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H: Determining output impedance for a pulse generator
I have a basic question about determining the output impedance of a circuit. Output of this circuit is through R6 in the Figure above. This will be an input for a data-acquisition hardware channel which has 1Gohm input impedance. Setting R7 and R6 an equal resista... |
H: Figuring out mininum/maximum clock frequency [VHDL]
I made my first design in VHDL with arctgs and sums and now I'm trying to synthesize it into an FPGA.
However, before that I need to understand more about:
How to discover how many clock cycles my design takes?
How can I discover the maximum (is there a minimum a... |
H: Why put vias underneath an IC?
Several designs I've seen have a load of vias underneath high frequency or analog ICs. For instance, this is a part of a PCB design for a DDS unit:
Design from http://rudius.net/oz2m/ngnb/dds.htm
Note the grid of vias underneath the AD9912. This is not a particularly good example, as... |
H: Whats does "hr" mean among "V" and "Ah" in batteries?
I have a battery which indicates 12V25Ah/10hr.
What does 10hr mean here? I guess "hr" stands for "hour".
But 25Ah already means if battery is fully charged and if I load 12V 25A (=300W) to it, it should last for an hour (correct me if I am wrong).
What does "/1... |
H: DIP package: meaning, dimensions and nomenclature
I'd like to know exactly what DIP means, since googling it gives me several outright contradictory answers.
I used to assume that DIP and DIL mean these guys only:
That is, through-hole packages with two symmetrical rows, 0.1" (2.54mm) spacing between leads and 0.3... |
H: In-place programming of ATtiny85
I've been playing around with an idea for a little hand-held gaming device using a Nokia 5110 screen and an ATtiny85.
The ATtiny is programmed using my Genuino UNO as ISP.
I was wondering if it's possible/sensible to include a breakout connector on the attiny pins so I can just plug... |
H: A question on pulse conditioning implementation
Here is the aim of the circuit from input-output perspective:
Below on the left side of the arrow are the possible input pulse train signals. On the right side are the desired sharpened output pulses.
input .............. output
0 - 100mV --> 0 – 5V
0 - 3V --> 0 – 5V
... |
H: What does "frequency test" mean with regards to inductors?
I am shopping on Digikey for an inductor for use in a radio application. The frequency range I am working in will be 200kHz - 900kHz. I noticed that there is a "frequency test" column where most of the inductors have 1kHz written in (a few have 250kHz writt... |
H: Extra spacing between some traces and the ground plane
I have seen several designs where there is extra spacing between some traces and the ground plane. For example, see the traces between the points A and B or C and D in the following picture (this is a Raspberry Pi 2, but I have seen it on other boards too):
Wh... |
H: Diodes in boost/buck converters?
In either dc power converters, there must be a diode. I don't understand the need for it? Would a buck/boost converter function without a diode?
Also, what is the maximum reverse voltage for a diode in both cases? Does it have to be higher than the output voltage?
AI: If you look at... |
H: convert 2.5VAC to 5V DC wave
I have converted mains from 240V RMS (330V) AC @ 50Hz to 2.5V AC using a transformer and am now trying to put the wave into an ADC that operates at 0-5V.
I am looking to convert a 1.76V RMS (2.5V) AC @ 50Hz (5V pp) sin wave into a 5V DC sin wave (5V pp), i know i require an op amp altho... |
H: Altium error: Un-connected Pin Constraint
I have a pad in a IC left unconnected. I have set No ERC on that pin in the schematics to suppress of all violations.
But I still get "Un-connected Pin Constraint" error in PCB.
How can I suppress this error in PCB editor?
AI: I could not come up with a good direct answer... |
H: Can I use a Zener diode to convert 14 V into 5 V in a small-current circuit?
I'm working on a microcontroller-based device, and I need it to detect an input voltage (distinguish between zero and non-zero). When it's not zero, it can be anything between 10 V DC and 14.6V with some added noise of various frequencies.... |
H: Multiplexed LED matrix resistors
I'm trying to build this multiplexed LED matrix with 216 LEDs, NPN transistors, a PIC microcontroller and several shift registers (74hc595) , however I don't know how to calculate the value of the resistors that are connected to the anodes, and also would like to know if I should ad... |
H: Calculating Timer Tick STM32F4
I'm trying to use the timer (TIM4) to log rising and falling edge times from an external sensor.
