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H: What does this mean in the datasheet for PWM motor control?
My aim is to control a DC servo motor through PWM. It has a motor controller attached to it that takes in some DC source and PWM for controlling the motors.
I programmed/used a myRio (MCU) to produce PWM from one of its pins and connected it to the motor c... |
H: UART printing gibberish to the terminal when the STLink Debugger is not connected
Custom board, not an ST development board.
MCU: STM32G031J6M6 SO8 package. UART RX/TX are Pins 1 and 8 respectively.
Pin 8 is also SWDCLK
Pin 7 is SWDIO and not used except for SWD
NRST is Pin 4 and has an internal pull-up.
From readi... |
H: Is it bad practice to use the positive/rising edge of a "non-clock" signal?
Situation:
Before a data ready signal can go high it must wait for a data valid signal to go high. Once data ready goes high, data ready must remain high until a separate process is complete which should reset data ready to low and again da... |
H: Which Kicad footprint represents a 2.2 µF MKP audio coupling capacitor?
I'd like to add six rectangular-shaped 2.2 µF MKP capacitors used as coupling caps for an audio circuit to my PCB in Kicad, but I'm not quite sure about the right footprint.
What makes the choice even harder, is the fact that these caps are ver... |
H: Can I automatically create a net class from this Blanket + Parameter? [ALTIUM]
I added this blanket + parameter to my schematic, and now I want to create a net class from all of the nets that lay within the boundaries of the blanket.
Do I have to manually add all of the nets, or is there an easier way to do it?
AI:... |
H: Line termination for single-ended to fully-differential conversion
I am trying to convert a single-ended signal from a sensor to a differential one by using THS4500 from TI. The output of the sensor goes through a buffer before being connected to the fully differential amplifier.
There are two configurations that I... |
H: Switching a load using a 2N2222 transistor with a Wemos d1
So I have this... device... that draws about 0.1~0.2 A and requires 3.6 V. In the below schematic it's represented as a speaker. I want to be able to toggle the power to this device with a Wemos D1 mini (sadly, represented below as an Arduino since I can't ... |
H: Changing opamp reference in linear power supply not giving expected results
I am currently working to make a 30V 5A linear power supply and came up with this circuit so far. The circuit is supposed to give twice the reference voltage Vref.
This is the output voltage that I am getting which is the expected output.
... |
H: Slayer exciter doesn't work
I know that similar questions have been asked here, but none of the answers seem to work for me. Also, I am new to this site, and I am not much of an expert when it comes to electronics, so feel free to tell me if I forgot any important information, or if you need more information and wa... |
H: Positive edge reset and negative edge reset
I am new to Verilog and I am trying to implement an asynchronous reset.
I have difficulties understanding the difference between using always @ (posedge clk or posedge reset) and always @ (posedge clk or negedge reset).
What are the differences between them and which one... |
H: Is there less noise in an E-MOSFET than in a D-MOSFET and if so, why?
Since there is a threshold voltage needed to switch on a E-MOSFET, as compared to no threshold voltage needed to switch on a D-MOSFET, I would deduce that a E-MOSFET has lower noise than a D-MOSFET.
Is my reasoning correct? Is there less noise in... |
H: Valid Use of Voltage Divider Supply?
I know it's not a good practice to use a voltage divider as a power supply, but I'm considering it for an unusual circuit. Is this a good use of a voltage divider or is there a better way to do this I'm not considering?
This is a latching power shutdown circuit. The purpose is t... |
H: Sony HiFi STK 403-130 Question
I am going to separately use sony HiFi stk 403-130 amp circuit.
In the below image, I marked numbers in RED
1 - What voltage 5/9/12 DC/AC should I input to run number 3 Relay.
2 - What voltage 5/9/12 DC/AC should I input to mute sound.
AI: 1 - What voltage 5/9/12 DC/AC should I input ... |
H: SOIC-8 package size error
I designed a PCB using both NE5532 and OP177 opamps. In principle both opamps are in SOIC-8 packages. However when I received the opamps, I found the NE5532 are much larger than the footprint they were designed to have on the PCB (using the KiCad SOIC-8 3.9x4.9mm footprint).
If I measure t... |
H: Why are we able to ignore the henries, Hz, farads, siemens and ohms when calculating the characteristic impedance of a transmission line?
