Activity for coquelicot‭

Type	On...	Excerpt	Status	Date
Answer	—	A: Inductance vs frequency If your question is theoretical (you are dealing with ideal components), then the answer of Olin is just fine. If it is concrete, that's the answer of Andy. In the concrete case furthermore, I would add that what interest the engineer in general is not only the inductance, but the whole picture, ... (more)	—	about 2 years ago
Answer	—	A: Let's make all downvotes public I have finally downvoted the post of Andy "Very short answer - get rid of downvotes on answers" despite it is rather close, in some respects, to my own views. Let me clarify myself. I've never said that downvotes are a bad thing by themselves (to be clarified below), but that downvoting without indic... (more)	—	about 2 years ago
Answer	—	A: Let's make all downvotes public I have proposed to fix a threshold of 100 pts to have the rights to downvote, which solves partially the problem of massive downvotes by trolls creating new accounts. This suggestion seems to have receiveid a positive reaction. Nevertheless, I would like to point out that the original suggestion... (more)	—	about 2 years ago
Answer	—	A: Let's make all downvotes public I've upvoted the post of Olin because I think this is obviously better than the current situation. Nevertheless, this does not completely solve the problem of trolls using multiple accounts. I think a minimum of 100 pts to get the rights to downvote would solve it completely, in addition to the sugge... (more)	—	about 2 years ago
Answer	—	A: Creating an "Insights" category @Olin. I already read the help/papers doc you pointed out. And that's why I think a part of the papers are very far from the description there (except the "to educate" clause, at the most). As far as I understand, this category is intended to "presenting useful information to the world", be "m... (more)	—	about 2 years ago
Answer	—	A: How long does it take for energy to propagate in a circuit? I add my answer here because I think the other answers are incorrect or irrelevant: namely, the answer of Andy is nice after he has redrawn the schematic and changed the problem, answering to another (actually more interesting) question. The answer of Olin seems to me a bit misleading: even if th... (more)	—	about 2 years ago
Question	—	Creating an "Insights" category Looking at the "papers" category, I found that several papers do not fit the very purpose of this category (that's the reason I've not upvoted them). Nevertheless, they are relatively well written, well thought out, and probably interesting for new comers in electronics. I think for example most of... (more)	—	about 2 years ago
Answer	—	A: How to protect RF switches from ESD? Somewhat a pity to throw money for an expensive ultra-low capacitance TVS. You have not specified what is the frequency range of your antenna system, but since you say you have to protect it from human fingers, it is likely to be a small antenna in the gigahertz range. So, all what you need is... (more)	—	over 2 years ago
Answer	—	A: During a Li-ion cell charge or discharge at 1C rate, are the electrode interfaces at thermodynamic equilibrium? Please, have a look at this thesis, from P. 12 to the end. The bottom line is that the Buttler-Volmer equation, which is in fact equation (13) derived in P. 12 to 16 (called by the author the electrochemical diffusion model), is said to be the most accurate battery model. So, it is certainly not ... (more)	—	almost 3 years ago
Answer	—	A: Unexpected phase shift in results There is a mistake in the last line: $$\eqalign{V{C1}(t) &= V1(t) - RI{C1}(t) \cr &= \sin(t) - \dfrac{\sin(t) + \cos(t) - \mathrm{e}^{-t}}{2} \cr &= \dfrac{\sin(t) - \cos(t) + \mathrm{e}^{-t}}{2} \cr &= \dfrac{\cos(t-90^\circ) - [-\sin(t-90^\circ)] + \mathrm{e}^{-t}}{2}\cr &= \dfrac{\cos(t-90^\c... (more)	—	almost 3 years ago
Answer	—	A: Contactor control - Higher voltage PWM While your basic idea seems fine, I will not enter into this matter, especially after Olin has said he will. Instead, I will give some other ways to do that, that may be useful in other circumstances. First of all, there are also inductorless convertors, working with capacitors, that are much ... (more)	—	almost 3 years ago
Answer	—	A: Capacitor ESR vs. Impedance I'll try first to give a general introduction to the problem, then I'll switch to your particular questions. Passive linear components, like capacitors, inductors or resistors are not ideal. For this reason, they are often modeled electrically as a more or less complex circuit involving resistanc... (more)	—	almost 3 years ago
