# All Questions

116,704 questions
95 views

### 1960's video showing early computer design & simulation of a low-pass filter circuit?

I ran across this IBM computer aided design and simulation software demonstration from the 1960's in the video The Incredible Machine (1968) The gain vs frequency plot shows what looks like the ...
36 views

### How to calculate slew rate given capacitance and input current [on hold]

Capacitance C = 10 pF and the maximum available input current Iin = 1 mA. The voltage Vout can be written as: $V_{out}= I_{in} \cdot R (1-e^{-t/RC})$ find the slew rate.
45 views

### RS422/RS485 data input series resistor

I am using an RS422/RS485 driver to send Arduino 5V logic data over longer distances. I use the SN75174 driver for this purpose. In order to avoid ringing, I am not sure if I have to connect a series ...
59 views

### Battery required for a portable immersion boiler

Immersion heaters like the one pictured are typically plugged in. I'm interested in potentially developing one that is battery operated so it can be used on backcountry camping trips. A water heating ...
44 views

### Voltage source & current input

I am working on a project where I have a current source (analog output from a PLC) controlling a VFD. Based on the position of the dipswitch, the VFD will accept either a current or voltage input. The ...
32 views

### Obtaining Plant Input data from System Identification (PID)

I'm trying to obtain a mathematical model from a physical plant using MATLAB. Using the system identification tool you need the plant input and output data. I'm struggling to match the theory to my ...
18 views

### Node analysis with voltage source, How to solve with matlab?

So i have this matlab homework where i need to find voltage on Y2 and Y3 using node analysis. Arrows indicate direction of current flow in branches. simulate this circuit – Schematic created ...
14 views

### Synchronous generator load angle curve

How the curve of load angle vs steam flow rate will look like for a synchronous generator used in a generating plant ? Mine is a 540MW nuclear power plant. I was asked this in an interview.
50 views

### how to make a hdmi output for atmega328p [on hold]

Can you please help me I am trying to make a single board computer with the atmega328p and i cant find a way to do it and the other ones use a aurdrino and i am not going to use a aurdrino so please ...
37 views

### stabilize a wavy voltage source using analog components [on hold]

I would like to know the circuits that can be constructed using active and passive circuits to stabilize the frequency and voltage of an ac voltage source.
32 views

### Electromagnetic Fields course [on hold]

I'm taking this semester a course about Electromagnetic Field Theory in a foreign language. I was wondering if there is a specific place where I can find the same course with more or less the same ...
37 views

### Address decoding different bank sizes in 64K memory

I'm doing a small Motorola 6809-based computer project, and since I'm a bit rusty when it comes to boolean algebra I'm wondering if I'm doing my address decoding a bit too complicated for my simple ...
54 views

### How do I process headphones and increase the volume of the sound coming out of the earphones? [on hold]

How do I process headphonesand increase the volume of the sound coming out of the earphones?
55 views

### I want to create a stable 0-10 V DC output from a 3.3V PWM signal (arduino/esp8266)

I want to control an EC motor, but I have some difficulties with the motor's control input. According to my measurements it has a ~50kOhm input impedance, and probably also has an (unknown) RC low-...
113 views

### Heat dissipation by convection for ICs placed upside down

I'm currently designing a PCB with a couple of fast electronic elements (600MHz ARM, DDR3 ram etc.) and I'm quite puzzled which layer should those elements be placed upon. The product will be closed ...
51 views

### Data transfer on sliding contacts

I am currently working on a two-wheel self-balancing robot project for my Bachelors thesis, which is essentially an inverted pendulum on wheels. The picture below should give you the basic idea. [1]: ...
46 views

### Second order opamp circuit problem

I was trying to understand the way this problem was solved and I got confused with the latter part of the solution. I encircled the part that confused me. They seem to contradict each other. If dv(0+)/...
56 views

### Current flow in circuits and nature

This video shows that current only travels in circuits or "circles". This is in a way intuitive because a battery needs the electrons to return otherwise the reactions inside won't continue (I guess). ...
45 views

### 12 battery with stepper to 30 or 30v battery [on hold]

I have 2, 50w COB LED they work 1.5A@30v I'm thinking to go solar with them but i have a dilemma. Should i invest in 12v batteries and panels and step up the voltage to 30v and have some waste or ...
55 views

### replacing capacitors

C6 and C8 are ceramic capacitors. Can I replace them with tantalum capacitors?
42 views

### How to design planar toroidal inductors using Altium designer?

Prior to this, I did spiral inductors which was relatively easy. But I am now stuck in designing toroidal inductors. I know the distance between each turns but having trouble placing them in ...
62 views

### SPI communication between MCU and slaves

If there is only one SPI master and 8 SPI slave devices, How to we connect them together? I am not allowed to have 8 dedicated Slave select pins on the master, nor am i allowed to daisy chain the ...
118 views

### Why no current in neutral wire_kids question

One school child asked me - If current means flow of electrons, or entering to a bulb from one wire (Live) then going back through another wire, then why there is no current in the neutral wire, ...
35 views

### Operational amplifiers basics [on hold]

Does the same action is driven in op-amp output for below conditions? 1. Vd = 0 i mean V1 and V2 are same 2. Vi =0 where no input is given
31 views

### How do voltage and frequency fluctuations affect switch mode power supplies?

I have a high power (6000W) sub-woofer amplifier which has a switch mode power supply. This amplifier only worked few hours before it stopped working and it looks like an issue in the power supply. ...
29 views