I need to set the timer so that it ticks every 1µs and has a period of 40ms (so counts 40, 000 ticks before overflowing).
TIM4 has a source clock speed of 84MHz.
The datasheet says:
"16-b... |
H: Comparator latch circuit
I need a VERY simple latching circuit using a comparator that will simply be off until a signal hits it (can be either + or -, I have no preference). The circuit should remain on until I reset it.
AI: You could do something like this- the comparator output goes low when the input passes +2.... |
H: r0 vs ro in transistors ac modeling?
I'm a beginner in electronics field . In hybrid and pi and T models we have a resistance called r0 or ro . What's the correct name ? Is it "r-zero" or "r-o (15th alphabet letter)". Pls give references . Different people say different stuff !
Thanks ...
AI: It's a subscripted le... |
H: Is a linear voltage regulator necessary in AC to DC?
I was doing research on AC to DC power supplies and I came across a lot of schematics that use regulators like the one below:
credit: http://www.instructables.com/id/Make-a-simple-12-volt-power-supply/
Initially I drew out what I thought an AC to DC schematic wo... |
H: average of dBs or dB of average?
In several papers, books etc. I have encountered to expression of "average gain of the path is ... dB", now I wonder this is the average of dBs or dB of averages? The sources have not mentioned anything about their usage. Which one is used as a common definition?
AI: Strictly speaki... |
H: BLDC Motor Driver: Justifying better design approach
When and why it is better for a design engineer to design a BLDC driving circuit using individual MOSFETs, instead of selecting a ready made driving IC to simplify the design?
Here I just do not mean to run a BLDC but also control its different parameters. For i... |
H: What is shunt regulator in comparison with voltage reference
I know what is voltage reference but I am really confused about the difference between voltage reference and shunt regulator
for example TL431 can I use it as voltage reference ?
what is the applications for the shunt regulator anyway?
AI: The main differ... |
H: MOSFET H-Bridge Shunt Resistor position
I am designing a MOSFET based H-Bridge to handle high current. I would like to place a SHUNT resistor in the circuit in order to detect over current. The voltage across the shunt resistor is to be read by a PIC micro controller (so the + voltage side cannot exceed 5V). The on... |
H: Minimizing mosfet interactions and overshoots. A case study
I'm back again with another headache of my own creation. It seems I'm constantly learning things the hard way.
Straight to the point questions:
I've noticed that my reverse voltage protection mosfet interacts with another p-mosfet switch in a bad way (y... |
H: The ratio of the current to base vs the current to the collector
I'm doing an experiment while reading the self-study book by Kybett "electronics self teaching guide" In the experiment I measure the current to the base and collector of a NPN transistor then observe that the ratio is basically constant and consisten... |
H: Selecting a capacitor for use in feedback loop
I'm designing a DC Lab Power Supply; the voltage regulation circuit looks like this:
I'm developing the BOM, component by component, and next in line is specifying the capacitor in the feedback loop for the op amp, C1 in this schematic.
As I'm going through the select... |
H: finding the gain of a two stage voltage amplifier
i currently do not know how to approach this question, in terms of simplifying the circuit and which formulas to use in order to find the gain
AI: General approach
First, you must calculate the bias conditions, as any of these values will serve to find transistor pa... |
H: How to send out 60khz signal from antenna?
BACKGROUND
In Japan there are radio-controlled clocks. Time is synchronized by 40khz (in west Japan) and 60khz (in east Japan) radio, which is broadcast from transmission towers. The signal is known as JJY:
https:/ /en.wikipedia.org/wiki/JJY
After the earthquake in 2011, t... |
H: Eagle-how to change footprint?
I know its basic but google just doesn't give me anything .
I have Eagle on a mac, i have a design with a few resistors, i would like to change their footprint to 0805 .
The menu is just not showing me this option to see the part footprint.
thank you.
AI: Right click on a component a... |
H: How do I increase the drive current from the arduino digital pins?
I'm new to the Arduino (using the Leonardo). I am working with a heatplate that gets hot when you apply power to it.
When I use the 5V Vcc pin it works fine. But when I use the digital pins I don't get enough current.
