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Q&A

General Q&A about the design and function of electronic systems, electric power systems and infrastructure, their theory, and tools specific to those fields. Read these guidelines before posting.

Filters (None)
75%
+4 −0
What is the difference between rise/fall time and Turn-On/off Delay Time?

Hi guys so recently i was looking for a mosfet and a gate drivers and between a lot of their specification the rise/fall time and Turn-On/off Delay Time sometime it called propagation. My question...

2 answers  ·  posted 1y ago by deleted user  ·  edited 8mo ago by Lorenzo Donati‭

71%
+3 −0
Is it possible to calculate the rise/fall time of an operational amplifier ?

I am planning to use the LM318 operational amplifier to generate a PWM signal and I need to know how to calculate the rise/fall time. LM318/LM218/LM118 datasheet -The slew rate is 70 V/µs maximum...

1 answer  ·  posted 1y ago by deleted user  ·  edited 9mo ago by Lorenzo Donati‭

37%
+1 −3
Need help to replace 555

Hi guys, Can anyone help me please replace the NE555 IC in this circuit by MIC1555. I need to modify also the Voltage to 18v thank you. MIC1555 datasheet NE555 datasheet Edit: The circuit a...

1 answer  ·  posted 1y ago by deleted user  ·  last activity 1y ago by Jasen‭

555
77%
+5 −0
How to perform initialization of static storage variables in embedded systems?

Whenever declaring a variable in C outside a function at file scope or when specifying it as static, it gets assigned a life time known as static storage duration. Meaning it will be accessible thr...

1 answer  ·  posted 1y ago by Lundin‭  ·  last activity 9mo ago by Lorenzo Donati‭

22%
+0 −5
BJT common emitter amplifier equivalent circuit (π hybrid model) [closed]

Im studying the equivalent model of a BJT common emitter amplifier at high frequencies.At university we tought that the BJT at high frequencies looks something like this: However when designing ...

0 answers  ·  posted 1y ago by MissMulan‭  ·  closed 1y ago by Olin Lathrop‭

28%
+0 −3
Thermal stability coefficient [closed]

The thermal stability coefficient is defined to be: $S = \frac{dI_{C}}{dI_{CBO}}$ where $I_{CBO}$ is the reverse current of the BJT when voltage isnt applied to the base of the BJT. In case of a ...

0 answers  ·  posted 1y ago by MissMulan‭  ·  closed 9mo ago by Nick Alexeev‭

71%
+3 −0
Energy harvesting from non-invasive current sense transformer

I have a non-invasive current sense transformer (SCT-013-030) which according to its datasheet it is voltage output type. I want to harvest energy and supply a wireless sensor that consumes 5-6 uA...

1 answer  ·  posted 1y ago by DeadMouse‭  ·  last activity 1y ago by Andy aka‭

66%
+2 −0
Ceramic filter vs ceramic resonator

I have a design of a power line communication using the following IC. https://www.yamar.com/datasheet/DS-SIG60.pdf My design is the same as the example circuit in the datasheet of the chip. Th...

2 answers  ·  posted 1y ago by DeadMouse‭  ·  edited 8mo ago by Lorenzo Donati‭

77%
+5 −0
Buck-boost converter fed from split input supply

I have recently finished designing a buck-boost converter for a job that uses a split (+/-) input power supply. Load power is taken equally from both positive and negative input supplies and, the ...

1 answer  ·  posted 1y ago by Andy aka‭  ·  edited 8mo ago by Lorenzo Donati‭

77%
+5 −0
Low-pass filter after the output DAC in CD players

[Disclaimer. This is not for an academic class. I'm self-studying.] I’m reading an introductory book on DSP for audio and computer music [Steiglitz 1996, ISBN 0-8053-1684-1 p. 287]. One of the ...

4 answers  ·  posted 1y ago by Nick Alexeev‭  ·  last activity 9mo ago by Lorenzo Donati‭

77%
+5 −0
Deriving resistor values for a taper pad attenuator

A taper pad is a resistive attenuator that maintains impedances on both ports and provides a specific amount of gain-loss ($A_{12}$): - I have derived formulas for each resistor (that I know to ...

3 answers  ·  posted 1y ago by Andy aka‭  ·  last activity 8mo ago by Lorenzo Donati‭

57%
+2 −1
pH Electrode Buffer - Offset when solution grounded

Problem pH electrode buffer offset appears when solution is grounded. Detail I have a pH electrode in some conductive solution (~1000uS). The output (measurement electrode) is buffered by an el...