I have seen calculations, and every time we just take the coefficents of these values and end up calculating a simple complex number. The units all equate to various exponents of... |
H: Where is my capacitors energy missing?
To avoid "mistakes", may I recall that, mathematically, \$\infty \times 0 \$ can be ... finite!
Otherwise, why use a Dirac impulse?
After reading this and this, I have yet a "question" about the energy stored in a capacitor and transferred to another capacitor of the same valu... |
H: BJT Amplifier Simulation
I am trying to build a simple CE amplifier for an AM signal as part of a home-brewed transistor radio. I would like to have a working simulation before I get a breadboard. My simulation works in small time-steps but not large time-steps and I have no idea why. Falstad Simulation
Before you ... |
H: Input resistance of a non-ideal op amp
OP1 has a finite input resistance, but an infinite open loop gain (other parameters are also ideal). The other two op amps are ideal as well. Can I still assume that there is a virtual ground between the positive and negative terminals of OP1 and the input resistance (Rin in ... |
H: How to derive the below equation
First, I would like to verify is the circuit I drawn correct? Rin is consider large enough to be negligible in the equation.
I tried using KVL to obtain 3 equation as below, considering to get vth and Isc so Ro=vth/Isc
$$-v_i+i(R_1+R_2+R_{out})+A_{vo}V_d=0$$
$$-v_i+iR_1-V_d=0$$
$$... |
H: Power rating for a 2 ohm resistor on the input power rail of a 5V DC circuit
I'm working with a surface mount IC in an SOP-8 package. The IC handles LIPO battery charging at up to 2.1A. It also provides an integrated boost converter with 5V, 2.4A output. Below is an image of a prototype I built that works fine usin... |
H: What is this symbol that looks like Ø on a schematic?
I'd like to ask about this "empty set" like symbol with a diagonal line through a circle, as shown in the picture below. I have found it in an old electrical schematic. What is it exactly?
AI: Those are terminals. Usually they indicate where external devices are... |
H: TTL voltage drop
I recently bought a lot of TTL components like 8-bit registers, bus transceivers, etc. to build an ALU and 2 registers. My issue is that when I build a register, the voltage drops to 4.2, sometimes even below 4V even though I put resistors in every output in series with the LEDs. I built 2 8-bit re... |
H: How to add a flyback diode to protect a relay on another PCB that does not have a flyback diode
I have a PCB (SEPARATE PCB) that I want to test by building up a "Test PCB". The test will involve switching the relays. This PCB (SEPARATE PCB) has a few relays on it, however, they do not have any flyback diodes on it.... |
H: Why does increasing torque on DC motor in circuit affect the speed and functioning of another DC motor in the circuit?
I am working on a project in which there are system components listed below as module:
8 ultrasonic sensors 12-30 V (Sensor module)
3 DC motors (Drive module)
35 V to 5 V buck converter and a 35 V... |
H: 80% amperage rule for continuous loads?
I'm trying to understand how an electrical load affects a circuit.
Let's say, for example, I have a setup that is on a 120 V, 15 A circuit:
120 V x 15 A = 1,800 W max
if we have a continuous load (3+ hours), then we should aim for 80% amperage; so 15 A becomes 12 A and 120 V... |
H: Asynchronous generator - Is the calculated stator current here phase current or line current?
Please see the below circuit schematic for an induction (asynchronous) generator.
I have a delta connection, with a voltage = 380V, so phase voltage = line voltage = 380V
Then I calculate the stator current: I_stator = Vo... |
H: BJT astable multivibrator frequency increasing with voltage
I'm trying to get a 27V 120Hz square-wave, so I tried this circuit :
I get a decent 128Hz signal with 9V, which is close enough. However, if I increase the input voltage past a certain point, the frequency increases too. For 27V, it is about double, 250Hz... |
H: How does a power plant's increased output translate to the Volts, Amps and Watts on the power lines?
In the context of a power plant, that wants to output more electricity.
If the formula for Watts is V*A=W, does Voltage or Current get increased to supply more Watts?
AI: How does a power plant increase load?
Power... |
H: Will this power supply be able to power raspberry pis
I don’t know if this is the correct place to ask but I was wondering if this power supply will be able to power 4 raspberry pis.
