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Other Basic Electronics, Multimeters, & Oscilloscopes

This thread is about basic electrical, electronics, Multimeters, and Oscilloscopes. It is an outcome of interest that various members have expressed about these subjects.

@Janger , @Johnwa , and @kevin.decelles have all recently obtained a starter Oscilloscope so I think the timing is good for a thread like this.

The primary resource will be a book (available on Amazon in paper or kindle) called Electronics for Dummies by Kathleen Shamieh. The book isn't a requirement, but it always helps to have a reference of some kind to facilitate discussion. Other references might get added as the thread progresses.

I'm not picturing this thread as a course, just a good place to ask questions, find answers, and share knowledge and experience about basic electrical knowledge and testing.

As always, a good time and lots of great jokes are expected!
 
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Susquatch said:
In all my life, I've never seen that and I've been involved in Electronics for 50 years.

That said, 4.7 is much more common than 4. But I confess that I don't know the real reason why. I used to think it had more to do with overlapping ranges for a given tolerance than any real functional reason. But that only partly makes sense. The theory goes to hell in a hand basket when the tolerances tighten up.
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Actually that's a really good question. Why 2.2, 3.3, 4.7, 6.3 etc...
 
jcdammeyer said:
Actually that's a really good question. Why 2.2, 3.3, 4.7, 6.3 etc...
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Like I said, I think it's tolerance related. If you apply a tolerance of 20% to a wide range of values, the intervals are not linear. As the base number increases, the tolerance gap increases too. So covering the entire range for a set of numbers means they have to grow non-linearly. You end up with 6 values per decade. 1.0, 1.5, 2.2, 3.3, 4.7, & 6.8. A 20% tolerance covers the whole waterfront with some overlap. But I could be totally wrong. I've never read that anyplace.

I don't know where your 6.3 came from. Perhaps it's in the 10 or 5% range. I'm just speculating. It's just what I always assumed.
 
As John says above, the "u" serves two purposes. It replaces the decimal point and indicates the range of the value, in this case micro farads. The same as if it was hypothetically 4p7, 4.7 pico farads. In my experience its use is quite common on schematics particularly European and has been becoming more common over here lately. It has nothing to do with tolerance, just a shorter way to write the value. you will find many modern components themselves marked that way, resistors and capacitors, ie 1n2 on a cap would be 100 nano farads = .1 micro farad.
John
 
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JohnP said:
As John says above, the "u" serves two purposes. It replaces the decimal point and indicates the range of the value, in this case micro farads. The same as if it was hypothetically 4p7, 4.7 pico farads. In my experience its use is quite common on schematics particularly European and has been becoming more common over here lately.
John
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Another Fn metric fiasco....... LOL!
 
I don't think it has anything to do with metric, just another, and shorter, way to define the value of a component.
john
 
jcdammeyer said:
Actually that's a really good question. Why 2.2, 3.3, 4.7, 6.3 etc...
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I remember this lesson from school about 50 years ago...

The standard resistor values are spaced so that when the tolerances are added, there is a smooth transition because a linear spacing (e.g.10 Ω, 20 Ω, 30 Ω, 40 Ω) is inefficient for electronics. Moving from 10 Ω to 20 Ω is a 100% jump, whereas moving from 90 Ω to 100 Ω is only a 10% jump. Geometric spacing ensures that the ratio between consecutive standard values remains roughly constant across every decade (1–10 Ω, 10–100 Ω, 1 kΩ–10 kΩ).