Is there any easy way to increa... |
H: Tradeoffs when choosing the op-amp package: quad vs dual vs single
Let's say as an example that I need to use four op-amps in my project. I don't have any super strict requirement of space and price.
Which are the parameters to take into account when choosing the package to use, beside the space occupied on the boa... |
H: BJT Amplifier has different gain for negative and positive inputs
There were some errors in my old question so I decided to close it and redo it here.
I am working on a 3 stage npn bjt amplifier for my circuits class. The first two stages are common emitter stages. These are responsible for achieving the required v... |
H: Advice on wiring power supply to digital temperature controller
I'm trying to wire a power supply to a digital temperature controller. I know squat about electrics, but am following this guide - I bought the same components he used to keep it simple, but it seems that the wiring on the temperature controller is dif... |
H: what will be the output of the following circuit
simulate this circuit – Schematic created using CircuitLab
I want to find the value of Vo in terms of E1, E2 , E3, E4 , R.
Note that E1, E2 , E3, E4 are voltage sources.
I don't know how to proceed for positive feedback.
EDIT 1: My answer
Apply nodal analysis at V... |
H: BLDC Outrunner Motor Windings
Is there a specific way Outrunners are normally wound? (Wye or Delta)
What are the pros/cons to winding the motor a certain way?
AI: A Wye connected BLDC motor will have a \$K_t\$ that is \$\sqrt3\$ larger than a delta connected motor (assuming they are wound exactly the same. This m... |
H: Split a 512 bit numbers into 16 words of 32 bits using HDL
How to split a 512 bit binary number into 32 words of 16 bits using HDL?
AI: input_word[511 downto 0];
zeroth_output = input_word[15 downto 0];
first_output = input_word[31 downto 16];
...
thirty_first_output = input_word[511 downto 496]; |
H: Summing Amp Response in a Cascaded Butterworth Notch Filter
I'm having trouble with a cascaded butterworth notch filter I'm designing and was hoping to get some insight on the summing amplifier stage at the end. I'm still a student, so my question may be a bit basic. I'm trying to get a unity gain response for the ... |
H: How to derive apparent power formula for three phase AC system?
I know that the total power output of a three phase system is √3 EI cosØ
Where E and I are the line voltage and line current.
Now my question is how can one derive the apparent power equation i.e.. √3 EI
from the totalpower equation √3 EI cosØ ?
AI: ... |
H: High Frequency Transformer Design and Materials
I have designed fly-backs and inductors and understand the basics about flux density, saturation and core losses. What I have never been very clear on is design of SMPS transformers. I get the concept that ideally you want to transformer to not hold any magnetic energ... |
H: Proper storage of ferric cloride PCB etchant
I etch about half a dozen printed circuit boards each year at home, using an aqueous ferric chloride AKA iron(III) chloride etchant solution. As I want to minimize the costs and hassle of buying new and disposing of old etchant, I would like to know what steps can I take... |
H: Does the order of connections on a protoboard matter?
I am a beginner in the field of electronics. I am trying to learn about applying schematic diagrams to protoboards.
Let's say that I have a schematic depicting connections between pin #2 of a fictional IC chip, then a resistor, then a capacitor, then pin #6 o... |
H: Is there a way to proof that you don't see the cut-off frequency in the plot?
In my previous question, I've asked something about acut-off frequency (Finding the cut-off frequency).
But in my plot I don't see those, I see the one that I find when I pick the zero and the pole ones. Is there a way to proof that we do... |
H: How much power can a 20AWG USB cable safely handle?
I recently got a device that uses a USB cable (USB on one end and a power connector on the other end) as a charge cable. The device draws 16.5V, 3.65A Max. I want to extend the charge cable by using a USB extension cable. I tried using a 26AWG USB cable and it ... |
H: Is it ok to connect batteries in parallel?
I've seen some questions about connecting batteries in parallel to increase capacity, and the answers all indicate that it's fine to do. But why? Isn't that creating a short if the batteries aren't at the exact same voltage? I understand there's some internal resistance in... |
H: How to create an interrupt based on potentiometer value(s)?
I am using an Arduino to power a motorized potentiometer and I wanted to know if there is a way to create an interrupt (stop the motor) when the potentiometer reaches within a certain range of values (like in one case stop motor if the potentiometer is bet... |
H: Brand new soldering iron tip turns black, solder won't stick
I have a brand new soldering iron, the tip turned black while heating on my first use, and now solder won't stick to it, it just rolls off.