Here is the link: https://m.aliexpress.com/item/32946637768.html?spm=a2g0n.shopcart-amp.item.32946637768&
I’m planning on making a pi... |
H: NPN transistor resistor from base to GND. Is this useful?
I have a circuit where many NPN BJTs are interfacing 3.3 V GPIOs with higher voltage circuitry. Each application has a similar setup to the image below (resistor R422 is what's in question). I did this myself, but I am not sure where I got the idea to add ... |
H: Circuit to convert a pulse signal to square wave
How can I convert a pulse signal into a square wave.
I have a pulse signal created using a Function Signal Generator, ZK-PP2K Pulse Frequency Generator 8A Driver Module LCD Pulse Frequency Cycle Module 1Hz-150KHz Motor Controller LCD Display https://www.amazon.com/Fu... |
H: AVSS pins in PIC18f46k80
I'm trying to use ADC module in PIC18f46k80 and I want to connect VREF- to AVSS. But the problem is that I can't find AVSS pin in this microcontroller:
Is AVSS the same as VSS here? meaning I simply have to connect VSS to gnd?
AI: That is correct. On the package types which does not have t... |
H: Current versus voltage not exponential above forward voltage of diode?
I have done a simple current over forward voltage simulation for a PN diode with LTSpice.
I wonder why the curve is only exponential around the "knee-point" but it seems to be linear when going above that point. I assume that this is some effect... |
H: Controlling Relay using ESP8266 Module
I have 5 such relays attached to an ESP-12E module with a 600ma Power Supply. The LED (LED4) glows but the relay doesn't switch. Is there anything wrong with my schematic?
Using MMBT3904 instead of a BC848B and using a 5V sugar cube relay.
AI: For comparison, as you have a dri... |
H: Why don't oscilloscope probes use twisted pairs?
I was reading online about how Ethernet cables use twisted pairs instead of coaxial cables because it's better in some way. Some websites say that twisted pairs cost less, can carry higher frequencies, and filter out noise, cross talk, interference, etc.
This website... |
H: Identify PCB components from picture
The whole pcb represent a filtering and amplification stage for an incoming analog signal, before leading to and A/D stage.
reference: page 20
doi:10.1088/0967-3334/33/6/943
(I didn't want to post a reference that somebody might not have access to, but yes, it might be helpful)
... |
H: Designing a pi filter (C-L-C) for the output of a TPS62740 buck converter
We are using a TPS62740 IC as DC-DC converter.
We are getting ripple at the output in the range of 10 mV to 12 mV, so we are thinking to add a pi (C-L-L) filter at the output of the DC-DC converter.
As you can see, the peak-to-peak voltag... |
H: High-side current sensing questions: Gain formula and circuit type
What is the formula for the gain in this circuit? I can not find a good description of the operation of this high-side current measurement. Why is there a PNP transistor at the output? What is the name of this configuration?
This is the circuit from... |
H: Diodes made using separate p and n-type semiconductors
Can a diode be made by connecting, in series, separate n and p-type semiconductors?
Assume that all ends are attached to Ohmic contacts. I am hoping that this will prevent any discontinuities in the potential.
I have seen a similar question on the Physics Stack... |
H: P-channel high side mosfet getting hot when not in use
My high side mosfet shown as Q2 in the diagram gets very hot when not supposed to let any current through it.
When DIR1 is high and DIR2 is low current is supposed to run through transistor Q1 through the motor and through Q4 and Q5.
These three transistors see... |
H: Should battery be disconnected on both terminals?
I am building an EV and I was wondering, should I disconnect only positive or both main HV battery terminals? Which option do car manufacturers use? I don't see any disadvantages with disconnecting only one, unless there is some damage to battery pack and possible s... |
H: Include a txt file in an .ac Ltspice simulation
I have a .txt file containing measurement of an impedance I have performed.
I know that in .TRAN simulation I can easily include a measured voltage or current (saved in a .txt file) in my LTSpice simulation. However, how can I do the same in an .ac simulation? I do no... |
H: Why do Zener diodes have a lower breakdown voltage than normal?
Here I do not understand some physics.
So for normal diode we have a depletion zone width say Wn, and for Zener diode we have Wz.
