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Keyboard diode design

I have a question about keyboard diode placement. (Pardon my ignorance if this is simple question I have no electrical engineering background.) The diagram below shows how a keyboard schematic is laid ...
• 101
63 views

On the internet, it is frequently mentioned that for a fully discharged capacitor at the instance it is connected to a voltage source, it acts like a short circuit, thus drawing maximum current. At ...
• 511
1 vote
37 views

Latching Comparator Problem

I am working on a latching comparator design for the purposes of overcurrent protection. This is built around an LMV331 open collector high speed comparator. VIN is sourced from a current sense ...
29 views

Common base amplifier's input impedance

simulate this circuit – Schematic created using CircuitLab In a BJT common base amplifier configuration the input impedance is ~$r'$ (emitter resistance), right? If I understand correctly, ...
• 21
22 views

Voltage output on thyratron gas tube relaxation oscillator VCO?

I know that thyratron gas tubes can be used to make a sawtooth like relaxation oscillator: My question is for a modification of this same circuit that makes it act like a voltage controlled ...
1 vote
26 views

Periodic noise on peak-to-peak plot

I've encountered a strage behaviour and would like to ask for suggestions. I have a servo motor that is doing a jog movement with a fixed 250rpm. The motor drives a shaft through an epicycloidal ...
1 vote
25 views

DC-DC converter circuit LM5164

I would like to build a DC-DC converter circuit using EasyEDA that can output about 8 V from 7 Nissan Leaf battery modules that are about 55 V nominal. I am looking at the datasheet for the LM5164 and ...
• 11
41 views

Ethernet Switch with Mux

I'm attempting to design a circuit that is capable of simulating an Ethernet disconnection event for a piece of test equipment. There doesn't appear to be any reference material that uses back-to-back ...
• 53
53 views

Biasing a DIY current feedback opamp

For a personal project, I'd like to make a discrete current feedback opamp. Here's a simplified schematic: The question is about how to bias Q3/Q4. For a nice class-AB output, the sum of both Vbe's ...
• 59.8k
31 views

Attach thermocouple to a PFC inductor

The inductor I am talking about is simply a toroid. I am attaching a thermocouple junction to this component with help from thermal paste and aluminum tape. Anything I should be careful about in this ...
• 59
45 views

Grounding resistance dependency on distance

I am currently learning about grounding in electrical installations and there is something that intuitively doesn't really make sense to me. It is related to the resistance measured between two ...
• 101
25 views

Where can I find the RF69H Transceiver IC? [closed]

I found this module on the Digi-Key: https://www.digikey.com/en/products/detail/sparkfun-electronics/COM-13909/6023504?s=N4IgTCBcDaIMIHkCyBaAjAZgJwAYsgF0BfIA and I want to find the actual RF69H IC ...
• 641
33 views

Do conduction electrons recombine with positive donor atoms?

Once the 5th valence electron of a donor atom left, it will be to the conduction band, so the donor atom becomes positively charged. My question is if it is possible, that a free electron from the ...
66 views

My 16x4 LCDs are printing out junk [closed]

I have checked every other post on this, and no solution currently works and need an opinion. I have an LCD (P/N: FC1604A01-RNNYBW-66SE) that is being powered by 5 V and is controlled by a 3.3 V ...
26 views

BM59100 / 3,8VDC / 1700mAh battery registering 2.68VDC [closed]

I have a phone battery that is rated at 3.8 VDC but currently giving 2.68 VDC and when I test the current it givea 0 A! Question: How can a battery still have 2.68 VDC but no current? Or perhaps my ...
• 399
20 views

How to know whether SRV05-4 is working or not

There are couple of SRV05-4 array of TVS diodes on our PCB. I want to know how can I tell whether one of them is working or not i.e. whether it's still alive or dead. I was interfacing my board with ...
• 121
44 views

Does anyone know a good RS232 to USB B converter? [closed]

I have an instrument that controls a temperature controller via RS232. The controller is no longer available with RS232 input, but now has a female USB B port. Is there a converter that will go from ...
15 views

How to calculate the two port Y parameter of this network?