All the answers in similar questions here tell me to stick solder to the tip but it won't stick because the tip is ... |
H: Fast Fourier Transform (FFT) of power consumption signals
I want to compare two power consumption signals, i.e., how the power consumption varies throughout a day. Now I have two options:
Take two raw power signals and compute the Euclidean distance between them
Convert the input power signals using Fast Fourier T... |
H: Soft-on/off circuit turns on on startup despite being jumpered to stay off, why?
So, I am building the soft-on/off circuit shown below and described here on a breadboard to test it out before I actually put it into a design.
However, to better fit the parts on hand, I decided to alter a couple of the R and C value... |
H: Is there any reason to prefer one MLCC manufacturer over another?
I'm specifying some SMD chip capacitors for the first time and I note there are several manufacturers out there: muRata, Yageo, Vishay, AVX, Kemet in particular, perhaps others.
Is there any good reason to prefer one of these manufacturers over the o... |
H: Consequence of uncomplimentary MOSFETs in Hbridge
I am constructing my own H-Bridge to control a high current motor (24V at 25A), as such I was looking to use high current MOSFETs for each quadrant of the H-bridge. My go too MOSFETs for these applications is the IRF1405 unfortunately the manufacture for these MOSFE... |
H: How to plot "voltage drop" across a specific component in LTSpice?
In the above circuit I can only be able to plot |Vr1+Vc1| = V1 in green plot and Vc1 in blue plot. I use the voltage probe in LTSpice and click on the lines to obtain the plots. If I click on the line between V1 and R1 it plots |Vr1+Vr2| = V1. If I... |
H: Auto start and stop water AC motor using these two circuits
Problem:
I have a AC motor (pump) which pumps water from the ground floor to 4th floor. On 4th floor, I have water tank. The problem is I have to start the motor in 5AM in morning. I have installed a water alarm buzzer which beeps when tank is fu... |
H: critical inductance value when designing a buck converter
From the formula used in this literature from Texas Instruments
http://www.ti.com/lit/an/slva057/slva057.pdf - Page 15
Here are my requirements:
Vo-Output voltage(v) 98
Vi(max)-Maximum input voltage(v) 120
Ts-Time period(sec) 0.000001
Io(crit)-Minimum ... |
H: Symmetrical components: phase voltages
In the following question on symmetrical components, the 11kV of the source is the line-to-line voltage. When using symmetrical components you want to be working with line-to-neutral voltage. Am I right in saying this? In the memo for this question the 11kV is devided by squar... |
H: Is it safe to connect a USB port to a transistor to a power strip, so I can control Christmas lights with a USB port?
Okay, so a usb port has 4 pins, a ground, two I/O pins, and a (may or may not be switchable) 5V pin. I had an idea to to connect one of the pins to the base of a transistor. Then I would rip the but... |
H: How can a powersupply have a large input volt range
I see that computer power supplies that can take a voltage input of anything between 90V and 260V at a frequency between 47Hz and 63Hz.
Meanwhile it can output power at a very precise voltage.
How does that work?
AI: It is done by magic ;-) Just kidding, it is not... |
H: Is using a high sample rate on an oscilloscope ever a bad thing?
A while back i was gathering some ECG data for a colleague at a reasonably high sample rate (around 20kHz - 100Hz is enough for ECG). She came back to me and asked me to regather the data at a lower sample rate - claiming that the high sample rate was... |
H: Understanding Peak Current given in datasheet
I am using M.2 LTE module in my design. The datasheet says "The host board shall provide 2.5 A peak current." What does this mean from supply current point of view??
Also, in the power consumption table it says 1629 mW max. That makes around 484 mA @ 3.3V.
What should I... |
H: When to use State Machines - FPGA
I've read a lot about FSMs (Finite State Machines) when doing VHDL tutorials. They are easy and I've used them a lot but I still don't understand something and can't find the answer online:
When should I use FSMs (Moore or Mealy) in my VHDL design?