Then, we know that Wn > Wz. By reverse-biasing we make the depletion zone wider, until Epn is too high, and eventually eve... |
H: A circuit cannot contain two different currents in series; otherwise KCL will be violated
I'm currently studying the textbook Fundamentals of Electric Circuits, 7th edition, by Charles Alexander and Matthew Sadiku. Chapter 2.4 Kirchhoff's Laws gives the following example:
Kirchhoff’s current law (KCL) states that ... |
H: How to control voltage using PID when driving SCR?
I am designing a scr based digital battery charger for the first time and have successfully driven scr to provide 110V-DC from a 140V singe-phase transformer. 2 SCR-diode combination forms full bridge rectifier and each scr driven via gate driver controlled from so... |
H: What do the stars in a power meter symbol mean?
Sometimes I see stars in a power meter in three-phase circuit are drawn as below.
What do the stars in a power meter symbol mean?
There is another example here (page 14/20):
Now it seems to me that they are dots to indicate the polarity of the windings.
AI: Power i... |
H: Expected behaviour of a non-inverting buffer IC
I am using an NL17SZ07 buffer w/ open drain. Is it to be expected that I need to pull the output high with a pull-up resistor to have the output behave as expected?
I would have anticipated that the output would step with the input at the supply voltage, without the n... |
H: Voltage drops when current reaches limit on supply
Why is it, when I'm powering a circuit via a lab bench power supply set to limit 2 mA and the current drawn from the circuit reaches the limit, the supply voltage drops?
AI: That is called Constant Current Constant Voltage (CC/CV). The power supply has to lower the... |
H: Which IC with top mark 15ZL is shown in this image?
Can anyone determine the part number of this IC with top mark 15ZL and find the datasheet?
AI: Looks like a Torex XC6201P302MR 3.0V LDO regulator. |
H: Is there a way to determine polarity of a DC device that has missing power adapter?
Let's say someone has bench power supply and a multimeter, then is it possible in safe manner without damaging device to use these tools to determine devices polarity?
Update#1:
In this specific case it is braun shaver. I was able t... |
H: DC coupled amplifier circuits
How can the transistors in an op amp's differential input turn on if the input voltages are smaller than \$V_{BE}\$, like 0.2V? How can the transistors in the differential amplifier start conducting with such small voltages? I understand how with AC coupling one can bias the inputs of ... |
H: Are "switched" TRS connector pins (sense pins) suitable for audio multiplexing?
TRS jacks are commonly available with "switched" or "sense" contacts, like this:
This form is commonly used to ground the input pins when nothing is plugged in. But can these contacts also be used to multiplex an audio signal, like thi... |
H: Modelling I2C capacitance for cables under water
My setup works fine with following combination of hardware:
Raspberry Pi4 connected to a TCA9548A I2C Multiplexer from Texas Instruments, whereas each channel is connected over 4wires (GND, VCC, SDA, SCL) with 140cm 30awg silicone wires to two more I2C sensors.
In th... |
H: Low voltage at N-Channel source pin
I made a pcb which uses an N-Channel Mosfet for enabling/disabling the NTC thermistor as in the schematic below. The problem is I get 2V at the Drain pin instead of 3.3V. I measure 3.3V at NTC_TRIG and power pins with a voltmeter so there isn't any issure there.
Currently using t... |
H: Is low humidity bad for HIPOT testing electrical harnesses?
From what I understand for HIPOT testing high humidity could be a potential issue because if cable insulators absorb moisture that could affect their resistance.
What about low humidity? Is there any reason why low humidity would be bad for HIPOT testing? ... |
H: Can anyone please identify this chip?
Is from an LED board from a modern Pinball machine. Seems like the output is connected to a 74HC594D legs RCLR and SRCLR.
AI: Possibly ST Microelectronics STWD100NYWY3F watchdog timer. However other SOT23-5 ICs could bear this marking, so this is by no means definitive. |
H: DC DC converter
I am newbie trying to build a circuit, please help me out.
I am trying to build a DC-DC converter whose input will be 24V and output would be 5V 3A.
I have picked AP63301WU-7 DC DC converter from Diodes Inc.
As per the application circuit, I have to use two resistors 158Kohm and 30.1Kohm that act as... |
H: Stand alone CAN bus module or STM32 embedded CAN?
