Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Oscilating Resistor For Flame Lighting ?

Status
Not open for further replies.

smokiedabong

New Member
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
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?
 

rfs100

New Member
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.
 

smokiedabong

New Member
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**
 

ronv

Well-Known Member
Most Helpful Member
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.
 

smokiedabong

New Member
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:

audioguru

Well-Known Member
Most Helpful Member
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.
 
Status
Not open for further replies.

Latest threads

Top