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  1. WHONOES

    Resistors in combination circuit help

    OK. You don't need to calculate any voltages. Total circuit resistance is defined as 12V / 2A which = 6Ω R3 is passing 1.5A which is 75%, or 3/4 if you like, of 2A. Therefore 25% of the current is flowing in R2. To calculate R2, divide 75% by 25% the result of which is 3. To get the value of R2...
  2. WHONOES

    Uninterruptible power supply ratings: conflict between VA and W?

    Nice description RATCH.
  3. WHONOES

    Charging a smaller capacity SLA battery from a larger bank.

    As a general rule, you should limit the charge current for a Sealed Lead Acid battery to no more than 25% of capacity. If you intend to charge the smaller capacity battery in isolation you will need to limit the charge current to 12.5A or less. To establish when your batteries are fully charged...
  4. WHONOES

    switching the VSS line of an IC

    My original comment was based on fairly ancient knowledge. Did a quick Google search and it seems that there is now a number of op amps that consume sub μA power without any special trickery. A number of them have a supply limit of 5V. Also they tend to have fairly slow slew rates. Have a look...
  5. WHONOES

    switching the VSS line of an IC

    Try looking for an IC that will switch into ultra low power mode. They generally have a pin just for that purpose. Never used one.
  6. WHONOES

    6V battery charger

    Charging sealed lead acid batteries is usually achieved with a 2 or 3 stage process. For the 2 stage process. they are initially charged by constant current. This because the general recommendation is for them to be charged at no more than 25% of current capacity. When the charge current drops...
  7. WHONOES

    Looking for help with some projects that require electrical expertise

    How about something like a DLE 222cc 2 stroke boxer engine rated at 22.5HP @7500RPM and weighing just 10.5lb (have a look on ebay) mated to a high output car alternator (Volvo do one rated at 245A can run at up to 10,000RPM don't know what it weighs but guess at around 20lb or so). You will need...
  8. WHONOES

    VFD causing noise

    These converters use PWM to create the 3 phases and generally require a specific filter on the output.
  9. WHONOES

    Edifier x600 subwoofer very weak sound

    Generally if 2 bass drivers are wired in anti-phase the lower frequencies will sound very weak. The anti-phase aspect means that as one driver cone is going out the other is going in. This means that the pressure wave produced by the motion of the cones cancel each other out. Has the subwoofer...
  10. WHONOES

    Edifier x600 subwoofer very weak sound

    Could be the speakers are not in phase.
  11. WHONOES

    Solve

    Looks like a precision rectifier.
  12. WHONOES

    MOSFET Issues

    Try putting at least 5vdc on the gate and see what happens.
  13. WHONOES

    Ultrasonic sonar

    A piezo transducer is a little more complicated than you might think. It has mechanical and electrical resonances. It is effectively a capacitor in series with an inductor in series with a resistance with a capacitor in parallel with the lot (if I remember correctly). It is possible to ascertain...
  14. WHONOES

    Save 18650 battery

    Buy a new one. Once it's dead it is dead, don't try to revive an old one especially a LiPo.
  15. WHONOES

    How to make this circuit unity gain?

    Yeah. I could have made it a lot more complicated but, the brief (sort of) was for a simple circuit with reasonably good performance which is what it is. It is only required to deliver 100mW or so, any more would be damaging.
  16. WHONOES

    How to make this circuit unity gain?

    Hi AG. You are right, I did inadvertently say NE5534 when I meant NE5532 as in the circuit under discussion. I am fully aware that the 22pF on the 5534 is for stability, the linearity mentioned was not referring to the opamp but the configuration following it. I did not actually say that the...
  17. WHONOES

    How to make this circuit unity gain?

    OK. See attachments for schematic as promised. The amplifier on my schematic is a TL072. I only used it as I don't have a model for the NE5532.
  18. WHONOES

    How to make this circuit unity gain?

    I'll put together a schematic and post it in the near future. Your new configuration with the extraneous components removed is a voltage follower and has unity gain.
  19. WHONOES

    PSU advice

    Why have you gone to the bother of mounting your transformer on a sub chassis?
  20. WHONOES

    How to make this circuit unity gain?

    The datasheet that I referred to is NE5532 specific and makes no mention of an external compensating capacitor requirement. It states that it is internally compensated for unity gain. Clearly other manufacturers products differ. See link to datasheet : http://www.ti.com/lit/ds/symlink/ne5532.pdf
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