Activity for Andy aka
| Type | On... | Excerpt | Status | Date |
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A: What should be considered when picking a flyback diode? > a coil with plain on/off functionality, for example a 24VDC relay coil with 700mW max coil power. That means a coil current of 0.7 watts / 24 volts = 30 mA. A relay might have a coil inductance of anything from 1 henry upwards but this can be estimated by the relay activation time in the... (more) |
— | over 3 years ago |
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User's reputation score not displaying on top ribbon It appears that a user's reputation score has disappeared from the top ribbon at the side of the user's login avatar/picture. Is this an intentional thing? (more) |
— | over 3 years ago |
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A: CAN Bus - Internal Oscillator CAN is asynchronous and, if you receive a string of consecutive zeros, the UART mechanism that turns raw CAN data into "a byte" might have to wait a great deal longer than 1 bit of data before it can re-sync. If data is coming 101010101010 then that's great but, if data is 010000000010 then you ha... (more) |
— | over 3 years ago |
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A: Driving ADC with opamp with large rails > Is the risk of the opamp overdriving the ADC too great for no input protection to be used? I would certainly say yes but, this can usually be easily solved by using a current limit resistor in the feed line to the ADC. Most ADCs specify a maximum current that their inputs can take. This is an... (more) |
— | over 3 years ago |
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A: Transformer - Vsec or Current rating parameter > If I connect this to a 12V supply and expose it to 10us pulse: 12V10us/475uH = 252mA $$$$ This current flows in the primary magnetization inductance (475 μH) after applying 12 volts for 10 μs. This causes core saturation based on the volt-second figure limit of 11 volt-μs. $$\dfr... (more) |
— | over 3 years ago |
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A: What is the difference between differential amplifier and differentiator? > I need to know what is the difference between differential amplifier and differentiator A differential amplifier amplifies the difference voltage between two signal voltages. A differentiator performs a type of mathematical calculus on a signal. The two processes are wholly unrelated. (more) |
— | over 3 years ago |
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A: Understanding the s11 and s21 coefficients of a microstrip line with resistor to ground In the absence of VNA product documentation...... > Now, -9 dB is equivalent to a ratio of 0.34 approximately, and -3.53 db is equivalent to a ratio of 0.66 approximately. I expected S11 to be near 0. A 9 dB return loss is a reflection coefficient of \$\pm\$0.355. Accounting for slight discrep... (more) |
— | over 3 years ago |
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A: Emitter Bypass Capacitor in a CE Amplifier > Is it because for AC signals the emitter looks like a short to ground and that essentially increases the voltage drop across the collector resistor? Yes. The gain of a common emitter amplifier is approximated by the ratio of R3 to R4 - this is when there is no emitter decoupling capacitor.... (more) |
— | over 3 years ago |
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A: Control circuit for Power Converters These are my general thoughts: - - Easiest - power management IC (PMIC) - Smallest footprint - PMIC usually - Cheapest - usually PMIC (for a certain minimum performance level) - Highest performance - PMIC will outshine all others - Best reliability - PMIC - Best stability - PMIC - Qui... (more) |
— | over 3 years ago |
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A: Filter Impedance Consideration Apart from the need to match impedances to prevent possibilities of signal reflections and the knock-on issue of signal nulls at your receiver LNA input, an antenna "expects" to be terminated in the "right" impedance in order to get best performance. The ratio of E-field to H-field of a radio wave... (more) |
— | over 3 years ago |
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A: High pass filter design > How the real pros would translate these needs into design rules for a calculator? Speaking as a pro I wouldn't use a calculator because I'd use a simulator and tinker with a few values until I got the response I wanted. I'd probably use standard building blocks like high-pass sallen key filte... (more) |
— | over 3 years ago |
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A: Purpose of emitter resistor in a common collector amplifier If you are AC coupling to a load then you need an emitter resistor to set the DC operating point and quiescent current of the amplifier. An external AC coupled load cannot do this and, it needs to be done to ensure the amplifier works as intended. If your load is a resistor and directly connected ... (more) |
— | over 3 years ago |
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A: How to define Vsat for MOSFET as a switch? $$\boxed{\text{What maximum value of } I{OUT} \text{ did you have in mind?}}$$ Using \$I{OUT}\$ and \$V{OUT}\$ we calculate power uplift. Using power uplift and switching frequency, we calculate how much energy the inductor needs to store (and transfer) in each switching cycle: - $$\text{Power... (more) |
— | over 3 years ago |
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A: Complementary transistor pairs - what is the point ? To understand why complementary pairs are used, it's probably a good idea to think about the limitations of the NPN emitter-follower circuit: - Image alt text It's a good circuit for delivering modest powers to a load but its main disadvantage is that it dissipates excessive power in the emitte... (more) |
