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  1. Alec_t

    Adding LED lights to Kid Battery powerd Ride-on

    One of those regulators, set for say 300mA constant current, could drive a series chain of 2 head-lights plus 1 tail-light. So you'd need 2 regulators of that type. A 6V battery won't do, unless you use it to drive a DC-to-DC boost converter which in turn could drive all 6 LEDs in series.
  2. Alec_t

    PiezoElectric Tiles

    Welcome to EP, Dave! Download and read the 741's datasheet to be sure of connecting the pins correctly. A bad guess can destroy the op-amp. Can you post a schematic of your circuit?
  3. Alec_t

    Trouble with solder

    Oily finger marks on the component legs? Are you using lead-free solder or leaded?
  4. Alec_t

    Programmable Potentiometer/Resistor For 12V DC Motor

    Here's the basis for another option, providing your motor is a brushed DC type :- Any PC, tablet or phone is used to generate a suitable programmed sequence of different tones. This circuit receives a tone as a line-level input. Each cycle triggers a monostable circuit (U1a, U1b) giving a fixed...
  5. Alec_t

    sample and hold pulse source?

    .... and if you want the post #20 circuit to have an inverting function, just take the output from the first inverter. The nice thing about that Schmitt trigger is that you can easily adjust the hysteresis (dead band) by choice of resistor values.
  6. Alec_t

    Adding LED lights to Kid Battery powerd Ride-on

    If the forward voltage of the LED is 3.2V then two strings of three require about 600-700mA total. My concern would be that a simple switch for the LEDs could result in a flat (and damaged) battery if the LEDs were left on inadvertently. Won't you need a timer to switch them off automatically?
  7. Alec_t

    I need a looping digital timer

    Any real-time clock counts up to 1 min repeatedly. What do you want yours to do when each minute is up? Beep? Flash a LED? Play the Stars & Stripes? ....?
  8. Alec_t

    Power supply circuit question - Transformerless good idea? Still pass certification?

    .... and because of the huge amount of heat generated (as already mentioned above)!! Your pcb would catch fire in no time :eek:.
  9. Alec_t

    Speed control for A.C. Model Railroad locomotives

    Is the voltage rating of the loco motors 16VAC or something less?
  10. Alec_t

    Metronome Project

    It's a device to convert an electrical signal into a sound (or vice versa).
  11. Alec_t

    Problem charging battery

    Is your charger designed to be able to power the tablet and charge the battery at the same time?
  12. Alec_t

    Metronome Project

    Welcome to EP! What is the purpose of the latch? When you say 'change the pitch', do you mean the repetition frequency of the clicks, or the tone of each click? Over what sort of distance does the metronome need to be heard? What will be used as the audio transducer? Loudspeaker? Earbud? ....?
  13. Alec_t

    Transistor bias configuration

    :confused: I'm glad I didn't have your lecturer when I was a student! I think Old Steve has it right, in post #13.
  14. Alec_t

    Phone with two ear phone sockets

    If you order enough, I'm sure there's a manufacturer in China that would produce a custom mobile for you.
  15. Alec_t

    Transistor bias configuration

    In answer to your question, Googling "transistor biasing" gives lots of hits for tutorials and other educational resources to help you.
  16. Alec_t

    Transistor bias configuration

    @ M Sridhar You have hijacked someone else's thread. That' considered bad practice. You should start your own thread in the appropriate forum if you expect help.
  17. Alec_t

    What does this capacitor do?

    What markings are there on the battery? If it's a lithium battery the device may have something to do with protecting the battery.
  18. Alec_t

    Induction heating gold

    Even if you could generate eddy currents, since gold has excellent conductivity (low resistance) I think any heating effect would be small.
  19. Alec_t

    led driver selection for project

    The measured 20mA-50mA currents for 12V-15V input suggest otherwise. My guess is there's simply a series resistor.
  20. Alec_t

    Self regulating ramped voltage oscillator?

    You do realise that for even a 'small' gap, the voltage required to produce noticeable conduction in a dielectric material is going to be 'very high' and hence dangerous?
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