1st project creating a nightlight using LEDS

Discussion in 'The Projects Forum' started by 18point, Mar 5, 2012.

  1. 18point

    Thread Starter New Member

    Mar 5, 2012
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    Hello all, this is my 1st post on this forum so ill get straight to the point:

    I am designing a product that acts as a nightlight, by using a three way switch i will aiming to achieve the following settings, white light, red light and blue light . . . . operated manually for user preference.

    I will also need a fourth setting, that when movement is detected the product will light up dimly, by using a PIR Motion sensor.

    I am trying to design my pcb design/schematic, however i am a novice at electronics so any advice/information would be hugely appreciated.

    many thanks
     
  2. mcasale

    Member

    Jul 18, 2011
    210
    12
    Sounds like you want a 4-way switch, which includes your "auto-on" mode?

    What do you mean "when movement is detected the product will light up dimly"? What lights come on?

    For doing your schematic and PCB artwork, a good tool is ExpressPCB.com

    Their stuff is free and easy to learn. They also will provide blank boards, but you have to load them.
     
  3. 18point

    Thread Starter New Member

    Mar 5, 2012
    7
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    sorry mcasale reading back i wasn't to clear with explaining my intentions.

    the product needs to offer the user 3 separate options of white light, red light and blue light. as well as a fourth option, which using the white led's would activate when motion is detected (using the pir motion sensor) . . . so in all 4 settings available to use and can be selected manually according to the users preference.

    the fourth setting, called 'night mode' if you like, could be activated and left while sleeping in a tent, then if you was to get out of your tent in the middle of the night, your emergence would cause for a light to come on and light the area around you, therefore no tripping over tent wires etc.

    my idea is to use a lithium ion 12v battery to power it, however once again I'm not sure if this would be viable either.

    hopefully I've made myself a bit clearer,

    appreciate the website as well, had a look and it looks ideal for designing my schematic.
     
  4. mcasale

    Member

    Jul 18, 2011
    210
    12
    Here's a schematic. :)

    I didn't know what sort of motion detector you are using.

    If you drive LEDs using a 12v supply, the resistors will need to dissipate more power. This is set for 20mA and 2v on the LEDs. The resistors need to be at least 1/4 watt.
     
  5. 18point

    Thread Starter New Member

    Mar 5, 2012
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    Thanks mcasale! much appreciated . . . .

    would this work for bright powered LED's? or would more power be needed, as the light is intended for outdoor use the light source needs to be bright enough to light a designated area.

    many thanks
     
  6. mcasale

    Member

    Jul 18, 2011
    210
    12
    would this work for bright powered LED's? or would more power be needed, as the light is intended for outdoor use the light source needs to be bright enough to light a designated area.

    This scheme should work with ANY LED, but you need to look at the LED specs. For higher current you will drain the battery faster. The resistors have to be sized to give the rated current at a typical voltage across the LED (usually around 2 volts).

    Look at the power dissipation in each LED and resistor [V*I or I^2R] and be sure the parts can handle it.
     
  7. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Do you have a seperate ON-OFF SW?' or want a 5 pos. SW. You can use several LED's in series with 12V. A single bright white , 10,000 mcd,worked quite well in motor home for night light. Most PIR modules will need a driver, some will take 12V, KC7783, Electronics123.com, & others 3.3 to 5V like RS 276-0033 or Parallex 555-28027 also from RS. A single Li cell would also work.
     
    Last edited: Mar 6, 2012
  8. 18point

    Thread Starter New Member

    Mar 5, 2012
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    Sorry to be a pain again guys, but how would such a schematic look if i changed the Led output to 4 ultra bright Led's per colour? in total 12 in the circuit, would i need extra resistors to deal with this? :confused:

    only 4 would be on at one time as the user can't mix the colours, either choose from white, red, blue, or the Pir setting.
     
  9. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Would help to know specs on LEDs. With 4 in series, might run out of V @ 12V, so use 3 or go to series parallel for white & blue.
     
  10. Audioguru

    New Member

    Dec 20, 2007
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    896
    I got some Air Wick perfume squirters with PIR motion sensors for free.
    They came with 3 AA alkaline battery cells. There is a 3-position timer and a motor that is supposed push the button on a can of perfume that squirts perfume into the air.

    It has a green LED that blinks twice when it detects motion then after a few days the LED blinks continuously when it thinks you must buy more perfume for it. I will not use it to squirt perfume so I won't buy any.
     
  11. 18point

    Thread Starter New Member

    Mar 5, 2012
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    Ok cheers!

    i am currently trying to identify the best LED's from Maplin, Farnwell etc, then i can provide you with spec . . . so many on offer i don't want to spend money on the wrong ones!
     
  12. 18point

    Thread Starter New Member

    Mar 5, 2012
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    audioguru, would that motion sensor work on a product such as mine? I'm only asking because i have know idea what variations of motion sensors are available, but if that is the case I'm thinking i could get my hands on one of those air fresheners, un - solder the pir and use it for my own board?
     
  13. Audioguru

    New Member

    Dec 20, 2007
    9,411
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    When RadioShack was still here in Canada they sold PIR sensors and PIR alarms.
    I don't know who sells that stuff in the UK, MATE!

    Look at the fairly complicated circuits for a PIR motion detector in Google.
     
  14. Georacer

    Moderator

    Nov 25, 2009
    5,142
    1,266
    Most online electronic stores have a range of available sensors, with full documentation. You will need to pay a little extra on postal expenses, though, as they are mostly based in the US.
    Sparkfun.com and Pololu.com are the ones that come into mind right now.

    But I 'm sure that there are retailers in your area, or even UK based online stores.
     
  15. 18point

    Thread Starter New Member

    Mar 5, 2012
    7
    0
    thanks for the help guys, managed to locate a few pir's now. . .

    question, if i was to use 8 ultra bright white led's, would i be able to use a dimmer as well as an on/off power switch, and dim the brightness across all 8 manually at the same time? so that the user could control the overall light output to their own needs or, because they are ultra bright led's would this create a problem and not be possible?

    i want to use 8 to create a broad light spread, however i don't want them to bright so that you end up blinded if you accidentally glance in the direction on the light. :confused:
     
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