2 answers  ·  posted 1y ago by rherma‭  ·  last activity 1y ago by TonyStewart‭

22%
+0 −5
Designing a circuit to verify thevenin theorem with induction motor as load [closed]

Design a suitable experiment and an AC circuit to verify Thevenin's theorem when the load is a single-phase induction motor with a capacitive start and two supplies feed the load. Ratings of load:...

0 answers  ·  posted 1y ago by dkumar94600‭  ·  edited 8mo ago by Lorenzo Donati‭

83%
+8 −0
Technique to reset pulse transformer core quickly

I am analysing a pulse transformer which is required to transfer below communication protocol pulse from primary to the secondary side. The pulse duration is 32 μs and off time available to reset t...

2 answers  ·  posted 1y ago by kadamrohan16‭  ·  edited 8mo ago by Lorenzo Donati‭

62%
+3 −1
Power amplifier for remote controller

I'm designing remote controller based on NRF24L01 and STM32. I want to use SMA antenna. My question is regarding power amplifier (PA). When is it necessary to use one? The range I'm aiming for is 2...

3 answers  ·  posted 1y ago by Stefan‭  ·  edited 8mo ago by Lorenzo Donati‭

75%
+4 −0
Can confusing the plugs for earphones and microphones do any damage?

The plugs for microphones and for earphones are the same, however their functionality obviously is quite different. Now because of the same plugs it is easy to insert one of them in the wrong socke...

2 answers  ·  posted 1y ago by celtschk‭  ·  last activity 1y ago by TonyStewart‭

66%
+2 −0
Circuit which create ac sine wave from dc pulsed signal

A full wave rectifier converts a sine wave to DC pulsed signal of double frequency. Is there a circuit which does the reverse process?

2 answers  ·  posted 1y ago by MissMulan‭  ·  edited 8mo ago by Lorenzo Donati‭

AC DC
75%
+4 −0
What are the key programming skills for an embedded systems engineer?

I am looking to improve my knowledge of embedded systems programming, specifically regarding microcontrollers and embedded Linux systems. A lot of the information that can be found regarding C/C++...

1 answer  ·  posted 1y ago by Mu3‭  ·  last activity 1y ago by Olin Lathrop‭

20%
+0 −6
Need help design a digital circuit which divides two binary numbers [closed]

Before the circuit here are the digital blocks which have been already designed and exist as part of the division block 1 bit subtractor: 2 bit subtractor(in the digital block diagram of the di...

0 answers  ·  posted 1y ago by MissMulan‭  ·  edited 8mo ago by Lorenzo Donati‭

75%
+4 −0
Battery protection circuit

I am using two 18650 cells in series to power a RC car. Is the voltage goes below 6.2 V, the battery should be disconnected to prevent over discharging the battery. At the same time I want to imple...

2 answers  ·  posted 1y ago by Stefan‭  ·  edited 8mo ago by Lorenzo Donati‭

71%
+3 −0
Pick & place file generated by Altium does not match the actual component rotations/positions

I am generating files for manufacturing my design in Altium 22 and ordering through Eurocircuits. What I noticed during the ordering process is that the rotation of many components (and sometimes ...

1 answer  ·  posted 1y ago by Mu3‭  ·  last activity 1y ago by DSI‭

33%
+0 −2
Op Amp Hartley oscillator

Im designing a Hartley oscillator this time with a opamp providing the open-loop gain.I have tried drawing the small-signal analysis of my circuit to use KVL and KCL to find the conditions of opera...

1 answer  ·  posted 1y ago by MissMulan‭  ·  last activity 1y ago by Olin Lathrop‭

60%
+1 −0
Results of analysis of Hartley oscillator dont make sense

I want to find the conditions of oscillation of the following Hartley oscillator.I have attached a load (ZL) to my Hartley oscillator I have written KCL for nodes A,B: For node A: $$\frac{V_{A...

3 answers  ·  posted 1y ago by MissMulan‭  ·  last activity 1y ago by TonyStewart‭

71%
+3 −0
Altium. Reusing schematic symbols for pin-compatible parts.

I want to create a schematic symbol and reuse it for multiple ICs which have identical pinouts. For example, OpaMPS, or the venerable SN74LS00, SN74HC00, SN74HCT00. How can I do this in an Altium...

1 answer  ·  posted 1y ago by Nick Alexeev‭  ·  edited 8mo ago by Lorenzo Donati‭

50%
+0 −0
Modelling tunnel diode relaxation oscillator

I have been trying to model this oscillator I was wondering if we can somehow predict the frequency of the oscillations.For small currents inside a diode from the Shockley diode equation $$ e^{x...

