# All Questions

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### Powering 3 DC motors (with limit switches) with AC-DC adapter

I have 3 DC motors: each motor is being used to drive an independent system of pulleys. This system of pulleys spins a threaded bar in order to raise/lower a shelf in a linear motion. Thus, I have a ...
3 views

### How to verify capacitor voltage rating?

Ceramic capacitors are not marked with any kind of code that we can identify their model. Think that we have a batch of capacitors (lots of nearly identical capacitors) with unknown ratings. We can ...
5 views

### Amps spent in the following design

I have a question about potential current wastage. I am looking at connecting the output of a low power 2 input XOR chip to a GPIO on a microcontroller. The input to the XOR chip will be connected ...
3 views

### connecting 3 pin led pc fan to battery

I have a 12v 120mm led pc fan and I would like to connect it to a 9v battery. I can light up the led but I can't make it to spin. I assembled it and got this circuit board: The 4 pin IC on board ...
7 views

### Calculating Power Dissipation in a Filter

Apologies in advance if my question seems too basic. I don't really know where to go from here. I understand that power can be calculated as P = IV or P = V^2/R or P = I^2 x R. I think I'm not ...
13 views

### Why did it short circuit? [on hold]

I attached a USB adapter to outlet and because my multimeter has short leads plugged the meter to the prongs on the adapter and shortly after it short circuited, my question is why?
8 views

### Why do the polarities of the capacitor change while discharging?

I was going through the working of class D commutation and the article said: As soon as the capacitor completely discharges, its polarities will be reversed but due to the presence of diode the ...
9 views

### Should we include Source and Load Impedance while calculating two port parameters?

While calculating the $Z$, or $Y$ or $h$ parameters of a two port network, should we include the source impedance and load impedance or not? In other words, for finding $Y_{11}$, we short the ...
9 views

### 120 volt pond pump, trying to make the on and off work from an irritrol rain dial controller , from the pump switch

120 volt pond pump motor is direct wired in to breaker. I have a transformer reducing to 24volts for a toggle switch. Seems as though I can't take wires from toggle switch and put on controller pump ...
25 views

### MIPS invert - why are the 2 operands always inverted first thing?

I'm learning about MIPS 32 bit. I understand that CMOS technology uses NAND and NOR for the AND and OR commands, but still, I don't understand why is the inverter at the begining. Another thing is ...
13 views

### AMI CO4346 Integrated Circuit

Does anybody know what this, AMI 1982 vintage, part is?
14 views

### How do I get started on my RFID project (beginner)?

This is related to a recent, off-topic post I had linked here. I'm trying to make this post more for advice on my project, since I'm new to electronics and RFID and not entirely sure what I'm looking ...
12 views

### STM32F103RCT6 custom design check

With little experience with electronics and comming from an Arduino background I am designing my first STM32 PCB. My question here is, since this is my first attempt, I would like to have some advice ...
33 views

### amplifier power wire gets super hot at battery conection when the car is running [on hold]

the problem is that i have a car sub woofer amplifier and when i turn the car on and turn on my audio system and start to raise the volume the power wire (4 gauge) starts to get hot where it conects ...
15 views

### Eagle 7.7.0: Disable Label tool middle mouse button popup

Sometimes when I create a label using the label tool, I want to mirror its orientation. Unfortunately, the middle mouse button has been overloaded in the new Eagle version (7.7.0) and instead of ...
52 views

### How to better understand binary data streams as electric signals?

I'm aware that at any step of any computer process the input of a user/program (that gets translated from code to machine language and then to cpu instructions), is represented using both electrically ...
33 views

### Automotive tachometer signal interpretation

community! I'm trying to build a custom dashboard for a car (Daewoo Lanos 1998). Tachometer signal, that comes to dashboard with a separate wire looks a bit strange to me. It seems that the signal is ...
40 views

### Telephone Call and Electromagnetic Waves [on hold]

Can you give me a simple explanation of how do telephone calls work? I know that when I receive a telephone call, it means that my mobile has just received a certain Electromagnetic field. But in air ...
33 views

### Understanding the failure mechanism of capacitor

Most ceiling fans and table fans designed for household use, eventually slows down before completely failing to work. By close observations I found these fans are using capacitor-split-phase motor ...
55 views

### How to cut a nano SIM out of a 8-pin SIM?

I have a 8-pin SIM, which I want to cut into a nano SIM (which only has 6 pins). Looking at the Wikipedia X-Ray image, I assume I should cut the lower 2 pins. Is this correct?
35 views

### KiCad problem, schematic to PCB layout generates empty PCBnew window

I am using KiCad 5.0.0, after I built my schematic I annotated schematic symbols, assigned PCB footprints to the schematic symbols, then generated the netlist, and finally when I clicked on the tab of ...
58 views

### Derivation of formula for voltage drop across capacitor

This is the formula that our professor mentioned in our class. What does Vf refer to here? Will Vf be equal to the voltage of the battery? Also, how was this formula derived?
12 views

### Generate XCF file for Lattice Diamond from command line

I am writing a Makefile for Lattice Diamond and have come as far as to cover all steps from synthesis to bitfile. To program the FPGA (a MachXO3L in my case) I looked for a command line tool, and ...
83 views

### Temporary but hands-free JTAG/SWD connection

I have a PCB that will have very little clearance on both sides so that putting a normal Cortex SWD .50 spacing connecter is too big. However, I'd still like to have the option of connecting via SWD ...
148 views

