$50 Robot Resistors

[RS232]

Hi, I am trying to make my first robot. I am trying to order parts but it seems that the 1.62K ohm resistor is on back-order on digi-key until mid August. It is also out of stock at mouser and everywhere else for some reason. Is there some other resistor or series combination I can use to make this work? Thanks!

[SmAsH]

The resistors don't have to be spot on, so something around 1.62 would do fine, or a combination of two resistors to make something close to 1.62 would work too.

[Selenaut-14]

So do resistors in a series act like batteries in a series?

[SmAsH]

Put resistors in series and you can pretty much + the resistances to get the desired resistance.

[Selenaut-14]

Okay... It seems a bit counterintuitive though. :s

[SmAsH]

Yeah, but if you cant get that exact resistor... Sometimes this can work as a good fix...

[Selenaut-14]

I'll keep this in mind... Thx

[RS232]

Okay... It seems a bit counterintuitive though. :s

How is it counter-intuitive? The current travels through one resistor and then the other.

[Selenaut-14]

Because I thought that two resistors of different amounts would just resist as much as the larger one... See what I'm getting at? Like say there was a 100 ohm and a 50 ohm resistor. I thought it'd just have a combined power of 100 ohms, not 150.

[RS232]

^But as the current passes through each resistor it loses energy. So, it loses energy in the 100 ohm and ten again in the 50 ohm so same as 150 - as long as in series... In parallel its different: 1/R1 + 1/R2.


I was wondering if anyone could point me to another possible combination cause I'm not used to purchasing these things and the different ratings for them - I don't want to pick the wrong thing. I found a 1.65K ohm... But why specify 1.62 if a range will work? I'm not yet sure how to calculate all the stuff out to make sure its OK, since I've never put together a complex circuit. I have had an EE circuit analysis class in college, but I haven't mastered that stuff.

[random robots]

a good combo is 1k and 620 ohm. if you have a radioshack that has electronic components, you can buy that large reel of 1/4 watt resistors which has both resistors.

hope this helps,
Patrick

[RS232]

a good combo is 1k and 620 ohm. if you have a radioshack that has electronic components, you can buy that large reel of 1/4 watt resistors which has both resistors.

hope this helps,
Patrick

Thanks, those are both on back-order as well. Radio shack has a reel of assorted resistors of all ohm ratings for 1/4? If so, I may try that as I am going to take some stuff back to RS that I found much less pricey on digi-key.

[random robots]

actually, no. radioshack only has about 30 common resistors in the reel. but i have been able to use them in different combos for circuits, and i haven't bought any other resistors ever. buy the reel!!!!!!!!!!!!!!!!! it's a great buy.

[GearMotion]

Order the $50 robot kit from here: http://www.circuitgizmos.com/products/cgsorkit1/cgsorkit1.shtml

[RS232]

Order the $50 robot kit from here: http://www.circuitgizmos.com/products/cgsorkit1/cgsorkit1.shtml

Huh... good suggestion. I'll do that.