When resistors are manufactured, they fall within a specified tolerance range (such as +/- 10%). The E-series values are chosen so that the maximum value of one resistor meets the minimum value of the next higher standard value:

  • A 3.3 ohm resistor with a 10% tolerance ranges from 2.97 to 3.63 ohms
  • A 3.9 ohm resistor with a 10% tolerance ranges from 3.51 to 4.29 ohms
  • A 4.7 ohm resistor with a 10% tolerance ranges from 4.23 to 5.17 ohms
Notice how 3.63 overlaps smoothly with 3.51, and 4.29 overlaps with 4.23

And Wiki has this graphic which shows the progression. Wiki: Resistor value range

E6 series are 20% tolerance - 6 values per decade: 1.0, 1.5, 2.2, 3.3, 4.7, 6.8
E12 series are 10% tolerance - 12 steps per decade: 1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2
E24 series are 5% tolerance - 24 steps per decade: 1.0, 1.1, 1.2, 1.3, 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.7, 3.0, 3.3, 3.6, 3.9, 4.3, 4.7, 5.1, 5.6, 6.2, 6.8, 7.5, 8.2, 9.1
theres also the E48, E96 and E192 precision series.

So if you find an odd value resistor between these standard values, it will have a tighter tolerance. However 6.3 is not a standard value even in the E192 range.



🙂
 
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Susquatch said:
Another Fn metric fiasco....... LOL!
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After quick AI-ing 🙂 -

These specific values exist because of logarithmic scaling and standardized manufacturing tolerances known as the E series of preferred numbers (specifically the E12 and E24 series). [1]
In electronic design, components like resistors, capacitors, and zener diodes are not made in perfect, round numbers because components have natural manufacturing variations (tolerances). To prevent gaps or redundant overlaps in coverage, values are spaced geometrically rather than arithmetically.

Standard Capacitor Values: UF & E12 | StudySmarter

Standard Capacitor Values: ✓ List ✓ Values in UF ✓ E12 ✓ Definition ✓ Examples ✓ Principles StudySmarterOriginal!
www.studysmarter.co.uk www.studysmarter.co.uk
 
JohnP said:
I don't think it has anything to do with metric, just another, and shorter, way to define the value of a component.
john
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I was making a joke. Just hijacking the metric thread. Blame metric for everything and anything. My sense of humour is seldom appreciated by others - prolly for good reason.
 
Arbutus said:
I remember this lesson from school about 50 years ago...
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I don't remember anything from highschool except the crush I had on my English teacher.

What you have described in great detail is exactly what I was getting at. Except I always have to redo the math from first principles because I can't remember numbers, names, formulas, etc. I do remember the way things work and why they work that way so math was never a problem for me. Some guys passed the exam by remembering everything. I passed because I understood it. I have never regretted my weaknesses or my deficiencies. Besides, it was always easy for me to appreciate people whose strengths complimented my weaknesses.
 
ChazzC said:
This is casting my mind back 50++ years, but IIRC 6.3V is filament voltage. Why, that I can’t answer.
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Yup. It was selected for the vacuum tube heaters because it was the standard output voltage of a 3 cell lead acid battery.

There are days when I miss vacuum tubes....
 
Chicken lights said:
What's a vacuum tube do? Is that like yesteryears relays?
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It's sort of like a modern transistor except voltage controlled instead of current controlled. You apply a voltage to a control grid between the two main terminals (anode and cathode) in a vacuum chamber and that regulates the current flow across the main terminals.

Like transistors, think of them as a way to amplify small signal differences into big signal differences.
 
Susquatch said:
It's sort of like a modern transistor except voltage controlled instead of current controlled. You apply a voltage to a control grid between the two main terminals (anode and cathode) in a vacuum chamber and that regulates the current flow across the main terminals.

Like transistors, think of them as a way to amplify small signal differences into big signal differences.
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Then no, I don't understand. I understand relays how you can input low voltage on one side to switch for a higher voltage on the other legs

Vacuum tubes were largely 1980-ish and older?
 
Chicken lights said:
What's a vacuum tube do? Is that like yesteryears relays?
Click to expand...

I should add that vacuum tubes were much easier to understand because the parts were physical and visible. You could look at one and see the heaters, the gate, anode, and cathode. I personally think that's what made it possible for so many mechanically minded people to understand them. Basically a valve controlling a flow.

It's harder to imagine or visualize a tiny transistor using a small current flow in an NP silicon junction to control even more flow in a three way NPN junction.

Just my 2 cents observing the whole revolution of vacuum tubes to transistors take place in front of my eyes.
 
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