— | over 3 years ago |
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A: How could a damaged wire in split-phase power delivery create these voltages? > When the outage occurred, I observed the following - The L1/G voltage difference was 120V (good). - The G/L2 voltage difference was 90V (bad). - The L1/L2 voltage difference was 30V (very bad!). If the L2 wire was broken then, due to capacitive coupling between L1 and L2 (and the use of... (more) |
— | almost 4 years ago |
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Strange things happening Why has my reputation dropped significantly over-night from around 352 to 316? Why are there a bunch of new people listed with decent reputations who seem to have appeared from nowhere? (more) |
— | almost 4 years ago |
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A: How do I calculate and manipulate the inductance and capacitance of outputs to a connector on a PCB? > How do I calculate the inductance and capacitance out from the barrier to make sure it is less than the sensor values? The output capacitance and inductance from your zener barrier is irrelevant - you design the barrier components (fuse, zeners and output resistor) to limit the short circuit ... (more) |
— | almost 4 years ago |
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A: How do I design a flyback converter? What are the basics I should know? Equivalent Circuit, 1:1 transformer Start by simplifying the circuit and change the transformer to a single inductor. This simplification ignores the benefits of isolation but, flyback converter theory is about transferring energy and not fundamentally about isolation: - Image alt text We al... (more) |
— | almost 4 years ago |
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How do I design a flyback converter? What are the basics I should know? I need to design a simple flyback converter like this: - Image alt text I want to control duty cycle from another circuit such as an MCU but, I'm unsure how to proceed. My requirements are: - - Input voltage `125 volts` - Output voltage `500 volts` - Load resistance is `10 kohm` - Tra... (more) |
— | almost 4 years ago |
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A: Humming noise from a boost converter's inductor A couple of problems stick out; one glaring and one a little subtler. Read this in the data sheet: - Image alt text You have the enable pin connected to your 25 volt output. I'm not saying this is definitely causing your problems but you might well have broken the chip in some way that gives yo... (more) |
— | almost 4 years ago |
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A: What benefit has a differential amplifier when measuring a sensor signal? General cause of noise/interference The interference can be distant (such as lightning) or much closer (such as cables connecting "other" equipment) but, whatever the source, interference can be regarded as "dosing" the same energy onto both sensor wires (whether screened or un-screened). Non-d... (more) |
— | almost 4 years ago |
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What benefit has a differential amplifier when measuring a sensor signal? What benefit has a differential amplifier when measuring the signal from a sensor that is remotely located such as in this example: - Image alt text Why can't I use an arrangement like this: - (more) |
— | almost 4 years ago |
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A: Op-amp output error voltage Input offset voltage \$V{OS}\$ Your problem might be input offset voltage or \$V{OS}\$. This can be several milli-volts and manifests as this modification to your original circuit (in red): - Image alt text So, for an op-amp like the LM358 or LM324, you can expect a typical \$V{OS}\$ of abou... (more) |
— | almost 4 years ago |
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Op-amp output error voltage I've built a non-inverting op-amp amplifier with a gain of 101 using this circuit: - Image alt text My input is 10 mV DC and I expected to measure 1.01 volts at the output but I measure 0.81 volts. What has happened to cause this error? (more) |
— | almost 4 years ago |
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A: How to avoid shoot-through in MOSFET bridge drivers To avoid shoot-through you should ensure that the active-low P-channel MOSFET gate drive voltage never overlaps with the active-high N-channel MOSFET gate drive voltage. With an inverter driving the N-channel MOSFET's gate, the increased propagation delay can often mean that the N-channel device rema... (more) |
— | almost 4 years ago |
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How to avoid shoot-through in MOSFET bridge drivers I'm using a variable duty cycle square-wave oscillator to drive a half-bridge MOSFET pair like this. Upper MOSFET is P-channel type, lower MOSFET is N-channel type: - Image alt text And, I think I'm getting shoot-through current pulses. Is there a simple way to resolve this? (more) |
— | almost 4 years ago |
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A: Electrolytic capacitor lifetime rating The lifetime rating is (usually) quoted as "so many" hours at a certain temperature and that is the crucial thing to be aware of. For instance, consider a capacitor like this one: - Image alt text Some in the range are only rated for 5,000 hours at 105 °C but, if they were run at an average tem... (more) |
— | almost 4 years ago |
