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  1. E

    Adjustable 0-5v ground switch

    Hi everyone I am new on here and only getting my toes wet with electronics. But I want to build something to switch a ground for a solid state relay. I have a 0-5 coming from a laser and when it reaches a gives height it will trigger the ground on the ssr I would like to have a rotary...
  2. E

    Can two N-Channel MOSFETs be connected in series to perform a "AND" function?

    Hello, I'm designing a circuit to ring a bell using a code set by the user. When powered the circuit steps through the code which is set via DIP switches to decide where a "ding" or a space should be within the code. Each "on" position within the code actuates a modified car relay which hits...
  3. E

    BJT or MOSFET for 4017 Relay Driver Circuit retaining High-Level Logic Output

    Hello there, I'll start by saying I'm by no means an expert in electronic design, so please bear with me. Also my schematic and the datasheets I'm using will all be attached to this post. I'm designing a circuit whereby the output of a 4017B IC is driving a relay via a BC337-25 BJT Transistor...
  4. R

    Short-Circuit Protection for 3-6 Volts AA Batteries

    I’m looking for a circuit that can protect 3-6 Volts AA Batteries when a short-circuit happens. When the short-circuit happens, a second circuit (LED blinking) must be triggered and the batteries must be protected. The goal is that the LED won’t stop blinking until the short-circuit is undone...
  5. T

    MOSFET Board, reversible logic

    Hi. I have the need to drive two MOSFET boards in opposition. When signal from the signal generator (5v Arduino type signal) I want two have two MOSFET boards operation is opposed When signal is high MosFet 1 is on and MOSFET 2 is off When signal is low, MOSFET 1 is off and MOSFET 2 is On...
  6. Danirov

    TP4056:Disconnect load while charging and avoid battery discharge below 3v

    Hello everyone. I would be very grateful if you can help me with this circuit I am working on (sch.png). It consists of a TP4056 charger/controller (Photo 2) connected to a 3.7v/3Ah Lithium Ion battery to supply a low battery level indicator, and a load (three white leds and two fans) through a...
  7. L

    Selecting MOSFET Configuration

    Hello Everyone... I am trying to make a Low Voltage Buzzer Warning that beeps on and off, without a microcontroller.... I have a latching detection circuit here that puts out about a 6V signal until the battery is dead, then it drops off and latches off until it is reset.... This is the...
  8. MacIntoshCZ

    How to turn mosfet on when its not possible. Another Voltage supply needed. "Galvanic isolated"

    Imagine situation when you have to switch mosfet on, but its not possible becouse current "can not flow". This thread would be just theoretical. For knowledge. This actually do not represent any circuit I build. To switch Q2 On (For discharging something), you need to apply 20V (above 5V) to...
  9. A

    N-MOSFET as AC switch, triggered by DC (Hypothesis).

    Read about N-CHANNEL MOSFET’s. Gate and Base act as a capacitor; When gate reaches Threshold Voltage it allows current to flow from Drain to Source terminals by attracting negative charged electrons in between, constructing a conductive bridge. It is easy to select two oposite charges on DC...
  10. M

    IRF540 Won't turn off

    Hello! I would like to ask for some help in my circuit. What could be the possible reasons why my IRF540 doesn't turn off? I check the gate voltage of mosfet when I toggle the gate of 2n3904. when I put 5v on the base of BJT the gate voltage of mosfet is 0V and when I switch it to ground the...
  11. P

    Remote control 4x 50W LEDs with ESP8266, HC05 and Smart Phone

    Hi! Here is the project: I bought a spotlight which contains 4x 50W LED Lamps. The spotlight is powered by a 28VDC battery. My vision is to control the spotlight with a mobile app (turn on/off and blink the LED's). Also the space inside the spotlight is limited (10cm X 7cm X 4cm at most since...
  12. J

    Can a 5A Switched Supply Peak at Much Higher Currents?

