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# Questions tagged [small-electronics]

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### Why use a PMOS transistor instead of a diode for ESD protection?

I am working on updating a PCB design by adding ESD protection to the power supply. I see that an experienced engineer at my company has placed a PMOS transistor rather than a series diode, and I'm ...
5 views

### How to replace a manual timer by a simple on/off switch on a home appliance [migrated]

Case On a simple 220v home appliance equiped qith a maual timer switch ( a knock that you can turn clockwise up to the desired position -time- and will then automatically turn counterclockwise for ...
56 views

### Transistors and Diodes maximum current per size

As you can understand my knowledge in electronics is limited. I am trying to find throughout the internet a way to find the maximum current I can put through a transistor or diode versus their size. ...
90 views

### Can I use a 24V, 1A fuse for a 5V application?

I have a 5V power supply which needs protection. I only have a 24V, 1A fuse. Can I use this fuse for the 5V power supply. As Watt = R * I * I = V * I. As rated W is constant for a given fuse, will ...
144 views

### Deviation from typical I-V characteristics of a diode in high frequency

Why the diode shows a loop in the I_V characteristics?(Diode part N4003, Frequency was 100k) My instructor told me something regrading the retardation of charge carriers but I couldn't understand/find ...
71 views

### How can I connect a sensor to two LEDs so that one will work when the sensor's output is HIGH and the other when it's LOW? [closed]

(Moved from the Arduino stackexchange) Let OUT be the sensor's output. If I connect LED1 to BAT+ and OUT LED2 to BAT- and OUT is this Ok? Instead of LEDs those could be units that need even ...
35 views

### Insufficient current using Elegoo UNO R3 and breadboard

I'm completely brand new to electronics and just bought a breadboard kit to try and get my feet wet. I have a 9V battery and I'm trying to fire up a green LED. I have a 330 Ohm resistor in series ...
81 views

### Need a processor to be able to turn off its own power

I have a processor that is powered by a mains 5V power from a wall adapter, and has a short term battery backup. I need the processor to turn on automatically and immediately when 5V mains supply is ...
80 views

I found this term many times on this website : https://www.renishaw.com/en/rgh34-incremental-encoder-system-with-rgs40-linear-scale--6450 It seems to be something related to a sensor or a transducer, ...
50 views

### Trigger based on Time Difference between two sensors / Catch a Miss on sensor

I have two Sensors S1 and S2, S1 is a 24v inductive proximity sensor which i isolated using octocoupler to work at 5v and S2 is a transmissive type phototransistor sensor, both are placed at a fixed ...
27 views

### Isolation voltage of a flyback transformer

How to calculate the isolation voltage of a planar flyback transformer? Or if there are any standards about it? I am designing a planar flyback transformer that need an isolation voltage of 1000V, ...
54 views

### Switch placement on electronic circuits on the positive wire

Why are main on/off switches in electronic circuits/appliances (any small, low power electronics) always placed on the positive wire (in case of DC circuits) between the power supply (batteries, ...
1k views

### Single pulse when circuit is powered on [closed]

I am new to electronics and I am wondering how can I use my Vcc to produce a short single pulse.
90 views

### Calculate resistance of an unknown resistor in a circuit

I am currently studying some old exams for the upcoming one and I got stuck on this question, I seem to get the right answer by eyeballing the circuit but I want to be able to calculate the value. ...
117 views

### How to convert 0-3 V (PWM range) to 0-24 V (device voltage requirement)

I have an Arduino with some PWM pins, output range is 0 to about 3 V and I need 0 to 24 V range. I need to active a solenoid - a hydraulic proportional solenoid A 12V and 5V source is also ...
54 views

### Is diode reverse recovery time related to diode capacitance?

The title. Is there some relationship between the two parameters? For example, fast diode recovery time indicates low capacitance, or even farther, can one be calculated from the other? Thank you in ...
80 views

### Can I use 13003 transistor in place of 2n2222?

I am working on a project which requires a npn 2n2222a transistor as recommandation. But as of now the transistor is not available to me. Alternatively I have transistor 13003 and c945 available as ...
46 views

### Choosing clock buffering circuit

The modular 5V-powered design's module is having two output clocks (21 MHz and 3.5 MHz) to other modules in the system. I am looking for the best way for buffering these signals so that they would be ...
41 views

### SPI pins logic level issue [closed]

I have ESP32 and the popular dot matrix module MAX7219 8*8 module to interface. It is connected through SPI pins. After a sample word printing on the maxtix it shows garbage outputs. Is it happening ...
80 views

### Difference between cutoff and subthreshold region of nmosfet?

I understand that some current does flow from drain to source when Vgs is below vth and Vds is greater than zero. But why this has a different name?(and a different region in Cadence virtuoso tool) ...
35 views

### Low power, low profile binary indicator

I am looking to find a way to communicate an alarm on a tiny device with a very low profile low power consumption component. The alarm is binary in nature, basically it is either on or off. LED does ...
2k views

### Does anyone have problems with micro USB connectors on PCB?

In a PCB I've been developing, I included a micro USB connector. The problem is that when I plug in and out cables on it, seems to get weaker and weaker and needs to be resoldered, even the pins on ...
67 views

### Can the FTDI Tx and Rx tension level be different that it's VCC?

I'm building my own FT232RL to convert a UART signal to USB. The source of power will be the USB 5V, but for reasons of the circuit i already have it would be easier to let more of the circuit keep ...
47 views

