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H: Is the small signal model of a BJT amplifier valid for any sinusoidal signal?
According to the small signal model, a CE amplifier amplifies only the signal component of the input voltage that causes small perturbations around the operating point. My question is if we put say a > 1 V sinusoidal signal on the base te... |
H: How does this step up converter work?
Just bought an adapter to use an ATX psu as replacement to an HP proprietary one. It has a step-up module which converts the ATX 5vsb to 12vsb. I just want to know what the extra 12v input is for and if it can be removed. It seems like it passes the 12v rail together with the s... |
H: How to control the amplitude of a Wien-bridge oscillator?
I am trying to design a Wien-bridge oscillator and understood the basic working principle of it. Now I got to the point where I want to add a system which would make the gain >3 during startup and <3 when exceeding the target amplitude range.
Apart from inac... |
H: Power electronics on a PCI/PCIe expansion card
I'm not sure if its been done before but how feasible is the idea of building an computer expansion card (PCI/PCIe) that carries mains power on some areas of the expansion card being switched by relays, TRIACs or IGBTs mounted on the board that talks to a controller on... |
H: Why do some circuits work in LTspice, but not in Proteus?
Why do some circuits work in LTspice, but not in Proteus?
I was playing with my amplifier circuits in LTspice by changing the values forth and back, I had calculated. I was thinking about a special amplifier circuit and decided to omit the input signal and l... |
H: "Dirty" response from paired TSOP4838 IR receivers
I have connected the outputs of two TSOP4838 IR receiver modules using diodes to prevent reverse current. The idea is to mount them on a moving model vehicle at 180 degree orientation to one another so that the field of reception is closer to 360 degrees. If this... |
H: Should I throw these boards with soldering issues out?
I've just baked some boards. The first two looked normal, but upon closer inspection I noticed that paste did not melt under one chip with exposed pad package. I used a slightly different profile with 30s longer preheat and 10s longer peak (both are leaded prof... |
H: Issue with influence between channels in a dual-channel high-side current sensing circuit
I've designed a two-channel current sensing circuit integrated into a board that outputs two separate signals. However, I'm encountering an issue where one channel seems to influence the other, which, to my understanding, shou... |
H: Does a single input differential amplifier remove noise?
It is known that the purpose of using a differential amplifier is to remove noise from the input signal, apart from giving some small amplification. To my knowledge, there are two inputs and two outputs in a differential amplifier. Usually, two inputs are giv... |
H: Doubt in applying KVL
I want to apply KVL to loops abcda and befcb in the circuit given below. Is there any role of the 2A current source in those two loops, that I need to consider before applying KVL?
AI: Is there any role of the 2A current source in those two loops, that I
need to consider before applying KVL?
... |
H: PC power supply bench breakout board. What is -12V used for?
I bought a useful PC power supply breakout board, fused. It has the following outputs:
-12V
+12V
+5V
+3.3
What is -12V and how would I use it? The -12V has its own negative.
AI: -12V is a negative 12V output. Used for something that needs a negative s... |
H: If RF signals require matched impedance to remove reflections, why do approaches to shunt noise need only a “good path to ground?”
From my understanding, for signals to propagate without reflection the impedance of the path must be constant and can be shown via the telegraph equation.
When it comes to noise on the ... |
H: ESP32: unexpected voltage readings on EN and IO0
I am designing a PCB for the first time with the ESP32-PICO-V3 chip, but the chip doesn't boot. The chip is connected to the rest of the PCB as seen in the simplified diagram below, where I measured the voltages at EN and IO0 during my troubleshooting.
When I give my... |
H: What is the exact reason for grounding (earthing) of a transformer?
I have some misunderstandings with the grounding of a transformer. As far as I know, the utility transformer's (the last transformer before my mains plug) neutral point (star-connected point of 3 phases, this image is probably from the US) connects... |
H: How on Earth can a solid state relay be constructed?
