leds

Basic electrical and electronics, such as DC/Analog control.
raypell
Posts: 12
Joined: Tue Oct 30, 2018 7:48 pm

leds

Postby raypell » Sat Dec 08, 2018 7:53 pm

Hi, brand new to this, got my set , timber ready to build base. bought some platform , extra track and 10 led lamps. 3 volt. Can i just get all 10 plus wires, 10 minus wires wire them to plus and minus to my 3 volt old xmas light switch (2 x 1.5 volt batts) . Even with adding power points everything seems to be made difficult. you must get point motor, then then another part for voltage etc etc , costs about £20 to power one point ?
thanks
Ray newbie .

MOD: Posts moved to Electric/Electronics area of forum as the correct area and is likely to get more replies/views

Dad-1
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Re: leds

Postby Dad-1 » Sat Dec 08, 2018 8:42 pm

Certainlt I double the cost of a point when estimating the final bill,
point motor & polarity switching, as to wiring cost it's just 'lost'.

Exactly what you're planning for those LEDs is unclear, but using
batteries is a logical way. However exactly what you Xmas tree lighting
system is not clear so I wouldn't liketo comment.

Geoff T.
Remember ... I know nothing about railways.
viewtopic.php?f=22&t=32187 and Another on viewtopic.php?f=22&t=28436&start=60&st=0&sk=t&sd=a

raypell
Posts: 12
Joined: Tue Oct 30, 2018 7:48 pm

Re: leds

Postby raypell » Sun Dec 09, 2018 7:37 am

thank you, sorry for being unclear. The cheap xmas lights £2, have a 3 volt little batrery box with an on off switch i was going to cut xmas lights off and wire all my plus and minus wires onto the switch . 10 leds and switch a few quid ? job done. I have been watching a bloke on youtube how to make a layout without costing an arm and a leg. I got a really nice steam loco for £15 on ebay , looks great . Thank you very much for your comment. This is a great site to learn from and nice people.
cheers Ray.

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Flashbang
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Re: leds

Postby Flashbang » Sun Dec 09, 2018 5:38 pm

Hi
You need to be a little cautious.... You say you will wire Pos and Neg into the switch. You can only do this if the switch is a Double Pole type That is it has two totally separate sets of contacts. Some On/Off switches will be Single Pole and only switch the Positive feed wire. Here the negative wire passes right past the switch uninterrupted.

How long the AA batteries will last powering the LEDs is uncertain, but probably will not be that long!
Consider for long term LED powering using a Regulated DC power supply such as a 5 volt ex mobile phone charger or other regulated power source perhaps at 12 volts DC. In either case each LED will then require a series resistor wired into one lead of the LED - doesn't matter which lead. For a 5 volt supply I would be looking at using a 220R (220 Ohm) minimum Ohm resistor and for a 12 volt supply a 1K0 (1000 Ohm) resistor. Resistors can be wired either way around as they are not polarity conscious devices. Any resistor will be fine that is rated at 250 milliwatt (1/4 watt) or a greater wattage per LED.
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raypell
Posts: 12
Joined: Tue Oct 30, 2018 7:48 pm

Re: leds

Postby raypell » Mon Dec 10, 2018 7:57 pm

Thank you very much for your help , yes adapter 12v sounds way to go with the resister added to led wires.
Great help .
cheers
Ray

Bramshot
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Joined: Thu Jul 07, 2016 6:55 pm

Re: leds

Postby Bramshot » Tue Dec 11, 2018 11:15 am

If the leds have already got a resistor connected in one of the led leads, then adding another one is a bit power wasteful, though the simplest way to go. With a 12 V DC supply, you should be able to power 4 of these leds at full brightness by connecting them in series ( led 1 positive to led 2 negative, led 2 positive to led 3 negative ... and so on, including the existing resistors) and connecting the two resulting ‘end’ wires to your supply. Other groups of 4 can then be connected in parallel ( ie ‘alongside’) each other. This way you get more leds to your power supply without wasting a lot of power in the additional resistor required to connect a 3 volt led to a 12 V DC supply. If the leds are a bit bright for your liking, you could try more than 4 in series ( though there will be an upper limit above which they will not illuminate) or add a single resistor to each series string. Best get a selection of resistors between 200 and 2000 ohms to try out.

raypell
Posts: 12
Joined: Tue Oct 30, 2018 7:48 pm

Re: leds

Postby raypell » Tue Dec 11, 2018 9:21 pm

Excellent advice , i am going to wire up 4 led lamps on my station platform , really appreciate all your help.i will do a photo when sorted out. Thank you very much


Ray


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