The Y parameters of two-port 1&2 and the three port are given. I need to find the Y parameter of this overall network. Furthermore, if the input-referred noise of two port 1&2 are known and ...
63 views

Transimpedance amplifier circuit not working [closed]

I am making a trans-impedance amplifier using AD549 op amp that simulates a current-to-voltage conversion on a satellite radiation detector. In my circuit, an ultra-high value resistor (10G) is placed ...
37 views

Photovoltaic solar cell attached to load device

I am new to the field of power electronics so please bear with me. From what I understand, photovoltaic cells are often connected to a DC/DC converter and a MPPT power system that allows for (1) ...
37 views

I'm considering a power supply to convert 240VAC single phase to the equivalent of three phase Wye [closed]

I want a switching power supply. 240VAC split phase to same VAC but 3 phase wye equivalent. I am running a three phase power supply, auto regulator water cooled, for an antique Spectra Physics 10 watt ...
49 views

Effect of 5V on 3.3V GPIO

I am using a shield on top of a board with headers. One of the headers of the shield needs 5V but it also makes a connection to a 3.3V GPIO pin. I am ok if that input is damaged since I am not going ...
• 11.3k
48 views

Zener diode not regulating capacitor voltage

I am trying to harvest energy from a stepper motor by turning its shaft with my hand. Since it is a 2 phase motor, I rectified both phases and connected them in parallel to get more current, then a ...
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19 views

Why do some channels of the capacitive sensor fail to calibrate and how to fix this?

I am unable to get 6 of the 8 channels of the CAP1298-1-A4-TR to calibrate and they therefore remain inactive whenever I place my finger on. My board is a 4-layer rigid flex board and the 2 working ...
• 456
101 views

Does a resonant peak produce a distorted wave form?

Context I am re-enforcing my understanding of the frequency response. From 1, I understand that, In an audio system, [the frequency response] may be used to minimize audible distortion by designing ...
• 147
29 views

Building subwoofer into a car audio system [closed]

My buddy has a car audio system and wants to connect a subwoofer to it. We would like to do it ourselves but are not sure how to proceed. What we have is: Car radio Subwoofer Cable with connectors ...
• 47
76 views

What value of resistor is needed to limit current to 0.5 ampere in a 12V DC circuit?

I have a 12V DC motor that uses 1 ampere from a 12V battery. I want to limit it to 0.5 ampere because it runs too fast on 1 ampere. I know that I can achieve that by adding a resistor but the question ...
28 views

Fractional N Synthesis and Frequency Meters

I bought a 30-year-old frequency meter from EBay. It has the ultra-stable OCXO reference option, but hasn't been calibrated in 9 years. It seemed to work straight away so I fed it from the Arbitrary ...
• 942
55 views

What is the difference between tantalum and aluminum capacitors?

There are two different motor control modules in the images. Different capacitors are used in both modules. As far as I know, the intended use of these capacitors; when the motor is turned on or off, ...
• 317
40 views

Hardware testing of the 1:1 cable for opens and shorts

I have a board/cable (DUT = device under test), featuring (in addition to other things, which are not important for this question) 2 connectors - A and B. The connectors are connected 1:1 at the DUT. ...
• 198
16 views

How to adjust a 3S BMS to connect a 2S Lithium ion battery pack to it?

I have a 2S Lithium ion battery pack and a 3S 18650 BMS protection board. I need to connect the pack to the board. While researching, I've noticed that this can be done by connecting a component ...
38 views

IC identification - Analog Devices with top marking S 1E

What is this IC from a board I should repair? IC is from Analog Devices, I suppose. It could be a buffer or similar. It is marked as S 1E. The IC has 8 pins.
25 views

A question about input rating of a transistor module

I'm planning to use this relay board. It says here on their website the input is 5V. In my case Vcc is 5V but the input signal to Q1 and Q2 will be 3.3V, so I'm not sure if the input signal to the ...
• 402
19 views

555C Part taking long time to simulate

I am currently trying to simulate the 555C part in OrCad. However, every time I run the simulation, it runs extremely slow. I'll wait about 10 minutes and it won't even be 1% of the way done. I'm ...
40 views

How does a BJT differential amplifier amplify?