For example, if I implement an al... |
H: Inferring D-latch on Zedboard within Vivado Error
I'm trying to implement a simple latch on a ZedBoard via Vivado.
begin
process(D,Enable) begin
if(Enable = '1') then
Q <= D;
Qbar <= not(D);
end if;
end process;
I'm using user I/O on the constraints for the inputs/outputs. I assign the inpus ... |
H: Misbehaving CD4021BE Shift-in
I have a CD4021BE set up very similarly to the Arduino ShiftIn Tutorial (the main difference being that I don't currently have 8 buttons so have just connected PI-5 to PI-7 to ground with a resistor, I get the same misbehaviour if these are left floating).
All of the values that I'm ge... |
H: Is the datasheet of the AVR ATmega32 wrong?
I'm currently using an ATmega32 to keep time, so I carefully read the datasheet and configured the Timer 1 to generate an interrupt each second.
According to the following formula on the datasheet, using a 16 MHz clock, a prescaler of 256, and OCR1A = 31249, I should get ... |
H: VHDL: TextIO, End of Line, Hread
process
variable vGoodRead : boolean := true;
while (vGoodRead = true) loop -- read till end of line.
hread (vLineIn, vInData, vGoodRead);
........
end loop;
vGoodRead := true; -- cos at End of line, it turns false
end process;
I am using this... |
H: Where is the ground/earth used in the Sparkfun Logic Level Converter
I am studying the Sparkfun Logic Level converter and the basic aim of this is to understand how these BSS138 transistors are used in logic level conversion. I have used transistors before in driving high current motors with MCU's i.e. small time h... |
H: How to step down from 5VDC to 3VDC?
just a newbie here.
I just want to ask how I can step down my 5vDC adapter to 3VDC? Cause I'm afraid that my LED lights will burn out. Thank you so much for answering.
AI: If you're worried about burning out LEDs, then current is your problem, not voltage. You can limit the curr... |
H: Brushless DC Outrunner Motor Control
My question arises from interest mainly in Outrunner motors which are used on RC planes/drones.
With that being said, I understand that these motors are controlled by an Electronic Speed Controller (ESC), which is used to switch DC power into two of the three different phases o... |
H: MSP430 how to make configurable ISRs in a module (Code composer studio C)
I have a question that I think the answer to is quite simple. But I've been unable to find a straight answer to.
If i have this service routine in some module foo.c
#pragma vector = SOME_VECTOR
interrupt void fooISR(){
dosomething;
IF... |
H: Is there anyother way to construct an FM transmitter
I recently built an FM transmitter that uses a combination of coil and capacitor as an oscillator to generate the carrier frequency.
I built this transmitter:
Now my problem is that I find it difficult to wind coils properly. The chance of winding properly is ve... |
H: Connect to external monitor using HDMI
I want to connect my laptop to external monitor, but it doesn't have VGA socket. It only has HDMI.
I recently purchased a HDMI to VGA cable and tried with it, but still it doesn't recognize the input.
I checked on the internet and found that I need to use HDMI to VGA Adapter a... |
H: Cascading Common-Emitter Common-Collector for maximum power transfer
Hi Am trying to understand what am doing wrong, I connected CE to CC with a small Rload am designing it so Zout of the second stage equal Rload to get Maximum output.
From what i read in CC-amp Zout = RE||(r'e+ ((R1||R2||RS)/Bac)) were RS is the s... |
H: Using an Arduino to measure wire capacitance
I wanted to use an Arduino as a capacitance measurement device for a coaxial wire. I started at measuring the wire capacitance using digital multi-meter UT58B. I turned the knob to 2 nF and then measured the capacitance depending on the wire length. These are the results... |
H: Silkscreen versus assembly layer
Is there any example, preferably by photos, how does assembly layer on PCB differ from the silkscreen? I understand, that silkscreen reference designators should be left visible after the parts are mounted on the board, and assy layer information can be obstructed after the assembly... |
H: FPGA IP core vs. AFU
What is the difference between an FPGA Intellectual Property core and an Accelerator Function Unit?
As far as I understand, an AFU is an IP core developed by the end-user (as opposed to IP cores delivered in the hardware by the vendor). Is it correct?
AI: The term IP core typically refers to a ... |
H: Programmed IO vs interrupt for devices
Although I can understand the difference between programmed IO (PIO) and interrupt (INT) transfers, still there is something vague.
