93

It's a piezoelectric disc buzzer with a weight. It's being used as a vibration sensor, not a sound generator. The weight amplifies the strain produced by vibration.


66

Step 1) Identify the package, note how many pins, match up the pins first. Note that sometimes the package pins are underneath the part or extended away from the part. Also get the dimensions of the part with a ruler or (preferably) calipers and match them up with a chart, write them down for a later step. Make sure that when measuring pin pitches (distance ...


65

There are four physical quantities of interest for electronics: voltage, flux, charge, and current. If you have four things and want to pick two, order not mattering, there are 4C2 = 6 ways to do that. Two of the physical quantities are defined in terms of the other two. (Current is change in charge over time. Voltage is change in flux over time.) That ...


51

Properly designed, built and used, today's LEDs have incredibly long lives and the wearout mechanisms are not catastrophic in nature, so instead of using incandescent lamp MTTF statistics, a luminosity percentage (70%) is often used to define the lifetime- this doesn't mean that the LED burns out, it means that the light out put is only 70% of what it was ...


49

The industrial PCB assembly process usually leaves residues — mostly soldering flux — on the circuit board. One step in the process is to wash the board (by dipping or spraying) with a solvent to remove those residues for long-term reliability and for the sake of appearance. Some devices (such as sound or pressure transducers) have openings for ...


40

How to get the most out of a potentiometer? In many precision, low-noise designs, it's a bad idea to start with to even have the signal routed through the front panel. So, at the very least, the control element should merely produce a voltage signal that governs a voltage-controlled amplifier/attenuator. With a potentiometric source, you can buffer and low-...


37

Because wires and traces are not perfect. They all contain some inductance which impede high frequency currents trying to flow through them. Needless to say: Radio frequency = really high frequency. The bad effects are increased noise, voltage spikes when the chip's current demand decreases and voltage dips when the chip's current demand increases. So ...


35

It is an "axial-lead cement wirewound resistor" rated at 3W. Resistance is 0.22\$\Omega\$ +/-5%. Here is a datasheet. I've been in their factory. ;-)


34

There is a clear definition: Passive elements have no function of gain, or control over voltage or current: their controlling function is linear -> I/V = R in the case of a resistor. There are exactly four kinds of passive elements: Resistors, Capacitors, Inductors and Memristors. All other components are active. Source http://de.wikipedia.org/wiki/...


34

It's a snap-on ferrite core which, when clamped over a number of conductors, becomes part of a common-mode choke. Here is a complete datasheet for a similar product. The ferrite is lossy so it is better characterized as an impedance at a given frequency. In the case of my example, every wire that goes through the core behaves like it has 241 ohms in series ...


33

It's a ferrite choke. It is a passive electric component that suppresses high frequency noise in electronic circuits.


33

That is a piezoelectric buzzer: Photo from the linked Wikipedia article.


32

It is a "Chip on board". It is an ic wire bonded directly to the board, and then protected with some epoxi (the "black thing").


32

It's a resistive hygrometer (or simply put: a humidity sensor). The resistance across the contacts varies depending on the relative humidity of the air it is suspended in.


32

The device Spehro Pefhany's answer builds out of two pots is actually available as a single unit, for example the ALPS RDC803101A. If you turn it, you get two sawtooth signals that are 180° out of phase, so when one output is in its “dead zone”, you can use the other one instead to determine the position. This model also has no detents, so no clickyness at ...


32

If you are installing a CPU in a motherboard, you don't really care about grounding - what you really want to do is to make sure that you, the CPU, and the motherboard (and any tools) are all at the same potential. If you have one of those grounding bracelets, you should connect its ground lead to the computer case or motherboard Ground - whether that is "...


31

NOTE: It is long. But when you're done, you'll know a lot more to design more, even cooler schematics than you imagined possible. I have included some Breaks where you could stop, go to bed or have a drink and decide later whether you feel you need to learn more. First, I'm going to go with an NPN transistor, because: You say you're happy to flip some ...


31

That would be an inductor with a resistor style color code. Here's a picture from that Wikipedia page showing some similar 100 µH axial lead inductors: Vahid alpha at English Wikipedia CC BY 3.0, via Wikimedia Commons


30

OS stands for "Oscillator" in this case. The pictured component OS1 is a 3-terminal ceramic resonator, such as this: Image Source With the marking 400C it is probably a 4MHz frequency like the one pictured. This is a fairly standard frequency for cheap MCUs. The resonator will provide a clock to the microcontroller. These resonators are very cheap parts ...


29

This is Light dependent resistor (LDR). Its similar to a normal resistor, but the resistance decreases with increasing light intensity.


27

I printed the E12 resistor series eight-to-an-A4 page, cut them up and purchased 100 ziplock bags (on eBay) to suit. The plywood box was a woodwork project! This upgrade replaced my previous similar system that lasted > 30 years.


27

When set for voltage measurements a multimeter will normally have an impedance measured in megaohms. Although that impedance combined with capacitance may affect the operation of some circuits I can't think of many practical situations where damage is likely to occur. When set for current measurement it's a different story because the shunt resistor may ...


27

I guess the answer is maybe. Yes, if... you're in the process of fixing something and the hard-to-get spare part is readily available on a junk board in the corner of your lab. Hard to get can even be a standard 10k resistor, if it's Sunday afternoon and you don't want to order parts online or wait for the next electronics shop to open. Sometimes, I even ...


26

Disclosure: I currently work for one of the manufacturers mentioned, I completed an internship with a second, and I know current and former employees of a third. I can't reveal specifics but I can give some general reasons why ICs have variable costs and prices. I also can't speak about the specific ICs mentioned -- even if I knew why my company's version is ...


26

They're IF transformers (T is for Transformer) used in radios (relatively narrowband amplifiers at the Intermediate Frequency of usually 10.7MHz for FM and 455kHz for AM). The ferrite core adjustment is for trimming the inductance to tune the center frequency, called "aligning" the radio. Below image from this datasheet. There are many variations and you ...


25

I've really enjoyed your question and definitely upped it. Your question made me think about and do some additional reading on the topic. And I really appreciate what I've learned from the process and that you stimulated that process for me. Thanks! Historical Context I'm not going to go back to the Babylonian days here. (Probably, the whole concept does go ...


24

These LEDs are not a single radial die, they are made with a transparent substrate with many LED dies in series (probably 25) placed on it. The whole thing is then coated in phosphor. The light isn't completely uniform but it's good enough. There's a spec sheet here: http://www.runlite.cn/en/product-detail-145.html


24

For plastic overmoulded parts, the lead-frame (correct terminology) is held in place while the plastic is injected. For packages like PTH (Pin through hole) or j-leads etc. the surrounding support is cut away with shears and the individual chip is freed. In the package you show, these pads cannot be sheared and must be moulded into the package. that means ...


24

Yes, they are called current regulator diodes. They are essentially a JFET with gate joined internally to source so that you get approximately IDSS for voltages above the pinch-off voltage (and below the breakdown). There are much better circuits possible using IC technology, so I think the current regulator diodes are mostly a relic from the past. ...


24

Each of your "lanes" is a "pole" in switch terminology. 1P (or SP), 2P (or DP), 3P, 4P... The number of ways you can connect those to outputs is a "throw" (T) - Single being ST, double being DT and after that, numbers. 3T, 4T... Some switches add "center-off." Single-throw switches are "off" one way and "on" the other, while DT are always on in one ...


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