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  1. Hero999

    Spammer who is selling illegal drugs

    Same old story. We need to sign up to http://stopforumspam.com and have more moderators. I've cleaned up my sections but I can't do anything about the rest. The trouble is I don't think mixos wants to trust too many people, after our experience with the bulling moderator. I wouldn't mind...
  2. Hero999

    TIP142 Stepper motor driver

    IB = base current. V = logic voltage, which you haven't given so I assumed 5V. VBE = base emitter voltage which is on the datasheet and is typically 1.4V for a Darlington pair. The TIP142's saturation voltage (VCEis specified with IB = IC/100. With an IC of  1.7A and an IB of 17mA, VCE is...
  3. Hero999

    TA2024 Amplifier

    Its a bad idea to connect speakers in series because it reduces the damping factor. The datasheet doesn't actually say that the minimum load impedance is 4Ω but this can be gleamed from the fact that: it's not specified at a lower impedance, the efficiency and THD are  poorer with a 4Ω load...
  4. Hero999

    Program launch: "Get Paid to Publish your Project!"

    What do you mean by Roth? I'm glad you got it working but give 68R in the parts list as 67R will be hard if not impossible to get hold of because it's not a standard value. I don't see why it should limit the minimum duty cycle though, the transistors should be able to turn off continuously...
  5. Hero999

    Program launch: "Get Paid to Publish your Project!"

    How do did you calculate it? I reckon IB wil be between 17mA and 21mA, my calculations are shown below: IB(Q1) = (VDD -  VBE(Q2) - VBE(Q1))/R3 With VBE = 0.7V IB = (3.3 - 0.7 - 0.7)/100 = 0.019 = 19mA If VBE is lower IB will be higher and vice versa. I didn't account for R4 because the...
  6. Hero999

    Program launch: "Get Paid to Publish your Project!"

    Does the transistor get hot? How did you measure Ib? You need to use a 'scope with either a current probe or to measure the voltage across R3 and working out the current using Ohm's law. If you use a meter, you can only accurately measure it when the duty cycle is 100% because the  meter will...
  7. Hero999

    2V high current power supply for homopolar motor

    So you're using it as a motor not a generator, why didn't you say? Is there anything else you forgot to tell us such as the schematic, photographs etc? I'm not going to play the guessing game so I'll leave this thread until you post enough information to enable me to be constructive.
  8. Hero999

    NL5 Circuit Simulator

    When one buys a program, more often than not, they don't only buy the software but a support package i.e. updates and technical support. I wonder how far you'd get if you called the helpline about a problem caused by installing a certain update and you tell them you're using Ubuntu when they ask...
  9. Hero999

    Quick Heaters

    Agreed but I think he may have measured the open circuit voltage and closed circuit current which doesn't necessarily mean it's dissipating 2kW. awright, Anyway, this tread is over three weeks old. I don't think the original poster will return so why bump it?
  10. Hero999

    13.8V 20A power supply by Santa

    Yes,you need a larger transformer amongst other things. Read the text associated with the project: it gives a clear explanation of how it works and how to alter the current limit.
  11. Hero999

    2V high current power supply for homopolar motor

    Still why do you need 200A at 2V? To create a large magnetic field? How much power do you think you'll be able to generate? You should only need 200A at 2V for a short period of time, once the generator is started, it should generate enough power to create its own magnetic filed, otherwise...
  12. Hero999

    NL5 Circuit Simulator

    Running under WINE is not Linux support. I can run MS Word viewer under WINE but MS don't suppor Linux, unless it's as a guest operating system under MS Virtual PC.
  13. Hero999

    HELP NEEDED WITH DC POWER NOISE

    There's no magic formula, it's just something one should try when they encounter a problem like this. Why would it? It sounds like you don't understand what the capacitors do. The amount of energy stored by the capacitors is negligible compared to the batteries. The capacitors should be...
  14. Hero999

    2V high current power supply for homopolar motor

    No it doesn't
  15. Hero999

    TIP142 Stepper motor driver

    That depends on the logic voltage and collector current. With 2k2 and a logic voltage of 5V: IB = (V-VBE)/RB = (5-1.4)/2200 = 1.6mA So you'll be restricted to a couple of amps before the saturation voltage becomes unacceptable..
  16. Hero999

    Program launch: "Get Paid to Publish your Project!"

    Did you try it or is it what I've said about the fan drawing only 300mA put you off? I deliberately overrated the design, it should still be fine, the BC338 is rated to 800mA and you're only using it for 400mA which is just half it's rating. It's specified for an Hfe of at least 60 with a VCE...
  17. Hero999

    2V high current power supply for homopolar motor

    It sounds like your best solution. Just one question: what do you need such an insanely high current at a ridiculously low voltage for?
  18. Hero999

    HEX file for project

    Thanks a lot. The schematic may infringe some copyrights but not the code as it appears he's written it without looking at the code which came with the kit. I'm also surprised he's used assembler rather than C which is also quite impressive.
  19. Hero999

    TIP142 Stepper motor driver

    The only thing which should be connected to +V is the stepper motor common wire. You should consider using logic level MOSFETs rather than Darlington pairs because they turn off faster and have lower losses.
  20. Hero999

    Raising Ni-MH Voltage

    This really belongs in the other thread, as it's related to it. http://www.electronics-lab.com/forum/index.php?topic=20816.msg94020#msg94020 Creating circuit will will run from 2V, produce a reasonably clean sinewave with a frequency of 140Hz and 5% tolerance is not going to be hard, rather...
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