1. MrsssSu

    Why my Relay short-circuited ?

    I have a relay but rated at 3A, 30V DC only similar to this. When I connect the Pole and NC directly using a lithium ion battery (4V), a fire occur and it shortcicruicted. However, when i measure the resistance betwwen 2 pins (Pole and NC), it reads 16 Ohms. What should i do :) ? Thank you for...
  2. MrsssSu

    Can I use 5V 30 Amps PSU on a Lithium ion battery charger module?

    Hi, if I use a 5V 30Amps Power Supply Unit to plug into the input of this Lithium ion battery charger module, is it fine since it will draw a limited output of 1A to charge the battery which it requires right ?
  3. MrsssSu

    Buck Converter (Wide range of Input Voltage to Output a fixed Voltage)

    Hi People :), This is a step up dc to dc converter. This schematic inputs a 15V and outputs a 22V DC. However, I want the input range to be between 3V to 50V and all gives the same constant 22V DC output current. How can this be done with UC 3845. I have attached the schematics below and spice...
  4. MrsssSu

    Battery Charging Circuit efficiency

    Hi readers:), Click here . This link refers to making a lithium-ion battery charger using a BC 547. Question: How efficient is this circuit in (%) that is useful output power/ input power to charge a battery? I am planning to build a 4.2V charger but with a much higher ampere limit by...
  5. MrsssSu

    High Voltage PMOS recommendation

    Hi readers, is there a P-channel Mosfet with Vds of -400V but has very low Rds(On) because I want an efficient mosfet ? I a planning to power a 400V device and its negative terminal must be connected to ground (That's the reason why i use PMOS and not NMOS). I find a lot of NMOS that can...
  6. MrsssSu

    Will voltage across transformer drop when charge a lithium ion battery?

    If I have a 4W transformer that has high inductance, thick windings, (4V ,1 A) and converted to DC via a rectifier, in order to charge a lithium ion battery (low internal resistance) , will the output will still be slightly less than 4V or will it be very low (close to 0 which makes it...
  7. MrsssSu

    Maintain constant voltage across a variable load (op-amp)

    Hi readers :), Vin is fed with the PWM signal coming from an op-amp to be amplified and fed into the load R1 (1 Ohms). The purpose I design this is I want the voltage source to be a constant 5V which is independent of the load (1 Ohms or 100 Ohms). So basically, this circuit has an op-amp which...
  8. MrsssSu

    How to use PMOS mosfet?

    Hi readers, is this the correct way to power a PMOS mosfet? I am unfamiliar with PMOS but quite familiar with NMOS. Question: How to use PMOS to power a 10 Ohm Load? Thank you I attached LT Spice files below. Help me understand by attaching or posting a new schematic :) Thank you and have a nice...
  9. MrsssSu

    Regulate voltage using op amp

    Hi readers, I am doing an Op Amp voltage regulation of voltage drop across load. As you can see from diagram, I have a fluctuating_Vin (0V to 50V) and I want the voltage drop at load (100 Ohms) to be the same (14V) at all times no matter whether input voltage is 20V or 30V or 50V? Note: I...
  10. MrsssSu

    Convert triangle wave to sine wave.

    Hi readers, the IN node has triangular wave converted from square wave pulse. This Op-Amp acts as integrator. However, when I attach the same integrator circuit to convert this triangular wave (IN) to sine wave, the Output (OUT) I got is still quite triangular and not quite a good sine wave...
  11. MrsssSu

    Amplify Flip Flop signal from NE 555 timer using transistors

    Above is the graph across R7 (Load). Hi readers, Flip Flop with Ne555 timer means turning on an led and another one off, as shown in picture, and this alternate on and off pattern continues. This video can be found at Click Here . I have succeeded in amplifying one of the 2 signal as shown in...
  12. MrsssSu

    PNP transistor to amplify square wave signal received at its base

    Above is the load power Hi People, I created this npn transistor circuit and it works fine. So basically, it receives this square wave impulse (0 to 2V) and send it to the 10 Ohm(Load) to be amplified to become (0 to 10V). Question: How to simulate the same way (Load Power Output should be...
  13. MrsssSu

    Current direction using transistors

    Hi readers, I am trying to simulate current flow in both direction of the load by using 4 relays or transistors. For example, in this circuit, the load will have left current flow when 2 of the switch or transistors are on and 2 of the switch are off. The opposite way applies too if 2 of the...
  14. MrsssSu

    How Power Supply Limit its Current Output ?

    To view my We_bench power supply schematic Click here In the picture above, how does the power supply limit its max current and it has been fascinating for me to figure out how. Does anyone have a clue on this? I just know that the capacitor and diode help to rectify the AC output of...
  15. MrsssSu

    Relay Pins Identify

    Hi, do the green highlighted pin to connect the main voltage and is the blue one the input switching voltage on the relay? Since there are another 2 pins near the blue highlighted pin, I assume we can connect to either pair right?
  16. MrsssSu

    Would trapping heat in a vacuum flask on hot side of Peltier be effective to cool room?

    If I trap the heat on the hot side of Peltier using a vacuum flask where no heat can escape to the surroundings so that the room can get cooled faster. Would it reduces my Peltier's efficiency and damage it? Or must I remove the heat as much as possible from the hot side to improve its efficiency?
  17. MrsssSu

    Why transformer secondary only have 3 turns?

    Here is my We Bench Design=https://webench.ti.com/power-designer/switching-regulator/customize/3?VinMin=85&VinMax=265&O1V=12&O1I=2&base_pn=UC3842A&AppType=AC&Flavor=none&op_TA=30&origin=pf_panel&lang_chosen=en-US&optfactor=3&isolated=Y&Topology=Flyback&source=AC&line_fsw=60 Question: Is it even...
  18. MrsssSu

    20V max DC motor, how do hairdryer work on cool air without heating filament ?

    Hi readers, Hairdryers (240V AC) actually works on a design which current passes through the heating filament (Maybe consume 220V) to produce a lot of heat whereas through the DC motor (Maybe consume 20V). I have always been curious about this Question: Hair dryer has an option of choosing the...
  19. MrsssSu

    Switch on npn transistor not working (Simple circuit)

    I recently bought KSP 2N2222a npn transistors. The picture that I attach below shows the layout. The base of the transistor is applied a 1.5V which turns on the transistors and light up the bulb very brightly. However, I got a bulb that is so dim. The battery power and voltage is fine because I...
  20. MrsssSu

    Charging circuit modifications

    Hi. above is a charging cut-off circuit. As you can see in my demo. when voltage source is 5V, the load (R9) has 5W power. When voltage drops to 4V, the load (R9) has 0 W (cut off). However, my lithium ion charging pin for my battery is 4.26V. Thus, when battery fully charged at 4.2V, the...
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