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Electrolytic capacitor lifetime rating If you search through the electrolytic capacitor offerings from distributors like Farnell, RS, Digikey or Mouser, you find that the maximum life-time rating is commonly quoted as 5,000 or 10,000 hours at such and such a temperature. If I divide 10,000 hours by 24, I get 417 days = 1.14 years. This... (more) |
— | almost 4 years ago |
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A: Pi-Filter for EMC > What would be the main considerations to use Pi-filters for EMC? Using the filter correctly and understanding its limitations EMC or EMI (electromagnetic interference) is noted for its high frequency energy content. Applying a \$\pi\$ filter like the one below can significantly attenuate tho... (more) |
— | almost 4 years ago |
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A: Low loss impedance matching without a transformer Low-pass impedance transformation Image alt text Theory Input Impedance: - $$Z{IN} = j\omega L + \dfrac{\dfrac{RL}{j\omega C}}{RL + \dfrac{1}{j\omega C}} = j\omega L +\dfrac{RL}{1 + j\omega RL C} = \dfrac{j\omega L - \omega^2 RL LC + RL}{1 + j\omega RL C}$$ Multiply numerator and denom... (more) |
— | almost 4 years ago |
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Low loss impedance matching without a transformer I have a signal at 10 MHz produced from a 50 Ω source. How can I match that to a 300 Ω load with low losses without using an RF transformer (space constraints)? Are there any circuits and formulas that can help me achieve this? (more) |
— | almost 4 years ago |
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A: Moving average that uses less memory? I'm adding to Olin's answer with a little bit of theory (from the standpoint of an EE) and I'm also showing a 2nd order IIR filter. The 2nd order filter is based on cascading two 1st order stages with an additional feedback loop to control Q factor (or \$\zeta\$). Both these filters are IIR types... (more) |
— | almost 4 years ago |
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A: How do I design a boost converter? What are the basics I should know? An on-line boost converter calculator Image alt text Image from this website. The Operating Mode The circuit operates in either of two modes but, the voltage transfer equation is different for each mode. Therefore, you need to establish the operating mode before you can calculate duty cyc... (more) |
— | almost 4 years ago |
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How do I design a boost converter? What are the basics I should know? I need to design a simple boost converter like this: - Image alt text I want to control duty cycle from another circuit such as an MCU but, I'm unsure how to proceed. My requirements are: - - Input voltage 12 volts - Output voltage 16 volts - Load resistance is 5 ohms - Inductor 1μH ... (more) |
— | almost 4 years ago |
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A: Viewing the potential live output when editing a question or answer. A work around has been found for this and I'm sure this will get a proper fix before long: - - Go to the edit button for your answer (for example) and press it - Notice that there is no live preview screen of the edit-in-progress as per this: - Image alt text - What you see below the edi... (more) |
— | almost 4 years ago |
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A: Relationship between bode plot and pole zero diagram For any 2nd order low pass filter, the components (R, L and C for electrical and k, M and c for mechanical) can be reduced into two more meaningful quantities: - - \$\zeta\$ (the damping ratio) - \$\omegan\$ (the natural resonant frequency) Concentrating on the RLC circuit in the question, t... (more) |
— | almost 4 years ago |
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Relationship between bode plot and pole zero diagram What is the relationship between the pole zero diagram and bode plot? Case example: a 2nd order RLC low pass filter: - Image alt text $$\dfrac{V{OUT}}{V{IN}} = \dfrac{\frac{1}{j\omega C}}{R+j\omega L +\frac{1}{j\omega C}} = \dfrac{1}{j\omega RC +j^2\omega^2 LC +1} = \dfrac{\frac{1}{LC}}{\fr... (more) |
— | almost 4 years ago |
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A: Are we there yet? \$\color{purple}{\text{Are we there yet?}}\$ No, it's not ready: - The embed image doesn't seem to work anymore on the EE part of the site and neither does it work here. It did yesterday because I added an image to an answer I posted; but not today - I just get a message saying: - `javascr... (more) |
— | almost 4 years ago |
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Viewing the potential live output when editing a question or answer. I have just raised a Q and A but when editing the answer (that involves a picture) there is no "live" version of the potentially finished post and this will prove to be a problem when making a complex answer especially if MathJax/Latex is used. SE.EE does support this feature and I think it's vital. ... (more) |
— | almost 4 years ago |
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A: What to check for when buying an electronic component or module? 1. Any electronic component or module you buy for a project or design should have a data sheet. By data sheet I mean a portable document format (PDF or equivalent) like this: - Image alt text 2. Do not assume that the product will be OK based on marketing/sales claims without researching ... (more) |
— | almost 4 years ago |
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What to check for when buying an electronic component or module? How can I acquire electronic parts/items/modules and ensure that there is minimal risk of them being unsuitable for my project or design? (more) |
— | almost 4 years ago |
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