1 answer  ·  posted 1y ago by MissMulan‭  ·  edited 8mo ago by Lorenzo Donati‭

25%
+0 −4
DC-DC converter using Hartley oscillator and transformer [closed]

Instead of using a buck or a boost converter can we use for DC-DC conversion the circuit Im going to describe in the next lines? First we begin with a Hartley oscillator whose output is fed into ...

0 answers  ·  posted 2y ago by MissMulan‭  ·  edited 8mo ago by Lorenzo Donati‭

33%
+0 −2
Small signal analysis of BJT in saturation region

The small signal analysis of a BJT when the BJT is in amplification mode: is easy.However what happens when the BJT is in saturation mode? Can we replace the dependent current source with a r...

1 answer  ·  posted 2y ago by MissMulan‭  ·  edited 2y ago by MissMulan‭

28%
+0 −3
Design high -pass filter with 2 points of the bode plot

Im designing a high-pass filter which has a gain of -8dB at half of the roll-off frequency and I am stuck ,I dont know how to continue the design. In the bode plot of that filter we have 2 points:...

3 answers  ·  posted 2y ago by MissMulan‭  ·  last activity 1y ago by LvW‭

20%
+0 −6
Band pass filter given cutoff frequency and bandwidth

I have decided to try design a band-pass filter with a cut-off frequency of 10kHz and bandwidth of 2 Hz. $$ \frac{1}{\sqrt{LC}} = 10001 \rightarrow LC = 1/100020001 sec^{2}$$ $$ \frac{R}{L} = 2...

2 answers  ·  posted 2y ago by MissMulan‭  ·  edited 9mo ago by Lorenzo Donati‭

50%
+0 −0
Finding voltage gain of Hartley oscillator

I am trying to find the AC analysis of a BJT Hartley oscillator but I cannot continue. How do I find the voltage gain? When no feedback is there, we just find the output resistance and the current...

1 answer  ·  posted 2y ago by MissMulan‭  ·  edited 2y ago by MissMulan‭

50%
+0 −0
Complex frequency of a pole

If we have the transfer function of a LC high pass filter: $H(s) = \frac{sL}{sL+\frac{1}{sC}}$ If we want to find the pole of that filter in the end we get: $s = \frac{j}{\sqrt{LC}}$ and for a ...

3 answers  ·  posted 2y ago by MissMulan‭  ·  edited 8mo ago by Lorenzo Donati‭

33%
+0 −2
Effect of adding stages to a filter

Suppose we have a RC low pass filter of 1st order. If we add multiple stages every time we add a RC stage identical to our original does the slope of the curve in the bode plot db/Hz becomes wild...

2 answers  ·  posted 2y ago by MissMulan‭  ·  last activity 1y ago by a concerned citizen‭

60%
+1 −0
Cutoff frequency of single phase transmission line

Signals with frequency above the cutoff frequency of a transmission line cannot be transmitted through the transmission line. But how can I calculate the cutoff frequency of a single phase transm...

0 answers  ·  posted 2y ago by MissMulan‭  ·  reopened 2y ago by Olin Lathrop‭

33%
+0 −2
How to design a low-pass filter when certain conditions must be met

I am designing a low-pass filter with cut-off frequency = 100Hz and after the cutoff frequency from -3dB to -10dB the average decrease in db/Hz = -0.1 db/Hz.I know how to design a low-pass filter ...

2 answers  ·  posted 2y ago by MissMulan‭  ·  edited 2y ago by MissMulan‭

77%
+5 −0
Siglent1104 oscilloscope channels lagging

First I noticed that clock begins before chipselect gets pulled low on SPI. After eliminating potential sources I started to suspect the scope. I connected all 4 channels to function generator at d...

3 answers  ·  posted 2y ago by Elleanor Lopez‭  ·  last activity 2y ago by Elleanor Lopez‭

75%
+4 −0
Limiting current to DC brushed motor

This question is related to my previous question. I want to drive a brushed DC motor using H-bridge. To power the motor two 18650 cells will be used in series. The issue is that I want to limit th...

1 answer  ·  posted 2y ago by Stefan‭  ·  edited 8mo ago by Lorenzo Donati‭

71%
+3 −0
H-Bridge components and calculations

My goal is to make an RC car, and I have a couple of questions regarding driving the brushed DC motor. Schematic for half of my H-bridge looks like this for now (it will be identical on the other s...

1 answer  ·  posted 2y ago by Stefan‭  ·  edited 8mo ago by Lorenzo Donati‭

72%
+6 −1
Mysterious little cases hanging on street wirings in India

I have been observing these little cases hanging to the wires from a long time. They are almost everywhere here in India, but I was unable to find out what they are. I am not sure whether they are...

