# All Questions

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### Battery questions

I have some questions regarding making a battery pack for a electric bike. I’m looking at the Samsung 50E 21700 5000mAh 9.8A Battery as the base. The max discharge current is 9.8A, if I put two of ...
9 views

### Micro-USB B - female weird pinout

fixing up a kids toy today that used a USB Micro-B cable/port. The female port was smashed up. I have started to remove the old female socket and noticed it did not use a standard pin out. Rather than ...
6 views

### Grbl cutting mechanism

I would like to build a vinyl cutting plotter but lack the experience in cnc so I got 2 questions, There seems to be two options for the basic xy axis, rolling paper x axis like printers (might use an ...
8 views

### What is the impedance looking into a length of coaxial cable that is short-circuited at the far end and a half wave-length long?

What is the impedance looking into a length of coaxial cable that is short-circuited at the far end and a half wave long? I have been told that this the the basis of what is known as a wave guide &...
2 views

### What is “Number of occurrences” in DM16 - Binary data transfer at J1939 CAN-bus protocol

After I have send a DM14 memory access with the functionality read. Assume that I'm want to read 646 and 647 address. Then I want to use the lenght = 1, Pointer Type = 1(if I want DM15 message ...
16 views

### How does manufacturer determine initial tolerance for capacitors?

Short version: I understand resistor initial tolerance is commonly obtained through sorting process where manufacturer only picks resistor that has resistance within the advertised initial tolerance. ...
19 views

### Basic questions on capacitors

after reading some textbooks I realize that I do not understand how a capacitor physically works, I only understood it mathematically. Hence I would like to discuss with you the internal mechanism of ...
12 views

### MCP2551 with STM32 MCU

im learning about the CAN protocol, and bought the transceiver module MCP2551 like this: I made the driver for CAN controller first in loopback mode for debug, im sending the numbers 1,2,3 and 4 with ...
20 views

### What is the difference between a lock-in amplifier and a superheterodyne receiver?

I apologize in advance if the answer is obvious to many of you. I was looking at some block diagrams of lock-in amplifiers the other day, and I found them to be very similar to superheterodyne ...
29 views

### Temperature drift on volatge divider built with resistors from the same series

I am in the process of designing a data acquisition device that will be used outdoors, with temperature swings of around 30 degrees. For this i need to scale the input to a voltage suitable to the adc ...
15 views

### Protecting regulator from alternate power supply

I'm designing a module built around a Teensy LC MCU which can either run off of Eurorack power (+12/gnd/-12) or USB (mainly during development). The Teensy wants 5V and regulates down to 3.3V onboard, ...
23 views

### (Ideal) detector diode circuit becomes more sensitive with lower saturation current? Simulation wanted!

Application note 969 shows that a detector diode has in general higher sensitivity for lower saturation current. The voltage sensitivity at zero bias is derived as: gamma = Vout/Pin = 0.52/Is, which ...
41 views

### 1.2V AAA rechargeable batteries, voltage for almost full charged cell

Some weeks ago, I bought a new pair of AAA rechargeable batteries, Ni-MH. Its package shows "Panasonic eneloop" model with up to 800mAh. First I connected them in series and connected two ...
23 views

### Adding USB PD to my laptop

I would like to be able to charge my laptop via a USB-PD power source as seen in this article. I need to find out if my laptop input, which is rated at 19V 3.42A can handle the 20V provided by the usb ...
17 views

### What is “Pointer” in DM14 at J1939 CAN-bus standard?

What is "Pointer" in DM14 at J1939 CAN-bus standard? Can it be the memory Address[DEC]?
61 views

### Using solar power to create steam to spin turbine

Please read this question again now I have amended a glitch. The idea it to use a small solar panel to generate electricity, which will be sent to an element (or other device) which will heat up water ...
28 views

### Select power source with reverse current

I'm designing a Split keyboard where each half can be connected to USB, or to the other half, or both. If one half is not connected to USB, it receives its power from the other half. 99% of the time ...
17 views

### VIH of digital selection inputs for analog Mux when supplied with 4096mV - CD4051 IC

I will use CD4051BM96 part number, DATASHEET On page 7 is shown specs of VIH. It shows VIH of 3.5V for 5V supply (this 70% of VDD), VIH of 7V for 10V supply (70%) and VIH of 11V for 15V supply (73.3% ...
34 views

### How to apply high gain to filtered signal without shifting voltage level?

I have an op amp gain circuit at the output of a 2 stage filter. It seems like at high gain settings (x500), the steady state voltage shifts significantly. I am trying to keep it at ~1.7V and it ...
27 views

### BT speaker build

I want to build a BT speaker and have almost no clue ;) Ordered parts I saw in other builds. I have: 4 * 18640 batteries TP4056 USB-C charge module Switch 2 * MT3608 conversion board (2V-24V to 5V-...
23 views

### Delay timer circuit

I want to design a timer circuit to turn on a MOSFET based switch for 15 seconds. I did research on the internet but couldn't find any help. The idea is that if we give a voltage pulse on the gate of ...
37 views

### Why are radiated emissions standards for consumer electronics different from industrial?

Why are radiated emissions standards for consumer electronics different from industrial? Source:??
45 views

### Where is electrostatic potential energy stored in a capacitor system?

We know, $$U = \frac{ \epsilon_o}{2} \int_{\partial S} |E|^2 \mathrm{dV}$$ Now, suppose you have a capacitor system of the geometry as shown below, I know energy is stored between plates of a ...
46 views

