a good and cheap source for multiwatt-15 heatsinks?


I suggested recycled 386/486 CPU coolers to someone who recently bought an L298 shield.  But I like overkill on safety items,  and don't usually worry much about aesthetics.   ::)

Steampunk Professor

Whilst not a suggestion of components, a good place to get them cheap is to see if any local amateur radio clubs are having fairs. My local group have one every year and there are usually lots of stalls selling components and equipment at budget prices.

marklar

If you are working with RGB leds .. make sure you have the correct resistor sizes.  Hard to find locally (for me anyway).  I use 100ohms for the green and blue legs and 180ohms for the red leg.  Many times you can get the RGB LEDs from e-bay with resistors included, but make sure you specifically say 5v (maybe check first that you can before ordering) .. or you will most likely get resistors for a 12v system.  One e-mail seller send me both 5v and 12v resistors .. labeled .. how nice.

Have fun!

doublet

First off all: thank all of you for helping! I don't know what I would do without you!

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Also - you might want to buy one or two L293 or L298 h-bridge ICs (note that the L298 can -not- be plugged into a breadboard or perfboard as-is - but it does have a higher current rating than the L293 and can be bridged as well - there are people and places online that sell adaptor PCBs). Once again (and especially with these parts, as they can eat into your budget) only buy these if you think you will be doing projects with DC motors (and even then, you might want to wait); I don't consider them expensive parts, but I don't know your budget, either.


The L298 was exactly why I went to Tayda. They seemed the only one to sell them so cheap ($2.16; I searched through Google products, if you don't know that service, you definitely should check it out at http://www.google.com/products?q=L298&scoring=p).
That was because I ordered a 'Mr Basic' and needed a motor driver for it.

(Photo/render of robotshop)
Does a L298 need cooling? This is what I found about the motors:
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The motors are rated 4.5V-6V with a no load current of 250mA and a stall current of 1.8A @ 4.5V each.

At Tayda they sell only 1 kind of heatsink, nothing of information, only '4 fins aluminium TO-220'. :-? It looks small, and TO-220 is a kind of transistor package (I'm so proud I know that, I studied that for the Sparkfun Free Day). Is this the heatsink you are talking about?

It's the 'multiwatt heatsink' of Sparkfun. god I hope I get some luck at Free Day, I convinced my parents so that they would write a note so I don't have to stay in the study (after school, you have to stay 1.5 hours, untill 18.00 to study)


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Finally - you might want to think about (and perhaps purchase) something for storage of your parts. I always reccommend Stack-On multi-drawer bins, but they are fairly expensive, and you need the room for them, and they may not be ideal for your "workbench".


My mom works in a laboratory, they just throw away these awesome boxes there. I asked her to keep them to make me happy :) Now, all my resistors are in a nicely labeled box.


And here are the today-arrived samples from AustriaMicroSystems in a nice DVD-a-like box. There antistatic foam and plenty of space in it, so I might use this to store ICs in. "Commercial value: $25.xx".



sorry for long post
Sorry God members, I'm an atheist.

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