I have spent days studying and trying to achieve simple communications with CAN bus from scratch using stm32f1, but I still have not achieved the desired results and it is difficult to understand and program.
On the other hand, there are CAN bus modules that communi... |
H: Touching the antenna of a crystal set
I built the crystal set shown in the diagram below and I find that the signal it receives is clearer when I touch an uninsulated part of the aerial (i.e. the node labelled "green" on the diagram). Would anyone be able to explain why this happens? Thanks.
(Source: S. Voron, R. ... |
H: Equation (mathematical function) of ramp signal vs saw tooth signal
I have a sawtooth current source whose peak value is 1A. 0A to 1A. with a frequency of 1kHz.
This current source is going to charge a 1F capacitor, so I was trying to find the equation for the current source so that I can calculate the voltage acro... |
H: Slider operating force range
I'm reading the datasheet of PTB0153-2010BPB103. It states:
Mechanical Characteristics
Operating Force ................10 to 100 gf
Stop Strength ................. 5 kgf min.
Sliding Life .................. 15,000 cycles
Soldering Condition ........... 300 °C max. within 3 seconds
Trave... |
H: Attenuation in current booster circuit with op-amp
I was testing a current booster circuit in Multisim with a TL081IP when I noticed that I'm getting high attenuation at surprisingly low frequencies (above 1 kHz). The circuit and the frequency response is shown below:
From my understanding, I can't see why this i... |
H: practical connection of LED to a MCU
While aiming to blink an led with this 8051 MCU, I used configuration 1 to connect my LED. It doesn't work. But 2 and 3 worked. logically, there should not be any reason behind why configuration 1 do not works. Because it will alternatively give 5V (assuming no tolerance) and 0... |
H: Feasibility of obtaining a 210µF 4.5kV DC capacitor?
I'm looking for a high-capacitance, high-voltage capacitor for a experiment I'm interested in trying out (i.e. order of 100µF rated for at least 4.5kV DC). I realise these specifications may be unrealistic, and am yet to find any capacitors like this available on... |
H: What is the purpose of capacitor C4 (47 pF) in the feedback network of this buck converter circuit?
What is the purpose of capacitor C4 (47 pF) in this circuit?
Datasheet
AI: The trouble with converters like this is that they can go unstable quite easily and need a hand to prevent this from happening. Unlike linea... |
H: What does Hot Swappable mean?
new to electronics. I am not quite sure I understand hot-swapping fully. It appears that hot-swapping is when you could replace a device while the system is operating without interruptions; however, how would you replace a device that needs to always constantly be turned ON if it turns... |
H: Replacing a 18650 battery that was being charged at 5 V
I'm trying to change my wireless speaker's battery that uses one 18650 battery, but when I checked the voltage that goes to the battery while it is being charged, I saw that it was 5 V.
I know that the charge voltage should be around 4.2 V - 4.3 V only, so my ... |
H: Do laptops use different batteries than powerbanks
So I was researching about laptop batteries and I got confused on whether laptop batteries and other batteries like power banks are the same. To clarify I was looking at the new MacBook Pro battery specs and it has a 100wh battery capacity which is around 8,800 mAh... |
H: What does it mean to have a large time constant of a RC network than the time period of an input AC signal
What does it mean to have a large time constant of a RC network than the time period of an input AC signal?
Can someone tell me how to understand this and what sense does it make?
AI: What does it mean to have... |
H: LTSpice: How to change x-axis (ac sweep)
I want to plot a Bode diagram. LTSpice automatically plots the results as a function of frequency. I would like to multiply the frequency by 2*π, in order to obtain the angular frequency.
How can I modify the x-axis quantities?
AI: Maybe this is ugly, but it seems to provide... |
H: What is this bridge like component?
As I was looking at some Texas Instruments evaluation module, FDC2214EVM to be precise, I found a component unknown to me:
AI: It's just a test point for easily attaching a scope probe ground.
The silk screen indicates it is connected to ground, there may be some for other signal... |
H: Working of a clamper circuit
I was reading about the clamper circuit on wikipedia and found this below image for a positive clamper circuit.
My question is
During the positive (Rising/increasing portion) half of the input AC waveform, the capacitor gets charged right? Meaning the positive charges are accumulated o... |
H: Can I amp a radio transmitter to increase its range?