### Power 9 IR LEDs 850 nm with a forward voltage of 1.7 V and forward current of 100mA

I am looking to power 9 IR LEDs 850 nm with a forward voltage of 1.7 V and current of 100mA. i want to make a circuit where i can use a small power supply or could I use the raspberry pi to power it? ...
31 views

### In a forward bias diode, why do electrons continue into neighboring holes?

When an electron from the n-type side fills a hole on the p-type side, it fills the valence shell. For reference, consider this video: https://youtu.be/7ukDKVHnac4?t=230. I learned in chemistry that ...
73 views

### Need help to identify this timer

This device is installed in our electrical panel which act as a timer to control the on/off operation for our LED billboard outside my office. I searched around the device for the brand and model it ...
20 views

### Analyze Series Circuit Graph [on hold]

Q2: Draw a series circuit to follow the graph given below (from points b through g). You can suppose (and must mention) the ratings of the resistors to be used in the circuit. In order to solve this, ...
32 views

### USB internal control to on/off a pc fan molex circuit

I am new to electronic circuits so I might not have the correct nomenclature for some items. Description: I have 3 high power 12V PC fans (NON PWM) connected to a hub that draw power from MOLEX ...
69 views

### How to reduce DC Voltage and Current [on hold]

I have a 12VDC/5A from battery. I want to use that battery to supply 3.3VDC / 600 mA of microcontroller. How should I do it?
26 views

### PIC 18F26K83 ADC clock frequency

Hello I am using PIC18F26K83 and I need to use ADC module in it, in order to measure voltage value of a spesific pin. MCU clock frequency is 8 MHz. This PIC has 12-bit ADC inside of it. So my question ...
2k views

### What is the role of the transistor and diode in a soft start circuit?

Please can someone explain the purpose of both the transistor and diode in this soft start circuit
33 views

### DMA Init code for ADC sampled data

I am trying to figure out how this DMA Initialization code is used to sample following 4 ADC channels and save data in 'adc_data'. ...
90 views

### Disadvantage of using a Schottky diode across the LDO input/output for reverse voltage protection

I'm studying a linear power supply circuit design for my future project and I started off disassemblying a good(expensive) LPS out in the market. While I was studying it, there was a part that I wasn'...
15 views

### How to post file to HTTP server with SIM7600I

I have tried AT commands provided by SIMCOM, but the module is not responding. AT+HTTPPOSTFILE,AT+HTTPREADFILE commands are giving error even for execution command....
27 views

### SIMPLE digital control over 555 timer frequency and PWM?

I'm looking to create a sound generator with only simple ICs and components. I believe the 555 timer IC is a good candidate to be at the core of it, but I cannot for the life of me find out how best ...
21 views

### Relay F. Bv. 153e

This is an old relay from a Hitachi electron microscope vacuum gauges power supply. Is there another equivalent version available? I have located an Omron F. Bv 153b but there are too many pins. Mine ...
137 views

### Why won't this circuit work?

I made this circuit. I calculated everything, but all I get is THE LED JUST WONT TURN ON. simulate this circuit – Schematic created using CircuitLab
51 views

### How does voltage/current limits work in switches?

I want to get a rotary switch, it says that it can handle 600 V and 40 A. I will use it to turn ON two DC brushed motors of 12 V 20 A. So, the voltage is way too high but the current is just right. ...
81 views

### Trying to recover audio from PWM

I am trying to make a Raspberry pi Bluetooth receiver. I finally got the raspberry pi to output audio via bluetooth, however the output seems like it is a modulated PWM. The width of the PWM seems to ...
28 views

### Using IR2110 driver in synchronous buck converter?

in using MPPT charger for battery, can use a variable input- fixed output voltage regulator that will be connected to the solar panel input?, this way I can have 15V for VCC and 5V for VD. I really ...
47 views

### Neutral current

I have an old switchboard with a 16 mm2 mains cable and a 16mm2 neutral return. At a different date, someone has added another 16mm2 single main cable to the board. The two phases are feed from 2 &...
118 views

### Is there a way to change AC 120 V @ 60 Hz to AC 120 V @ 40 Hz?

My grandfather has Alzheimer’s and I read in a science article that a sound or light “played” at 40 Hz interacts with the waves in your brain to break apart the plaque build-up and reduce memory loss. ...
71 views

### op amp rail to rail voltage follower latching up

I have selected a TS922 op amp to use in a voltage follower configuration. The specs for the TS922 in summary are: Rail-to-rail input and output Low noise: 9 nV/√Hz Low distortion High output ...
32 views

### How will the batteries of new phones manufacturered two years ago, and bought now be? [on hold]

We are thinking to buy Samsung Note 8; it seems to have been launched 1.5 years ago. In reddit, a user said: "Samsung still sells the phone? BTW, lithium ion batteries degrade whether they are used or ...
54 views

### Does regularly spaced via stitching contribute to standing waves on an RF PCB?

Should vias be irregularly spaced? Can consistent spacing between ground vias create standing waves. Has anyone ever heard of this? I've been doing this for awhile and I've never heard this and ...
41 views

### How to get output of 12V from a 15V output without dropping the current

I am planning on using NI myDaq to power a motor and encoder which requires 12V, but myDaq outputs 15V. How can I reduce the voltage to 12V without dropping the current? I was planning on using a ...