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  1. Alec_t

    how to determine the right voltage for led lamp?

    That's a much clearer image and points to the LEDs being arranged as a series of 18 groups, each group having 5 LEDs in parallel. So I reckon you'd be looking at a power supply of at least 18 x 3V = 54V, capable of supplying a constant current up to 5 x 60mA = 300mA.
  2. Alec_t

    how to determine the right voltage for led lamp?

    Does each dot have 2 conductive tracks going to/from it? They don't show up in the picture.
  3. Alec_t

    Input power vs Output power in pro amps

    Yes you could, if 175W in is the RMS rating and 700W out is a transient peak rating. But, as Bob said in post #2, you couldn't get 700W out continuously. So Crown's 700W figure can't be RMS.
  4. Alec_t

    Convert a 6 volt to 12 volt on my motor cycle . Any ideas how that's done

    Welcome to EP! Actually, you need a voltage regulator set to about 6.9V to charge a "6V" lead acid battery. Have a read of this.
  5. Alec_t

    how to determine the right voltage for led lamp?

    o_O That rules out a series connection of groups each having 5-in-parallel. The only reason for wiring them that way, that I can think of, is if the groups are multiplexed, or selectively switched. Seems unlikely. Edit: It's hard to tell from the post #10 picture, but it looks like the 5 LEDs...
  6. Alec_t

    how to determine the right voltage for led lamp?

    Assuming all the LEDs are the same, then 18W/90 = 0.2W per LED. If we now assume the LED Vf is 3V, then the implied current per LED is 200mW/3V = ~66mA. So a group of 4 LEDs in parallel would draw 264mA max. There could be 90/4 = 22 such groups wired in series (can you check?). The wide input...
  7. Alec_t

    how to determine the right voltage for led lamp?

    Yes, the number is important. LEDs should be current-driven. You need to know the maximum allowable current draw of each LED (at least approximately) as well as the series/parallel configuration of all the LEDs and the number of LEDs.
  8. Alec_t

    1.5 volt bulb won't light in my circuit newbie

    It won't work (at least, not for many seconds) with a little 9V battery if the bulb needs 0.3A to light up. See post #11. Have you considered replacing the bulb with a white LED? That will be pretty bright with much less current.
  9. Alec_t

    1.5 volt bulb won't light in my circuit newbie

    With your circuit there won't be 1.5V across the bulb..... much less. Think of it this way. The 2kΩ in parallel with the 0.7Ω bulb is virtually short-circuited by the bulb, so can be ignored. That means the voltage divider is now just 10kΩ and 0.7Ω. Virtually all the circuit current passes...
  10. Alec_t

    Micro hydro-electric generator help

    Sadly I have to agree. 1) A boat going at, say, 10 knots won't build up much pressure to drive the genny; certainly nothing like 174psi. I think you'd be lucky to get 10% of that. 2) Let's be generous and assume you could actually get 50mA out of the genny. That's insignificant compared to the...
  11. Alec_t

    Micro hydro-electric generator help

    I naively thought the idea behind any wilderness trip was to get away from the trappings of civilisation, hence not taking anything needing charging? :)
  12. Alec_t

    Off grid house lighting

    The lighting cables (typically 1.5mm2, rated for 5A) may get a tad warm, especially if enclosed at any part of their run. As per Oz, there are UK regs re running low voltage cables in the vicinity of mains cables.
  13. Alec_t

    Bee Venom Collector

    Welcome to EP! Check out this thread.
  14. Alec_t

    Battery Insulation resistance Caluculation [Software code ]

    The impedance between battery V+ and V- is extremely low, i.e there is no insulation.
  15. Alec_t

    Battery Insulation resistance Caluculation [Software code ]

    Welcome to EP! Insulation between the battery and what? Do you have any programming skills, or electronics experience? Is this a school/college assignment/project? 350V can easily KILL you!! You shouldn't be messing with it if you have to ask basic questions such as in this thread.
  16. Alec_t

    Capacitor as backup to 12v train camera system power

    Presumably the individual caps are series-connected, but in the post #34 link there is no visible circuitry for equalising the cap voltages as they charge/discharge :confused:. Also, the module is rated for an input voltage of 11.1V max, so that could be a problem if the TS uses 12V on the track.
  17. Alec_t

    Capacitor as backup to 12v train camera system power

    Can you post a link to your power supply's specs/datasheet? The supply might not like the huge current surge charging the supercap up from zero.
  18. Alec_t

    Sourcing a Coil

    You can get replacement coils for solenoid valves. Perhaps one of those would suit?
  19. Alec_t

    Replacement Optical Isolator

    An H11F1M optoisolator (one of these), with a suitable input current-limiting resistor might do, providing the output terminals don't see more than 30V across them.
  20. Alec_t

    Capacitor as backup to 12v train camera system power

    I may be confusing you with another poster, who was proposing to power the tracks with unsmoothed DC and use on-board processing on the train. Suppose you have a 12V battery/supercap as backup. Would you want to have a DC track voltage less than 12V? If you can keep the track voltage above the...
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