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Everything posted by Hero999

  1. An electric motor with gears will do the job. Another possibility is a piezoelectric linear actuator.
  2. Try converting it to monochrome (1-bit per pixel). Not only is it more clear but the file size has shrunk too.
  3. Hero999


    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?
  4. Apart from the fact it contained copyrighted material so has been deleted.
  5. If you don't have access to shift registers or adders, then you'll have to make them, from the other ICs. Of course, the easy way is to use a microcontroller but you're probably not allowed to do that.
  6. 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
  7. It should help to improve current sharing, since the diodes connected in parallel are in the same module. Copper is a good conductor of heat, better than aluminium. The only reason why it's not used very often is because it's more expensive and heavier than aluminium.
  8. If you cut the cord and connected a standard mains connector, it would probably work. It wouldn't be safe, since the metal case wouldn't be earthed. The correct way of doing it is to use a three pin plug, witht he eartht conductor connected to the motor's case.
  9. 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.
  10. I have not used the MRF49XA before. How did you build the prototype? According to the datasheet, board layout is critical, as with any circuit running at UHF.
  11. Hero999

    DC Timer

    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.
  12. 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/
  13. I thought he was using strip board but there's no way of knowing for sure without a photograph. As far as the potentiometer is concerned: you may have to solder wires to it but keep them short and they may have to be screened, if it's carrying a small signal.
  14. That sounds about right. For bridged stereo there's the TDA7297. http://docs-europe.electrocomponents.com/webdocs/0a33/0900766b80a339df.pdf
  15. 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
  16. 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.
  17. A comparator & voltage reference IC will do this. See links below for datasheets: http://ww1.microchip.com/downloads/en/DeviceDoc/22269B.pdf http://www.micrel.com/_PDF/mic841.pdf
  18. 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.
  19. 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.
  20. Can you please save it and attach the file in plain text or PDF format, as the forum software doesn't allow Word documents.
  21. The resistance of the copper wire can be calculated using the formulae in the Wikipedia article linked below: http://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity The power dissipation can then be calculated using Ohm's law.
  22. Do you have any qualifications? You say you have 5 years experience using Altium but is this working on your own hobby projects or professionally? If you don't have any qualifications and have only done it as a hobby, your best bet is to look for a job as an apprentice and get the proper qualifications before going alone.
  23. What are ytou trying to do? Quite often a resistor will do. A simple constant current source can be built using an LM317 but it has a high drop-out voltage, typically 2.75V at 20mA.
  24. Hero999

    What are these?

    The look like capacitors.
  25. Rather than messing around with PDFs, the address to the original image is at the top of each page. It doesn't look like it'll work very well. The peak value of VCC will be around 15*sqrt(2) - 0.7 = 20.5V. Q1 and Q2 are source followers with a voltage drop of over 5V for even a small current drain and 0.5V of headroom doesn't allow for much ripple. If it's just a headphone amplifier, this could be fine but it's much easier to replace that op-amp and MOSFETs with an LM7815 and LM7915 which should give you superior regulation and current limiting too. A properly designed audio amplifier doesn't need a well regulated amplifier. You could probably use a 12V-0-12V transformer, with an appropriate rectifier and filter capacitor.
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