Relays are very handy components. Relays allow current to both directions on the controlled load circuit so they can be used for both AC and DC. However, relays have a finite lifetime if connected/disconnected often, produce a loud audible click and consume power... |
H: Sensing plugged in 3.5mm jack with the TRRS contacts
I am using the pictured TRRS connector and want to detect whether a plug is plugged in via the builtin switches (pins 2/3/4). However, the switches seem to be connected to the audio lines as well. Surely connecting a resistor divider/voltages/other sensing would ... |
H: Replace BJT with a MOSFET for a mini 24 V motor
I have a mini 24 VDC motor (RH-370CC) with the following specs:
It is controlled by an ESP32 (3.3 V output). My initial design was the following:
I know, I made a poor choice with the SS8050 transistor.
It worked well in the early tests but it lasted a few seconds w... |
H: What's wrong with my FET transfer function?
The following is from the book Design of Analog CMOS Integrated Circuit, page 207.
Find the transfer function of the circuit in Fig. 6.47(a):
Suppose the voltage at node A is \$V_x\$.
with the use of KCL at node B,
$$V_x g_{m1} + \frac{V_{out}} {r_o} = (V_x - V_{out}) ... |
H: Equivalence in circuits
I'm studying circuit theory, with only linear elements and no capacitors or inductors or mutual inductances, so no differential equations. All the sources (current and voltages) are constant.
To be even more precise, that means that resistors, ideal current/voltage sources, dependent curren... |
H: How to space stitching vias to avoid affecting the power plane?
On a four-layer with the standard sig gnd pwr sig stackup, when flooding top and bottom layers with copper and stitching them to the ground plane, I know the standard rule is lambda/20 spacing for the vias. However, isn't there a risk of there being to... |
H: Which is the best method to measure AC voltage?
I am trying to make a UPS circuit. I need to have a high speed measurement for the input AC voltage (220 Vrms) (in order to know whether to turn on/off the inverter). I had tried using this circuit:
It works, but it is very slow: it takes more than 500 ms just to det... |
H: Can't add text after automatically numbering nets on a bus (Eagle 7)
In Eagle 7, when I draw a Bus line I can quickly assign a number of nets to the bus by using the [N..M] format; for instance, say i want to add data lines D from 0 through 8, I can Name the bus D[0..8].
However, this fails if i add text after th... |
H: Not able to correlate the graph and table for the I2t rating in a fuse datasheet
In the datasheet, the I2t rating of a 5A fuse is 0.055 at 10 times In.
Using the same value to estimate the trip time for the 10 A condition, I get 0.0022 seconds. In the graph below, it comes around 0.02 seconds.
Where am I going wr... |
H: How is the power of a component fixed?
How can we say that a bulb is a 100 watt bulb or a heater is a 1000 watt heater when when according to the relations
P=VI, V^2/R and I^2*R
the power depends upon the current and voltage applied to the component while its resistance is fixed?
What if I apply a much lower voltag... |
H: Step-up power supply for motor
I know very little about electricity. I am a private detective. I am converting on older surveillance periscope to modern IP cameras. The periscope has several motors that raise/lower turn 360% and on the tilts the periscope mirror up and down. These were all wired to a 16 pin cord... |
H: What causes these spikes in an LTspice circuit analysis of a full adder?
For the following full adder circuit:
I get the following output for s (I have the same problem with COUT):
The graph itself is correct, but those spikes should not be there. I know that I have to change the sine wave somehow but I can't fig... |
H: Ground rod in an area surrounded by trees
I have some questions about ground rod installation.
If a small part of the rod is kept outside the soil, wouldn't be that a low resistance point where a lightning can choose to go?
Does it need to be covered with something to increase its resistance to the outside or ther... |
H: Why are the lookup tables in FPGAs small?
An FPGA can be seen (visually at least) as a matrix of cells. Each cell has a LUT (look-up table) inside, implemented with SRAM and MUX.
Why does the size of such a LUT (and hence of the SRAM) need to be kept small in FPGAs (usually less than 10 input bits)?
Please correct ... |
H: 433 MHz crystal 3 feet pinout?
What are the pins A, B, C of this 433 MHz crystal oscillator?
https://nexelectronics.in/wp-content/uploads/2023/01/433-MHZ-CRYSTAL-OSCILLATOR-1.jpg
I suppose these are input, output, ground. Could you explain or give me a link to datasheet on internet? I researched, because I have ju... |
H: USB on ATmega32U4 powered at 3.3V
I have an already-designed board that uses an ATmega32U4 (a board of our own design). It is USB-powered at 5V and it has an external 16MHz crystal.
