Help solving a puzzle:

[sniper007]

If 618 is correct, I got that by just doing series/parallel reduction from left to right.

Lefty

Yes my mistake, could be reduction with general series/parallel.

 

[RODALCO]

These puzzles are fun somtimes even I did not get the correct answer.

Starting from the left and working my way to the right first time i got 333.33hm: second time different approach yielded 454.54hm:

Then get the soldering iron warm and solder 9 of these 1 khm: resistors together 617hm:

( I checked the R values and most were around 993-995 hm: )

Good exercise, I have forgotten the tricks how to do these

Regards, Raymond

 

[dyverdwn]

The answer....

It seems the answer is indeed 333

Can you explain how you arrived at that? (Just for my own understanding)

How come th eactual measured difference is so different? Is this due to a change in th ecircuit by adding the ohm meter itself?

Hmmmm.....

-Michael

 

[ericgibbs]

It seems the answer is indeed 333

Can you explain how you arrived at that? (Just for my own understanding)

How come th eactual measured difference is so different? Is this due to a change in th ecircuit by adding the ohm meter itself?

Hmmmm.....

-Michael

Then get the soldering iron warm and solder 9 of these 1 k resistors together 617

Using a typical bench DVM, with an input resistance of say 1Mhm: the resistance would still be a nominal 618.2hm:

The fact that someone has taken the trouble to assemble and measure with a meter, which gave 618hm: should convince you its 618hm:, UNLESS you havn't given us the FULL puzzle...

 

[sniper007]

It seems the answer is indeed 333

Can you explain how you arrived at that? (Just for my own understanding)

How come th eactual measured difference is so different? Is this due to a change in th ecircuit by adding the ohm meter itself?

Hmmmm.....

-Michael

I suspect you are joking with us, but nevertheless here is step by step result.

 

[DamoRC]

LTSpice model results in 618.18 ohms.

I prefer the 42 answer from denikar.

 

[DigiTan]

Alternately, you can do a Δ-Y translation on the center two triangles. But after trying that, I wouldn't recommend it over sniper007's method.

 

[RODALCO]

The key to this puzzle is where you start from. I found my notes again and decided to have an other go at it. I hadn't look at this thread so all the newer solutions were unknown to me.

Firstly the connecting leads are at the RHS of the puzzle so the minimum value of the RHS string can never be less than 500hm: It will be the parrallel value of 1khm: in parrallel with (1khm: + Xhm

Then I started working the way through from the LHS of the puzzle by series parralleling the sections of three resistors.

2khm://1khm: yields 666.6hm:
1.666khm://1khm: yields 625hm:
1.625khm://1khm: yields 619hm: = X
1.619khm://1khm: yields 618hm:

I didn't put all the decimals in the example but you get the idea.

Regards, Raymond

 

[scorpio19]

Can you help me troubleshoot something?
It is about prototyping a 3D puzzle for toddler.

 

[mneary]

Can you help me troubleshoot something?
It is about prototyping a 3D puzzle for toddler.

Is this related to your OTHER TWO THREADS ?

 

[MrAl]

Hi,

I did the same thing, collapsing the network from left to right using
series and parallel formulas. The result i got was:

6800/11 ohms exactly,

or

618.1818181818181 ohms approximately.

 

[Ross Craney]

I solved from the left also and got 618.18 ohms. I can't see how you could do it from the right when your parallel values are unknown