### Why should care be taken while closing a capacitive circuit?

The other day in class, our professor told us that care should be taken while closing a capacitive circuit and while opening an inductive circuit? Why is this so? I partly understand the inductive ...
147 views

### How do we test and determine if a USB cable+connector is version 2, 3.0 or 3.1?

How do we test and determine if a USB cable+connector is version 2, 3.0 or 3.1, without using port, PC and/or having data transfer but instead with basic physics tests e.g. using multimeter?
57 views

### Amplifier Transfer Function Question

Hi, this is from Razavi's Analog CMOS IC Design book (2nd edition) - Pg 49. He says that " We observe that the circuit provides a gain of about 3 in the input range of 0.4V to 0.6V" But if you look ...
45 views

### Is the Raspberry Pi polarity protected on the USB?

I am building a Pi into some equipment just to drive a display. Now this is normally powered by a USB lead with the usual 5VDC. So I will have to cut the USB cable and put ferrules on the leads (...
41 views

### Calculating the voltage at a node (P) by applying superposition

Question 1a below is my problem which I need to solve. I am confused on what steps to take and how to find a voltage at a node by using superposition or can I use a voltage divider rule here as well?
44 views

### Charger compatible with device [on hold]

Is this charger compatible with this device?
23 views

### STM32F030CC reset into system memory after NRST deassertion

I did lots of search before this post here. The problem I met is STM32F030CC reset into system memory after NRST deassertion. The burned-in-flash program can run well after POR, but not any more after ...
69 views

### How to use gold finishing to reduce corrosion on a moisture sensor?

Background I have a raspberry pi with a moisture sensor that suffers from corrosion. My setup is similar to the one described in this raspberrypi.stackexchange question about corrosion of a moisture ...
48 views

### VHDL UART core transmitter bits

I was studying the VHDL uart core given here. At the bottom of the page is shown the transmitter code. Notice the line tx_data <= "1"&data_i&"01"; ...
48 views

### Designing an analog high voltage multiplexer

I'm putting together a design for a vacuum tube tester and curve tracer. The circuit I want to build is capable of powering up a tube and measure the voltage and current at the tube's pins. I would ...
26 views

### Wiring a stereo TRS socket as a mono output

I'm designing a product that provides mono audio output via a 1/4" SN49B12B board-mounted socket. This socket is actually a stereo socket, but I'm wondering if simply wiring the ring and sleeve pins ...
67 views

### Two different LED types: diode test on two different multimeters shows just “1”

I have two multimeters - granted, they're both the super cheap DT830B types, but slightly different models and one is straight from the packaging. I also have two bags of LEDs - bright red and bright ...
85 views

### Why is this potentiometer and comparator circuit not working?

I'm quite new to electronics and I'm afraid I'm missing some basic knowledge. (also please forgive me if I'm not always using the right terminology) I'm trying to use a potentiometer (R1 in the ...
28 views

### Finite State Machine using 3 bit down counter in Logisim

I had previously asked this question: Start/Stop MOD N Counter And this is sort of a continuation off of the original question as my main goal is to be able to stop the counter from counting when it ...
30 views

### should land patterns match the typical or the maximum part footprint dimension?

I've read that for QFN packages at least, the width of the pads on the board should exactly match the width of the feet on the bottom of the chip. However, the datasheet for the part I'm working with ...
44 views

### stm32f107 uart frame and noise error

I made a device with a stm32f107 and sim800l gsm module . Module is in data mode(PPP) and I'm using LWIP library . My MCU clocks at 72MHz . My problem is that I get frame error and noise error when ...
486 views

### Why does current not increase when batteries are connected in parallel?

I built a simple circuit consisting of two battery holders each including x2 1.5 V batteries, a slide switch, a LED and a 100 ohm resistor. The current I measured with a multimeter when the two ...
157 views

### Piezo buzzer vs Speaker

Can anyone explain that what kind of sound a piezo can and cannot produce when compared to A speaker. Can it just play notes? Is there some quality reduction in piezo buzzer?
74 views

### Is it possible to patch together a DC system with these random materials? [on hold]

I have a small collection of random batteries and solar panels, plus two charge controllers. I am hoping to build a system which can charge devices like phone, tablet, portable power banks, etc. (...
25 views

### Sensor to charge battery

I'm doing a project here. I'm designing my own generator using genset and motor to produce 12V of electricity. The main objective of my project is to produce a 12V from the generator. This 12V is ...
29 views

### What is the minimum size of that a segment can take in 8086? [duplicate]

I know that the minimum distance between any 2 segments is be 16 locations (10H) , but some say its 16 bytes , how is that possible if the the locations are of 2 bytes each. It would total to 32 bytes ...
76 views

### Will a parallel capacitor placed before a series inductor be capable of self-resonance?

If a parallel capacitor is placed in a circuit before a series inductor or ferrite bead (CL instead of an LC), will this combination be capable of any self-resonance? Or does the inductor have to be ...
74 views

### If we can access (64*4) 256Kb of memory at a time in 8086 and you can move those segments around, what is the use of the remaining memory

If we can access (64*4) 256Kb of memory at a time in 8086 and you can move those segments around, what is the use of the remaining memory? Some say that we can move around the segments but what is the ...
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I built the attach circuit, I was simulating a solar panel buck boost voltage regulator to regulate the output voltage. The problem is that while it works and shows the appropriate output. It doesnt't ...