### Why 2 diodes in parallel buck converter design?

I have been looking up dc-dc buck converter designs and have question regarding the diodes. It says "5A High current Schottky diode" is it common in buck converter design to parallel ...
27 views

### 4-20mA to adjustable set point relay

[![Why doesn't this work? I can adjust pot and relay will energize. 4-20mA will not energize relay. ]2
21 views

### Common Source vs. Common Drain for N-Channel Switches

Most discrete load switches I have seen (Using N-Channel FETs) have been in the common-source configuration. What, if any, are the operational differences between this and the common-drain ...
32 views

### LTspice: reverse biased diode fails in ac analysis

I want to read out the diode saturation current with ac analysis. In this example, 100uA. Hence I bias the diode at -1V where the diode current is effectively the saturation current (*-1). It works ...
32 views

### what would happen 25w bulb(g4) in a 20w socket?

I have a 20w(12v) desk lamp and a 25w(500 lm) bulb. type = G4/halogen I know putting a 75w bulb in a 60w socket can damage it or cause it to break. In my situation there is only 5w difference. would ...
30 views

### design Am circuit [closed]

Design and simulate an AM modulator in Multisim. The modulator should be based on transistor differentiator AM modulator followed by suitable tuned circuit and class B power amplifier, show using ...
110 views

### Why are there resistors on the input of this regulator?

I am looking at an older circuit, and I was wondering why the designer added these two resistors in series with the input voltage of this 5v regulator. The regulator would be powering a system that ...
32 views

### desing am modulater [closed]

Design and simulate an AM modulator in Multisim. The modulator should be based on transistor differentiator AM modulator followed by suitable tuned circuit and class B power amplifier, show using ...
35 views

### PIC10F206 MPLAB X IDE v5.40 - Light a LED

I am trying to light a LED with a PIC10F206, a PICkit4, the IDE MPLAB X IDE v5.40, and the pic-as Assembler. This is what I tried: ...
46 views

### Problem in the output current of an PNP current mirror

I have a problem in the implementation of a current source, based on an OPAMP voltage-to-current converter followed by a PNP current mirror (see picture). Indeed, the output currents are identical to ...
16 views

### stm32 usb connection error (USB device not recognized)

I'm almost new to electronic, and i'm trying to send and receive data from computer using usb cable, i was watching a video in the youtube and i followed the instructions, but when i connect my board(...
25 views

### Material selection of heating element

I am interested in heating coils which are heated using Ohmic/Joule/resistive heating - specifically, how the material for the heating coil is selected. When I read about heating coil materials - ...
51 views

### Measuring very dim light— charged glow in the dark paint

I am not even a novice, but was directed here by several companies when they couldn't help me with finding a tool. I am setting up an experiment to determine which glow pigments are brightest. Full ...
34 views

### Startup voltage help: How can I change the input voltage to this IC when starting the circuit?

I am currently trying to find a solution to switching the supply voltage for U12 (PN: UC3842BVD1R2G) in the included schematic. What is special here is that U12 will draw 22mA no matter the input ...
11 views

### Decoupling capacitors for circuit with two voltage converters and stepper motor driver

I have two questions regarding my first design - a simple speed/direction controller for a small (24V, 0.7A) stepper motor. How it works: 12V from DC plug is converted to 5V to power Atmega and a4988 (...
39 views

### How do I design this op-amp circuit? [closed]

Using the parameters given in the picture, how I design this operational amplifier? I just can't approach this problem.
36 views

### Resistors in high-speed I/O trace when impendance mismatching

I am little bit confused over impedance matching when dealing with high-speed digital I/Os. I would like to share some perspectives in hope to clarify a few things. Let's consider a digital output ...
20 views

### Filtering Alternator A/C whine

I have designed/cobbled together a small BT receiver for my vehicle which is getting some RPM dependent alternator whine due to stray A/C. Though I know this is likely an issue with the battery, the ...
55 views

### NOT gate power consumption

Given this NOT gate schematic using a transistor, and assuming the power supply is a battery, won't flow from Vcc to ground discharge the battery when the transistor is on? If yes, are there any ...
53 views

### Conceptual Question regarding necessity to do level shifting

I have a circuit where a 3.3V MCU which is not 5V compatible needs to drive an MCP23017. The MCP23017 will drive and read inputs and outputs from various 74HCT components. I'm thinking that based on ...
64 views

### Triggering Raspberry Pi GPIO with 127V AC

I'm building a home automation system with raspberry pi and would like to trigger it with a regular pulse switch, connected to my home's 127V AC power network. I'm doing this so I don't need to rewire ...
27 views

### How to calculate load flow/power flow in a DC grid?

From my understanding this depends exclusively on the voltage level, but I have not found documentation about how this happens or is done. Is it purely based on KCL? Are there any tools or procedures ...
275 views

### What is this part of the webcam called?

What is this camera component called? I was recently taking apart my old laptop and found that the webcam module had this circular component that screws on and off. I saw that it contains the lenses, ...
27 views

The below code gives me an error hat i cant read from out object Q Im sure newer version of VHDL supports it, how do i enable in Vivado does anyone know? Before i used GHDL compiler with a flag option ...
34 views

### Relation between heat & resistance

Heat produced across a resistor can be computed by the following formulae H=I²Rt H=(V²/R)t Going by #1, heat is directly proportional to the resistance whereas going by #2 heat is inversely ...