Below is a screencapture of the relevant portion of the schematic:
The firmware is built as an Arduino project (a single .ino file),... |
H: Differential pairs / Single ended and the need for baluns
Excuse any blatant mistakes, I'm very clearly learning this new. Anyway from a purely transmission line perspective, it seems you can have a single ended line and a differential pair. I see the single ended (like coax line), where the return path is the shie... |
H: TO-220 vs TO-3 advantages/disadvantages
Simple Question:
What are the advantages and disadvantages of TO-220 package vs TO-3 package in different applications/power requirements? Is there a best route?
AI: TO3 package is obsolete. It was introduced in 1956 along with the first germanium power transistor. To its cre... |
H: Limit of applicability of "quasistatic"/capacitive picture of devices
When analyzing the transitories associated with switching in semiconductor devices, in textbook treatments one often sees the time dependence considered by including (potentially nonlinear) capacitors in the device. My question here is about tryi... |
H: Ferrite Loopstick Antenna Grounding
I've built a simple tuned frequency radio based a description in Ronald Quan's book. I have two questions about the tuning part of the circuit. The radio has a ferrite core antenna with two separate coils. The primary (most turns) is connected to a variable capacitor and the s... |
H: Assign statement in testbench doesn't seem to work as it should
I have a small Verilog code example asked as an interview question. I am not sure why it prints "p=01" but not "00" since assign should update p as soon as the value of q changes. Or does it work differently in a testbench?
module tb;
reg [1:0] p,... |
H: Why does light doping imply a large temperature coefficient?
In a discussion about how one can make integrated resistors in a given IC technology, Gray, Hurst, Lewis, and Meyer (Analysis and Design of Analog Integrated Circuits) remark that if we want to use a lightly-doped layer (e.g. a layer targeting the base re... |
H: OrCAD - Splitting signals
how can I split signals like in the picture below in OrCAD? I was trying to find it, but unsuccessfully.
AI: Those are voltage ports and its essentially like drawing a wire between two points. If you need another point, just add one with the same name or attach another set with a different... |
H: Where is the body terminal of a FinFET connected usually in digital circuits and in analog circuits?
What is the usual practice in industry regarding the body terminal of a FinFET?
Is it connected to the source to eliminate body effect?
Or is it connected either to the ground(nfet) or the supply(pfet)?
Is this matt... |
H: I need the name of an electrical spring switch with a thin rod inside that completes a circuit upon impact
I had a transparent ball that lit up when you bounced it. Inside it had a tall thin stiff spring, and inside the spring was a metal rod. When the ball bounced, the spring moved to contact the rod and completed... |
H: Confusion regarding solar cells
I am very confused by these two videos.
This video mentions at 1 minute onwards that a solar cell has a PN junction.
This video mentions N type solar panels and P type solar panels.
From that what I am able to understand, N type solar panels do not have a PN junction. It only has N t... |
H: Output voltage not changing with a constant current driver
If I attach a voltmeter to the output of this constant current driver and lower or raise the input voltage (100-230V,) the output voltage remains constant at 56V. Should it not fluctuate between 40-58V?
AI: This means this driver will output 350mA constant ... |
H: Why do manufacturers label differently seemingly identical components?
I am not sure if this is the relevant place to ask this (I think it is.)
I am still relatively new to the electronic design world, but I notice that a series of parts (example - Torex XCLxxx) can feature ICs whose specifications can be 90% ident... |
H: Capacitor polarity marker significance
What I am not asking is what capacitor polarization means, or how to apply it in circuits.
Is there any physical significance to whether a capacitor uses its positive or negative leads to mark its polarity? Prompted by Andy aka's comment on this answer.
AI: The short answer is... |
H: Transfer function of a heating system
I wanted to design a small temperature-regulated DC heater for the sake of educational purposes in the field of control theory.