I am reading The Art of Electronics. I found a related question here. I understand that differential gain of the amplifier is $$G_{\text{diff}}=\frac{R_c}{2(r'+R_e)}$$ but how? OK, using hybrid-pi ...
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34 views

Calculating capacitor discharge time with constant current sink

To calculate capacitor discharge time the formula is: But because the current being sink from the capacitor is constant from highest voltage to zero volt, I think the capacitor should discharge ...
• 2,046
35 views

TPS61230A efficiency [closed]

I'm working on a project that uses Raspberry Pi Zero powered from Battery. So, I'm using a DC converter to have 5V for Raspberry (~5.2V to avoid dropout). The Rpi do some IA calculus. As per the ...
18 views

LoRa setup not working properly

Hi guys I hope you can help me. I'm new to LoRa communication, just bought two RA-02 433MHz modules, these ones to be more exact: https://shop.m5stack.com/products/lora-module With them, I connected ...
24 views

Connecting ULN2003 gnd pin to a different pin, for example, microcontroller in Proteus [closed]

I want to use several ULN2003 ICs to control several 7 segment displays and toggle grounds to achieve persistence of vision. I have tried connecting the hidden ground pins of the ULN in Proteus to a ...
29 views

Low voltage from simple PWM circuit

I'm attempting to make a simple PWM speed controller for a fan motor. I am powering the circuit with a 12V 10A PSU and have successfully tested the motor directly connected to it. When connecting the ...
• 215
51 views

Looking for a replacement high voltage power transistor for a vintage CRT [closed]

My vintage Apple CRT monitor (M1212) is dead with a suspected shorted NPN transistor (Motorola MJF16206). Does anyone know what model of NPN Transistor is compatible with Motorola MJF16206 that I can ...
481 views

Is this component a resistor or an inductor?

I found this this component at the power supply input of a circuit. I tested it with the multimeter. It measures an open circuit. I couldn't figure out its value or its type. It is located before a ...
• 301
1 vote
56 views

Current shunt not working

I was using a 12 ohm current sensing resistor and I was getting 26mVAC across IN and IP. When I switched to a 100mohm resistor then I was getting around 8.2mVAC across IN and IP Load = 300W and ...
33 views

How to make adjustable current source 20-200mA with supply voltage 16V [closed]

New to electronics, I need to do a project for uni. Have no idea where to start. Any help would be appreciated. I need to make an adjustable current source from 20mA to 200mA with supply voltage 16V. ...
37 views

Can I reprogram the XY-BJ Timer Relay Module?

I have a XY-BJ Timer Module and I would like to know if that's even possible to access its source code and reprogram it to my own desired delays. What application do I need to install to access/modify ...
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36 views

How can I generate the waveform below and inject it into the LTspice circuit? [closed]

Is there have any special function I can use in LTspice to generate this waveform voltage instead of just do an operating point analysis for different input voltages?
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1 vote
38 views

Cascoded op-amp: What practically limits CMRR and input impedance?

I am interested to better understand the practical limitations to input impedance and common-mode rejection ratio in cascoded op-amp structures. I already simulated quite a bit, but I am running into ...
• 11k
64 views

What are the rationales behind real wire (transmission line model), real capacitor and real inductor model?

I have been pondering about how the real model of circuit elements (wire, capacitors and inductors) and transmission model are derived through intuition (based on physics). Here are my references from ...
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74 views

How to attach cable to a solder eyelet? [duplicate]

I believe that's what such connector is called. I want to attach 18 awg wire to it. Is slide on terminal the best choice?
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