All Questions
192,801
questions
0
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16
views
Using an SSR to regulate voltage to a bridge rectifier
I've connected my SSR to the inductor and then the bridge rectifier then the DC choke and finally the motor.
The motor seems to be running fine at various speeds and duration though I have not yet put ...
0
votes
0
answers
21
views
PCB Design multiple grounds with different ICs
I want to make a board that have differents ICs and looking at the datasheets, I can see different grounds connected in different ways and I'm not so sure about how to connect them/which ground should ...
0
votes
1
answer
31
views
Is it possible to switch a 200 Vpp AC signal @ 2000 Hz in under 1 millisecond?
I want to switch a ~120 V AC signal with a frequency of up to 2000 Hz.
For my application (driving electrolumnescent wire) it is important that the switching duration is not higher than about one ...
- 145
-1
votes
0
answers
17
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How I do to negotiate POE+ IEEE 802.3at, and pick out the 48 VDC? [closed]
I have tried to find anything about this.
But I have a IEEE 802.3at switch, for where I want to pick out 48 VDC power from the network cable.
I have found both that you need to negotiate with data ...
0
votes
0
answers
22
views
How to level shift bidirectionally with a high impedance output state?
I have communications bus I am trying to reverse engineer. It is based on a 9600 bps UART but inverted so it sits at 0V when idle, and pulses at 5V to send a binary 0. Unlike a normal UART the TX ...
- 1,649
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votes
0
answers
22
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Effect of semiconductor doping on threshold voltage
After reading online, I have modeled this as an relation between the threshold voltage and the doping concentration:
For a N-channel MOSFET on a P-type substrate:
$$
V_{T,N} \alpha \sqrt{N_{A}}
$$
...
- 11
0
votes
0
answers
40
views
Any cheap way to capture the timestamp when a electric device is turned on? [closed]
I want to capture the timestamp when a electric device is turned on and off. What's the cheapest way to do it? From my own knowledge, I think a cheap smart plug off Amazon would do the job but is ...
1
vote
1
answer
56
views
How to draw edge plating in KiCad?
I need edge plating for a KiCad PCB and I'm not sure how to draw it. I've checked this explanation and it looks like I need overlapping copper on the PCB edges. But KiCad is trimming the polygons on ...
- 422
0
votes
0
answers
29
views
Advice on differential amplifier for long term stability
I am experiencing drift issues in my circuit. One thing that I suspect is the drift of the differential amplifier gain.
A differential amplifier is used with a gain of 0.5 biased at 2.5 V. The opamp ...
- 11
0
votes
0
answers
37
views
Constructive suggestions how to retrofit a wireless remote control to a powered device?
1:
A Gorilla LG-EH-0100 hoist 240V
doesn't have remote control, but simply controls up and down.
There are wireless remote controls 12V
with up and down controls.
How could the device be retrofitted?...
0
votes
0
answers
13
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amphenol-sensors’s /temprature sensor/74-1463 [closed]
I would like to know manufacture that handle similar items witch is below.
https://www.amazon.co.jp/dp/B09SJ3Q6L2/
- 1
0
votes
2
answers
31
views
Need support for ERC in KiCad
I am a beginner in KiCad and looking for support for following errors in ERC KiCad -
Below are the Eeschema snapshots for reference -
How shall I resolve these errors?
0
votes
1
answer
49
views
How to determine the directions of voltages across resistors in circuit diagrams?
In the following diagram, the directions of both currents and voltages for voltage sources are shown. My task is to write KCL and KVL for all 3 loops, and my question concerns KVL.
I believe I am ...
1
vote
0
answers
26
views
WS2815 circuit erratic behaviour
I have been having problems driving WS2812 LEDs; the radiated emissions were too high to pass UK tests. See Radiated emissions from WS2812 LEDs
I finally bit the bullet and went for LEDs on a printed ...
- 81
0
votes
2
answers
53
views
Can we place capacitors parallel to the speaker (30 ohm headphone) and aux jack?
I am working on an audio amplifier PCB circuit, where I have used LM386 as an amplifier, an aux jack for audio output, and a small speaker of headphones (30 ohm).
I have two 220 uF molded and one 470 ...
1
vote
0
answers
21
views
How to determine the length of a quarter wave transmission line which would be added to an existing circuit for impedance matching?
Are the values I have calculated accurate? With this setup, there seems to be a 90 degree phase difference across Tx2. I'm not sure if the 90 degree phase shift is supposed to across just Tx1 or ...
