1. grandslam67

    How do I design a Multistage Amplifier with given specifications, specifically the upper 3dB cutoff frequency?

    I have been tasked to design a multistage amplifier with the following specifications: Gain(V/V) = 30, Rin = 20 kohms, Rout < 25 ohms, Power supply = Dual +12V -12V, Max Symmetrical Swing > 9Vpp (peak-to-peak), lower 3dB down point < 200 Hz, Upper 3dB down point > 5 kHz, Rload = 200 ohms. I...
  2. K

    ATMega328P Communication with 24V PLC

    Hi All, I am designing a ATmega328P based PCB control board that has a function of sending and receiving discrete digital signals to and from a PLC. The PLC has sinking outputs. The PLC can accept sinking or sourcing inputs. I want the PCB to output Sourcing (PNP) signals to the PLC. (mostly...
  3. Julianna

    What is the simplest way to check transistor flow with a multimeter?

    Set your multimeter to diode mode. This activates a small forward bias voltage, mimicking the typical operating condition of a transistor.
  4. L

    MOSFET - can't control DC Motor

    Hi! I am working on a university project. We are building a vehicle similiar to the BattleBots competition. Everything is working well but I have a problem with a 12 VDC motor controlled with transistor/MOSFET. I am using this motor water pump...
  5. rohanroy93

    Simple FM Tuner Transistor Alternative

    Hi, I am trying to make a simple fm tuner as per the circuit diagram attached. Problem is, BF494 transistors are not readily available in my locality. Hence, I have used 2N3904 transistors as an alternative choice but the tuner doesn't seems to work. Can this transistor be used in this circuit?
  6. Deadpidgeon37

    identifying a transistor from a 70s microphone

    i have a sony stereo electret condenser from the 70s. one of the transistors has failed but i cannot identify the transistor. can anyone help? the code reads K39A CI2 the microphone is an ecm 99 if that helps.
  7. J

    Monostable multivibrator BJT

    Hello, I'm a computer science student and I was assigned by my professor to make a monostable multivibrator circuit on a bread board with an unstable duration of three seconds. Keep in mind I have very little knowledge about circuitry, we were only given the schematic and were told to find the...
  8. A

    Simulating button press on monitor using transistor and arduino

    Hello everyone, I have next to no knowledge of electrical eng or circuitry and am having some trouble with my homebuilt arcade. The essence of my problem is that I want to wire both the computer and monitor to the same rocker switch. The monitor turns on via a button press that completes a...
  9. I

    FoM for power consumption on a transistor level

    Hello Everyone, I am fairly new to this so please bear with me. I have been looking at reducing the static power consumption in an IC, and have been mainly focussed to reduce the parasitics in the wiring in the BEOL. However, I was wondering that whether in the FEOL, on an n-type transistor...
  10. Daniel28

    Emulate battery in charging state

    I am trying to build a circuit to emulate a lipo battery. Basically the circuit consists in a power supply to emulate the discharge behaviour and a variable load to eulate the charge behaviour. This is the circuit in a simplified way This basically generates 2 circuits...
  11. bmbouter

    "closed by default" transistor design?

    I have an external switch connecting GND to RST on an 8266, it looks like this: [GND] ------ [normally open switch] -------- [8266 RST pin]. The ESP goes to sleep, and then the switch wakes it up. However while in operation I want this reset functionality disabled, but at a hardware level...
  12. MrsssSu

    Buffer AM signal (5W)

    Dear all, may I ask how to buffer an AM Signal so that it contains more power, maybe 5W for my Remote Control RC? I have buffered the AM signal using op-amp but the power output is just not enough. I have tried using this push-pull transistor pair, but the waveform seems to be unbuffered. I...
  13. JLoundy

    Small-Signal Analysis Symbolic equation for voltage at x?

    I am having trouble finding a symbolic voltage at node x for this circuit using small-signal analysis. Any thoughts would be appreciated.
  14. MrsssSu

    Linear Frequency to Linear Voltage circuit

    Dear all, the circuit above is quoted from here, and I wish to try to produce similar graph in LT Spice but I am unsure of it. The LT Spice schematic is correct since I tested it with specific 10V input AC, and it produces linear voltage on its output. However, I want to do an AC sweep on this...
  15. MrsssSu

    Reduce Frequency of Waveform

    Dear all, may I ask if there is a circuit that produces the following input and output which basically reduces its frequency by 2 times which also basically stretch out the input waveform to produce the following output? Thank you for reading :)
  16. MrsssSu

    How to freeze CD 4017 (Rain Led Chip)

    Dear all, I have successfully simulated a continuous led array that light up consecutively one after another using LT Spice and have even built one on breadboard and it works well. Well, my question is how would you freeze the led and how do we activate the clock inhibit on both the chips? Like...
  17. C

    Driving motors with atmega

    Is this circuit okay to drive dc motors with atmega? While sending to one signal input other one will be grounded from microcontroller. If not okay what additions or substractions are needed to create ideal h-bridge for dc motors to drive with atmega?
  18. Topad

    Output logic source and sink

    Hi all, Im working to design a circuit that can sink after a load is apply, but when there's no load also be able to output logic levels 5v/0v. The max that a load could be is 12V and not not more than 100ma, therefore I decided to use octocapulers to make some output logic. In my attach image...
  19. ajob

    What am I missing on my interpration to the following circuit?

    Well... I set up the following circuit and it didn't work as I expected. At this point, I'm no longer interested in "Why didn't it work?" question, but on "Why does it work like this?". Below I will describe how I think it should happen when I press SW1 and then I will tell you what actually...