# All Questions

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### In this simple transformerless power supply, which component(s) controls the output amperage?

I have the following diagram for a transformerless power supply. I tried for real and worked, however I'm not sure what would be its max output amperage. I have reviewed a few sites about this but all ...
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162 views

### How to design a circuit with dual power source?

I have a LED that can be powered and controlled by a MCU (ATmega328) and would like it to be able to take power from battery. The battery (5 V) can be plugged or unplugged when needed, it's the ...
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55 views

### How much is the output voltage Vo

Suppose we have this circuit: simulate this circuit – Schematic created using CircuitLab Will Vo be 0 or 1V?Both voltages seem correct.At DC the inductor acts like a short so in that sense the ...
1 vote
147 views

### Is this a cold solder joint and do LEDs dim if it is a cold solder?

Are the solders in blue cold solders or something else? They are connected to LEDs and they are glowing dim now, but they used to glow bright when their wires were soldered properly.
61 views

### 12V adapter rated for 4A has trouble outputting 0.12A

I just bought a new 12V adapter on Amazon and tested the performance. It came with, what they call, a led connector tip which has a postive and negative connection point making it possible to connect ...
60 views

### Need to build a power supply from 127v AC to 3 DC outputs

I need to build a power supply that takes 127v AC and outputs 3 DC voltages: +90V, +1.4V, -4.5V. It is for a small tube amp, actually I'm powering the amp with batteries. I general terms, can you ...
9 views

### Converting beam index to angular units

Assume I have a MIMO channel matrix $H$ of dimension [$N_r$ $N_t$ $N_f$] where $N_r$ are the number of antennas at the receiver, $N_t$ the number of antennas at the transmitter, and $N_f$...
28 views

### STM32H750B configuring DMA to transfer from GPIO to RAM

on STM32F769i I used DMA2 triggered by TIM1 to read data from GPIOB port like this so timer1 counted and when it triggered DMA read data in circular mode from GPIOB into my buffer ...
1 vote
73 views

### Grounding issue causing problem with capacitive soil measurement

I am using a MonkMakes board to measure the wetness of some soil in a pot. This board measures the capacitance of the soil, converts this into a wetness percentage, and sends this value to the ...
47 views

### Can a car's radiator-cooler fan be used as an air ventilation pusher [closed]

Ideally i would love to run this fan (80w 12v DC 2000+rpm) at around 800rpm max. I am wondering how i would power this 12v DC fan and how the motor's sound would be (E Magnetic noise) has anyone tried ...
155 views

I wanted to know about solderless breadboard sizes; a standard breadboard has five holes in a row. There are a lot of options to get a bigger workspace, like assembling two breadboards, or buying a ...
49 views

### Node method circuit analysis

There is my ungraded homework. I have watched many node method videos but they didn't help me in this question. I'm struggling the determine where ground should be and choosing points A and B for ...
33 views

### Driving a dual coil latching relay from a single logic signal

I need to drive a dual coil latching relay with from a single logic signal. My problem is how to generate the two logic pulsed on the edges of the input signal: on a rising edge of the input, I need ...
• 5,139
96 views

### I am having problems making two independent oscillators with a CD40106

I'm having problems making two different oscillators with one CD40106 chip. For the first one, I'm using the first hex inverter to make a sawtooth oscillator with the pin 1 and 2. When I make the ...
63 views

### Connector with low-cost crimper for DIY Projects [closed]

I have a few PCBs I designed for personal DIY projects. I have been mainly using Sub-D connectors to connect them, but would love to switch to something like a DF11. However the crimpers for DF11's ...
52 views

### Which transistor is the best for switching on/off a LED with an ESP32?

I have bought a transistor set a while ago and I never used it so I thought I would give it a shot to make a simple circuit. I'm very new to electronics and the math behind it so I'm sorry if it's a ...
34 views

### Not able to read Interrupt Status Register on MAX30102

I am currently trying to develop a pulse oximeter. For this I use the MAX30102 sensor and the NXP LPC1768 microcontroller. The communication is done via I2C. I have configured the MAX30102 sensor to ...
• 1
143 views

### Are semiconductors (specifically silicon) the only materials that can be used for making image sensors in digital cameras?

