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\$\begingroup\$ I am going to answer my own question. Feel free to offer alternatives. I won't accept my answer. When I was a junior engineer, a senior engineer demonstrated transmission lines in the lab with a pulse generator, a scope, and a few BNC cables. I learned more playing with real circuits than I learned in school. Later, I would repeat the demonstration for other engineers.
Is it possible to receive information if the received power is below the noise floor?
\$\begingroup\$ This relates to my previous question, which I think I have asked in the wrong way: How to insert background EM noise into pathloss equation? I wasn't really interested in detectability of the signal, and I have phrased that question very ambiguously, so let me ask what I would really like to know.
Voltage drop across LED in open circuit
I've searched the forums but can't find an answer for my issue. I've got a simple LED circuit powered by 5V DC. When the switch is closed, I've got 2.8V across the resistor, 2.2V across the LED, and 0V across the switch (as expected). However, when the switch is open, I get 3.45V across the switch but no other noticeable readings (0V across resistor and 0V across the LED). Where did the other 1.55V go? If I shunt across the LED, I get the expected 5V across the open switch connections.
What conditions could be expected to occur if one or both inputs of an op amp are left floating?
I'll interpret your question a bit more broadly, since the results with one or both inputs floating are unlikely to be working usefully. In general there are two categories of op-amps, bipolar ones which have significant bias current that is of guaranteed direction, and FET or MOSFET-input types which have smaller bias current of undetermined (and possibly changing) direction.
Searching for the right temperature sensor with 0.001
1mK resolution is not such a big deal, and 1mK accuracy is not such a big deal for the electronics, at least over a narrow range (just expensive- a 0.03% reference resistor with a minimal tempco). The problem is calibration. Other than the triple point of water, which is a (relatively) easy source of 0.01°C +/-0.1mK it's expensive and difficult to calibrate the sensor to such tolerances.
Will Two Op-amps connected to the same input effect each other
I've been given the following circuit to build for an education lab. The values of the resistors aren't accurate, they're only to illustrate that the gains of the two op-amps are different. The aim is to have two separate op amps of different gains connected to the same input signals, and then a SPDT switch connects the required output to \$V_{out}\$. The two op-amps will be in the same chip (LM353).
Does a 24V inverter consume the same amount of wattage as a 12V inverter?
I'll give you an answer covering a bit of general principles, since the specific outcome will have some dependence on the specific type of inverter. An inverter seen from the terminals of the battery pack (however it is arranged, 12V, 24V, etc.) will look as a constant power load, i.e. as a two-terminal device that always absorbs the same amount of power, as long as its load (the bulb) draws the same amount of power.
Will Two Op-amps connected to the same input affect each other?
I've been given the following circuit to build for an education lab. The values of the resistors aren't accurate, they're only to illustrate that the gains of the two op-amps are different. The aim is to have two separate op amps of different gains connected to the same input signals, and then a SPDT switch connects the required output to \$V_{out}\$. The two op-amps will be in the same chip (LM353).
If an FM signal has different frequencies, how does the radio receive the signal in a fixed frequency?
The frequency you tune to is the centre frequency of the spectrum created by the modulation. The input from the aerial is generally modulated down to an intermediate frequency (to make it easier to work with) and then fed into a Phase-Locked Loop (PLL) circuit which creates a signal proportional to the frequency shift from the centre frequency. This signal turns out to be the originally encoded audio (if you work through the maths).
Why are pull-up resistors required to be connected to the 2 lines of I2C?
I2C has some features that improve on other communication busses, and to implement that, it had to switch to a different style of connection. If two devices force a line to two different states, you can short the line and possibly damage something. UARTs/Serial and SPI are uni-directional communication. By that I mean each line is dedicated in a single direction. You have a transmitting and a receiving pin.
Capacitor discharge at lower voltages
You say no confusing formulas, but the problem with your not-understanding the issue is explained by at least some simple formulas, which I'll try to explain below in a simple way. First of all it seems you confuse power with energy. Power is the rate of change of energy, i.e joules/seconds. When you have a current I flowing between two points across which there is a voltage V you have a power \$P=V\cdot I\$, i.e. there is an energy transfer of \$V\cdot I\$ joules for each second that passes.
Making LM78xx fail safe against short, open, reverese bias, flyback, etc
I want to use LM78xx for various applications. What I am concerned about is its failure modes. Not shorting Vcc to ground!! I mean shorting V_input to V_output. Assume that you have a delicate and expensive piece of electronic equipment that works with 5V. You are using LM7805 to reduce voltage from 12~13VDC to 5VDC. For some reasons your LM7805 fails to short and your delicate electronic device sees the 12VDC instead of 5VDC and fries. I have seen this all around the web. How to protect against this?
Finding gain from a transistor datasheet
As they've not labelled the different curves it looks pretty dubious to me. Normally the graph would apply to typical values so you would not necessarily find them in the tabulated values (this one does not show typical values). I might guess it's showing you either temperature (highest trace would be highest temperature, lowest trace lowest temperature) or unit to unit distribution for the high gain version, with the middle trace the typical value.
Is this transistor datasheet correct?
Usually the columns min/typical/max on datasheet refer to the spread of the mentioned parameter among a manufacturing batch. This means that, for example, Vceo is guaranteed to be at least 45V for any specimen in the batch (at the given conditions). In other words, if you buy 100 such BJTs and determine their Vceo you'll discover that each one has a different value, but all the values will be at least 45V. Could they also list the maximum value?
Why do characteristic impedances matter only when traces are longer than half a wavelength?
