!!

Not Registered?

Welcome!  Please register to view all of the new posts and forum boards - some of which are hidden to guests.  After registering and gaining 10 posts you will be able to sell and buy items on our N'porium.

If you have any problems registering, then please check your spam filter before emailing us.  Hotmail users seem to find their emails in the Junk folder.


Thanks for reading,
The NGF Staff.

Author Topic: Bonfire simulator  (Read 128 times)

0 Members and 1 Guest are viewing this topic.

Offline texhorse

  • Trade Count: (0)
  • Full Member
  • ***
  • N Gauge Society Number: 3953
  • Posts: 654
  • Country: gb
  • Gender: Male
    • YouTube
    • Awards
Bonfire simulator
« on: November 06, 2017, 09:20:33 pm »
OK, please bear with me, and definitely no complex wiring diagrams please!

I bought some cheap flickering tea lights from Pound shop.  They operate from a 3V flat circular battery.  I dismantled everything out of one, and now the bulb will flicker when you put the 3V battery to both "legs" of the battery.  However, I have now got rid of the plastic casing, switch etc.  Still with me?  Good!

Now the lights on my layout run from the 16V AC output from a DC controller via a pair of bus wires.  I want to run this flickering bulb off the bus wire.  How do I convert the 16V AC to the 3V which makes the bulb flicker, thus giving me my bonfire simulator?  I read online that you can do it with two resistors in series, and with the bulb coming off between the two resistors.  However, when I did this in practice, the bulb was very dim and I accidentally blew it!

I do have another tea light to dismantle, but can anyone tell me in "Der basic" how to make my flickering bulb run off the 16V bus?

Many thanks.

Andy
UK
Montrose and Highland Railroad



Offline Lazy-Ferret

  • Trade Count: (0)
  • Full Member
  • ***
  • Posts: 79
  • Country: gb
  • Gender: Male
    • Lazy-Ferret
    • Awards
Re: Bonfire simulator
« Reply #1 on: November 06, 2017, 09:33:53 pm »
Online you can find LED resistor calculators, but they do require you to know a bit about the LED...

Here is one. http://led.linear1.org/1led.wiz

I did a quick search on Ebay for flickering LED's, and most seem to be around 20mA, but depending on the LED vary between 2 and 3.3v, so would need a resistor of 680 to 820ohm. I would start with the higher value, and then try reducing it if it is too dull.
"Only a man that drives a second-hand car knows how hard it is to drive a bargain!"
South East 4x4 Responder

about our other loves

Online themadhippy

  • Trade Count: (0)
  • Full Member
  • ***
  • Posts: 311
  • Country: gb
    • Awards
Re: Bonfire simulator
« Reply #2 on: November 06, 2017, 09:40:32 pm »
D'is this simple enough? ive gone for 2 x  330 ohm resitors,but 390 or 470 ohm might be a better choice if  its to bright


Edit to add
you maybe best  adding in a diode (1n4001 will do) as depending on the leds flashing circuitry it may get upset having Ac shoved upit,


however the led will only work 1 way around
« Last Edit: November 06, 2017, 09:54:41 pm by themadhippy »

Offline ntpntpntp

  • Trade Count: (0)
  • Full Member
  • ***
  • Posts: 1181
  • Country: gb
    • Awards
Re: Bonfire simulator
« Reply #3 on: November 06, 2017, 09:51:42 pm »
I'd probably try a 1k resistor or maybe even 1k2, auxiliary ac supplies are notorious for being higher voltage than stated!
If you're going to play around with LEDs and resistors it's worth having a small kit of a range of resistor values to experiment with.  Always starting with a higher value than is actually recommended by a resistor calculator, it's surprising how little current you can get away with.

As it's being fed from an AC supply, it may also be worth adding a standard diode in inverse parallel, to shunt the reverse half of the AC cycle past the LED. LED's don't always have a particularly high maximum reverse voltage.  In fact, I'd probably construct or purchase a basic bridge rectifier and feed the LED with DC anyway.
« Last Edit: November 06, 2017, 09:52:55 pm by ntpntpntp »
Nick.   2016 celebrating the 20th anniversary of "Königshafen" exhibition layout!

Online keithfre

  • Trade Count: (0)
  • Full Member
  • ***
  • N Gauge Society Number: 5036
  • Posts: 633
  • Country: nl
  • Gender: Male
    • Awards
Re: Bonfire simulator
« Reply #4 on: November 06, 2017, 09:58:08 pm »
In fact, I'd probably construct or purchase a basic bridge rectifier and feed the LED with DC anyway.
That makes sense to me, as the battery the LED's designed to work with supplies DC, not AC.

Offline ntpntpntp

  • Trade Count: (0)
  • Full Member
  • ***
  • Posts: 1181
  • Country: gb
    • Awards
Re: Bonfire simulator
« Reply #5 on: November 06, 2017, 10:14:09 pm »
... the battery the LED's designed to work with supplies DC, not AC.
Indeed, and depending on the design of tea light you may have a genuine flickering LED or instead a little circuit board with an integrated circuit.  Some of these ICs are actually playing music, you can connect an audio amplifier or small piezo speaker! They're probably circuits originally intended for those annoying greetings cards.
Nick.   2016 celebrating the 20th anniversary of "Königshafen" exhibition layout!

 

Please Support Us!
December Goal: £55.00
Due Date: Dec 31
Total Receipts: £55.00
Below Goal: £0.00
Site Currency: GBP
100% 
December Donations


Advertise Here