I want to buy a sub-gigahertz radio module which has a TX power of 16 dBm. With the inverse square law, I can see that it has a power of -90 dBm at 50 km. I don't know if this is the correct way to determine power at a certain range or not, but either way, this i... |
H: Do Output Voltage rails get an identifying symbol in schematics?
For example, I have a 3.3V regulator using 5V input from a USB port. I use that output 3.3V rail all over my schematic.
Sure, I can read the entire schematic and see - yep, that's the output. But is there a graphic or unique symbol that indicates th... |
H: Is there any use of a 65 mV reference voltage?
I am a senior studying electronics, and have happened to make a bandgap reference circuit that gives out an output reference voltage of ~65 mV. I've constructed this after quite a few months of research and simulations alongside my mentor.
I wasn't really paying attent... |
H: Will internal signals impedance be affected by adjacent planes?
I am routing an 8-layer PCB, and need to have strict impedance control on one of my nets. The signal layer that the sensitive net is on is in between a ground plane and a power plane. Such as:
------- GND
------- Signal
------- Vcc
My question here is,... |
H: Are AC coupling capacitors required for the Clock lanes in the PCIe spec
I'm working on implementing a PCIe 2.0 x2 system on a with a Xilinx Ultrascale. Reading through the PCIe 2.0 specification it requires 75-200nF AC coupling capacitors on the TX lines coming from the baseboard device. What about the clock lanes... |
H: Is there a fuse holder equivalent for a diode?
When using a protection diode if it blows it does its job and saves a much more expensive component from getting damaged or destroyed. That's all fine and well but I was wondering about how we then can design this diode to be more easily replaced. Perhaps even by less ... |
H: STM32G030 BOOT0 pin - SWCLK
I designed a board with an STM32G030C8T6 MCU and some peripherals. The board is working just fine, regarding the functionalities, but I have some issues with flashing.
So, the first "strange" thing to me was that the BOOT0 pin is the same as the SWCLK pin. Generally, I always pull the BO... |
H: How to spread a current spike?
I have a 12V circuit powered by a 'smart' power supply feeding two USB sockets (similar to this one). The two sockets are parallel to each other and in series with a simple switch.
Whenever I flick the switch on, the supply's short circuit protection is triggered.[a] The supply stop... |
H: PSpice and calculations don't add up for an active band pass filter
I designed a basic active band pass filter and used these equations to come up with a center frequency of 29.9 kHz:
$$f_0 = \frac{1}{2\pi\sqrt{(R_1||R_2)*R_2*R_3*C_1*C_2}}$$
In PSpice, it looks like the center frequency is almost 36 kHz.
Did I use ... |
H: Parallel electret microphones
I want to make an electret microphone setup for my accordion. 4 mics on the treble side and 2 on the bass side.
Would I need a preamp for each mic and then mix the outputs using an opamp?
Or would it be possible to make it not using preamps or an active mixer? Would the signal be loud ... |
H: Decoupling capacitors in power card
This is a power card. I have highlighted the part between the EMI filter and the Transient protection module. Are those capacitors needed? As per the data sheet, there has to be an R*C cell.
Please correct me if I am wrong.
AI: Are those capacitors needed?
The Gaia FGDS-10A-50V ... |
H: Extract the nodal admittance matrix of a given circuit in LTspice
I am wondering if there is a way to extract the Nodal admittance matrix of a very complicated circuit using LTspice. Like draw the circuit or automatically generate a netlist (in the case of a very complicated circuit -using python for instance-) and... |
H: I can't figure out how to design my transistor practice circuit in way that it would work
I wanted to test out making a circuit with a transistor. The way I understood transistors from online videos:
The transistor (using BC327, see below) needs a closed circuit from the positive terminal through a resistor (first ... |
H: What is the function of emitter biasing of a transistor?
I have been reading about transistor biasing to counteract inaccuracies in transistor manufacture, add stability etc.
One circuit I can't see the benefit in, which is diagrammed in the datasheet for the PEMD17, has a resistor between the emitter and base. Of ... |
H: What crystal oscillator for a CH340G?
I think this should be a relatively simple question.
I need to know what would be the best kind of 12Mhz crystal to run with a CH340G driver.