- 11
1
vote
1
answer
118
views
Identification of shiny metallic blocks on the PCB
What are these shiny metal-like components in the images below?
Is that kapton tape covering for ESD protection?
- 127
1
vote
0
answers
36
views
Why does a 1k resistor between signal and MOSFET gate minimize the output rise time of a CD4000 IC?
I've come across a circuit behavior that I find surprising and don't really know how to go about researching it further except just to ask here:
I am building a circuit that needs a momentary RESET ...
- 368
0
votes
1
answer
64
views
How to run fans out of phase?
I am working with server fans. The noise generated by these fans is quite disruptive, and I've read that running them 180 degrees out of phase could potentially reduce the noise.
I'm looking for ...
0
votes
1
answer
45
views
What type of transformer configuration?
I am curious on what type of configuration (all I know is this is related to a three phase) is this and what are the requirements for it? For example, does the kVA need to be the same? What are the ...
0
votes
2
answers
53
views
Layout- Should the output and input traces of this hex inverter be superposed
I am using this hex inverter in one of my pcbs; the inputs are TTLs, so fast switching signals going from 0 to 5V very fast ( I don't know yet the rise time of these signals, maybe 10 us ?). Both ...
- 259
0
votes
2
answers
94
views
Does current prefer to take a series path over a parallel path?
simulate this circuit – Schematic created using CircuitLab
Based on the simulation I have done, current here prefers to take the C1 - R2 path first and once C1 is saturated and cuts off it then ...
- 439
1
vote
1
answer
31
views
How to do high voltage high-side switching in a simple and power efficient way?
Background
I am planning a system that needs to maintain low power draw (especially when in its standby state), which means I need to use some switches to turn off parts of the system when not needed. ...
- 11
0
votes
0
answers
24
views
SOC booting FPGA configuration file
I have some understanding on embedded system booting process, which includes step wise execution of:
ROM boot loader.
First stage boot loader - internal to SOC.
Second stage boot loader - stored on ...
- 1
0
votes
1
answer
34
views
How does current travel if disconnected from a voltage source part of RL circuit?
Specifically, this RL circuit confuses me. RL circuit with SPDT switch If the switch in a circuit is connected to a voltage source for a long period of time (t < 0), and then disconnected from the ...
0
votes
0
answers
32
views
AC Power Balance Equation
For the example on Page 7 of this lecture:
https://www.keithmoffat.com/IntrEPS/IntrEPS_Lecture11_PowerFlow.pdf
Are the following balance equations correct?
$$
1=-10 sin \delta_{11}+10|V_2|sin \delta_{...
- 1
0
votes
1
answer
50
views
Need help identifying crystal component
I have what I believe to be a ECS through hole crystal on this PCB. It has the markings "ECS V 4.19-12 A9." I looked at their product catalog and do not see anything that could be it. I am ...
- 11
1
vote
0
answers
50
views
Wrong Graphs for Ids (MOSFET)
I'm writing a MATLAB script that employs Shockley's model to derive the values for K and Vt of a transistor. Upon determining these parameters, I utilize them within the framework of Shockley's model ...
- 11
0
votes
0
answers
32
views
Untraceable datasheets of DC-DC buck converter (5 pin SOT23-5 IC) used in TP-LINK WiFi Router TL-WR720N V2
I am trying to search the datasheets of DC-DC buck converters used in the TP-LINK WiFi Router TL-WR720N V2.
LD5AX and
TR5XF
A couple of years ago, an above mentioned router, belonging to one of my ...
- 1
0
votes
1
answer
42
views
Certification - wall-plug power supplies
We manufacture small electronic products that use a wall plug power supply (100-240 International input to 5VDC 15W output - a "wall wart"). We want to change to a 20 watt wall plug power ...
- 1
0
votes
1
answer
59
views
Missing nets in PCB editor
I designed a schematic in KiCad 7.0.8, have verified that I have foot prints assigned to all components and when I hit F8, it switches over to the PCB editor, I get the "Changes To Be Applied&...
- 121
0
votes
1
answer
60
views
Transformer magnetics design
In transformer design, can someone help me understand how the no load flux is relevant to the transformer efficiency? What design parameters put constraints on the maximum core flux? Let's suppose I ...
0
votes
1
answer
51
views
Possible serial noise or corruption error when trying to upload code to ESP32 wroom32U custom board
When I try to upload any simple code, I get this corruption error, I have removed the IO12 as recommended, changed the baud rate, added 1 uF between enable pin and GND, tried both manual and auto ...