The idea is to heat up a resistive element through a buck converter of some sorts and to regulate that with a control loop involving a PID controller ... |
H: What actually causes the need for a balun on a dipole fed to coax
My current understanding: The line in the center of the coax and the inner side of the shield are the current paths, as in the signal/field propagates between these two, (i can't therefore imagine it matters if the outer shield connection is grounded... |
H: How does this SystemVerilog compiler directive work?
The text I am reading (Stuart Sutherland's text on SystemVerilog for Simulation and Synthesis) gives the following snippet which apparently should be used in order to avoid including the same package multiple times in the same compilation:
I am a bit confused ab... |
H: Dual MOSFET short circuit
I have a PCB as shown in the schematic.
Looking at only one of the dual MOSFET ICs, I apply 3.3V to MOSFET2 and MOSFET1, which should turn off MOSFET1 (because P-channel) and turn on MOSFET2 (because N-channel.) What happens is that both MOSFETs are on, even though the P-channel one should... |
H: Voltage detected on output SSR while in "OPEN" state
I have an SSR relay ( FOTEK SSR-25 DA ), it has load terminals marked (1) and (2).
In normal "open" position there's no connectivity between 1 and 2 - no current whatsoever.
The moment I apply 120VAC to the terminal 1 - I can immediately see that there's 120VAC o... |
H: Interrupted SSI clock sequence
I measured the following clock and data sequence (time axis is in microseconds) between a Beckhoff KL5001 encoder module and a 19-bit SSI encoder. Apparently the clock is interrupted 3 times before stopping finally.
I was not able to find more detailed description of such clock interr... |
H: How to extract voltage and current from this real-life circuit (with resistors)
I recently measured some voltages across two resistors as you can see in the images below.
I used a triangle wave as voltage source and measured the voltages across the resistors with an oscilloscope.
The top one is the theoretical circ... |
H: Scale and shift small positive analog voltage range for ADC input
I want to measure a small positive analog voltage, 3v +/- 200mv with the ADC of a microcontroller.
The ADC measures voltages between 0 and 3.3V, so ideally I would like the voltage I am measuring to be mapped to that range.
I was able to find this po... |
H: What happens when I drive a signal into the center tap of a center tapped transformer?
I am trying to drive both a high-side and a low-side MOSFET as part of an H-Bridge circuit and had the idea to gang both MOSFETs with the same input. My idea was if I drive one side of a center-tapped transformer the other side b... |
H: Does DC-DC 24V-12V waste less power than AC-DC 220V-12V?
I am modifying an existing UPS to allow for a longer backup time. I plan on adding a cooling fan along with an external current controlled power supply to charge the larger batteries. There are some appliances in the my setup that run on 12v (monitor, desk li... |
H: Reduce component count for BCD input error detection
I made this circuit that reads the input of the DIP switches and detects if the input is an error or not a BCD value. The problem is I have 4 inputs for my circuit.
The LED indicate if the input is correct or wrong; if correct then allow input to pass, if not, ou... |
H: Can you convert a radio receiver frequency from 315 to 433 MHz by changing the antenna?
I have an Audi Tyre Pressure Monitoring System (TPMS) module from the USA, which therefore means it operates on 315 MHz. It was not available in Europe and hence there isn't a 433 MHz version available.
However, interestingly th... |
H: Error Indicator Light on Heater
I have a heater with a neon bulb wired in parallel with a safety cutoff switch. The full current of the heater goes through the safety switch. If the switch trips, wouldn’t the full current just go through the bulb, very briefly, and burn the bulb out?
AI: No, because the bulb has a... |
H: STM32 and Elegoo supply voltage
I wrote code using an STM32F407 to read the voltage of a potentiometer on the input pin of the ADC.
This is the circuit:
I tried taking the power directly from the STM32 and then, as in the photo above, I tried taking the power from the Elegoo board. In the case of the STM32 I can ... |
H: Verilog code for three-storey building
Ground, first and second floors and the inputs are r0 for ground, r1 for first floor, and r2 for second floor. The output will be d1, d2, up1, up2, and n (no action). Frequency is 215 Hz.
State diagram (Moore design) for a lift (elevator):
This is the code I tried:
module l... |
H: Struggle with gated sound - Fuzz stompbox
I built my first fuzz pedal based on the Tone Reaper but I can't handle with gated sound.