3 answers  ·  posted 2y ago by aditya98‭  ·  edited 8mo ago by Lorenzo Donati‭

77%
+5 −0
What effect will extreme temperatures have on characteristic impedance of a wire?

My scenario is this: radio equipment controlling an overhead crane inside a steel mill. Specifically it is used for transporting melting pots. With the current, unfortunate installation, the antenn...

2 answers  ·  posted 2y ago by Lundin‭  ·  last activity 9mo ago by Lorenzo Donati‭

42%
+1 −2
Find Q point in common base BJT configuration

Suppose we have this graph: How can we find the operating point (Q)?In common emitter collector we just draw a line from the vertical axis (Ic) at the point (0,VCC/RC) to the horizontal axis a...

1 answer  ·  posted 2y ago by MissMulan‭  ·  edited 8mo ago by Lorenzo Donati‭

77%
+5 −0
Unexpected impedance spike when paralleling capacitors

I was watching a video from EEVBLOG about bypass capacitors, and he presented a theory that randomly connecting different values of capacitors in parallel can create unexpected impedance spikes: ...

3 answers  ·  posted 2y ago by Elleanor Lopez‭  ·  last activity 2y ago by Andy aka‭

33%
+0 −2
Re model of transistor is the same in 2 different configuration

I was studying the Re model of a transistor: But the Re model for 2 different configurations (common emitter and common base )turns out to be the same! I don't know why I am really confused.How...

2 answers  ·  posted 2y ago by MissMulan‭  ·  last activity 2y ago by LvW‭

71%
+3 −0
Thévenins Theorem for Transistor Circuit

I am calculating the base current of transistor Q1. To simplify the circuit equations, I applied the Thévenin's theorem twice and converted V1, R1 and R2 into Vth and Rth, as shown in the image. ...

2 answers  ·  posted 2y ago by kadamrohan16‭  ·  edited 8mo ago by Lorenzo Donati‭

80%
+6 −0
What is this fourth connection in NMOS device?

I know that in transistors there is base, collector and emitter, and in FETs there is gate, drain and source, but what is the fourth grounded connection opposite the gate in this NMOS circuit?

1 answer  ·  posted 2y ago by NMOS lover‭  ·  edited 8mo ago by Lorenzo Donati‭

70%
+5 −1
How do PLCs normally measure 4-20mA current loops?

I'm looking for input from anyone with insight in the PLC world. How do PLCs usually measure 4-20mA current loops? I would assume it's one of these two alternatives: Through an external "shunt"...

3 answers  ·  posted 2y ago by Lundin‭  ·  last activity 1y ago by KalleMP‭

75%
+4 −0
Level shifting of a 3 state logic pin

I want to design a simple battery charger using MCP73831/2. This chip has a 3-State state pin according to the table below: I have a 3.3V MCU and I want to connect this pin to a GPIO. The MCU is...

2 answers  ·  posted 2y ago by dekker‭  ·  last activity 3mo ago by Nick Alexeev‭

81%
+7 −0
When do I need to put anti-aliasing filter in front of SAR ADC?

Signal characteristics are: 0 to 3.3V span 0 to 100Hz range( there will be noise superposed on top with unknown characteristics) Output resistance Rout=4700 ohm I want to sample that with a...

2 answers  ·  posted 2y ago by 2kind‭  ·  edited 9mo ago by Lorenzo Donati‭

75%
+4 −0
Oscilloscope potentially ESD striked

I have a Rigol DS1104 oscilloscope. Last week I stood up quickly from my table and saw a spike on the scope. Right now all the channels have a DC offset when probe is connected to ground or unconne...

2 answers  ·  posted 2y ago by ScopeMan‭  ·  last activity 1y ago by Lundin‭

70%
+5 −1
Duty cycle of buck-boost converter

I have the following problem: - Using Wikipedia I find that during CCM we have the relation: - $$\frac{V_{out}}{V_{in}} = -\frac{D}{1-D} $$Solving for $D$ and inserting values gives me $$D...

2 answers  ·  posted 2y ago by Carl‭  ·  edited 8mo ago by Lorenzo Donati‭

80%
+6 −0
DAC controlled high side current source.

I'm designing a high side current source that can be controlled with a Digital-to-analog and can source up to 100mA with voltage supply up to 36V. By high side I mean one side of load will be alwa...

1 answer  ·  posted 2y ago by DeadMouse‭  ·  last activity 2y ago by Olin Lathrop‭