Amplify current of a flickering candle LED

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OK, a quick lashup of the concept I came up with, which seems to work fine at anything from 4.5V to over 12V (limited by the supply I'm using).

The flickering LED has negative to 0V and a 1K resistor to V+

The LED-Resistor junction connects through a chain of six 1N4148 diodes (= zener around 3.6V) to the base of an NPN transistor, with emitter to 0V and a 10K base-emitter transistor.

That transistor switches with the LED (but inverse) as it only has enough base current to turn on when the LED is OFF. The LED voltage is too low for the diodes/zener to conduct while the LED is on.

The first transistor has a 1K collector to V+

The second transistor has 10K from the first collector, emitter to 0V and the final "load" in its collector - just a single LED and resistor with this.

The second transistor is re-inverting the flickering LED on-off switching, so the LED connected to it flickers in sync with the original LED.







 
rjenkinsgb said:
OK, a quick mashup of the concept I came up with, which seems to work fine at anything from 4.5V to over 12V (limited by the supply I'm using).
Click to expand...
thank you RJ.
Ive been reading the recommended book by Forest Mims and i have to say that I can actually understand the language in your documentation. I still have a way to go but im pleased with my progress.

Ill get this breaded up this evening and create a schematic in SMD.
NOTE: I take it the diode chain can be replaced with a single zener with a value of 3.6v. I have an assortment with values from 2-30V in increments of .3v
 
I found this schematic that exaggerates the flickering led creating a random blink. I can only get it to work at 9 volts as anything above and the 555 does not trigger the standard led. at this point im not sure if its the trigger or the output on the 555 that's causing it to fail. My guess is its R2 that needs adjusting. I welcome and appreciate and suggestions to make this function under 12V

NOTES:
not using the speaker.
the CMOS 555 has been replaced with the NE version

I plan on using both circuits #62 , this one + one other I found to create the desired effect.
 
The 555 trigger and threshold pins level are referenced to a resistor divider across its power, so at higher voltage the trigger level will spread out.

Add an eg. 1K resistor from pin 5 to V+ & see what that does?
Pin 5 is a tap on that resistor divider & pulling that higher will increase the trigger and threshold levels.

(You could try an eg. 10K pot instead, find what range allows it to work at 12V and then use a fixed value around the centre of the pot working range).
 
This is the 3ird circuit i will be using. Ill be using all SMD components.
I creates a nice random flicker (blink)
It runs on 5-12V
ill be using just 4 leds

==============================================
The finished led tree will look something like this with each circuit running 4 leds on each level
 
ThomsCircuit said:
so its needs to be reversed?
Click to expand...
I was using normal diodes, so forward conduction.

Zener diodes work on reverse breakdown; the forward voltage would be around 0.6V, like other diodes.

It looks OK otherwise, glad you could make sense of the description!
 
It must be miserable to live in an oven. I am glad that I am comfortable up here in Canada.
 
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