Could no other type of materials be used even if it means an entirely different sensor design or layout?
44 views

I live out in the country with a lot of fields and forests around us. I am missing my cat and this just kind of got me thinking. I know almost nothing about these kind of things and I’m struggling to ...
1 vote
36 views

### Identifying MCU communication protocol in low-power toy

I am new to analyzing logic traces. Using a Salae Logic clone sampling at 8 MHz, I used PulseView to run a capture on two connected Radica Cube World figures. It looks like only one of the connections ...
35 views

### Output capacitor PCB layout

I am routing a 4 layer PCB of a buck-boost switching voltage regulator circuit. Space is limited and my input & output caps are large. Is there anything to look out for if I lay out the output and ...
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90 views

### Why does the MOSFET drain potential show this strong turn-off overshoot? How to fix it?

I am trying to build a PV charger (PWM), which I guess is kind of a buck converter. Below is a first LTSpice simulation. V1 are the PV modules, V3 is the battery. V2 is the microcontroller's supply ...
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10 views

### Appropriate servomotor for vending machine applications [closed]

I am trying to develop my own vending machine and I am looking for appropriate motors to get the same functionality as the commercial ones. I have read and seen that many vending machines use 24VDC ...
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46 views

### How safe is it to plug a resistor on a 12 V transformer?

I was thinking about using an old fridge as a seedling cabinet. I am tempted to use the resistor of an out of order pizza oven plugged on a small 12 V transformer to heat the cabinet. I didn't do the ...
1 vote
47 views

### Parallel RLC circuit doesn't produce expected results in Multisim

I am trying to create AC from DC. My device is based on the transient response of a parallel RLC circuit: simulate this circuit – Schematic created using CircuitLab If there is some energy ...
35 views

### SSD1309: I2C and SPI pin voltage tolerance?

In SSD1309 datasheet (this is an OLED driver), I found some misleading information: VDD is 1.65V to 3.3V for IC logic VCC is 7V to 15V for panel driving I couldn'...
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37 views

### New Idea: On/Off Remote for iPad - but iPad can't boot! Suspect SENSE

I am installing a mini remote controlled switch in the iPad 8th Gen. The ideas is to be able to cut the power to the iPad at the battery using a remote control. 1st attempt: I wired up the remote ...
68 views

### How standardized are LCD panels?

I have a project in mind where I would like to re-use LCD panels from old monitors to save them from landfills. I'd like to bypass the existing driver and implement my own controller to bypass all of ...
1 vote
17 views

### Reballing / Estimate size of solder balls for BGA-132 NAND chip with 1mm pitch and diameter of pads 0.3mm (Kingston FB64B08UCT1-0D)

For reballing, I need to estimate the size of original solder balls for the Kingston FB64B08UCT1-0D BGA-132 NAND chip coming from a Kingston ssdnow 256GB SSD, model RBU-SC180DS37/256GH. Another SSD, ...
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1 vote
125 views

### How to wire a 480 V AC to 380 V AC transformer?

I have to install a reflow oven which needs 3-phase 380 V AC to power on. There is a transformer (as the picture shows) that came with the oven. I assume that the black wire is the "hot" ...
• 11
60 views

### Op amp stability consideration

I would like to have your opinion on this circuit : The source voltage V12 is a feedback of an other loop hidden. So the operating point of the system is changing. When the 47 Ohm resistor R1 is ...
• 2,270
71 views

### Op-amp level shifter to shift 0.33-3.3 V to 0-10 V

I have an input signal ranging from 0.326 V to 3.3 V and I need to amplify and shift it so that the output will swing between 0-10 V. How can I achieve that using an op-amp? I know I could do that ...
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38 views

I have aquestion about LM310. Forgive me because I am not a native English speaker，I used Google translation. The internal resistance of my input signal terminal is very large, about gigaohm level, ...
30 views