- 11
1
vote
2
answers
89
views
Reverse engeneering the control of an inductor
I tried to make the schematics of a toaster of mine. I don't have access to the toaster anymore but here is a part of the schematics I got.
It shows the control of the inductance that acts as a magnet ...
- 208
1
vote
0
answers
54
views
Constant current LED driver temperature issue
I am using a DC-DC step-down constant current LED driver to power up four high power LEDs in a series connection. The LEDs are drawing a 2 A current at 100% power and they have forward voltage about ...
- 33
1
vote
1
answer
42
views
Barrier block vs. Lever wire splice for power distribution in a mobile robot
I am a beginner in robotics and am learning by building a four-wheel mobile robot. I will supply electrical power from one Li-ion battery to four DC motors. I plan to use a barrier block to distribute ...
- 41
1
vote
1
answer
84
views
Resistor in RC circuit
I have an RC circuit connected to a switch node as a snubber. I am facing difficulties determining the required power rating for the resistor. I have looked at this and this, however, it remains ...
- 185
0
votes
0
answers
29
views
Delay-Free Switched-Capacitor Integrator Difference Equation Derivation
I want to derive the difference equation of a delay-free SC integrator using charge-domain analysis.
Here's the example I am following. This shows you that for charge domain derivation, all you need ...
- 396
0
votes
0
answers
77
views
Circuit design help w/transistor + resistor [closed]
I bought an Eagle A103-006 12V timer. Its specifications:
Type: NPN signal
Logic low<1VDC
High>2VDC
I "blindly" wired it into my circuit, see drawing so that when motor runs the ...
0
votes
2
answers
89
views
Why is the Gb/s usually matched with the GHz for SDI?
My knowledge in electronics and RF(because high speed data) is very surface level but attempting my best.
I'm attempting to do an application which utilizes 3G SDI, but am not understanding why there ...
- 1
0
votes
0
answers
37
views
Where is the majority of current drawn from for a servo motor? [closed]
I'm outlining some modifications I want to a servo motor project, one of them being to add a current monitor like the INA197 to the power line for a servo motor. The servo can experience some elastic (...
- 319
0
votes
0
answers
31
views
Is a matching receiver module needed in order to use a Bluetooth audio transmitter/transceiver/emitter module?
I'm using this audio Bluetooth emitter.
I connected it like so, the LED flashes, but no Bluetooth device is displayed on my phone or PC. How do I troubleshoot this or do I need a matching receiver ...
- 616
0
votes
0
answers
17
views
Driving multiple VFD controllers using collected data
I have a LoRaWAN sensor network that I setup which collects temperature data from multiple compost stacks and stores it in a database on the local network. I need to use that data to control the speed ...
- 101
1
vote
1
answer
310
views
What is this symbol for?
It looks like a connector, or as the diagram is about a dynamo, a light.
- 544
0
votes
6
answers
117
views
Can I utilize 3 phase power in a single phase appliance by connecting all 3 lines in parallel?
I can't seem to find an answer to this. Assume we have a 400V three phase power source. Connecting phase-to-neutral will give 240V. If you connect them in parallel you should still end up with 240V AC....
- 165
0
votes
1
answer
61
views
Automatic attenuation of audio signal to fixed amplitude
I have an audio amplifier and one of those cheap Chinese Bluetooth audio receivers.
The output of the receiver is way above audio line level, about 7V peak to peak.
When using that as input for the ...
- 147
-1
votes
0
answers
18
views
how to calculate on resistance (Rdson) mosfet in cadence virtuoso
To size mosfet, I need to know the on-resistance (Rdson) of the mosfet. Now How can I find the one resistance (RDSon) in cadence virtuoso for the MOSFET? DC operating point is not giving me any value ...
- 11
-1
votes
0
answers
37
views
12 volt dc to 6 volt dc adjustable converter [closed]
I have a 115ac to 12v 20amp lead acid battery charger...I would like to use it to charge 6 volt lead/acid batteries (and for other stuff)... (ideally) I would like to build a separate box that I can ...
- 1
0
votes
0
answers
53
views
CH340X issues with programming
I have found a simplified version of popular usb to uart schematic and decided to test it out
Unfortunately, it doesn't work at least for ESP32, while there is some activity on BOOT (IO0) pin, there ...
- 101
1
vote
1
answer
56
views
Reverse PNP to NPN endstop logic
I bought a CNC control board equipped with Teensy 4.1 and the T41U5XBB to replace the mks dlc32. I am sorry to discover that the endstop pins of the new board only accept NPN sensors, both NO and NC. ...
