Search results

Search Forums New Posts
  1. kellys_eye

    Oscilloscopes:2 Channel, 4 Channel, 100Mhz, 500Mhz etc.

    Getting a 'scope of higher spec for the same price is a 'bargain' and not to be overlooked - to an extent - but quite often the higher spec 'scopes come with functionality you will probably never use and/or complications that confuse and make learning how to use one that little more difficult...
  2. kellys_eye

    Type of single phase AC motor?

    Why control it? They are made for a purpose and not meant to be variable (speed). They rarely exceed a few watts (or 10's of watts for the larger versions) so power saving, if any, would be minimal and cost savings would never exceed the expense of making a controller for it. A typical...
  3. kellys_eye

    Oscilloscopes:2 Channel, 4 Channel, 100Mhz, 500Mhz etc.

    Add-on. for the most part you might find yourself fixing SMPS devices, audio amplifiers, basic receivers and some digital stuff ALL of which can be done under 20MHz bandwidth. If you think you're going to fix microwave stuff or even VHF/UHF etc stuff with one then think again - that kind of...
  4. kellys_eye

    Oscilloscopes:2 Channel, 4 Channel, 100Mhz, 500Mhz etc.

    For a 'beginner' I'd suggest an analogue 'scope, dual channel, 20MHz. Sounds 'weak' but there is no 'beginner' who's going to fix RF Microwave stuff! That's something best left to (lots of) experience, by which time you may have learned how to use a basic 'scope properly and utilised it to its...
  5. kellys_eye

    Liquid Volume Measuring Project

    Flow meters generally have a 5% accuracy - unless you want to pay big $$ for them - but you could always calibrate one yourself or use two to measure flow and return and calculate the difference.
  6. kellys_eye

    How would you go about testing this port without its adapter?

    If I understand you correctly then you have a power SUPPLY that has inter-changeable tips. It's possible to fit these tips in one of two directions (for positive-pin or negative-pin - centre-pin that is) and it's often confusing to tell which is which. As a result I always use a test meter to...
  7. kellys_eye

    Scoreboard repair

    Indeed you are. If you had the relevant reader/programmer you could try to extract the code but that also assumes the OEM didn't 'lock' the device to prevent just that. TBH it would be easier to program an Arduino to drive the board instead.
  8. kellys_eye

    need help with Powercolor R9 390 PCS+

    There are a couple of clues that we can gather from the way the board is populated. a. The device isn't a buck or boost converter as there isn't a suitable inductor close to the device. b. Board markings indicate a 5V source on one side and 1.8V on t'other side. c. The inference is that the...
  9. kellys_eye

    High power, low capacity UPS circuit

    ISTR you used to be able to get an internal UPS-like card for desktop PC's (if I recall it just buffered the main supply rails) that allowed sufficient time for a proper shut-down process in the event of power failure. A few Li-ON's and some charging/diode-switching could achieve this quite...
  10. kellys_eye

    Audio spontaneously develops volume flutter at about 10 Hz

    Are you using a power pack/charger? I've had BlueTooth audio issues from leaving the device on permanent charge.
  11. kellys_eye

    High power, low capacity UPS circuit

    Can you not take a signal wire from the genset key (ignition) line to use as a UPS 'on' signal?
  12. kellys_eye

    Doorbell modification

    Not easily. Buy a wired doorbell.
  13. kellys_eye

    Custom Sound Detection

    As Harald says, voice (sound) recognition is pretty well advanced and achieving what you require is certainly possible but not without considerable effort and research/design. Dual (possibly more) microphones (for direction sensing), audio filtering (to eliminate as many non-required sound...
  14. kellys_eye

    Marantz 2230B with Weak FM

    Sweep generators can output a signal that 'sweeps' through the range that your IF (intermediate frequency) works at and thereby allow you to plot the response of the circuit - usually displayed as a 'hump' with appropriately sloped sides and flat top representing the sharpness of the filter (the...
  15. kellys_eye

    need help with Powercolor R9 390 PCS+

    The device is probably a MOSFET and can be determined by careful inspection of the PCB tracks (post some pics) - however - such failures are never an isolated case and more usually point to other failures elsewhere in the system. If replacing that part fixes it then count yourself lucky but I...
  16. kellys_eye

    High power, low capacity UPS circuit

    You know the difference between an online and an offline UPS system?
  17. kellys_eye

    Problem video of board PC

    Seems a rather pointless exercise to me. If you have a Radeon video card of that spec just get a monitor that can deal with it too. You are wasting system resources and missing out on the benefits of a matched card/monitor. It's like buying a 4k TV and using an NTSC signal source for the...
  18. kellys_eye

    Build a variable power supply

    You can put a diode in series with the LM78** ground lead to increase the output by 0.6-0.7V (two or more if necessary) to achieve 'intermediate' voltages. I'd recommend the LM317 anyway.......
  19. kellys_eye

    need help for my circuit

    Build it without Q1 and Q3 and save yourself some components. They aren't necessary and do nothing. What? You state, in the next sentence, that you : which is an OSCILLATOR!
  20. kellys_eye

    Build a variable power supply

    Put the 12V source into a 7808 device to get 8V at 1A. Three components (one IC and two capacitors)
Top