Whatever the fuzz pot is set the sound is gated. At low position the signal is very weak and chopped, even with no compressor in the signal chain.
I verified all components and replac... |
H: How can this RF amplifier increase the voltage above power supply level?
It must be something simple I am not getting in electronics, but this UHF RF amplifier (of which China has helpfully erased the part number on what I take is the transistor) produces 13 watts of output power while only takes 12-15 volts of sup... |
H: Keep a relay latched for 2-3 seconds using capacitor
Building a simple prototype to keep the relay latched for a couple of seconds after power is removed - so essentially the power to relay acts as the Input signal. This means I have to store energy in a capacitor (to keep the relay latched) and possibly use resist... |
H: PV Microinverter Topology Explanation
Can anyone explain how this topology works and/or point me to any literature where it is discussed?
I've found Microchip's application notes on single stage interleaved flybacks with SCR or MOSFET unfolding bridges and have a pretty good understanding of those. My best guess i... |
H: How is a resonant bandpass filter similar/different from a damped mass-spring oscillator? They seem to behave different in testing
Background
I am using resonant bandpass filters as musical oscillators. One can excite an array of them at harmonic frequencies and given Q values for a note by, for example, running a ... |
H: Diode in reverse lights up LED
I have small issue with my circuit that I can't wrap my head around.
I have made a custom PCB powered both by USB and battery. I put a diode between them to block battery power from flowing into USB when both are connected.
This diode doesn't work as intended because when I plug in th... |
H: Can TSOP1130 work also at 850mn?
In the sheet, they test it with a 940nm IR LED. There are no clear specifications for the wavelength (range) it works with.
But I have 850nm LEDs (powerful ones).
Will it work the same, or will it perceive a weaker signal?
AI: From the question:
But I have 850nm LEDs (powerful ones... |
H: Can TCC-100/100I Series Industrial RS-232 to RS-422/485 converters with optional 2 kV isolation convert RS485 to RS232?
I want to convert RS485 to RS232 to connect it to a Moxa Nport 5610 - 16 port RS-232 Ethernet serial device server.
Can I use a TCC-100/100I Series Industrial RS-232 to RS-422/485 converter to con... |
H: Calculation of the cross section of the busbar in the switchgear
To calculate the cross-sectional area of the copper busbar, it is necessary to calculate the permissible current of the busbar.
One of the correction coefficients that must be multiplied in this current is "the copper busbar surface temperature correc... |
H: Why aren't baluns needed for a monopole to unbalanced coax connection?
I've asked before regarding dipoles connected to unbalanced lines. From what I gathered, the current in the inner shield when reaching the dipole (in transmitting case) can either go into the pole connected to the shield and also the shields out... |
H: Base resistor on BC817-40
There are base resistor calculators and multiple questions are answered on the subject of base resistor calculation. However, the BC817-40 I am using from MCC is showing two different gains (HFE1 and HFE2). That is confusing me to do the calculation of the base resistor.
I have 3 IR LEDs (... |
H: Varistor-based SPD device - how does it protect the load?
These common SPD devices are put in the main panel of residences: https://aptghana.com/wp-content/uploads/2020/11/SPD-2.jpg.
This basic circuit showcases how they are installed:
simulate this circuit – Schematic created using CircuitLab
They are put in para... |
H: Does speeding up a diesel generator result in a better load response?
If I speed up my prime mover (500 kW CAT diesel generator) from 60 to 61 and 62 Hz 1800/1830/1860 rpm and hit it with 25/50/75/100 percent load steps, how much, if any kW/HP is gained?
I am simply trying to get more HP for a temporary transient a... |
H: What does (DW) mean in the TI equivalent of SOIC (16) package?
TI datasheet says:
SOIC-16 Wide Body (DW) and Extra-Wide Body (DWW) Package Options
It doesn't mention what DW stands for.
I am annoyed when manufacturers come up with their own naming conventions without explaining clearly the accronymns or the logic... |
H: Altium Layer Stackup for Aluminium (IMS) PCB
I am needed to do a single layer PCB in Altium. I have no routing on the bottom layer but in the layer stack manager, I am not able to remove the bottom layer copper. Also, I can't choose or find any aluminium core.
