Resistor Kit - yes or no?

mjgillen

mjgillen

Active Member
I don't have a decent inventory of common resistors yet (is there such a thing?) and I get frustrated when I'm working on a board and come across a component that needs replacing and I have to make yet another small Mouser order. It's not so much the cost as it is the wait time which interrupts the Zen flow I'm into when working on something. As an example I am working on the driver board in my Sansui 8080 and the dreaded Sansui glue under two of the caps was all over an adjacent resistor so after I cleaned up the mess I wanted to replace the resistor however I don't have one of those 120KΩ 1/4w carbon composition resistors :( So yeah I could order one and it'll arrive in a week and then I find another component that needs replacing etc. I try to do due diligence on the boards before I start however there are sometimes surprises...

Years ago when I was working on tube stuff (and thought I would continue) I ordered one of these kits so I have a pile of Metal Oxide / Carbon Film 1 Watt (Flame Proof) Resistors however I don't think they are very applicable to the solid state stuff I'm working on now (please correct me if I'm wrong).

So I am thinking about ordering a kit and wanted opinions from the Knowledge Base here. I've already read a couple threads on this and some say that you won't use most of the stuff in the kits and just order as you need them however I'd rather have the part when I need it and have a few "extras" than have to interrupt my Zen as I wait for another shipment (like I am right now).

Looking for opinions on the kits from AES:

Resistor Kit - 0.5 Watt, Carbon Composition, 5 of each value

Resistor Kit - 1 Watt, Carbon Film, 5 of each

Resistor Kit - 0.5 Watt, Metal Film, 5 of each

Resistor Kit - 1 Watt or 2 Watt, Metal Oxide, Power, 5 of each

Thanks in advance.
Michael
 
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Resistor kits can be handy but, I always wind up with lots of resistors I have not needed . It seems I am better off ordering 5 packs or even 25, 50 to 100 of the common ones I use the most.
Also, I prefer higher quality resistors in hifi applications and most of the kits are cheap quality ( still can be ok) . In most of my uses the 1/2 watt is the most useful all around. I can use in 1/4 w positions the same . The higher wattage (power resistors) tend to be more specific and I just order 5 packs. But it is more economical to bulk up your orders for sure.
look back at what you used and what you think you will be needing soon . And order those. Combine caps too and you might have enough to justify the order.
 
I bought a kit when I started. Metal film, 1/4 watt, 10 each of maybe 120 values for <$18. Here is what I found:

- The cost per resistor was under 1.5 cents per resistor.

- I got cheap versions with flimsy leads. They measure fine, but feel thinner than stuff from mouser or digikey

- I use up maybe 20 values regularly and replace them when I place an order from a supplier. Another 20 are running at about 1/2 full strength. The remaining 70 to 80 values are lightly touched. It is nice to have them in hand to keep going.

- when I was working on something in the audio path, I’d want something better so I’d order new, higher quality parts.

if I had to do it over again, I’d find the 40 most popular values and buy 10 to 100 of each at mouser/digikey. Assume 1000 resistors at 2 cents each is about $20. I’m not sorry that I bought as I did, it was the right thing at the time, but I’d do it differently today.

With regard to the linked kits, they look really expensive to me and 5 resistors per value is going to disappoint pretty quickly for some values. I see a big premium for convenience. You can do better with an hour’s research and order yourself.

Question: why the carbon comp? Metal film in 1/4 watt is typical replacement in solid state equipment.
 
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I just bit the bullet initially and put some extra parts in my first 2-3 initial orders. Not only resistors but capacitors.
Looking at schematics is a good way to find common part values. Easier for resistors, harder for capacitors - there are much more variables to consider.

With resistors, I would not look at anything other than metal film 1% at 1/4 and 1/2W variants. New resistors are smaller than older ones and a 1/4W resistor will easily fit where 1/8W resistor was.
E24 values are the most commonly used. Small value resistors are usually needed to be higher power (more current passes through) and very high values (>1MΩ) are seldom encountered.
Of course, there are some that are very common, like 1K, 2.2K, 3.3K, 4.7K, etc.

OTOH, you will seldom need resistors when servicing solid state equipment, unless something fried something. Capacitors is another thing altogether.
 
Too expensive, Try this:
https://www.mpja.com/Pack-of-2600-1_4-Watt-Resistor-Service-Kit/productinfo/33418+RS/
mjgillen said:
I don't have a decent inventory of common resistors yet (is there such a thing?) and I get frustrated when I'm working on a board and come across a component that needs replacing and I have to make yet another small Mouser order. It's not so much the cost as it is the wait time which interrupts the Zen flow I'm into when working on something. As an example I am working on the driver board in my Sansui 8080 and the dreaded Sansui glue under two of the caps was all over an adjacent resistor so after I cleaned up the mess I wanted to replace the resistor however I don't have one of those 120KΩ 1/4w carbon composition resistors :( So yeah I could order one and it'll arrive in a week and then I find another component that needs replacing etc. I try to do due diligence on the boards before I start however there are sometimes surprises...

Years ago when I was working on tube stuff (and thought I would continue) I ordered one of these kits so I have a pile of Metal Oxide / Carbon Film 1 Watt (Flame Proof) Resistors however I don't think they are very applicable to the solid state stuff I'm working on now (please correct me if I'm wrong).