Question	—	Is this AD8307 fake? I am trying to test a AD8307. Here are my connections: AD8307 (pins not shown are left unconnected, and also pin 8). I get a quiescent output voltage at pin 4 of about 850 mV with respect to ground, which, to my best understanding, means that the IC is fake. What do you think? ADDED: ... (more)	—	about 3 years ago
Answer	—	A: Why is the resistance of water so high and still so dangerous? I think your measurement instrument is fine. What is not is your understanding of resistance: there is nothing like this "resistance of water". In your case, the measured resistance depends on the distance between the immersed probes. The relevant concept is "electrical resistivity" or "volume re... (more)	—	about 3 years ago
Answer	—	A: Why is it is always power consumption or power delivered more in usage? No. You use the right concept whenever you need to use it. There is no preference of "power" over "energy". For example, the energy stored by a cap is equal to ${1\over 2} C V^2$. This is often used in computations. It's also the energy you have wasted that you have to pay to your electricity... (more)	—	about 3 years ago
Answer	—	A: Why do DC/DC switching controllers seem to favour the buck-boost topology over similar ones like Cuk, SEPIC and Zeta? I think the point is simply that there are much more demand on the buck-boost topology than on the Cuk/Sepic ones. And there are GOOD reasons for that: Several years ago, I asked a question on the SE forum: "where are Cuk converters". You can read the excellent answer there. The main point i... (more)	—	about 3 years ago
Answer	—	A: 555 timer, PAM with digital signal The 555 timer has a maximum output current rating (for example 250 mA for the NE555, check your 555 version datasheet). So whether or not you have to introduce a mosfet depends on whether your application is current demanding or not. For less than 100 mA (say), you can connect directly your 555 to wh... (more)	—	about 3 years ago
Question	—	How building a follower satisfying rather extreme requirements. What is your best suggestion for building a follower that would ideally satisfy the following spec: frequency: from 100 Hz (or lower) to 1 GHz input signal impedance: 1 Mohm input signal amplitude: from 1 mV to 1V at least output load to be driven: 50 Ohm. The follower need not be absolut... (more)	—	about 3 years ago
Answer	—	A: Measuring Input/Output Impedance with a VNA The input and output impedance of these amplifier is 50 Ohm. You don't need to measure them. That's because they are intentionally matched to the characteristic impedance of the coaxial cables that connect to their SMA connector, which is always 50 Ohm for most microwave devices, except television ... (more)	—	about 3 years ago
Question	—	My grid dip: how does this electron tube technology work? Here is a video of the AN/PRM10, and here is a schematic (I believe the image can be zoomed): an/prm10 As most commercial grid dip meters produced in the past, this one possesses several functions in addition to the grid dip function. One of these is the "absorption type wavemeter", that ... (more)	—	about 3 years ago
Question	—	Is it always necessary to use the ground terminal of the oscilloscope probe? Assume my oscilloscope is grounded, and the DUT is grounded as well (earth ground). I am using a standard 10 Mohm impedance 1:10 passive probe. So, the ground terminal of the probe is in fact connected to earth through the oscilloscope chassis. Is there any reason to connect the ground tip of t... (more)	—	about 3 years ago
Answer	—	A: MOV vs. TVS diode MOV are bidirectional components suitable for both AC and DC circuits, TVS are most often unidirectional, despite bidirectional TVS are also available; conducts more current compared to TVS diodes (in general); dissipates energy in a solid material and not in a junction. I would use a MOV whe... (more)	—	over 3 years ago
Answer	—	A: ESD USB Shield Connection & Filtering >It's kind of surprising that the TVS diodes dumping ESD into the GND plane don't affect the microcontroller; however, if the shield dumps ESD into the GND plane it has a very strong effect. That's what makes me think that the answer of Nick Alexeev is very relevant: the TVS diode has a small capa... (more)	—	over 3 years ago
Answer	—	A: Confused about the amplitude and shape of output voltage pulse You haven't explicitly stated what is the voltage supply at the anode of the LED, but according to your schematic, it is apparently 3.3V. So, I'll assume this value in what follows. There is a flaw in you logic: Whenever the PWM signal is high, the mosfet is conducting (ON state) and the volta... (more)	—	over 3 years ago
Answer	—	A: Driving ADC with opamp with large rails Here is a solution to protects very well the ADC from over-voltage spikes, avoid any simulation and design consideration, and that also protects the ADC from a possible negative output spike from the op-amp output at startup. protectADC For high frequencies, it may be necessary to put a "compen... (more)	—	over 3 years ago
