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How to use LTspice

Discussion in 'General Electronics Discussion' started by ThomasWheeler, Mar 19, 2018.

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  1. ThomasWheeler

    ThomasWheeler

    32
    1
    Apr 25, 2016
    Hi, I'm 17 years old and currently studying electronics at a technical school in Thailand. I want to be able to analyze circuits by using LTspice, but it is really hard to use. I can connect components and draw a circuit but I don't know how to test it. Often there won't be components I need in the program and I'll need to use some thing else. I tried learning from linear technology's videos about ltspice but they're not helping. I'm really lost when I'm using this program.
    I really need advise and ways to learn how to use LTspice.:(
     
  2. davenn

    davenn Moderator

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    1,958
    Sep 5, 2009
    Hi Thomas

    there's a zillion youtube videos, and other tutorials on the net

    we also have a bunch of tutorials on this forum most, if not all written by @Harald Kapp
    https://www.electronicspoint.com/resources/categories/simulators.10/

    do some reading up and video viewing, Harald would best help you if you have specific questions on a particular situation
    and you haven't found an easy answer elsewhere



    Dave
     
  3. ThomasWheeler

    ThomasWheeler

    32
    1
    Apr 25, 2016
    I have a problem. I want to analyze this battery charger circuit with LTspice but I can't find the IC in the program. The IC is a 6HKB 07501758 IC. Where can I get the IC? What can I do to make this circuit complete and test it?

    [​IMG]
     
  4. davenn

    davenn Moderator

    13,867
    1,958
    Sep 5, 2009

    never heard of that particular IC
    Do you have the datasheet for it ?
     
  5. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    If the manufacturer of the device doesn't provide a simulation model for this IC on the manufacturer's homepage, you will most likely not be able to find a model anywhere else.

    Get the datasheet for the IC and calculate component valuies according to the datasheet (usually you'll find an application example in the datasheet and instrcutions for calculating component values). Then build the circuit and test it.
     
    davenn likes this.
  6. davenn

    davenn Moderator

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    Sep 5, 2009

    Thanks for chiming in Harald :)
     
  7. ThomasWheeler

    ThomasWheeler

    32
    1
    Apr 25, 2016
    Thanks Harald. I'll try it out.
     
  8. ThomasWheeler

    ThomasWheeler

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    1
    Apr 25, 2016
    There another problem, I can't seem to find the datasheet of 6HKB 07501758 IC any where. Is there a website that will give you this information. I looked at www.st.com but can't find it.
    [​IMG]
    This is the picture of the IC.
     
  9. davenn

    davenn Moderator

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    Sep 5, 2009

    hard to say if the 07501758 or the M993P0426B is the part number

    I couldn't find any info on either number
    It's possible it's a manufacturers special done for a specific client, in which case you will not get info on it
     
  10. Harald Kapp

    Harald Kapp Moderator Moderator

    11,667
    2,700
    Nov 17, 2011
    Right. 07501758 seems to refer to a custom programmed microcontroller by ST Micro.

    Why do you want to simulate/build a circuit you don't understand with an IC you have no datasheet for?
    There are many well documented charger ICs on the market. Some even come with SPICE models (especially those from Analog Devices aka Linear Technology).
     
    davenn likes this.
  11. ThomasWheeler

    ThomasWheeler

    32
    1
    Apr 25, 2016
    My Bosch cordless drill battery charger is broken. When I put the battery in the charger an LED light is suppose to blink indicating that the batt is charging, but the led is not blinking. So I left the batt in the charger for a while but it didn't gain any charge and I can't figure out what is wrong with the charger circuit. So my dad wants me to analyze the circuit using LTspice to figure out what is wrong it.

    Here is the charger.
    I get 17V AC coming out of the transformer and roughly the same in DC after the diodes, so every thing is good up to that point.
    [​IMG]
    [​IMG]
     
    davenn likes this.
  12. davenn

    davenn Moderator

    13,867
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    Sep 5, 2009

    unfortunately, in this case, with that unknown IC, circuit analysis isn't going to happen :(
     
  13. Harald Kapp

    Harald Kapp Moderator Moderator

    11,667
    2,700
    Nov 17, 2011
    Not via simulation. We still can try to find the issue with the PCB.

    1. Check all solder joints. Although from the picture they look o.k., see if any are cold solder jionts.
    2. Check the SCR on the heatsink (probably this is the one denoted V5 in your diagram. You will have to remove it from the PCB for testing, otherwise other components on the PCB will influence your measurements.


    But: before you tear down the charger: Have you checked the battery in another charger or this charger with another battery? The fault could as well be with the battery, not the charger.
     
  14. Alec_t

    Alec_t

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    What goes into the 3 clips?
    Looks like a scorch mark on the pcb by the top clip.
     
  15. ThomasWheeler

    ThomasWheeler

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    1
    Apr 25, 2016
    I don't have another Battery or charger, but I can charge my battery with my bench power supply. I use 8 VDC to charge the 7.2V battery and have a 10 Ω resistor in series with the battery. It works fine, I can use the drill continuously for about 12 minutes before i need to discharge and charge it up again. I did replace the battery once, there are 6 cells of NI-CD in the battery housing. It used to be 1.2 Ah but now it is 2.2 Ah. The third clip is for measuring temperature of the battery. I looked inside the battery housing and the temperature contact is not connected to anything, it looks like it is suppose to be connected to something though. May be that is the problem.o_O
    I check the SCR using an analog multimeter and it is still in a good condition. Both transistors in the circuit are also fine. I also got a new ic to replace the old one but the charger is still not working.:(
     

    Attached Files:

    Last edited: Mar 23, 2018
  16. ThomasWheeler

    ThomasWheeler

    32
    1
    Apr 25, 2016
    I really want to fix my Bosch battery charger so that it will be easier for me to charge my battery.
    Please help.
     
  17. Alec_t

    Alec_t

    2,974
    804
    Jul 7, 2015
    You should have nearer 22V DC if there's a reservoir cap. Those diodes look cooked. Have you tested them with your DMM's 'diode test' function? Have you reflowed the solder in case there's a dry joint?
     
  18. ThomasWheeler

    ThomasWheeler

    32
    1
    Apr 25, 2016
    I resolder every joint on the board but it didn't work, the battery is still not charging. :(
    I got 570, 580, 700 and 832 on my DMM's diode test function and when reverse bias they all got OL. Is that acceptable?
     
  19. Alec_t

    Alec_t

    2,974
    804
    Jul 7, 2015
    I'm surprised the power diodes are that badly matched. 570 and 580 seem rather low and 832 seems high; I'd suggest replacing those. I've just checked a mixed bunch of power diodes in my spares box and they're all around 700.
     
  20. ThomasWheeler

    ThomasWheeler

    32
    1
    Apr 25, 2016
    Thanks, I'll try that out.:)
     
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