A 1/4 wavelength trace or shorter can also have a substantial effect. The usual rule of thumb I've heard and used is that you can probably neglect transmission line effects when the length is less than 1/10 or 1/20 wavelength. For a simple example, say you terminate a 1/4 wavelength line with an open circuit and drive it with a single-frequency source. After the signal reflects back to the source (1/4 wavelength away), it will look to the source like it's driving a short circuit instead of an open.
Can anyone explain why a B-H curve with Hysteresis doesn't result in a highly non-linear input-output transfer function for a transformer?
You don't normally have a current driven primary, you have a voltage driven primary and, as saturation starts to kick-in, you get a higher current than for an unsaturating primary. The two effects of increased current at the peaks and decreasing dB/dt (at the peaks) I guess will tend to resolve themselves to something like linear volts out.
What to choose hFE or beta from the plot of transistor's datasheet
If you are using the transistor as a saturated switch then you decide what Ic/Ib should be. The saturated characteristics of the transistor are guaranteed at Ic/Ib = 10. Most often you'll use a bit less, maybe Ic/Ib = 20 unless you are very close to the limits of the transistor. hFE is gain in an unsaturated condition (as an amplifier) with a relatively huge Vce (2V in this case). It is a poorly controlled parameter and varies a lot from part-to-part and with temperature.
LM324 for 10,000x gain?
The op-amp is configured as an inverter and, with +100uV on the input, the output will try to go negative but it can't because you restricted the negative power rail to 0V. So this means your source has to have a negative voltage fed to the input (a possible constraint). The trouble with the LM324 is the input offset voltage is about 2mV i.e. about 20 times bigger than the signal and this may well be a positive offset and, as said above will force the op-amp output to go negative.
4-20mA to 0-3V3 Converter
It will work. You might want to use a somewhat lower value of resistor so you can detect overrange on the 4-20mA. The offset zero allows you to detect underrange (this is useful for sensor break detection and such like). Of course you lose a bit of resolution on the ADC- 20% on the bottom.
RF Energy Harvesting?
Consider an antenna that converts all the electrical energy from a power oscillator to an electromagnetic radio transmission. Let's say 1 watt is fed to the antenna and 1 watt is the emitted radio wave power. That power is flung out in most directions; just like a lightbulb emits light power in (virtually) all directions. The lightbulb isn't just a similar example it is exactly the same example - the light emitted is an electromagnetic wave.
Air gap on isolation space
Such cuts are made to increase the creepage distance. That is the minimum distances along the surface of the material between two conductors. The other metric that is important to isolation is the clearance. That is simply the minimum distance between the two conductors. The clearance distance needs to be some minimum so that the air can withstand the voltage across the gap without arcing. The hole in the board does nothing for this since the arc would simply jump across the gap.
Transmission of a digital signal over a medium
A digital signal is composed of a fundamental frequency and an infinite number of odd harmonics. This is how the nice clean and sharp edges of a digital signal is made. As in the image below, you have the fundamental frequency, and as you add more and more odd harmonics, the signal begins to take the shape of an ideal digital waveform. Now you mention that a medium cannot have infinite bandwidth. Which means, not all frequencies can pass through.
Measuring a huge resistance on low voltage
You can do what you want, but it won't be simple. Scratch that, it will be fairly simple, but it won't be easy. As von Clausewitz said, "In war, the important things are very simple, and the simple things are very difficult." It applies here as well. Actually, it's not as bad as it could be. Your nominal current is 250 pA. You can get op amps with bias currents in the 1 femtoamp range, so monitoring your current is certainly possible.
Where did the value of 0.1uF for bypass capacitors come from?
Higher value capacitors will not be as effective at dealing with high frequency current drawn by the chip. Above a certain frequency a capacitor will start to behave like an inductor. The value where its characteristic changes is the series self resonance of the device: - Thus, you'll find that on microwave devices 100pF capacitors are also present as decoupling along with the bulk capacitors.
Does current flow on an open transmission line?
Please take a moment to look at the diagram below: The question is if the lightbulb will momentarily flash when the switch is closed. I think it will but I get the feeling I am wrong.
Arduino resetting/hanging due to sparks in ac line
This is the PCB design of the project I have been working on recently (my first pcb design). The idea is to control ac appliances (fans, bulbs etc) without relays. I am using triacs which are better than relays for such applications. I am using opto-isolators for complete isolation from ac lines. I tried running the arduino using USB cable connected to my laptop (with charger unplugged) as well as wall adapter (12V). At first, circuit seemed to work fine.
Term for a chip that is used in a camera to detect light
This is called an image sensor. This particular image sensor in your picture is a CMOS image sensor, commonly found in pretty much anywhere a small to medium sized camera is used, as well in some big and/or professional gear. The camera in your phone is almost certainly a CMOS image sensor. It is probably also the type of sensor captured the image you posted here.
What are my options for detecting the position of a small moving metal object?
A circular coil around the outer perimeter of the target generates magnetic flux: - The flux density is at its minimum (but not zero) in the centre and as you approach the coil perimeter the flux density increases. If the current were an AC current the peak flux density would be \$\sqrt2\$ higher compared to the DC case. However, a big difference is that (due to eddy current induction) any conductive material will alter the coils inductance as it passes thru.
how to increase the voltage of a digital signal?
You might be able to use this. It's an 8 channel bidirectional level translator: - One side works with logic level of 1.2 to 3.6 volts and the other side works at logic levels of 1.6 to 5.5 volts. I would have thought that if your high side voltage logic is 6.6 volts, then supplying an input pin with a logic level of 5 volts (76%) would still be OK. When feeding out a 6.6 volt logic level you should protect the device with a 1kohm series resistor.
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