This is my current stackup:
For aluminium based, is th... |
H: Tri-state input to three logic states
I'm looking for an IC or small circuit that implements the following truth table:
Input
Output 1
Output 2
H
H
L
L
L
H
Z
H
H
Is this possible?
The purpose is to keep an SPI SS signal pulled high for two devices when the input is high-Z, and to otherwise select on... |
H: Capacitor test mode in ICT
My ICT machine has two capacitor measurement modes on the PCB:
Mode 1: Use DC source test method (Figure 1)
Mode 2: Use AC source test method (Figure 2)
Could anyone please help me with the questions: What is the importance of each mode? When do we use mode 1? When do we use mode 2? It ... |
H: Using ARM Cortex on breadboard
I want to know if can I use an ARM-Cortex-M4 processor directly on a breadboard and then create a microcontroller on a breadboard. I already tried searching google but didn't find anything.
Please note that I am taking about "creating" a microcontroller on a breadboard and NOT "using"... |
H: Puzzling 'conductor' in a bathroom scale
Hoping to scavenge the LCD from an old bathroom scale for another project, I took it apart. There were four sensors -- one in each 'foot' of the scale -- all wired to a small circuit board whose back half is shown below, with the neat line of traces near the top. Sitting ato... |
H: Power Supply for STM32G071CxU microcontroller (VDD/VDDA vs VREF+ for analog peripherals)
I am currently working on a STM32G071C8U7 microcontroller schematic and have some questions regarding the decoupling and general connectivity of the power supply pins.
First I am presented with this diagram that clearly indica... |
H: Highest speed of operation [BJT vs MOSFET]
This question was asked in a competitive exam in India.
Which of the following offers highest speed of operation?
(a) BJT
(b) FET
(c) Enhancement Mode MOSFET
(d) Depletion Mode MOSFET
As far as I know, the speed of operation depends on application. In some applications, MO... |
H: KVL on circuit with transistor
I have a question regarding applying KVL in a circuit with a npn-transistor. Unfortunately this is badly documented in the textbook, and I couldn't find the answer so far.
For the circuit below, it was given that V_BE = 0.7, and from this V_CE = 0.8V is derived. This was derived from ... |
H: Choosing Contactors for an EV Battery Pack
I’m designing a battery pack and am uncertain about which contactor to select. Many electric vehicles (EVs) use three contactors: one each in the positive terminal, negative terminal, and precharge circuits. I believe we can use one type of contactor for all three position... |
H: How to simulate a 30 inch FR-4 lossy channel (20dB loss) using ltline symbol in LtSpice?
For designing a high speed serdes system, I need to model a lossy channel of FR-4 substrate of length as 30 inch and 20dB attenuation. How can I implement it in LtSpice tool?
AI: Use the lossy transmission line element:
You'll... |
H: Matched junction S parameters
This question was asked in a competitive exam in India. Two-port S matrix is assumed here.
For matched junction S parameters, which of the following is correct ?
(a) S11 not equal to 0
(b) S11 equal to 0
(c) S21 equal to 1
(d) |S21| equal to 0
As far as I know, matching mean "zero refl... |
H: How to choose the proper value of resistors for current dividers
Edit: The original version of this question is malformed. There is an edit further down below with an updated explanation of the issue I'm trying to solve.
In a simple current divider, I know the ratio of the parallel resistors determines the current ... |
H: How to convert SR (NOR) latch into S'R' (NAND) latch
What is the general rule of thumb to convert SR (NOR) latch into S'R' (NAND) latch? I only know the two inputs (S,R) need to be inverted. What about outputs (Q)?
AI: For normal operation, the conversion is as you describe. A NOR ff has positive-true logic action... |
H: Wheatstone bridge connected to op-amp: confusion about Vout formula
I am not sure when the correct formula for Vout is Vout = G(VA - VB) or Vout = -G(VA - VB).
Can you explain the difference between these two examples? The circuits and the formulas provided are from my textbook, yet I struggle to understand how th... |
H: What is the "problem" with directly coupled amplifiers?
As in the title, my question is basically about understanding what is the "problem" with directly-coupled (below, I will use dc for "directly-coupled" and DC for "direct current") amplifiers which necessitates the use of coupling amplifiers? Note that this que... |
H: Could a voltage divider with more than two resistors be used?
