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Make illuminated switch light up dim when off then normal when switched on

Discussion in 'LEDs and Optoelectronics' started by GREEBO22, Jan 13, 2020.

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  1. GREEBO22


    Jan 12, 2020
    Hi Everyone,
    i want to add some LED lights into the boot/trunk of my car & have bought the LEDS & Switches to do the job, but could do with a bit more advice, the Switch has a LED Halo light which i want to wire up to the lighting circuit of the car so the Halo lights dimly when switched off and then lights up normally when switched on,
    I googled & found an old post in this forum " Resistor on illuminated switch but without dimming the circuit LEDs?? started by thunderbollocks, Jan 16, 2017." but thought it better to start a new thread rather than reply to a 4yr old thread,

    The above pic was posted by "Pyramid" post 18 on the above Thread, & i think shows how to wire the switch the way i want to & covers most of my questions, but i have a couple that i dont understand
    1, what resistors do i need ( tried to search on ebay but really dont understand what im looking for)
    2, what diode do i need ( again i looked on ebay but really dont understand what im looking for)
    3, as id rather take power from the lighting circuit of the car so there is only power to the new circuit when the lights are on, can this be done without effecting the "bulb check system" of the car ( a Seat Exeo with LED rear lights)

    as i dont want to post giant pics from ebay, i will add the item numbers of the switch & leds

    SmartSwitch 12V/24V 22mm IP67 Steel LED Illuminated ON/OFF HALO Button Switch
    eBay item number: 142394830989

    1Pair 18 Mode 20 LED Car Truck Warning Emergency Flashing Lamp Strobe Light
    eBay item number: 163972118443
  2. Bluejets


    Oct 5, 2014
    Resistors are shown above as 1K and 10K.
    Unless you are using the exact same LEDs then probably require a different value.
    Wattage of the resistors would depend on the current draw of the LED.
    Diode the same, any old gp diode such as a 4004 would probably be ok , current rating of it is 1A.

    No idea.....

    As far as your parts listing, post a link rather than a description on where to go and look.
    Link id the chain symbol...... so you go to whatever web page, highlight and copy the address, and then come back and hit the chain link symbol.

    Draw a sketch of what you want to do.
    One minute it is "Halo" and the next it's "emergency flashers".
  3. GREEBO22


    Jan 12, 2020
    Thanks for the reply Bluejets, Sorry if i didnt explain properly, the "Pair of 20 LED Emergency Flashers" are what the "Halo Switch" will be switching on, ive just found that i can "upload files" (pictures) rather than linking weblinks to online albums ( really not used to this sort of thing)
    This is the Halo Switch that i have...
    Brand: SmartSwitch
    Contact Material: Brass
    Contact Form: Single Pole, Single Throw (SPST)
    IP Rating: IP67
    Technical Specifications
    Rated Voltages (DC): 6V/12V/24V
    Rated Voltages (AC): 100-110V/220-240V
    Power Rating: 5A
    Mechancal Life: 500,000 Cycles
    LED Life: 40,000 Hours

    Editing "Pyramids" original schematic ...
    The "Load" will be 2 x 20 LED lights, ( can be used as strobes but have 18 different settings cycled by a momentary switch,, will be a constant light not flashing)
    White LEDs .jpg
    Brand: SUNDELY
    Wattage: 60W
    Voltage: DC 12V - 24V
    Flash Patterns: 18 Mode (With power off memory function)
    Material: Aluminum
    LED Lamp bead: 20pcs
    Power cable length: Approx 68cm
    Waterproof grade: IPX-66
    Life span: 50000-100000 hours

    And as the schematics, say 1k & 10k resistors, but when i type in 1k resistor into ebays search i get confused by all the different types and terms, and dont know whats the right/best type to buy,
    1/4W 0.25W Carbon Film Resistor ±5% 1 Ohm to 1K Ohms
    1/16W 0402 SMD/SMT Resistors ±1% -Full Range of Values ( 1Ω to 10MΩ )
    0.25W 1% Metal Film Resistors 10R, 100R, 1K, 10K, 100K, 1M
    Royal Ohm 1k 1% 0.4W Metal Film Resistor MFF04FF1001
    Metal Film Resistor 1/2W 0.5W 1% Tolerance 0.1 Ohm to 6.2M Ohm
  4. Bluejets


    Oct 5, 2014

    1/4w carbon film resistor is the standard old run of the mill resistor.
    As your first line of "type to buy" says, the values range from 1 ohm to 1000 ohm (1K)

    You will find though that resistors normally come in packs of perhaps a thousand or so and include values from 1 ohm to maybe 1 million ohm.
    Best to buy a pack if you intend getting in to electronics.

    Now the value of current flow shown in one switch direction will give approximately 10mA.(ON position)
    When the switch is in the other position with the 10,000 ohm resistor(10K) it will be approx. 1mA.(OFF osition)
    A standard red LED is rated at an operating current of 20mA and has 1.7v drop across it.
    At 10mA, you may not even notice the difference between 10mA and 20mA which is why I suspect they chose the former value.
    Also, at 10mA, there is approx 0.1W dissipation in the resistor so a 1/4w value is fine.

    The diode , as I said, could be a 1A style 1N4004. These usually come in packs also, perhaps 20 or so at a minimum.

    The rest looks fine, just no idea what the momentry trigger does but I'm sure you have that under control.
    One other thing, I'd be checking with the local DMV or whatever you call your government motor vehicle department.
    They may well frown on having strobe lights fitted to vehicle used on the roads over there.
  5. Tha fios agaibh

    Tha fios agaibh

    Aug 11, 2014
    It's could be a problem if current is much higher than the original circuit.
    Even so, it may not even send a fault given the fact that it's only occasionally in the "on" position.

    Good advice from bluejets, I would just add to buy a variety pack where you can experiment with different resistor values.

    Your led lights already have current limiting resistors built-in so there's no concern about blowing them out by selecting too low a resistance.

    Btw, the 20 led beads appear to only have 16.
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