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Not matching 50 ohm impedance

For my RF circuit (868MHz), I need 50-ohm impedance. When I calculate the impedance as PCB manufacturer layer stack-up, the impedance would be 66 ohms. How does this affect my RF circuit performance? ...
0
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2answers
15 views

Confusion in current calculation

I'm confused about two different approaches for current calculation through a 5 ohm resistor. The 5 ohm resistor is in parallel with a voltage source so the current through it should be 2 amperes. ...
0
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0answers
5 views

Low Power Toroidal Conductivity Sensor Inconsistent Values

I have been trying to build a low power toroidal liquid conductivity sensor using the principle given in this image. This link has more information about the principle behind the sensor. What I have ...
0
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1answer
16 views

PCB designing of GSM module

I want to design PCB of a GSM module. Inside a GSM module there is a place to put a (mobile cellular ) SIM card. And then this GSM module can send SMS text messages to different phone numbers. ...
0
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0answers
6 views

E/I inductive position transducer sensing device operation

so I have been doing some research on AC servo position flight control surface systems an was trying to find the component used to set the pilot's input command. Found out that a E/I inductive ...
-1
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0answers
11 views

Ethernet switch- Communication

I have a small doubt on using Ethernet switch. Query: Below is my setup will the communication happens between Board1 & Board2 through ethernet switch.
-1
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0answers
14 views

Trying to power up Amazon Echo in car

So I want to connect my car with Amazon echo show. Currently I connected it to the 12 v power output( cigarette lighter ), however when the car is started the power is interrupted ( while starting the ...
1
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0answers
15 views

Opto-isolation amplifier output is too off

(As a follow-up to an earlier question answered by the community - thanks!) So I've got the test circuit setup using the HCPL 7520 (datasheet) now and planning to use an Arduino Uno to measure the ...
0
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1answer
19 views

Differential gain of op amp

So I was reading the chapter on Op Amps in Microelectronic circuits by Sedra, Smith, the topic on Differential Amplifiers to be exact. Here's the amplifier: https://i.stack.imgur.com/3qWzi.png To get ...
0
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1answer
21 views

Non-inverting unity gain buffer appears to be inverting

I have constructed a circuit which uses two non-inverting unity gain buffers on one chip as stage seperation. I'm using a TL072CP chip with dual op amps on it and have followed the datasheet design ...
0
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0answers
17 views

4 layer buck converter layout

What is the standard layout for a 4 layer PCB that everyone follows for a buck converter or similar? I was planning to go like this: Signal Vcc GND Signal Since inductors and FETS are noisiest of ...
0
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2answers
34 views

How does the Colpitts oscillator provide positive feedback?

This is a Colpitts oscillator in a common-emitter configuration: For oscillation to occur, there must be a positive feedback. But I'm confused how can this oscillator provide a 360° degree turn for ...
0
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0answers
10 views

XR2206 Function Generator Kit on LM2917N-14

Please forgive my bad language I make Vehicle Speed Indicator with LM2917N-14. I tried it with cheap XR2206 Function Generator and NE555 Variable Square Wave. With NE555 LM2917 working properly, the ...
0
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2answers
31 views

USB Cable wiring

I have this usb cable from my old samsung phone. There's four wires which is red, white, green, and unshielded wire. Now these wires came from foil like cover which is surrounded with another ...
0
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2answers
16 views

Importing Altium schematics to a PCB is placing some components on a forbidden and an unaccessible area

I was using Altium 16 and generating PCB from schematics with no room generation. I have created my components library by mostly using "ultra librarian" files. I do these steps as many other ...
0
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5answers
51 views

Voltage comparator - how to get a stable voltage reference from a battery

I'm trying to build a circuit which will be used to monitor the voltage of Li-ion battery. The voltage comparator I'm using is LM393. Since the whole circuit will be powered by, it the battery will be ...
0
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0answers
18 views

Linear motion (quiet, variable speed)

I want to use a raspberry pi or arduino to create linear motion, back and fourth, my current goal is to make the pushing part for a baby rocker, but also a swing-rocker as a next project I have looked ...
0
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0answers
13 views

