1. S

    lm386/why this circuit works well with my iphone audio jack but when i connect a mic it makes so much hiss and noise

    as you can see this is the circuit that I made based on lm386N-1 whenever I connect my iPhone (it's a 5s if it makes any difference ) the sounds works great and clean only when I put it to max it has some distortions but when I connect the electret microphone it makes a lot of noise and hissing...
  2. Cyirxrc6vec

    Charging Li-ion circuit

    Hi, I made a circuit that charge Li-ion battery. When I simulated it, I found something strange; the time for charging was too short. I made it with 'LTspiceXVII' and here's my circuit's diagram and the graph, also I uploaded the 'Li-ion bat file'. So, would you like to help me if you don't...
  3. A

    Soldering dead bug circuits

    Hi there, I have been working on an AM radio test generator. It is from the book ”building your own transistor radios”. I would provide a schematic of the circuit although I believe the copyright would prevent me from doing so. The two ICs used in the circuit are the 74HC14 hex Schmidt...
  4. S

    Need help with DC-UPS

    I need an DC-UPS that can handle at least 300W, but I couldn`t find anything. So I come up with this: Battery: 4s2p Li-ion (3.7V) PSU: 14.8V P-Channel MosFET: IRF4905 (maybe? idk) N-Channel MosFET: idk Will it work? What should I change? Do you have any UPS suggestion? Thanks!
  5. Adrienboub

    VHF oscillator circuit w/ large frequency range and change according to capacitance value

    Hello, It's my first post. I'm new in electronics fields. I'm french and my english is not very good, excuse me. I want to make a VHF oscillator(~ 30 MHz) that his frequency can change with the value of the capacitance. I found in an another post the RF2506 which seems to works but it's...
  6. katerineblankca

    Confirming Circuit Configuration.

    Hello, I am in a research team and is designing a circuit system for powering a motor with battery and supercapacitor. The battery and supercapacitor powers the motor separately and the motor gives regeneration power back to the supercapacitor (motor driver allows for regen). Can experts in this...
  7. kwoki

    Bodeplot of simulation and network analyzer difference in magnitude with same characteristics

    Hello, I have a problem which I can't find the solution. It's related with the determination of the bodeplot of a circuit. According to my bodeplot in the simulation, the flat part of the magnitude plot is -23.02 dB (Simulation.PNG) and the cut-off frequency is equal to 17.67 MHz whereas the...
  8. specs365

    How to design a BJT Tansistor Amplifier with voltage divider biasing

    I'm not sure if this has been posted somewhere before, but I can't find anything that really addresses this type of a problem. For college we need to design an amplifier circuit using a transistor, this is not that bad. The problem is that there is no proper explanation that I can find of where...
  9. B

    Ability of PLC's to communicate via 4-20mA and 0-10volts between laboratory devices and the PLC

    Hey guys, I'm studying electrical engineering technology and the Coronavirus turned my capstone project into a research paper. My assignment is on PLC's, which we have covered the basics of, but I still know little about how they operate. Here is the prompt: "Research the ability of PLC's to...
  10. K

    Diagnosing/repairing a Laptop motherboard?

    Hey guys! First time posting here! I have an Alienware 17 R3 laptop that I picked up broken to see if it was repairable (I like learning new skills). All signs point to a short on the motherboard, I plugged in the charger and the blue LED on the charger cable goes out immediately if I attempt to...
  11. Lambo Av

    Circuit Breaker Location

    Hi, in IEEE 3 bus, why are circuit breakers connected at the 'load' rather than connected at the 'generator and load'?
  12. C

    Triangular signal cutting off

    I made a circuit to demonstrate the work of a 555 and a constant current regulator and wanted to add triangle wave input. I've done that by integrating the output of a 555 timer, and at the node 'tri' I do get the desired triangle wave of ~ +-8V. Since I want the the voltage positive at all...
  13. S

    Connecting 12V Inductive Sensor to Raspberry Pi 3B+

    Hello, I am not too strong with building electrical circuits so I am just wondering if I could get some feedback on the circuit I built. I am trying to connect a 12V inductive sensor to a Raspberry Pi 3B+ 3.3V port. The inductive sensor is being used to detect a metal sleeve inside of a valve...
  14. brenduan

    Arduino Motor Circuit Only Getting Less Than 1V

    Hello, I have built this motor circuit for my Arduino and when running it only gets less 1v and the motor spins very slowly and my bigger motor doesn't spin at all. I have attached the diagram that I followed below. The Motor should be getting 5v from the Arduino although something seems to be...
  15. Engineer wannabe

    Help with DT Project (includes an inductive charger).

    Hi Everyone, my DT project includes an inductive charger. I would like to build a circuit that when a voltage is received from the inductive charger (9Vdc in ~5Vdc out) one LED blinks then after 10s it remains constant. Then turns off when voltage is stopped. I’m not entirely sure how to go...
  16. Đorđe Jocić

    5V Adapter

    Hello guys, how are you all doing? During the past few months I've been going through the Textbooks AAC has published, experimenting with some minor circuits and even PIC microcontrollers. I've learned a lot during the process and decided to do something a bit more challenging - make a basic...
  17. L

    Casio CDP-100 keyboard piano dead keys - PCB issue?

    Hi all, Newbie to both this forum and electronics! I have a somewhat old Casio CDP-100 with 8 keys that went dead recently. All other keys are fine and speakers/power are working perfectly. Schematics here: http://www.warningwillrobinson.com.au/manuals/Casio%20CDP100%20service%20manual.pdf...
  18. danielzuliani

    Weird issue in toy circuit

    Hi, I'm new in the forum and I don't know much about circuit but I have a problem and would like your insights! I have this toy called B Symphony. Is a great music toy, you can google it and take a look. The point is it got wet and the main circuit suffered some damage. I cleaned it but know I'm...
  19. M

    How do you solve the following dependent circuit problem? I tried to use KVL to get i1, but I got .44, which is the wrong answer.

    Circuit problem: I have the answers to it, but I need to know the process of how to get there.