where To Buy Precision Resistors Fast

[MEXICOWANDERER]

This is for a 12-position click-click voltage selector switch for the Megawatt. Would love a 400 - 800 ohm spread using 9 resistors incrementally stepped. Also would like referral for a gold plated contact robust switch. .1% 1/4 watt metal film resistors would do fine. Need to order Mon morning and pick up on Friday. Thanks.

[theoldwizard1]

MEXICOWANDERER wrote:
Just found and ordered them. 20-30 ohm step spead. (5) each 20 ranges. Mil-spec. No color banding woowoo.

Okay, I have not done any electronics in over 10 years, but IIRC, no color band for tolerance meant 20%

[theoldwizard1]

Chuck_thehammer wrote:

Use to order this stuff for work..

I sat next to the circuit designers for some embedded system controllers. Everything they spec's was 1%. I asked if the accuracy was really that important. The answer was, "In the quantities we buy there us effectively no difference in price between 1%, 5% and 10%."

2-4 months lead time was not an issue.

[theoldwizard1]

westend wrote:
At Digikey, list of .5% resistors offered.

They list almost 20,000 part numbers. Less than a dozen are "in stock". Many of the remainder are 16 weeks+ availability.

[GordonThree]

Mouser shows over 2500 non surface mount resistors in stock with 0.1% tolerance.

Yes, a lot of values are available by special order, but there is some selection that is ready to ship.

Is such a high tolerance really needed for the application? 0.5% or even 1% are so much cheaper and more widely available.

[MEXICOWANDERER]

This is for a trial click-click-click 12 position rotary switch. Allows for a user to know in advance where a pre-set setting will limit. With an on-on selector switch controlling a selection either the 10-turn pot or rotary switch the ergonomics become simpler.

I am going to direct post the articles most likely from a hard bench in Starbucks Chula Vista. Thursday or Friday. Wish me luck. Photobucket + Gmail. It's going to get messy. Ptui

[MiPaJacks]

Mex, do we need to order one of these for your Megawatt project?
If so send us the link.
Thanks

[MEXICOWANDERER]

Just found and ordered them. 20-30 ohm step spead. (5) each 20 ranges. Mil-spec. No color banding woowoo. They are NOS Ohmite.

[westend]

At Digikey, list of .5% resistors offered.
I've had good luck with Vishay-Dale 1% 1/4 watt resistors. I use them for a lot of projects.

[Chuck_thehammer]

theoldwizard1 wrote:
Any resistor <1% is usually special order and volume is required.

100 percent correct. less then 1 percent or military spec.. special order... from anyone.. could be a month or more. 1 or 2 values might have limited quantity on hand..

Use to order this stuff for work..
Point 1 percent for A/D to D/A .. and D/A to A/D converters systems.

[theoldwizard1]

Any resistor <1% is usually special order and volume is required.

[GordonThree]

Mouser ships from Texas, so their shipping should be faster and maybe cheaper than Digi-Key, which ships from Minnesota.

There's also BGmicro.com in Texas, a great place to check for all sorts of electronic surplus.

I don't know about 0.1% metal film through hole. The finest I've bought were only 1%. Surface mount, yes 0.1% thin-film carbon resistors - laser trimmed - I use these usually in the < 300 milli-ohm range for current sensing on high power LED drivers

[westend]

Digikey or Mouser would be my recommendation for the resistors. Digikey carries a couple of lines of precision resistors, 1% to 5% in certain lines.

The stepped attenuator/switch with 12 steps may be difficult as most have more positions. I have a Russian stepped attenuator on the bench, a monster piece, probably from some military application. It's way too big for anything you have in mind.

OK, found a single deck 12 position switch from Goldpoint. You'll have to contact them about the shipping window. Their products are first class.