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  1. kellys_eye

    Small amplifier project power requirements

    Again (per my reply in #2 above), if you're driving headphones what's the point of such an amplifier? Save energy, expense, trouble etc by building for the actual application. If your intent is to use speakers regardless then a good (i.e. 'clean' and capable) power supply is often the most...
  2. kellys_eye

    Help Identifying this electronic component ?

    Looks like you started another thread on this but the answer remains the same - capacitor, 200uF 10V. Blown due to reverse power application, more faults likely all over the board. Not fixable.
  3. kellys_eye

    APEX JR. subwoofer amp blowing fuses, bad caps found

    Nope, those readings look ok to me. Gluing capacitors to the board is common practise given their physical size and potential for movement. Whether or not the black gunge is the actual glue is debatable - not something I can go into in detail without seeing/smelling it for myself (capacitor...
  4. kellys_eye

    Home Based Income as an Electronics Hobbyist

    Hmmmm - anyone here suspecting a chatbot (AI) trying to respond to the OP? The reply (above - #57) seems to be a rehash of comments others have already posted. Dead giveaway.
  5. kellys_eye

    How to drive ultrasonic transceiver

    Depends on what you want to do with it. Just apply a signal at the correct frequency/amplitude and add whatever modulation (or not) you find necessary for the application. According to the datasheet a 12V pk-pk squarewave at 300kHz is all it takes - something a simple 4000-series CMOS astable...
  6. kellys_eye

    Small amplifier project power requirements

    The amplifier chip is rated at 25+25W and will draw far more current than either your battery (maybe) but certainly what the 7660 can possibly deliver - in other words you are getting distortion due to an inadequate power supply. In which case why use such a high powered amplifier? Headphones...
  7. kellys_eye

    Burnt Component Help Identify

    Judging by other parts on the board I'd say it was an electrolytic capacitor same as the ones marked 10/201 (200uF 10V) - the fault looks to be as a result of reverse power applied - maybe the ribbon was inserted the wrong way around? Either way I reckon your problem may well be a lot more than...
  8. kellys_eye

    analogue perceptron

    Seem to recall seeing one in......fantasy land. If your aim is to 'impress' then try doing it with something you've really done, not just picked off t'internet and exaggerated....
  9. kellys_eye

    APEX JR. subwoofer amp blowing fuses, bad caps found

    Values in the Megohm region aren't a particular issue - the capacitors really need their ESR testing before we go off on a wild goose chase.
  10. kellys_eye

    Philips Tv will not power on

    It protects from power surges (faults). That's a typical Switched-mode Power Supply with the usual attendant faults - possible shorted bridge rectifier, dud capacitors, shorted switching transistor, blow controller chip etc. Try Googling the make/model and the words 'repair kit' as these...
  11. kellys_eye

    APEX JR. subwoofer amp blowing fuses, bad caps found

    Bridge is ok. Transistor seems ok too (the schematic link you give shows different designations than on your actual board i.e. schematic shows Q105/Q106 but the board is marked Q409 and .... dunno, can't see!)
  12. kellys_eye

    Sunbeam Electric Bedspread stopped heating. Anyone know what the element resistance should be?

    22 watts (or 11W if you are using 120V) isn't something you're going to 'feel' using your hand given it's spread over such a larger area i.e. one quarter of the whole sheet. If the same 11W is delivered by the other elements you're looking at around 50W for the whole blanket - sounds reasonable...
  13. kellys_eye

    The 'MAGIC' Hands-Free==>Audio Streaming Box....

    Never understood the desire for high-end audio quality in a car..... if you want to listen to quality audio get some good headphones and take a seat at home. BT/FM is more than sufficient for a daily driver situation or, if you want to 'get with it' look into getting your own DAB transmitter...
  14. kellys_eye

    Sony DAV-SR2 Rising High pitch oscillation noise on power up.

    Your diagnosis seems to be quite accurate. The high pitch is superimposed on the power supply rails to all sections of the amplifier so it would be down to those sections individual (local) filtering that decides whether or not it passes through. Time to look more closely at the components.....
  15. kellys_eye

    APEX JR. subwoofer amp blowing fuses, bad caps found

    Follow the blue-brown-blue wires from the transformer to the circuit board connector. Right beside that connector is a black device with four pins. This is the bridge rectifier. Do a diode test between each of the 4 wires on that device and post the results. The main output transistors are...
  16. kellys_eye

    Sunbeam Electric Bedspread stopped heating. Anyone know what the element resistance should be?

    What voltage? If there is voltage and resistance then there is heat. Impossible to be otherwise. One or the other (maybe both) of your readings must be defective.
  17. kellys_eye

    Computer Keyboard - prebuilt - function row not working

    Keyboards are nearly always 'scanned' on a row-and-column basis and if one of the rows or columns isn't working there will be a break in the tracks/wiring associated with that particular row and/or column. Easily traced.
  18. kellys_eye

    Tail lights help

    I don't think there's any way those 'tubes' will deliver enough light to satisfy the rules - one way ticket to a traffic infringement.... But.... it's your licence at stake, not mine. Those devices will require a resistor of approximately 560 ohms to work at 12V.
  19. kellys_eye

    buggy board, bad tech and strange readout... heh heh

    It's to allow an external computer to communicate with the board processor - potentially to reprogram after the board is initially installed or to upgrade it. Very common on processor controlled machinery.
  20. kellys_eye

    Sunbeam Electric Bedspread stopped heating. Anyone know what the element resistance should be?

    If they all measure the same it's unlikely that they have all developed a fault simultaneously. Any issues, whatever they are, don't relate to the heating elements themselves.
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