brumma
April 7, 2025, 10:01pm
1
Newbie looking to learn more about electronics so I don’t need to ask as many questions about the basics. Can anyone recommend a good, preferably free, class for a beginner (who knows how to solder)?
Thanks!
Semi-serious answer:
Serial resistance: R_{total} = R_a + R _b
Serial voltage: V_{total} = V_a + V_b
Serial current: I_{total} = I_a = I_b
Parallel resistance: R_{total} = \frac{1}{1/R_a + 1/R_b}
Parallel voltage: V_{total} = V_a = V_b
Parallel current: I_{total} = I_a + I_b
Ohms law: V = I * R
Watt’s law: W = I * V
Simple, right? If you read everything so far and understood it, then you can stop reading, because you know everything you need to know about electronics.
Still here?
Ok, let’s explain what these things mean:
Let’s start with the three serial formulas. Let’s assume we have three points, P1, P2 and P3.
We hook up one component, called A between P1 and P2, and another component P2 and P3. We then hook up a battery between P1 and P3 to pass some current through these components.
Now we can measure the resistance between P1 and P2, which is the resistance of the A component, which we call R_a , and if we measure between P2 and P3, we get the resistance of the B component, which we call R_b . If we measure between P1 and P3, the resistance should be R_{total} which according to the formula above should be equal to R_a + R_b .
Thus, we can summarize the first formula as: In a serial circuit, resistance adds.
For the second formula, we’ll need to hook up a battery to P1 and P3. This will send some current through our circuit. We can then switch out multimeter to DC voltage measurements and measure the same three spots again. This will give us V_a, V_b and V_{total}, which also add.
In a serial circuit, voltage adds.
If we want to measure the current that goes through this circuit, we have to cut the circuit somewhere and insert the multimeter at that point. However, as we can see from the third formula; it doesn’t matter where we cut the circuit, because there is the same amount of current at every point in the circuit. This is only true for serial circuits though, as soon as their is a branch in the circuit somewhere, then each branch will have a different amount of current.
In a serial circuit, current is the same everywhere
Ok, so, what if we have our components hooked up in parallel?
Now we only need two points, P1 and P2, because both component A and B are hooked up to P1 and P2.
Now, we have to be careful when measuring the resistance of the individual components. We can’t do it while the components are connected to P1/P2, because then we always get R_{total} . No problem though, we can remove the components from the cir…
The fact of the matter is that a large portion of electronics comes down to Ohm’s law and Watt’s law. The rest is just learning how to apply it.
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