### Is it possible to measure impact force using Flexible PVDF Piezoelectric Film?

If it is possible , should i use integrator circuit first to hold the signal then follow it by other signal processing signals (amplification and noise filtering ) ? , knowing that i tried to connect ...
77 views

### Where do I start to look for an automatic off feature on a circuit? (Guidance) [closed]

My child has a light up toy that turns off after 20 minutes and she likes it all night when she’s sleeping. I’m trying to figure out where to start looking among the circuit for the automatic off ...
51 views

### Unable to find data sheet for MAX8918ITM

I am quite new to electronics, so I apologise for the inevitable mass of stupidity in this question. I am trying to find the data sheet for the LCD driver MAX8918ITM, from a Nikon COOLPIX L110, and it ...
72 views

### Common ground for different voltages

I see there are a number of questions regarding this but none made it clear to me, so I'll risk being virtually stoned and go ahead and ask it again. I have a 12V battery which powers some 12V ...
53 views

### What can i do with a WM8192EU USB module?

I recently came across a wm-8192eu usb module from an old electronic doorbell. It had a socket on the board that it just slid right out of. When i googled the chip it showed a bunch of usb wifi ...
113 views

### Shift square wave down for electromagnet as load

I generate a rectangular wave (from an NE555) with a frequency which can be as low as 0.25 Hz. The rails are 0V and +10v. The output signal after a 33uF capacitor swings between 0V and 5V and is ...
93 views

### 3mm and 5mm LED

Why can't we use a 5mm LED as the flasher in this circuit? What's the difference between a 3 mm and 5 mm led? How do you identify one?
55 views

### What will be the effect of changing the order of the filters on the sound coming from each speaker in my audio system?

What will be the effect of changing the order of the cross over filters on the sound coming from each speaker in my audio system?
36 views

### Problem with PSPICE simulation

I am having a problem replicating some lab results in the PSPICE/capture CIS program for an assignment. I have this circuit right here: which is an oscillator using the uA741 op-amp which is supposed ...
35 views

### Problems with capture cis simulation

I am trying to run some simulations on capture(PSPICE) for a school assignment and then compare the results of them with the results that i got when trying these circuits in the lab. However the ...
87 views

### Limitations of sound card oscilloscope

I’m supposed to build a buffer circuit for pc oscilloscope using the sound card of the pc and a software “zelscope”; however there’re limitations: Not possible to display DC because there’s a DC ...
75 views

### Flat line on output of single supply sawtooth generator

I have built the following sawtooth generator using LM358 opamps: In simulation everything works fine, however in reality I get only flat line on output. Anyone got any idea what's going on?
94 views

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### AD5933 is not working with external clock

I am using AD5933 impedance measurement chip. There is an option to connect an external clock. I am using a function generator to give 250 kHz, 2-volts peak square wave signal to MCLK pin, but it's ...
112 views

### What is maximum symmetrical output voltage swing in this case?

I'm pretty new to Electronics and hence the following doubt. I could not understand how the authors reasoned out the swing limits for this problem ((b)-part only)
156 views

### How do I design my own FFC cable

I need to design a custom FFC cable for an electronic device (about 10cm and 34pins) I messaged a manufacturer who could make custom ffc but he needs a layout or something and I don't have experience ...
135 views

### Is it possible to wire car speakers straight to a 3.55 mm jack? [closed]

Is it possible to re-wire car speakers (model JBL GT7-5) to a headphone jack (3,55 mm stereo plug) directly without an amp? And if not, what do I need to-do? This what I know about the speakers: ...
1k views

### Operational amplifier basics

In closed loop (negative feedback) configuration of a OP AMP the input voltages are same that means the differential voltage is zero Vd=(V1-V2)=0 ,then how we obtain the gain? where the output is come ...
138 views

### How MCU pin reads whether it is being pulled up or pulled down?

I am a beginner in electronics. I searched on the web about Pull up and Pull down concepts. As far as I know, 1) When an MCU pin is pulled up, a small amount of current pass through the pull-up ...
51 views

### Can I leave it unconnected pins in the level shifter?

My concern is that pins are connected between DB25 and TXS0108E, but are not connected between TXS0108E and the Header 5x2. There is only the tracks between TXS0108 and the Header 5x2, but there is no ...
85 views

### Both sides of a voltage level shifter connected

The TXS 0108E is a level shifter circuit, performing, in my project, a shift level voltage from 3.3V to 5V . Because of a design error in the wiring diagram, I left some pins with the same name on the ...
2k views

### Indicator light circuit

I'm an electrician and my work is to maintain boats. I have a problem. On the boats are sailing lights, and for each sailing light is another light inside the boat that tells you if the sailing ...
51 views

### Can I connect a 15A surge protector to a 13A extension cord?

As someone who’s studied engineering, I should be able to answer this question. However, a quick search online has me confused. Provided what I’m plugging in (a laptop drawing relatively little power)...
76 views

### Avrisp mkii not recognizing atmega 328p chips

I have three different sets of chips, the attiny85, 328p, 328p-au. Initially, the avrisp mkii, was programming the atmega328p, however now it is not recognizing this chip (i.e. 328p) or the 328p-au. ...
106 views

### How do I stop signal looping with I/O port in this communication system

I am still a student. When I am designing communication system I am facing this problem: As shown in the figure I need to communicate with Master and Slave. But Master and Slave have single I/O port ...