Last time we discussed the importance of salvaged parts. One should calculate his/her personal optimum, whether it’ll be cheaper to ride to the nearest well-supplied shop or proactively spend time de soldering the parts off the PCBs and sorting them. For me the optimum is to desolder and sort – considering my somewhat different daily work, these activities serve me as a nice lone recreation.
Analyzing the topic more systemically, how perfect has the sorting to be? For certain parts, sorting by orders of magnitude (by 10-s powers) is good enough. This is how I sort my power resistors (I need these seldom, not too much of these stored):
In certain cases, the wholecategory goes to a single box. E.g. I do not solder much SMD components. However, I recommend a kind of separation offered by minigrip bags:
However, there are at least two categories of parts (capacitors and resistors) that need more detailed sorting. Your mileage may vary but I sort these in two takes: first by magnitude (kilo-Ohms, then tens kilo-Ohms, then hundreds of kilo-Ohms etc) and second, internally by E24 row. I feel that anybody attempting to store row E96 nominals is not a hobbyist anymore.
Building the blocks
It is easy to notice that E24 row contains 24 standard values. Thus, a 8×3 or 6×4 organization seems to be the best. Boxes with organization 5×5 and 4×6 and 6×4 are available but they tend to be relatively pricey.
On the other hand, there is a nice trick from Soviet time – Vesta style matchboxes, glued together with PVA and enforced by some MacGyver tape.
There are personal taste choices to be made – either 4×6 or 6×4, incrementing up or down, column first or row first.
Now the next question is, how many of these blocks should you prepare? Here you see blocks 1R0, 10R, K10, 1K0, 10K M10 and 1M0 – so seven. A 0R1 block is an absolutely necessity (PSUs, PAs) while most hobbyists do not actually need 10M block (high voltage, megaohmmeters). Thus the answer is: we need nine blocks for the standard small resistors. I keep 2 sets of blocks, one for old Soviet parts and yet another for contemporary Western parts (btw, DDR and Hungary once made very reliable parts between those two categories).
For capacitors, the problem is more complex. Capacitors of too small or too large value don’t tend to follow E24 line (5pF, 500uF) . At least five standard blocks are needed – 10p, n10, 1n0, 10n, u10. One should consider that certain capacitor values are extremely popular and need extra boxes (like 2n2, 47n, 0u1 etc). BTW, 1p0 capacitors are not adhering to E24 line.
For some applications (like Hi-Fi sound or PSUs) the capacitors are distinguished by dielectric materials (VIMA high grade audio vs cheap 220V stuff). And then, electrolytics are special in many ways – they tend to dry off (thus why to collect them?!), they are large and heavy. All capacitors have an additional important parameter – Volts.
Said honestly, I hate colour code. Whoever invented the colour code, he likely was very unaware of important psychological considerations. Here is one of the best cue cards I have ever seen:
When most visual aids try to deceive you off the Problem no 1 “Systemic considerations” – this picture does actually center on it. Although first two resistors belong to the same sorting box (10k), you cannot determine that fact by naked eyes. For the 4-band resistor, the magnitude strip is ORANGE. For the 5-band resistor, it is RED and for 6-band resistor, the magnitude strip is ORANGE again but the resistor actually belongs to the next, M10 box.
No, you are unable to visually determine (at least not intuitively), which strip is the magnitude strip. Calculation and formulas are needed. Even worse – for 6-band resistor you have to think long, which end is the left one, which the right one.
As an example, from the DIY standpoint these resistors are approximately the same (rather equal considering our resolution is E24 row). Are you able to define that fact without 20 secs of measurements?
Problem no 2 “colour ignorance” – while choosing the colors, Pantone color charts certainly weren’t in use. What one man think is red, another man evaluates as orange. The situation is even more worse due to the wildly varying background colour of the resistor that affects the eye’s capabilities.
The nastiest combinations are 2k2 and 33k resistors – you have no additional hint what the color number was. Last but not least – it occurs that digits 2 and 3 are by far most popular digits among E24 numbers. Here is the frequency table (digit 1 appears in 10 values out of 24, digit 2 appears eight times etc).
Anybody familiar with colour scheme design knows bloody facts that E24 row is blindly ignoring.
The last aspect of Problem no 2 is daltonism. 4% of men have some form of it. Let’s see how daltonism affects the ability to read colour codes. Here is what we consider a normal representation:
Here we have used an online “colour changer” to reflect how people with most distributed daltonism – protanopia (missing red sensitivity) – see it:
Let’s now summarize architectural and implementational errors of colour coding:
- the number of root digits is modifying the power multiplier (which it shouldn’t, see floating point, scientific notation)
- colours are not kept precise at production but vary wildly (red/orange, black/purple)
- background color does affect perception.
- E24 colors are badly chosen – two top3 usable digits occur to be non-interchangeable 2 and 3. (The most frequently occurring root digits should be the ones that are easy to distinguish (psychologically apart), not like 2/3, 1/8, 0/7, 1/3 pairs under various lighting conditions. Daltonism, if technically feasible (research needed), should be seriously considered – my reasoning is very simple – bestiality that affects only max 2.5 more people, is meanwhile strongly supported in modern western societies.