    Are switched mosfet boosts, like this 5A device, designed to handle brief load peaks which are many times higher than it's rated 5A? http://www.xlsemi.com/datasheet/XL6019%20datasheet-English.pdf thx
  13. X

    Gate driver circuit design

    Hi, I'm trying to calculate the gate resistors for the MOSFET that I selected which has a gate resistance of 1.3 ohms. Well, I attach its electrical characteristics (Parameters.PNG). Also, I add the Vgs vs Total charge curve. I would like to find the suitable configuration for this application...
  14. mading2018

    ZVS - LTspice?

    Is ZVS (zero voltage switching) possible in LTspice? :) In that case? How do I implement that in the simulation? Do I need special transistors that is not included in LTspice I imagine... What I understand, compared to hard switching, ZVS (soft switching) make sure to to reduce the turn ON...
  15. mading2018

    Temperature with heatsinkcalculator software

    Hello :happy:, I have in the recent days tried to simulate the temperatures levels in a charger (AC/DC-module) in a Heatsinkcalculator software: https://www.heatsinkcalculator.com/version-2-1/demo-calculator.html Based on the power losses calculations for half-bridge, where we have two MOSFETs...
  16. J

    Subthreshold Transconductance Amplifier Design

    As part of a broader project, I am designing IC circuit using CMOS to one of the first steps I'm working on is the filtering a series of pulses with of the noise. The actual pulses are around 1 kHz so I am implementing 2nd order sallen-key high pass filter. Since the capacitance is limited to...
  17. mading2018

    AC/DC converter + Totem-Pole

    Hello, I used the LT8312 PFC controller to controlling the switches, but somehow the switches seems not to operating in the bridge, only the diodes. Do anyone know what could be the problem why the switches do not operate? And how do I change the switching frequency to 150 kHz? I think that I...
  18. S

    Driving mosfet with opamp

    Hi, Recently I watched an old EEVBlog episode (#102) where Dave discusses and builds a basic constant current load. To try it out, I quickly built the circuit on a breadboard and got curious to fully understand how it works. For the op-amp I used the LM2904 and for the mosfet a STP60NF06, then...
  19. L

    3KW SR motor Gate driver

    Dear people, I'm designing power electronics for 3-phase 3KW SR motor by using power MOSFETS of rating 600V. To drive the gates of these MOSFETS, I'm using IR2183 gate drivers, one per each phase. The DC voltage at the drain of MOSFET is directly from the DC capacitor link which supplies...
  20. M

    MOSFET pull down in linear region

    I have a current sense IC powered directly from a battery. I want the current sense IC to be in the shutdown state when the 3.3V power supply is disabled. I have added a dual N channel MOSFET circuit (see attachments) to achieve a pull down on the shut down pin (active low and internally...
  21. F

    driving motor and simulation

    Hi, I work as inverter and dc / dc designer, but I'm new in three-phase motors' subject. I should make a project sketched in the figure. the characteristics of the motors are in the picture. I say the pilot will be in open loop. how are the discrete components (MOS or igbt) dimensioned in...
  22. abouabdelmajid

    Example of using Mofset driver

    Hi everyone.Here is a a circuit showing how a "PWM Solar Charge controler" works. the principal work of this controler is using arduino's PWM to switch on the transistor 2N3904 to let the 12V battery absorb the energy from the solar pannel when the voltage of the solar pannel is bigger than the...
  23. S

    Dynadim light dimmer circuit

    I remember either Electronics Hobbyist or Electronic Experimenter's Handbook from the early 1980's featuring a light dimmer circuit named Dynadim. The circuit dims an incandescent light bulb with a preset delay using a slide potentiometer interfaced to a MOSFET ( dual-gate like a 40673?)...
  24. A

    5V to 12V High Current Switch

    I am using a MSP430 to switch a high powered LED. MSP430 output pin can source 5ma at 5V. I want to switch a 12V source to a LED that will be driving 5A and it will be switched like a strobe very quickly. I need some help with choosing the right transistor or MOSFET in order to accomplish...

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