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  1. Hero999

    12v adapter and 12 v 7 ah battery to be charged

    Click Additional Options then Choose.
  2. Hero999

    12v adapter and 12 v 7 ah battery to be charged

    We don't know because you forgot to post a schematic of the current circuit.
  3. Hero999

    12 V to 3 V Question

    No, all LEDs have pretty similar voltage/current characteristics and drive requirements, unless you count the type with build in resistors or a regulator. The only difference between your LEDs and the standard type is they're much, much bigger and will most probably have a metal back designed to...
  4. Hero999

    Some brain draining needed, thanks

    The TRIAC still won't turn on because the the switch is just connecting the gate to A1. Why use a TRIAC when it's only being used as an SCR as a diode is connected in series with it? You should just replace it with an SCR. A resistor can be used to limit the charging current. The switch hardly...
  5. Hero999

    12 V to 3 V Question

    I've never seen an LM7803 before. I assume you're talking about a linear regulator, like the LM7812 but set to 3V. This will not work for a couple of reasons: LEDs are designed to work from a constant current source, not constant voltage. You need a current regulator, rather than a voltage...
  6. Hero999

    [SOLVED] Dropout voltage concerns.

    The datasheet covers a whole familly of regulators with the same architecture but differing output voltages and current limits. http://cds.linear.com/docs/Datasheet/1083ffd.pdf Yes, if the regulator has a dropout voltage of 1.5V and an output voltage of 12V, the output voltage will drop to...
  7. Hero999

    Some brain draining needed, thanks

    You don't need a double pole switch, SPDT will do. What's the resistance of the 2.7mH coil? The peak current will be near 200A, if it's nothing which can cause the switch contacts to weld. You should also limit the charging current otherwise the bridge rectifier will be killed as welll as the...
  8. Hero999

    Voltage above 13 vdc indicator

    The values you've chosen will work will draw a lot of current than necessary, 5mA may not sound like much but it will cost you battery life, if it's sat in standby. I'd recommend multiplying the resistor values by 10, giving 22k, 5k and 390k (the nearest E12 value to 407.4k) and using the BC328...
  9. Hero999

    Super simple flash camcorder

    The problem you've run into is one of the reasons why video cameras aren't cheap. It requires a powerful computer to compress the image data from the CCD and write it onto the SD. This is because uncompressed standard definition vidio (720x480 25 framse per second with a CD quality sound track)...
  10. Hero999

    Some brain draining needed, thanks

    It' good you haven't managed to turn the triac on given that it would probably blow up as it will be short circuited every half a cycle via the diode. Why all the complexity? Surely it's easier to just use a changeover switch so the capacitor charges when it's in one position and discharges...
  11. Hero999

    automated variac 0-220Vac

    A stepper motor and a belt actually seems like the most simplistic solution. Do you need voltage regulation? If so, an open loop control system won't be good enough. You'll need to adjust the variac to maintain the correct output voltage, as the load changes which will require a servo motor...
  12. Hero999

    Signal voltage adjustment problem

    If the command is connected to the same 0V rail as the regulator, ther wil be a short circuit on the 12V supply when the switch conects it to +12V.
  13. Hero999

    bike fuel indicator

    CApacitive or ultrasonic sensing is the way to go.
  14. Hero999

    Signal voltage adjustment problem

    Have you checked that the Command - isn't permanently connected to the same ground as the 12V regulator?
  15. Hero999

    Voltage above 13 vdc indicator

    Attached is a circuit which should do the job. The site linked below has the formula to calculate the values of R1 and R2. R5 is just a pull-up, make it 10k and R4 limits the base current to the transistor; 2k2 will do. R3 provides hysteresis, otherwise the relay could chatter, make it 100...
  16. Hero999

    Voltage above 13 vdc indicator

    I can't  help you, if you don't answer my question.
  17. Hero999

    [SOLVED] Dropout voltage concerns.

    No, it's not that simple. A good audio amplifier is designed so its volume is independent of the power supply voltage - a characteristic known as power supply rejection ratio. If the volume is set high, it will stay exactly the same until the battery voltage is too low to give the required...
  18. Hero999

    Voltage above 13 vdc indicator

    How much current does the relay coil use? The TL431 will be fine for small relays <50mA or higher with a transistor.
  19. Hero999

    0-30V Stabilized Power Supply

    What do you think? Google for the datasheets and read them.
  20. Hero999

    HOW TO FIND APPARENT POWER AND CURRENT SUPPLY FOR THIS CIRCUIT?

    Please don't post the same thing more than once. The formulae you require are linked below: http://www.nepsi.com/formulas.htm http://www.generatorguide.net/watt-acpower.html http://en.wikipedia.org/wiki/Power_factor
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