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  1. Alec_t

    Laser Lipo Clone Concept - Project Help

    Welcome to EP! :eek: I think they're vitally important. LEDs of that intensity could damage eyesight. I'm not sure I'd trust the Technology spec: are there 36 LEDs or 38?
  2. Alec_t

    Gate driver datasheet for IGBT

    Page 9 of ST's datasheet says: "The LM317L provides an internal reference voltage of 1.25V between the output and adjustments terminals. This is used to set a constant current flow across an external resistor divider (see Figure 4.), giving an output voltage V O of: V O = V REF (1 + R 2 /R 1 ) +...
  3. Alec_t

    555 PWM or is it?

    The frequency change is very small when the duty cycle goes from 10% (yellow trace) to 90% (blue trace).
  4. Alec_t

    LM3915 with dc motor

    The circuit in post #3 isn't usable directly, because each LED-driving output of a LM3915 is a switched current sink, not a switched voltage. A PNP transistor would be simpler, if of high enough gain to supply the motor stall current, or you could try something like this:
  5. Alec_t

    Gate driver datasheet for IGBT

    That circuit won't work as you want. U1 is a fixed 5V regulator and probably needs a minimum load exceeding the 5mA or so that would trickle through R1. A small 15VRMS transformer would do as a basis, or an off-the-shelf mains-to-DC SMPS would probably be cheaper than a DIY supply.
  6. Alec_t

    Any idea what this is?

    It's obviously a terminal for use in a betting shop, though I've never been in a betting shop so haven't seen one :).
  7. Alec_t

    Circuit Modifications for reducing current

    Change the fan for one with an inherently lower current draw. Reducing the fan current by other means will reduce its torque and speed.
  8. Alec_t

    Fire Fly drawing

    You already have the answer, over at the other site ;).
  9. Alec_t

    Popping and cracking sound

    Welcome to EP! Can you post a schematic for the Xenta and/or subwoofer if it's a powered type?
  10. Alec_t

    Arduino + Relay(220V) Problem.. Need Help!

    Do you have a star ground system, so that high currents through relatively heavy loads (relays etc) don't mess up the ground return for the Arduino?
  11. Alec_t

    Speaker output relay

    Then I guess the pops are due to those fat 1000uF caps charging. Perhaps you could wire a resistor of, say, >1k in series with the speaker so that the cap charges slowly at power-up, then use relay contacts to short out the resistor after ~2 secs. The contacts would have to be rated for the...
  12. Alec_t

    HELP!! TV Fault!! Photos Included

    The top-most leg of the transformer, near the cathode of diode DM857, appears to have a dodgy solder joint (or it may be a trick of the light) where it enters the main pcb. 10 flashes of the LED should tell you something. What does the manual/datasheet say?
  13. Alec_t

    Speaker output relay

    I'd try a resistor/capacitor combo on the Mute input of the chip, to provide power-up muting. Or perhaps a similar combo on the Gain0 and Gain1 inputs. Read the datasheet or any Application Note (if available) for advice re those inputs.
  14. Alec_t

    Arduino + Relay(220V) Problem.. Need Help!

    Welcome to EP! You MUST have a reverse-biased diode across the relay coil to suppress the back-emf pulse created when the relay is switched off. That pulse would drive the Arduino nuts and could also damage it!
  15. Alec_t

    Kinetic Phone Charger

    Exactly what is your AC generator? What is its impedance?
  16. Alec_t

    Frequency divider (less than 1MHz)

    I'm puzzled as to the "phase alignment". How can signals of 150kHz and 160kHz stay in phase with each other?
  17. Alec_t

    Mosfet driver IR2104 High out not working

    Unless the source of the high-side MOSFET is toggled high and low, the bootstrap circuit won't function properly to drive the gate 12V above the source. Is the source toggling?
  18. Alec_t

    Underwater Acoustic Simulation Software

    I doubt such software exists, but what information are you hoping the software will give you that text-books can't? Ultrasound is unlikely to be suitable for transmission beyond a few cm.
  19. Alec_t

    Ultrasound Modules

    No. See post #3.
  20. Alec_t

    Need help with battery power for my project

    If you do opt for a MOSFET, make sure to get one specified as a 'logic-level' type, to ensure that it can fully turn on with the 6V supply. 6 AA cells would provide too high a voltage for the servo.
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