In PIO, the processor repeatedly checks READY pin to see if the device is ready. However, in interrupt mode, the processor checks the INT pin at ... |
H: Is there altitude limit for GSM(SIM908)?
I'm using GSM(SIM908) in the machine. I need to know whether there is an altitude limit for gsm to operate. Does GSM just stops working after reaching certain height? I will use SIM908 or SIM808.
AI: I often have cell service at 25,000 feet. I have also launched a weather ba... |
H: bi-directional flyback diode for relay spike protection
A flyback diode is used to protect circuits against the reverse voltage generated by removing power from a relay coil.
Like this:
simulate this circuit – Schematic created using CircuitLab
But what to do if the polarity of my power supply isn't known?
placing... |
H: How to make a 240v ac to 12v 2amp dc transformerless step down circuit
I want to make a 100-240vac to 12vdc 2amp transformerless stepdown circuit any safe reliable circuit digram is accepted
AI: This circuit should work...
Where compnoent U2 in the above circuit is this...
Note that this component type is highly... |
H: Non-unique Sample Rate
Given
$$x[n] = \cos\left(\frac{\pi}{3} n\right)$$
That was obtained by sampling
$$x_c(t) = \cos(4000\pi t)$$
At \$T\$ samples per second, find \$T\$. Is \$T\$ unique? Why or why not?
$$x[n] = x_c(nT)$$
$$\cos\left(\frac{\pi}{3} n\right) = \cos(4000\pi nT)$$
$$\frac{\pi}{3} n = 4000\pi nT$$
$$... |
H: How does a logic gate behave with an input changing faster than its propagation delay?
I am attempting to create a simple logic circuit simulator. I am having a hard time figuring out how does a logic gate behave with an input changing faster than its propagation delay.
When attempting to connect a high frequency c... |
H: How to avoid garbage values received in UART communication
I am new to the embedded programming. I am doing a UART communication in PIC32MX795F512L MCU. I have somehow managed to transmit and receive data but not able to receive complete string.
I am doing something like this:
char Rx[5] ; //va... |
H: BJT power dissipation - Which value to use? (Ta vs Tc)
I'm using a TIP120 (Darlington pair BJT) brought to saturation for a project of mine. I have \$V_{CE(sat)}=1V\$, \$I_C=2A\$, \$V_{BE}=2.5V\$ and \$I_B=0.005\$A, which give me a total power dissipation of:
\$P_D=V_{CE(sat)}*I_C+V_{BE}*I_B \approx 2W\$
When I loo... |
H: Will this short range AM transmitter constructed using crystal work?
I have designed a circuit as follows:
simulate this circuit – Schematic created using CircuitLab
There are a few corrections in the circuit. I couldn't do it in the editor because I don't know. The corrections are:
1. The input is audio input.
2... |
H: INA122p replace to INA126p
I made a working circuit for an INA122p, for arduino, so it has a 5V PS . I bought 2 ina 126p ic's, because they are nearly the same, but when I change the ics, the 126p has a fixed 0,6v signal output. the gain is set to 500.
here is the modified circuit:
AI: The INA126 does not hav... |
H: STM32 chip specs do not match the datasheet?
I've recently purchased a couple of STM32L152R8T6 chips from a local electronics shop.
According to the page 11 of the datasheet, this chip is supposed to have 10K of SRAM and 64K of FLASH.
However, when I query one of those chips (that I've already soldered onto a perf... |
H: Discrete Logic with Seven Segment Displays Problem
As a small project, I decided to make this circuit from Gadgetronix. However after wiring it, the display is stuck on 20 and when I activate the pushbutton, the 0 (display of IC2) just dims, and when I let go it goes back to normal. Now, I know just showing the cir... |
H: Questions involving Injecting power into WS2811 RGB strands
I'm currently using an Arduino UNO (but may need to switch to a MEGA due to memory issues) to control about 20 strands of WS2811 RGB LED Strings(see similar product here). I'm Using the FastLED library to send all of the data at once through a central data... |
H: ULN2003 based stepper driver not driving 28BYJ-48, and nothing coming up on the indicator lights
I recently received five of the ULN2003/28BYJ combos, as described on the below link:
http://www.4tronix.co.uk/arduino/Stepper-Motors.php
I am powering the stepper controller with a 5v supply from the YwRobot breadboard... |
H: Voltage drops not adding up - beginner question
I'm fairly new to electronics and playing around with a very simple series circuit - 2 resistors of ~220k Ohm and a 3v power supply, which I'm measuring with a digital multimeter.