So I am thinking about ordering a kit and wanted opinions from the Knowledge Base here. I've already read a couple threads on this and some say that you won't use most of the stuff in the kits and just order as you need them however I'd rather have the part when I need it and have a few "extras" than have to interrupt my Zen as I wait for another shipment (like I am right now).

Looking for opinions on the kits from AES:

Resistor Kit - 0.5 Watt, Carbon Composition, 5 of each value

Resistor Kit - 1 Watt, Carbon Film, 5 of each

Resistor Kit - 0.5 Watt, Metal Film, 5 of each

Resistor Kit - 1 Watt or 2 Watt, Metal Oxide, Power, 5 of each

Thanks in advance.
Michael
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Semanon said:
if I had to do it over again, I’d find the 40 most popular values and buy 10 to 100 of each at mouser/digikey.
Click to expand...

Well that's my dilemma - what are the 40 most useful? I don't know I don't have the experience yet. If you have a list it would be helpful. I work on Sansui and Pioneer gear mostly.

Yes I always order 20 or more caps and resistors when I order anything so I am slowly building up stock however its these unexpected gotchas that really annoy me.

Semanon said:
You can do better with an hour’s research and order yourself.
Click to expand...
Yes, will just have to do it (insert Nike logo)

Semanon said:
Question: why the carbon comp? Metal film in 1/4 watt is typical replacement in solid state equipment.
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So if I need to replace a regular old carbon resistor I should just use a metal film? So just order a pile of the most common values in Metal Film and skip the carbon?
 
Look at resistor kits. Start with the values in the kits you link. Find other small kits and those will be the common values.

Use E12 values. Buy E12 x 10, 100, 1000, 10,000 and 100,000. That’s 60 values. At 25 of each value = $30. And that’s Vishay CMF55 (tape).

Google it. You are not going to cover every situation, but you will get better resistors at less cost with less for your grandchildren to inherit.
 
Or if you are in a position to spend $180 on resistors, get 100 each of E48 values in decade multiples. You will still need to order the occasional ones that are not in that grouping.
 
I have hundreds of values of resistors in all types and sized. Sometime even the one I need. For design and prototyping I always have what I need, but when fixing stuff I have to place orders more often than not. Same thing with capacitors. I think the odds of having what you need in a kit are slim. If you're serious, Semanon's solution is good.
 
Carbon comp resistors generate more self noise than metal or film. Inclusion in 1970s equipment was a legacy decision, IMHO. I’d consider carbon comp in a tube design, but would replace them in SS anywhere outside power supplies (and maybe there, too).
 
It sounds like I should order Metal Film in E24 values (still trying to understand that) in 1/4w and 1/2w 1% tolerance, start with 20 pieces each. I sure wish there was an easy way to create a Mouser order for this. I wonder if a phone call to them would be better. Perhaps they have the tools to make it easier?
 
Here are the E12 values in several decades:

- Base decade
- X10 decade
- X100 decade
- X1000 decade
- X10000 decade
- X100000 decade

10 100 1000 10000 100000 1000000
12 120 1200 12000 120000 1200000
15 150 1500 15000 150000 1500000
18 180 1800 18000 180000 1800000
22 220 2200 22000 220000 2200000
27 270 2700 27000 270000 2700000
33 330 3300 33000 330000 3300000
39 390 3900 39000 390000 3900000
47 470 4700 47000 470000 4700000
56 560 5600 56000 560000 5600000
68 680 6800 68000 680000 6800000
82 820 8200 82000 820000 8200000
FFE72C58-393A-4438-B6FD-E231CE4CD127.jpeg
Here is an article that describes the resistor value system pretty clearly

https://eepower.com/resistor-guide/resistor-standards-and-codes/resistor-values/

I’d curate the list a bit and remove the less than 100 and more than 1M. These will likely be higher power or very specific values. Remember what @ConradH said. You will still need to order, even after assembling this brilliant kit.
 
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Simplify ordering?

-Go to your favorite supplier.
-Download the data sheet for your product of choice
-Understand the product numbering.
-Load the number sequence into a spreadsheet
-Populate the spreadsheet with only the values of those resistors desired
-Upload the spreadsheet to said vendor
-Get a cup of coffee.

7AF097C4-2299-47FD-B25C-0E2F7E73C803.jpeg

This process is why they charge $180 for resistors. It’s inconvenient the first time because you are learning the ropes. I’d never buy a resistor kit again because I know how to do this and can get exactly what I want for the best price with a little effort. Bespoke offering for off-the-rack prices. :D

Edit: not necessarily promoting Vishay or that particular series of resistor. It just hits my sweet spot between quality and price for an on-hand resistor. The CMF 55 is good for 1/2 watt at temps normally seen in an amp (70C) or 1/4 watt in high temp applications (125C). There are better ones for specific applications, but this is a good general resistor, IMHO.
 
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avionic said:
I only buy modest quantities that I use most often..
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I treat it like a food shopping order. I’ll put it on a list before I run out. When I do my next order, I’ll add it in.

I also look for the best deal. If I need 4, I’ll see the quantity price break occurs and go for the best deal.

@avionic, I suspect that you order much more frequently than I do...
 
Going by the E24 table, and filtering on Vishay CMF series, some of those values are not there like 240. Should I order 237 or 243 or find the 240 in a different series? Thoughts?
 
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