Motor consumption with 1V vs 3V w/ 90% PWM

Using a DC motor, I can reach about 1200rpm using 1V/1A (laboratory style power supply) However, if I use 3V input and a PWMized MOSFET, I need a duty cycle of about 90% to reach the same rpms and the ...
2
votes
2answers
48 views

Are fins necessary/required for cooling in a closed room

i am trying to design an efficient cooling solution for my project. I planned placing a IoT computer in an aluminum housing which is completely closed. In this case, do I really need fins and large ...
0
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0answers
9 views

Polarization loss factor for antennas

What would be the polarization loss factor, if transmitting antenna is circularly polarized and receiving antenna is linearly polarized, but they are aligned in such a way that maximum radiation ...
0
votes
0answers
11 views

Photo-resistor and leds

I'm trying to build some system that would detect light and turn a 12v led strip ON. The only power that I have available is a 9v battery. I found some Arduino compatible boards but it seems overkill ...
0
votes
0answers
17 views

How does a USB-C to Lighting Adapter work / How to replace them?

So, I am fairly new here, and to be honest I have no clue if this is the right place to ask. I am currently thinking about replacing a Lightning port with a USB-C port, just for power supply. At first ...
1
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0answers
28 views

BJT Amplifier Circuit Analysis Feedback

I've been reading up on small signal analysis to try and better understand audio amplifier circuit design (end goal a discrete BJT guitar amplifier). I'm attempting to apply the knowledge I've picked ...
-2
votes
1answer
30 views

How to detect touch with arduino

I want to make hexagonal led lights like in this video.These lights touch sensitive. You can turn it on or off by touch to them. I' ll make the body by 3d printer. But I don't know how to detect touch ...
0
votes
1answer
19 views

How does the continuous/peak charge/discharge current change when combining cells with known values in series / parallel arrangements?

Example 16 identical battery cells rated as below: 3.2V 100Ah LiFePO4 Max Continuous Discharge 100A / 1C Max Peak Discharge 200A / 2C for 100s Max Continuous Charge 50A / 0.5C Max Peak Charge 100A / ...
0
votes
1answer
57 views

How to make sure this oscillator will be stable?

In my textbook, the Wien-Bridge oscillator and the Twin-T oscillator needs a tungsten lamp as the self-adjusting resistance: The lead-lag circuit connected to noninverting input has a gain of 1/3 on ...
0
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0answers
21 views

Power amplifier - Drain voltage should be pulsed?

I am trying to bias the power amplifier QPA1022. I am planning to bias this amplifier by fixed gate voltage and pulsed drain voltage.For this I am using MABC-001000-DP000L for the same. I am unable to ...
0
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0answers
31 views

Blocking voltage of diodes

What exactly is blocking voltage in relation with Metal-semiconductor junction diodes? Is it related to breakdown voltage?
0
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2answers
35 views

Charged Capacitor discharge into LC circuit (with Freewheeling diode)

With A capacitor initially charged to Vc (assuming ideal diode and ideal switch), I'm curious about determining the max current through the inductor and total discharge time (the switch stays closed). ...
0
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0answers
23 views

Fast switching constant current buck output capacitor

I'm using a 1A constant current buck LED driver (the TPS92518 from TI), in order to implement "shunt FET dimming", where the load (1A LEDs) is short-circuited using a MOSFET in order shut-...
0
votes
2answers
27 views

Understanding @(posedge) in Verilog

In the circuit below, I'm trying to count the number of clock pulses that happen while the decode signal is high. In order to do this, I create a ...
0
votes
2answers
39 views

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 ...
0
votes
0answers
33 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 ...
0
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0answers
19 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 ...
0
votes
1answer
48 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 &...
0
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0answers
7 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 ...
0
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0answers
33 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. ...
1
vote
1answer
57 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 ...
2
votes
0answers
24 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 ...
1
vote
1answer
50 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 ...
1
vote
1answer
39 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 ...
0
votes
1answer
31 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, ...
0
votes
0answers
25 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 ...
2
votes
4answers
188 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 ...
0
votes
0answers
32 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 ...
0
votes
1answer
24 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]?
-6
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2answers
79 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 ...
0
votes
1answer
35 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 ...
0
votes
2answers
19 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% ...
0
votes
2answers
36 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 ...

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