As a step in an exercise, I'm trying to find voltages \$V_1\$ and \$V_2\$ below
Could a voltage divider (with more than two resistors) be used here? So that, for example:
$$V_2 = \frac{2\ \mathrm{k\Omega}}{2\ \mathrm{k\Omega}+1\ \mathrm{k\Omega}+2\ \mat... |
H: Half-bridge driver giving high-side gate full input voltage
Using an IRS2513 half bridge driver tuned at 30 kHz with 1MBH60-100 1000 V, 60 A IGBTs, the driver is giving the high-side gate the full 24 V input voltage.
I have included a picture of how I configured the driver and how the oscilloscope looked when measu... |
H: Strange comparator behavior
I am testing the following comparator schematic:
simulate this circuit – Schematic created using CircuitLab
I've replaced the original 280 kΩ resistor with R1 and trimpot R3. The hysteresis resistors are calculated to switch on at 30.78 V battery (2.54 V on + input) and switch off at 29... |
H: Protecting parallel loads
I have a project that has two separate sections that must be powered from the same power source. I do not know the resistance of said loads, but I know the power supply that each of them on their own would need. I apologize in advance for any ignorant mistakes you find in this question, I'... |
H: Why is the output voltage across the load dropping a lot in this audio amplifier circuit?
I am making an audio amplifier circuit in LTspice. This is the circuit that I've made:
Notice that the input is 20 mV. The output plot is as follows:
That is around the gain I want to obtain. The speaker that I will be using... |
H: Trigger a 3 V line with 12 V
I would like to trigger a 3 V line (a push dimmer circuit) with a touch button (which is powered by 12 V).
Closing the 3 V will turn off (short press)/turn on (short press)/dim (long press) the LED strip.
Here is my complete circuit:
How can I connect the outgoing 12 V line from the to... |
H: CMOS (Energy Supply of voltage)
Can someone please explain why, when \$ln\$ is transitioning from low to high, the energy supplied is \$C_{vdd}\cdot V_{dd}^2\$?
AI: The formula for energy stored in a capacitor is:
$$ E = \frac{1}{2}CV^2 $$
In either state, one of those capacitors is fully charged, with energy \$\fr... |
H: Is 3004M1C a photodiode or a phototransistor?
The datasheet describes the 3004M1C as a "high speed and high sensitive PIN
photodiode". Distributors also label it as a photodiode. However, the datasheet mentions "Collector-Emitter Breakdown Voltage", "Emitter-Collector Breakdown Voltage", "Collector-Emitter Saturati... |
H: Assistance identifying an op-amp marked "H2P IFA"- includes photos
I'm looking for help identifying this chip, which I believe is a dual op-amp (pin 4 is grounded, pin 8 is power). Package appears to be QFN, possibly with a pad (there are no vias under the chip). I suspect an op-amp because of the application (anal... |
H: Why do different multimeters give me very different current measurements?
I was trying to calculate R_TH using an open-circuit voltage and a short-circuit current, and I am having trouble with the current measurement. I noticed that my calculated R_TH didn’t match my measured value.
I’ve tried 3 different multimete... |
H: DC motor control algorithm with low sample rate
I have a system driven by a geared DC motor spinning at between 500 and 1000 RPM. Once in operation, the load on the motor will not change and the speed should be held constant.
I have a single digital Hall-effect sensor sampling the output of the system once per rota... |
H: How to get megahertz frequency with a 555?
I need to produce a 1.7 MHz signal. Up to around 200 kHz the 555 IC and my simple astable circuit are working just fine as expected, but when I decrease R1 and R2 to less than 100 Ω the frequency doesn't increase more than about 200 kHz.
I tried reducing C, but got the sam... |
H: How to boost the gain of this comparator?
I'm trying to implement a comparator for ADC. The schematic is shown as follows.
Image source: S. Lan, C. Yuan, Y. Y. H. Lam and L. Siek, "An ultra low-power rail-to-rail comparator for ADC designs," 2011 IEEE 54th International Midwest Symposium on Circuits and Systems (M... |
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