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  1. Replies
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    Closed: Re: Tip41c/42c arrangement problem

    A question before moving on: that transformer you are using, does it have a center tap? In other words is it a 12V to 230V type with two primary wires and two secondary wires or does it have...
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    Closed: Re: Led project. Led on at nightime.

    The battery will still discharge eventually. You have to decide on how bright the LED has to be, noting that in general the brighter it is the faster the battery will drain, and how long it has to...
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    Closed: Re: LCD arduino printing issue

    You would have to show us your software to be sure but it could be a rounding error due to the math routines or the binary representation of decimal numbers.

    Brian.
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    Closed: Re: Led project. Led on at nightime.

    Those ICs are actually clever, they use an internal oscillator with inhibit input (for daylight detection) and a low Rds MOSFET output switch. All they need is a fixed resistor to make a potential...
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    Closed: Re: Led project. Led on at nightime.

    For simplicity, I think I would consider a "Joule Thief" design and single 1.2V rechargeable cell. The on/off control needs be nothing more than an LDR either directly shunting the base to ground or...
  6. Closed: Re: Modulation scheme of this pulsed/two-frequency radar system

    I'm not certain and I confess I have never seen this method used but I would guess it somehow uses the two frequencies to differentiate between objects arriving or leaving the beam path. With...
  7. Closed: Re: Help wiring a Ne555 Timer delay module (monostable?)

    If you have a test meter, do a continuity test between pins 1 and 2 of the NE555. Then do the same between pins 8 and 2. In either case, if there is a direct connection between them you will have...
  8. Closed: Re: Using a potentiometer to measure arcseconds.

    Sorry, slip of the brain cells, 16" is 400mm not 800mm but still quite a beast. Takes two people to lift it and a ladder to reach the eyepiece. The only thing it lacks is a gadget to make the clouds...
  9. Closed: Re: Switching Solar Panels in Series and Parallel

    8A Schottky diodes are plentiful and cheap. The most current any diode has to carry is 8A, when in parallel mode, each pair of panels has it's own diode so none of them carry the combined current of...
  10. Closed: Re: Help wiring a Ne555 Timer delay module (monostable?)

    If I'm right, the original wiring diagram shows the switch across the normally open relay contacts which are in series with the supply to the board. Closing the switch powers the board up and it...
  11. [ARM]Closed: Re: Environmental testing of Unit inside Chamber

    It could a faulty components but the environmental conditions are not particularly harsh.
    Can you show a schematic, obviously something is between the MCU and RAM if the signals are different...
  12. Closed: Re: O/P not Extected in CAMMON ANODE 7-SEGMENTS

    Obvious problems:

    Electrically you overload the PIC RD0 to RD6 pins, you must fit current limiting resistors in each of them.

    if(flag>=10) //wait till flag reaches 100
    {
    i++;flag=0;...
  13. Closed: Re: Switching Solar Panels in Series and Parallel

    Using MOSFETs is quite difficult because the gates have to be lifted close to drain voltage of each device. As the source and drain connections are all at different voltages, you need quite a complex...
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    Closed: Re: Chossing MOsfet for boost converter

    The question is rather like asking "if I fit two engines to my car will it go twice as fast?"
    The answer depends on so many other factors it is impossible to answer but the gut feeling is you need...
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    Closed: Re: SD Card not showing 4 GB

    I'm glad it's sorted. It would be worthwhile you learning about how partitioning works, it is useful to know for the future.
    Devices are the whole storage device, Partitions are just that, they are...
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    Closed: Re: Detect long string signal

    Or a monostable, set to time just over one cycle at 30MHz so anything slower lets it time out.

    Brian.
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    Closed: Re: PIC interface to control SSR

    if the sensor stays high it continually triggers 1000mS delays so the relay stays on all the time.
    From your description, I think what you want is this:


    if (sensor high)
    turn on load
    ...
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    Closed: Re: Led project. Led on at nightime.

    Sounds like a pathfinder for midnight fridge raids.

    When you say 'nightime' do you mean when it is dark or at particular clock times?

    Brian.
  19. Closed: Re: Using a potentiometer to measure arcseconds.

    I've got a 16" (800mm) telescope with opto-electronic guider. I'm not sure what positional resolution it has but as a guess it is around 0.1 degree so far short of one arcsecond. It's fine for...
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    Closed: Re: PIC interface to control SSR

    Your logic isn't right: if PIR==1 the relay stays on all the time.

    Brian.
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    Closed: Re: Tip41c/42c arrangement problem

    If you assume maybe 30% efficiency then 70% of the power is lost as heat.
    If that 30% gave you 20W, around 45W would be given off as heat. The current consumption would be about 4A from 12V.

    It...
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    Closed: Re: SD Card not showing 4 GB

    Yes, re-partition it. The problem is Windows is stopping you do it. Microsoft's assumption that all users are incompetent is the reason I switched to Linux years ago.

    Try this:
    1. open a...
  23. Closed: Re: Using a potentiometer to measure arcseconds.

    For such tiny measurements, use a graticule in the eyepiece or a large optical encoder. Even if you could get such precision from a 'cheap' potentiometer, the temperature and environmental stability...
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    Closed: Re: SD Card not showing 4 GB

    As a drive letter is allocated, maybe it is already seeing a single partition.
    Try formatting it, if it works the partition must be there.

    Brian.
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    Closed: Re: Multiple relay with controllers

    ... but yes, it is now correct.
    You don't need the resistor on the latch signal if the MCU is actively driving it.

    Brian.
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