I know barely anything about oscillators, and everything I found made me all the more confused. If anyone knows a simple answer to what ... |
H: Driving a Peltier Module via N-channel MOSFET H-Bridge
I'm working on a circuit to control a heating/cooling element (Peltier module) using an H-bridge. I'm using FDP8447L for that purpose. My Peltier is rated for 6 amps current and 15.4 Volts. The gate of the N-channel MOSFETS will be turned on through an output f... |
H: How do you convert dBm to Vrms?
I'm trying to convert dBm to Vrms.
The formula for dBm is
\$ dBm = 10 * log(P1 / P0) \$ where P0 = 1mW
so
\$ +13dBm = 20mW \$
If I convert this to a voltage using the formula
\$ P = Vrms^2/R \$ where R = 50 ohm, I find that
\$ Vrms^2 = 20mW * 50ohm = 1000mV \$
\$ Vrms = 31.62mV \... |
H: LPDDR3 length matching
I am designing a pcb using LDDR3 for the first time. There are some questions that confuse me.
Should I match all DQ,DQS,DM signals with equal length?
Should I match the common address CA signals with each other and with other DQ, DQS, DM signals at the same length? Is there a document you c... |
H: Advice to calculate the transfer function of circuits
I'm a bit confused, to get the transfer function, what's the approach to work out in the cascade arranges like these?
I know it should be done using superposition, but passing R2 and cR3 I got lost and can't land a KCL equation that makes sense.
I'm only asking... |
H: Grounding GPIO with separate PS to relay (not relay board)?
I am trying to control a 12 VDC Bosch Automotive relay with an RPi. I am using a separate 12 VDC power supply to trigger the relay. The RPi is using GPIO18 which is connected to a 1k resistor, which is connected to the base of a 2N2222 transistor whose col... |
H: Interfacing RJ45 to 3 pin RMII and bidirectionality
I am trying to add an Ethernet interface to a dev board (This board specifically).
From looking at the schematics, I see that it has a 3 pin PHY input (GND, TRX+, and TRX-). From my understanding, a CAT5 cable has 4 wires essentially (RX+- and TX+- and both can be... |
H: Is Ohm's law valid in AC circuits?
I am confused over this and I’m hoping for clarification.
By Ohm's law we can compute the resistance of a circuit as V/I. In the case of two sinusoids we have sin(x) / cos(x) or something like that. Doesn’t this give a sinusoidal resistance? I don’t understand this because resista... |
H: Is there a fluid that visually displays electrical voltage/current?
I have a device that subjects fluid in a cuvette to a DC voltage waveform for a few seconds. The device is pretty powerful (lots of capacitors), able to continuously deliver up to 1,000 Vdc @ 40 A through the cuvette.
I am looking for a fluid to u... |
H: Help identify an SMD (diode?) component
I suspect this is a diode: the board has PD13 marking next to it. I found a schematic for a similar product that identifies the PD13 as TVS_SMAJ20A. Would that make it a TVS diode?
AI: PD13 is a designator it doesn't really tell you the part number or the part characteristics... |
H: Impedance matching conditions for matching network
I'm trying to understand general concepts involved in impedance matching and I have a question about the conditions which should be satisfied by the matching network.
Assume we have in the most general case the classical problem of matching impedance between a sour... |
H: What is this component, is this a microphone?
I was researching projects and I saw a PCB. I am wondering what is this component. I don't know what it is so I want to ask you, what is this component? Is this a microphone?
I am asking about this big white thing.
Top side:
Bottom side:
Another PCB design, again they... |
H: Change range of a DC signal without changing the offset with op amps
I have a voltage signal with the following range:
low - 2.5VDC
middle point - 2.725VDC
high - 2.95VDC
I would like to condition this signal to:
low - 0.4VDC
middle point - 1.65VDC
high - 2.9VDC
I have only a +/-12VDC power supply available, op-amp... |
H: Why doesn't my LTSpice simulation get the same results as this one?
Here's what i want to have as a result:
Here is what i have:
I have an ideal op amp and the green curve only hits 5 Volts when input is 2.7V, in the video it's 2.55. The green curve only hits 0 volts when input is 2.3V, in the video it's 2.45 V.
... |
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