### Repurposing NRF52810 based iBecon / Click device

I have a leftover device that was used to unlock my doors. Since the membership is terminated, It was laying around for some time, so I thought to open it up and saw following, It almost look same (as ...
40 views

### Quiescent current in battery circuit

In this circuit I'm using an MCP73832 for battery charging and an AP2210 LDO. The mosfet is a DMP3099L. With the USB disconnected, VBAT set to 4.2V and the MCU (STM32F030F4P6) in standby mode (drawing ...
36 views

### DFM Now! Installer “DFMNow-V8.zip/exe” [closed]

A bit of a long shot, but would anyone have the installer for DFM Now!, which should be called either “DFMNow-V8.zip” or “DFMNow-V8.exe”, and would have originally lived here. If not, do you mind ...
54 views

### Can I use a buck converter and a 12 V adaptor to create a 5 V and a 12 V circuit?

I have a microcontroller that is powered by 5 V and some solenoids that need 12 V. At the moment I power the solenoids using a 12 V adapter and switch them on and off through MOSFETs which are in turn ...
37 views

### Emergency shut off a three-phase full-wave uncontrolled rectifier by using a MOSFET [closed]

As I am designing a three-phase full-wave uncontrolled rectifier, and I need to add a MOSFET for emergencies. I searched a lot for high-side and low-side MOSFETs but I can't decide which one is the ...
62 views

### How to read 0 current during unavailability of signal at line and neutral? [closed]

I want to read 0 current when there is no signal coming to line and neutral. How do I do it? Do I need to change the optocoupler resistor value or what? When there is no power connected to L and N ...
27 views

If the input is zero here, how was the response on the right obtained? Also, how was gain block changed to equal to τ? Please note this is a first order system with the equation dx/dt = 1/τ(u-x)
68 views

### Help with PNP transistor schematic

I would like to build a FM radio reciever with PNP germanium transistors but I can not find a simple yet efiicient schematic for this. Does anyone know of a schematic I can use? I have found one ...
34 views

### HB100 Doppler sensor calculation

I have a question about the first circuit schematics. I calculated the second circuit's fcutLow and fcutHigh frequencies like this: f2CutHigh = 1/(2 * π * 1M * 100p) = 1.6 kHz f2CutLow = 1/(2 * π * ...
42 views

### How turn a transistor ON when the control signal is OFF

I am creating a light control circuit with a low-power tilt switch (>0.1A) to automatically turn lights on and off when the switch is tilted. When the switch is level, it is open, and I want the ...
51 views

### How to connect a 24VDC LED light strip and 5V/500mA microcontroller board to power with a single USB-C cable?

I have a 24VDC LED light strip and 5v/500mA microcontroller board that I would like to connect to power with a single USB-C cable. At the moment they connect to their own power sources and the light ...
47 views

### Short circuit on a coil

We are currently manufacturing some coil assemblies. Our customer reported that some of the coils we shipped had failed once they received them. Some of the coils failed at the customer's incoming ...
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16 views

### 5T OTA Vout in Cadence simulation is always just VDD?

I'm working on an 5T OTA with the following schematic: Here's the simulation circuit: I'm using a VDD = 2.5V since the transistors are rated for that in the model library I'm using. My issue is that ...
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1 vote
47 views

### What is a 3-phase H-bridge called?

Simple question. An H-bridge has two phases by default - two half-bridges. But it can also be constructed with 3 or more halves. I assume it isn't called an ├├│-bridge :) For the benefit of Andy Aka: ...
• 10.5k
1 vote
106 views

### What is Vac(peak) in this question?

Bit confused at what Vm/Vac(peak) is. Either 230V or 325V. rest seems simple
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108 views

### 10 MΩ resistor needed on op-amp input for correct operation

Circuit: The 3 kΩ in series with the switch in the circuit represents a metal probe that gets connected to ground when water is present (switch open = no water; switch closed = water). Due to the ...
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