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szracer



Member Since: 10 Oct 2010
Location: Cotswolds
Posts: 356

England 2010 Defender 110 Puma 2.4 USW Stornoway Grey
Any electronics gurus out there?
OK, I suspect this is not really one that you need to be an electronics 'guru' for, but what I know about electronic circuits, you could scribe on a gnat's danglies.

As some of you know, my 'other' hobby is historic car racing. One of the issues I have is that it's sometimes difficult to see pit boards for driver changes, especially in endurance races at night.

So, my brainwave, was to have a remote controlled LED 'come into pits' light, which can be switched on from the pit wall, as the car comes past.

I found one of the following at Maplin, which has a (in theory) 70m range, and can switch on and off one circuit. Since this needs 12v for power, my aim is to run it from a cigarette lighter plug, to enable it to be moved from car to car.

http://www.quasaruk.co.uk/acatalog/Remote_Control_Systems.html

My only issue is how to wire up the circuit to the LED warning lamp. What resistor should I be using with a 5mm super-bright LED, and how do I wire it up?

Any help, much appreciated!! Smile 
2010 110 XS USW (the slow one)
1960 Alfa Romeo Giulietta SZ (the fast one)
2005 Ducati ST3
1954 Sunbeam S8
Post #66881 11th Apr 2011 11:05am
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Martin
Site Admin


Member Since: 02 Apr 2007
Location: Hook Norton
Posts: 6605

United Kingdom 2015 Defender 90 Puma 2.2 XS CSW Montalcino Red
This'll cost you a spin in the Giulietta Wink

Once the unit is powered from 12V, it basically operates as a remote controlled switch - so you can switch pretty much anything.

Have you got an LED in mind? I would go for the biggest, most super ultra mega bright you can find so you spot it! Wink

You need the Forward Voltage and Forward Current from the LED spec, and plug them into this (assuming you'd use the car's 12V to power the LED too):

R = 1000 * [12 - Fwd Voltage]
    -------------------------
      Forward Current in mA



This should give you a number between 100 and 1000 if you've plugged the right numbers in Wink Or let me know the LED and I'll do the resistor calc for you!

Alternatively you can get 12V LEDs, which have the resistor built in Smile  1988 90 Td5 NAS soft top
2015 D90 XS SW
Post #66882 11th Apr 2011 11:35am
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Martin
Site Admin


Member Since: 02 Apr 2007
Location: Hook Norton
Posts: 6605

United Kingdom 2015 Defender 90 Puma 2.2 XS CSW Montalcino Red
Also, I presume you're looking at the QS1 from that page? In any case they all say they are 30m range Confused

Try this for a wiring diagram:

  1988 90 Td5 NAS soft top
2015 D90 XS SW
Post #66885 11th Apr 2011 11:59am
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szracer



Member Since: 10 Oct 2010
Location: Cotswolds
Posts: 356

England 2010 Defender 110 Puma 2.4 USW Stornoway Grey
Thanks, Martin, you're a star! Bow down Bow down

Hadn't even thought about 12V LEDs but am now thinking of using one of these:

http://www.vehicle-wiring-products.eu/VWP-...ledgwl.jpg

Will get to it, and let you know the results.

And I may be doing a track day at Goodwood later in the season. If I do, you're welcome to a few laps!
Smile 
2010 110 XS USW (the slow one)
1960 Alfa Romeo Giulietta SZ (the fast one)
2005 Ducati ST3
1954 Sunbeam S8
Post #66956 11th Apr 2011 9:59pm
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