I am having to buy special resistors for old radios. I have to have a minimum buy. What would be common resistors that are used for different electronic projects? That way I can buy some other resistors that I probably will use later when I expand my hobby to modern electronics. Thank you.

 

what size(wattage) are your radio resistors - do the standard value ones have to be the same? That might make them large for everyday electronics use.

I note that for $12.49 Radio Shack will give you a 500 piece assortment:

Resistors. In an irresistible, money-saving assortment.
Save money with this assortment of 500 ¼-watt fixed carbon film resistors with 5% tolerance. Find exactly what you need for a variety of projects. You'll find 30 each of 1k, 10k, and 100k; ten each of 1, 10, 100, 120, 150, 220, 330, 470, 560, 1.5k, 2.2k, 3.3k, 4.7k, 15k, 22k, 47k, 220k, 470k, 1meg, and 10meg; five each of 2.2, 15, 22, 33, 39, 51, 68, 82, 180, 270, 390, 510, 680, 820, 1.2k, 1.8k, 2.7k, 3k, 3.9k, 5.1k, 5.6k, 6.8k, 8.2k, 12k, 18k, 27k, 33k, 39k, 51k, 56k, 68k, 82k, 120k, 150k, 180k, 270k, 330k, 1.5meg, 2.2meg, 3.3meg, and 4.7meg.

I bought one of these in the winter and it seems to have everytrhing I've needed since. I haven't needed many of the smaller values.

Also, I note that 1/8 watt resistors are becoming common.

 

Not for older radios their not. The norm for old electronics is more in the ½W, and 1W, sometimes more. The question is still a good one though, what is the wattage range you are looking for?

What part of the world are you in?

 

Good question. Yes, I have been to Radio Shack. One resistor that I need is 2 m ohms, Radio Shack only goes up to 1 m ohms. It has to be the 1/2w as Bill states. I am ordering from an online company that does radios. But you have to have a $15.00 min. So I decided that I would also buy resistors that I could use on future electronic projects. Not radio projects though, more up to date stuff. Thank you.

 

Two 1MΩ resistors in series is equivalent to 2MΩ.

 

Actually, you only need a ¼W for a 2MΩ resistor. I wouldn't want to be close to the voltage that uses half that wattage.

What resistors have you decided on?

I've done something similar, and posted it here, but mine was a lot easier because they were all ¼W.

http://forum.allaboutcircuits.com/showthread.php?t=12341

 

Check my math if you want - for 350 volts (figuring on highest imaginable B+) and 2M to ground, you get .175 mills. Using I^2 * R, that is 61 milliwatts (.06125 actual). More that I would have thought, but a long way from 1 watt.

 

Sigh. I should have done the math. Still 354V RMS or DC is pretty significant.

 

Also... don't forget to check that the resistors voltage rating is not being exceeded.

 

Hello,

Here is a page with some basic information on resistors:
http://www.interq.or.jp/japan/se-inoue/e_resistor.htm

And here is a page with standars values:
http://www.educypedia.be/electronics/resistancevalues.htm

Greetings,
Bertus