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Hero999

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Posts posted by Hero999


  1. I gave your white schematic as much contrast as is possible which caused its background to be a little grey.
    I noticed that you changed most of the parts designation numbers so that when most of the other schematics used R11 and R12 to set the gain of the voltage amplifier now you have R18 and R24 doing it. Therefore do you have a new parts list that matches your new schematic?
    Try converting it to monochrome (1-bit per pixel).  Not only is it more clear but the file size has shrunk too.

  2. Good!

    There are many excellent analogue oscilloscopes still around. They're something that should be treasured. Most models are no longer in production and sometime in the future will be difficult to get hold o
    of.

    Do you have any other oscilloscopes?

  3. http://www.electro-tech-online.com/threads/lm3914-calculator-and-build-questions-from-an-electronics-newb.107121/
    http://www.kawasakimotorcycle.org/forum/mechanics-corner/113080-can-i-add-fuel-gauge-bike-doesnt-have-one.html
    http://www.electro-tech-online.com/threads/electronic-fuel-gauge.93732/
    http://www.motorcyclephilippines.com/forums/showthread.php?277298-how-to-make-digital-tachometer-and-led-fuel-gauge

  4. Check ebay.

    You can buy a TDA7297 amplifier moduel (all the parts and board, fully assembled) for less than that!
    http://www.ebay.com/itm/DC-6-to-18V-TDA7297-Power-Amplifier-Module-2-X-15W-Double-Channel-10-50W-/310735726006?pt=LH_DefaultDomain_0&hash=item48594ae5b6
    http://www.ebay.com/itm/TDA7297-2-15W-Audio-Amplifier-Board-15W-15W-Dual-Channel-DIY-AC-DC-12V-Update-/371138196701?pt=US_Home_Audio_Amplifiers_Preamps&hash=item56698f74dd

    I don't know about the quality of the components (especially the capacitors and potentiometers) though.

  5. More information is needed.

    The ICM7555 can probably do this but a potentiometer will be needed to adjust the delay.

    A microcontroller can be used to build a more flexible timing device but will need a voltage regulator (5V or 3.3V) and an output buffer to interface with the 18V devices.

  6. The potentiometer shouldn't be connected to the main power input.

    The volume control is nearly always connected to the signal input. A potentiometer varies the amplitude of the signal going in by acting as a variable potential divider. Since your circuit has two inputs, you need to have a dual ganged potentiometer.

    Another thing to look out for is that the potentiometer needs to have a logarithmic track to match the response of the human ear. Here's an example:
    http://uk.rs-online.com/web/p/potentiometers/7293451/

  7. You'll never be able to drive those speakers from with a power supply voltage of 20V is 25W but in reality the usable power will be half that so don't worry about blowing those speakers.

    How many channels do you need? If it's just mono, then I'd recommend the TDA2009 bridged, if it's stereo, there are plenty of bridge stereo amplifier ICs to choose from.
    http://docs-europe.electrocomponents.com/webdocs/0acf/0900766b80acf1b0.pdf

  8. A transformer with a dual 28V secondary winding will do.

    D11 will protect the output in case of reverse polarity.

    Another diode can be placed with the anode on +Vout and the cathode to the positive of the bridge rectifier to protect against brief positive high voltage spikes entering +V. You could also consider a transorb across the bridge rectifier to protect against transients.


  9. No Hero99, that gain of 10 circuit is the same as the original project. Something simple. It is not the sort of circuit that is used.
    It isn't the same. In my circuit, the output transistor is inside the negative feedback loop of the operational amplifier. In your circuit, there's negative feedback before the output transistor.

    In a power supply circuit, the power element (i.e. output transistor) should always be inside the feedback loop of the error amplifier.
  10. What's the output voltage of the AC/DC converter?

    What sort of PSU is it? Switched mode, low frequency transformer?

    If it's a switched mode power supply, it should be able to work from DC as well as AC and 277VAC has a peak voltage of 390V so it should be able to work off 390VDC.

    It really isn't feasible to have a power supply with an input voltage ranging from 120V to 600V. Your best bet is to have two different models, one for 120V to 277V and another from 277V to 600V.

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