Answer	—	A: High Power Switch - High Side vs. Low Side Switching Answer to question 1: First, you need p-mos and not n-mos, as you are switching the circuit from the above. Second, it is better and simpler to parallelize mosfets for big current switches; this will reduce the power dissipation as well. So, even if there exist a pmos with 150A ability (which... (more)	—	over 3 years ago
Answer	—	A: How to plot the I-V curve of a tunnel diode? Don't put the "protective" series resistor: connect directly your regulated power supply to the diode (with a short wire) and measure the current: the voltage regulator is all what you need to protect the diode and ensures you are not missing the negative resistance part. Then you increase very slow... (more)	—	over 3 years ago
Question	—	Creating an additional "user" That may seem a pointless question, but life has taught me to be careful and to ask before any "somewhat unusual" steps. Also, despite it could be a Codidact question, I think it is also dependent on the particular EE community feelings. I am currently using this site under the pseudonym "Coqueli... (more)	—	over 3 years ago
Answer	—	A: Homework questions / "ask an engineer". I think the bullet list in the current on-topic page is clearer and easier to understand. Admittedly, there are some "confrontal" bullets, but that's OK in my point of view. Sure, there are always very delicate persons who will be choked by the crudity of the terms. But is it bad? these QA sites w... (more)	—	over 3 years ago
Answer	—	A: Understanding the s11 and s21 coefficients of a microstrip line with resistor to ground Eureka! thanks to the article cited in the question, I've finally understood the matter. I will describe here the general procedure for computing the network parameters of a grounded two port device (DUT), without entering into the intuition behind the math. The generalization to more ports is ea... (more)	—	over 3 years ago
Question	—	Understanding the s11 and s21 coefficients of a microstrip line with resistor to ground I thought I understood the theory of scattering parameters, smith charts etc. until I tried a practical example. The following stupid example is supposed to be a microstrip line shunted by two 100 Ohm resistors to ground, that is, an equivalent resistance of 50 Ohm (also checked at DC with a volt... (more)	—	over 3 years ago
Question	—	Using FET based followers and design rules Usually, voltage followers are built with bipolar transistors (or with opamps if better precision is needed). In this case, the simple rule says that the transistor emitter "follows" the input voltage one diode drop below, a somewhat approximate but understandable term. bip-follower It is per... (more)	—	over 3 years ago
Question	—	Name of the OP in the list of questions Is it possible to add the name of the OP near each question inside the question list? Only the name of the "last activity" person appears there. For me, that would help. I would like to see something like "Asked by Zoro, 3 months ago". (more)	—	over 3 years ago
Answer	—	A: More accuracy from multiple resistors in series or parallel? That depends on whether you are just building something for yourself, say a prototype, or if you are designing a product for mass distribution. In the later case, you are subject to probability laws, and the answer of Olin is just fine. In the former case, though, you may improve the performances... (more)	—	over 3 years ago
Answer	—	A: How to estimate time of completion while developing an electronic product? I'm actually an algorithmic engineer, not an electronic engineer. But your question is extremely general, and valid for every field of engineering. Also, it obviously depends upon the human and technical resources available to you. So, it cannot be answered at this level. Nevertheless, according ... (more)	—	over 3 years ago
Answer	—	A: Why Ib=const. for BJT output characteristics Ic=f(Vce) > In some books and other technical papers (also from universities) it is - surprisingly - still claimed that the bipolar transistor (BJT) would be a current-controlled element. And this is true, subjected to some conditions and approximations. >This is simply stated - without any explanatio... (more)	—	over 3 years ago
Question	—	Filtering the high frequency noise in switching PSU It is well known that it is difficult to filter the noise generated by switching power supplies, and this difficulty increases as the PSU is supposed to deliver large currents. For example, in a usual LC filter, the self may reach the saturation if a large current is passing through. I would l... (more)	—	over 3 years ago
