Blu-ray dummy load help, 1kohm resistor

[Darkarmyofone]

Ok guys, dumb move i know, BUT it was all that the 3 radioshacks neer me had in stock.

SO, i ask you this, if using a 1KOHM resistor, instead of a 1OHM resistor, how could i acuratly "or damn close to it" measure the Ma with my 6 IN4001 diodes.

im pretty sure i read on the old LPF that if you do use a 1KOHM resistor, you can apply a little math to get the right reading? is this true? if so could someone be kind enough to lend me a helping hand. but if it ABSOLUTELY cannot be done please let me know and i will refrain from using them. i wont even try it until i hear form someone.

thank you much in advance guys!

Dark

 

[Darkarmyofone]

bump, i could really use a little guidance on this one guys. im about to rip apart my LOC build for the 1ohm out of my LM317 here in a few.

 

[rog8811]

If you can use a 10ohm or 100ohm before considering a 1k... If they are not close tolerance, lets say 2%.
A 1k could be 20ohms out (unlikely)
a 10ohm would only be 0.2ohms out

All that said if the 1k is all you can get use it and multiply the meter reading by 1000

Regards rog8811

 

[Darkarmyofone]

rog, your the man, seriously, i had thought of that earlier, but i wasnt sure if there were some variables that would come into play. so i just waited. but yes 1K's is the closest they had.

thank you so much for the help. JUST in the nik of time too. i was in the midst of dismantling my LOC build for the 1ohm lol.

thanx a million man.

Dark

 

[Chuck]

Ehhh, you are going to set a current through a resistor. 100ma at 1ohm would require the regulator to supply 0.1V (if there were no diodes to make thinks easier).

If you used a 1k resistor you'd need 100V (0.100A x 1000Ohms = 100V) from the regulator. Me think no workee.

Radio Shack does carry large 1 ohm power resistors, that and 3 or 4 1n400x diodes should do the job. You could also consider mail ordering the parts from a place liek Digikey / Mouser etc.

 

[Archienj7]

Ehhh, you are going to set a current through a resistor. 100ma at 1ohm would require the regulator to supply 0.1V (if there were no diodes to make thinks easier).

If you used a 1k resistor you'd need 100V (0.100A x 1000Ohms = 100V) from the regulator. Me think no workee.

Radio Shack does carry large 1 ohm power resistors, that and 3 or 4 1n400x diodes should do the job. You could also consider mail ordering the parts from a place liek Digikey / Mouser etc.

1 ohm resistors ARE a hard thing to find at Radio Shack. I've never found one in stock there either, in going to 3 or 4 different stores in the same day. You'll see a lot of people post this, the best way to get it is online like you said.

 

[bennycast]

i got some 1ohm 1% tolerance resistors, i can give you some for free, you just would need to pay for shipping. I really don't know how much shipping will cost

Edit: I don't have more resistors.

 

[Darkarmyofone]

the 1kohm worked fine, times the reading by 1000. same dealio.

Dark

 

[dr-ebert]

Did you use the 1kOhm resistor in a test load? Maybe you got a reading then, but it definitely wouldn't work, unless you wanted to set up a current in the sub-mA range.