Oscilating Resistor For Flame Lighting ?

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smokiedabong

New Member

• Oct 6, 2010

• #1

I'm looking to build a pulsating light that imitates a flame , something like the flameless candles but much more powerful .
At first I bought some flameless candles because I was thinking to hook the oscilator of the electric candle to a transistor and power a more powerful bulb . But to my surprise they have no oscillator inside , it's actually the LED that's pulsating . Is there a component that will variate current like that so it'll pulsate an ultrabright LED or a small bulb ? Or a simple circuit that will do that without using an Arduino ?

 

MikeMl

Well-Known Member

Most Helpful Member

• Oct 6, 2010

• #2

How about using the varying current that flows through your flameless candle to control the base current of a power transistor which in turn drives your lamp, etc?

 

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smokiedabong

New Member

• Oct 6, 2010

• #3

I was thinking to do that , but I thought that maybe there is also another component that can do that

 

lilimike

Member

• Oct 6, 2010

• #4

In this month's issue of Nuts & Volts there is a simple design you can adapt called "Magic Candles"

Other than that just Google PWM+PIC+candle

Mike

 

rfs100

New Member

• Oct 6, 2010

• #5

years ago, beforethey built the electronics into the led, I just used an opto-isolator to drive an SCR...this allowed me to use 200 watt projection lamps.

 

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smokiedabong

New Member

• Oct 29, 2010

• #6

I have built the following circuit . IC are the special flickering LEDs and the transistors are 2N2222A . The 8 LEDs are white with 3.5V voltage drop and 25 mA . All the LEDs light up at the same intensity and flikered nicely . The problem is when I tried to measure the amps to the LEDs the reading for three of them was 2mA and for the fourth was 55mA and after a minute or so the first burned out . I checked the circuit and there are no shorts , is there something wrong with this design ?

**broken link removed**

 

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BrownOut

Banned

• Oct 29, 2010

• #7

after a minute or so the first burned out

Click to expand...

Which one burned out?

 

ronv

Well-Known Member

Most Helpful Member

• Oct 29, 2010

• #8

Seems like each transistor should have it's own base resistor so the one with the lowest Vbe doesn't hog all the base drive.

 

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smokiedabong

New Member

• Dec 5, 2010

• #9

Thanks for all your help

I made this changes to the circuit . The problem is when the switches A and B are open , the LEDs still have a dim light and after a while a group of 4 will get brighter and brighter . When I close the switches the LEDs will flicker for a 10-15 seconds and after that they will stay fully light . Do you think I need a drain resistor ?

**broken link removed**

 

Last edited: Dec 5, 2010

audioguru

Well-Known Member

Most Helpful Member

• Dec 6, 2010

• #10

Nothing turns off the transistors (are you using old germanium transistors?).
Leakage current turns them on a little then thermal runaway makes the leakage current go higher and higher.

Add a 10k resistor from the cathode of the controlling LED to ground.