Question	—	I have to choose: Arduino or Raspberry pi. Moderator Note If this site were mature, this question would be closed because it solicits opinions, or is too specific about particular models. In the interest of site activity, answers are being allowed that compare and contrast microprocessors boards to microcontroller development boards in ge... (more)	—	over 3 years ago
Answer	—	A: Is ESD overhyped? Just to let you know: if one day you have to use the LM337 negative voltage regulator, protect everything with TVS or Zeners. This is the most failing component I've ever seen (and I'm not the only one who thinks so, see youtube). I suspect strongly it is very sensitive to ESD. In my last application... (more)	—	over 3 years ago
Answer	—	A: Design rules for opamp bootstrapping I answer to myself because I believe this subject is interesting and not very well understood, even to professionals. Also, I want to point out that this answer is the product of my own investigations and simulations, and is not coming from reliable sources or knowledge. First of all, I want to p... (more)	—	over 3 years ago
Question	—	High pass filter design Despite there are many filter calculators available on the web, I still have difficulties to translate what I need into calculator design parameters. For my application, I need ideally a high pass filter that kill everything below 60Hz, and keep everything near 100Hz. More mathematically, I would... (more)	—	over 3 years ago
Question	—	Design rules for opamp bootstrapping Here is the bootstrapping technique for opamps, as exposed in the Art of Electronics:bootstrap. This technique is supposed to increase considerably the input impedance of the opamp for an AC input source (usually passed through a cap). The Art of Electronics considers it somewhat outdated, as it ... (more)	—	over 3 years ago
Answer	—	A: Constant Current Load Circuit with Op Amp let me begin with a schematic for an adjustable current source with a simple load: Image The operation is simple: The current I inside R1 gives rise a voltage drop equal to I/R1 (= I if R1 = 1). So the oamp will set the voltage to the gate of the mosfet in such a way that I/R1 = Vpot... (more)	—	over 3 years ago
Question	—	Darlington or Sziklai configuration - why and when using complementary pairs? Why does the Darlington or Sziklai configurations need complementary transistors? For these configurations, when should I use complementary pairs and when could I use not complementary pairs ? (more)	—	over 3 years ago
Question	—	Complementary transistor pairs - what is the point ? I understand that some applications require NPN-PNP pairs with identical electrical characteristics. But I would like to understand why. (more)	—	over 3 years ago
Answer	—	A: Driving LED with NPN transistor from I/O pin No need to power the led with 5V. 3.3 V should suffice! Before I come to problem of regulating the current with only 3.3V, I wish to state some general simple constructions. Technically speaking, the following current sink/source is perhaps insufficiently known: DiodeRegu1 The current is se... (more)	—	almost 4 years ago
Answer	—	A: How could a damaged wire in split-phase power delivery create these voltages? Well, here is was my logic tells me: The corrosion has caused a high impedance in the L2 wire, but there should be also a "short" between the L1 and L2 wire. So that the voltage between L1 and L2 falls to 30V, and the voltage between G and L1 is 90V. In other words: L1 - G = 120V = L1 - L2 + L... (more)	—	almost 4 years ago
Question	—	Is it possible to use two zener diodes in series back to back to replace a diac? I've accidentally burnt my dimmer with a short. It is a common dimmer with a triac/diac/pot of the simplest configuration (the triac is a BTA16). After replacing the triac, this still does not work, and I'm almost sure the problem is the DB3 diac (breakdown voltage at 32 V). I don't have this beast i... (more)	—	almost 4 years ago
Question	—	What is the added value - still unclear Hello, I come from EE.SE. I just would like to help you to build this site. And I have some observations: First of all, it is still unclear what is the added value of this site with respect to the well known EE.SE. I see almost exactly the same pattern of question/answer/score/meta and constructio... (more)	—	almost 4 years ago
Answer	—	A: Let's have a "Papers" category. That's an excellent idea. But I think there is no need in punishing bad posts here, because there will be very few posts here anyway, I'm sure. You have only to remove those infrequent "bad papers", and this is more than enough. For example, I think I have very good things to say about pulse generati... (more)	—	almost 4 years ago