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Author Topic: 1.62Kohm resistor ($50 robot)  (Read 493 times)

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Offline ValentineToddTopic starter

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1.62Kohm resistor ($50 robot)
« on: February 22, 2013, 03:44:28 AM »
Hi!

I've been looking at the required parts list for the $50 robot, and I've just about worked out where I'm going to buy all the parts from, etc.  The only thing I'm iffy about is the 1.62K ohm resistor.  Every other part listed for Digikey is also available on Mouser, but that resistor isn't.  There's something that I think is similar here:

http://www.mouser.com/ProductDetail/KOA-Speer/RN732BTTD1621B25/?qs=sGAEpiMZZMuMS2dUaCDnDIDmilskfb5X

but I'm so new at this I really don't know the limits of how different any replacement parts can be.  It's also 1.62K ohms, but it looks like it's 1/8W instead of 1/4W  (no idea what that means).  Does that matter?  Will I have to make adjustments elsewhere?  If I really have to, I'll buy it from Digikey, but I was hoping to get all the parts from one place for ease of shipping and stuff.

I saw another thread like this, but it didn't exactly answer my question.  Sorry if it was answered fine and I'm just being redundant.  It's very late where I am.  :(  The Digikey product is here btw: http://www.digikey.com/product-detail/en/MFR-25FRF521K62/1.62KXTR-ND/14911?WT.z_cid=ref_octopart_dkc_buynow  Thank you!

Offline newInRobotics

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Re: 1.62Kohm resistor ($50 robot)
« Reply #1 on: February 22, 2013, 05:34:31 AM »
Hi :)

It's also 1.62K ohms, but it looks like it's 1/8W instead of 1/4W  (no idea what that means).  Does that matter?
W denotes power dissipation capability, or in other words, how much heat can resistor expel before taking damage. Power dissipation can be calculated by multiplying current going through resistor by voltage dropped over resistor. For example, if You use 100 Ohm resistor to short 12V battery, by Ohm's Law current in circuit is going to be I(current) = V / R = 12 / 100 = 0.12A. As there is only one component in our simple circuit, it means that resistor has to drop whole 12V (voltage is not spread across components), hence power dissipation from resistor will be 12V * 0.12A = 1.44W. You can see that if our resistor is rated only for 0.25W - it will burn due to power dissipated being too high. To answer Your question, it does matter. What You can do, is connect two 1/8W resistors in parallel to get 1/4W power dissipation capability.

Also, 1/8W resistor from Mouser is an SMD (surface mounted device) meaning that it is very small compared to regular (through the whole) resistor, hence needing smaller soldering tip, lower heat and better soldering skills.

If I really have to, I'll buy it from Digikey, but I was hoping to get all the parts from one place for ease of shipping and stuff.
Have You considered eBay?
"Computer games don't affect kids; I mean if Pac-Man affected us as kids, we'd all be running around in darkened rooms, munching magic pills and listening to repetitive electronic music." - Kristian W

Offline ValentineToddTopic starter

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Re: 1.62Kohm resistor ($50 robot)
« Reply #2 on: February 22, 2013, 02:44:36 PM »
Your explanation helped a lot!  The exact product isn't on eBay, but I'm shopping around.  I'm hoping not to use the two 1/8W, because I've never used a solder in my life and can't say my skills are going to be good enough for the smaller ones, but I'm certainly glad to know my options. :)  Thank you again.

Offline newInRobotics

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Re: 1.62Kohm resistor ($50 robot)
« Reply #3 on: February 22, 2013, 03:58:46 PM »
Your explanation helped a lot!  The exact product isn't on eBay, but I'm shopping around.  I'm hoping not to use the two 1/8W, because I've never used a solder in my life and can't say my skills are going to be good enough for the smaller ones, but I'm certainly glad to know my options. :)  Thank you again.
Where are You from? When doing eBay search, try using 1.62k or 1k62 only in search field.
"Computer games don't affect kids; I mean if Pac-Man affected us as kids, we'd all be running around in darkened rooms, munching magic pills and listening to repetitive electronic music." - Kristian W

Offline ValentineToddTopic starter

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Re: 1.62Kohm resistor ($50 robot)
« Reply #4 on: February 28, 2013, 04:08:31 PM »
Sorry, I didn't realize you had replied again.  I actually ended up buying the parts from DigiKey.  I didn't have any problems and I'm working on my robot right now!  :)

 


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