If I measure the voltage across both resistors (or direct across the power supply termin... |
H: Verilog: slow clock generator module (1 Hz from 50 MHz)
I wrote a clock generator module. I think the problem is in my Reg4 module. The errors are:
ERROR:HDLCompilers:246 - "UpDownCounter.v" line 74 Reference to scalar
reg 'clk_1Hz' is not a legal net lvalue
ERROR:HDLCompilers:102 - "UpDownCounter.v" line 74 Conne... |
H: Using NPN-Transistor as switch not working
I have following schematic:
simulate this circuit – Schematic created using CircuitLab
But the motor is not working, the NPN-Transistor does not seem to let any current through. What am I doing wrong? the transistor does work, I checked, but there may be something very ba... |
H: Why is it bad to have traces close to the edge of the board?
I keep reading that one shouldn't have traces close to the edge of the board and am curious as to whether there is an electrical reason behind this or if it's a mechanical issue (like when they cut the pcb, it might somehow rip up the traces)?
AI: From Su... |
H: Ideal SPICE Model of Op-Amp with Power
I know that the ideal operation amplifier model is a single voltage controlled voltage source. My question is how to extend this ideal model, in a minimal way, to account for power supply rails (V- and V+).
AI: LTSpice offers the ability to make a VCVS with piecewise-linear tr... |
H: Motorola 68030 minimum frequancy
I am working on building a computer with a Motorola 68030. The one I got my hands on is the 40Mhz version. In the electrical specifications pdf they list the minimum clock frequency for the 40Mhz version as 25Mhz. I would prefer to at least at the beginning run it slower so I don't ... |
H: Where is pin 1 in Molex connector?
In 54722-0604, which is the pin #1?
connector page at molex.com
AI: Since the drawings don't indicate a pin numbering arrangement, it is up to the user to define it, I suppose.
I do see that there is a trademark on one end - I'd probably call that the pin 1 end, and number it like... |
H: Choosing components to clone ZX80
I have an idee fixe to make a clone of Sinclair's ZX80 computer.
So now I'm trying to find out which ICs I need for the basic prototype - and here are a few questions:
it seems Z84C00xxx is a modern substitution for original Z80 processor, right?
for SRAM, will UT62xx or LY62xx be... |
H: How would I find the total resistance of the following circuit?
I tried finding the total resistance but my answer isn't correct. The answer is supposed to be 6.66 kΩ.
AI: In this case whenever you are calculating the circuit resistance you want the total resistance seen by your only voltage source (18 V battery)
y... |
H: Formula for amplitude of volatge, decibell
There is a formula for power 1 and power 2 to convert to decibell. 10*log(P1/P2), but when I have a amplitude of voltage in DC, formula is 2*10*log(U1max/U2max). Why is there a 2? Thanks.
AI: Power is \$\dfrac{V^2}{R}\$ therefore (assuming the two R's are the same) the ra... |
H: precision and accuracy of a measurement system
I have read the difference between precision and accuracy. As normally (mistakenly) they are considered to be the same, but in actual they are two different things.
My question is regarding the accuracy and precision of a measurement system. Lets say if i am measuring ... |
H: Help to identify
I'm trying to identify a burnt component on a PCB. This is receiver from Hubsan H301 RC glider. Wings got detached mid air and it slammed into high grass. I forgot to release throttle stick and prop got entangled in the grass. When I found glider there was a smoke coming from the plane. I quickly r... |
H: What is going on in this VCXO circuit?
Here's a schematic of the VCXO oscillator section from a Siemens S55 mobile phone. AFC signal coming from the processor tunes the crystal via a varicap. There's also a thermistor going back to the processor for temperature compensation. It looks like a Colpitts oscillator, b... |
H: Clamping Inductive Kickback in AC Circuits
I want to eliminate/clamp the inductive kickback that would result from turning off a large inductor, such as a relay or a transformer.
In a DC circuit, I would use a diode to flywheel the current. But what do I use in a line voltage AC circuit?
Is an MOV an acceptable dev... |
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