Flip Flop Inverter Using Low Voltage Input

[SkyWatcher]

Hi folks, I have been trying to power some series leds, like christmas leds with the bare bones flip flop inverter and this one seems to be working well.
The idea was to be able to adjust the frequency and have a more true ac output on a secondary to play around with resonance to achieve higher efficiencies.
I'm using 3 AA nimh in series for around 3.8 volts for input and it is drawing 120 milliamps when powering a string of colored leds to about 85% of full brightness, though if i lower the 1.5 kohm resistors to increase frequency, I'm sure i can get full output of leds for a little more input.
Though just under 1/2 watt is pretty good for the light I'm getting and any possible resonance tuning may increase efficiency further.
You thoughts welcome.
Here is a circuit drawing.


Uploaded with ImageShack.us
peace love light
tyson

[SkyWatcher]

Hi folks, I decided to try and power some of the warm white leds i have in series, 30 in series i used and i then decided to hook up a full wave rectifier to the secondary output.
I am getting very good light output for 160 milliamps with the 3.8 volt input or around 600 milliwatts. What is interesting, is that it seems i may have hit a sweet spot with this setup.
If I use anymore voltage, like 6 volts or try and use less voltage, like 2.4 volts and no matter how i try and tweak the resistors to change frequency, i cannot get the impressive output i can with the 3.8 volts and the resistor and capacitor values shown in circuit diagram.
I may have got lucky and hit close to a resonant spot with the ferrite e-core i am using.
24 gauge bifilar and 30 gauge secondary.
Your thoughts welcome and i would encourage if anyone has these parts or similar laying around, to give it a try.
peace love light
tyson

[boguslaw]

I would like to understand such flip flop inverter . Do you have any tutorial or link I can learn and see how transistor are switched and what determine switching frequency ? I wonder what would happen when frequency match the LC resonance ....

[Joit]

boguslaw, does Circuit Simulator Applet work for you?
In this Applets it shows nicely how Circuits work.


Skywatcher, may you wanna try different Caps too, when you got some by the hand

[gyula]

I would like to understand such flip flop inverter . Do you have any tutorial or link I can learn and see how transistor are switched and what determine switching frequency ? I wonder what would happen when frequency match the LC resonance ....

Some theory on such astable multivibrators:

Transistor Astable Multivibrator

Gyula

[SkyWatcher]

Hi folks, thanks for replies, though of course, i go and compare this circuit with the simple joule ringer and the ringer slightly out performs the flip flop.
Oh well, it was worth a try, hehe.
peace love light
tyson

[kcarring]

tyson,

nice pnp variant.

thing i have found with flip flops, is - they tend to favor one side due to the fact that no two resistors are identical, seems to create heat and noise, and a lack of resonance. one should also be able to have an inline choke to limit current if wanted? have you tried the royer circuit, it utilizes such a choke.

@boguslaw

As I understand it, the current flies into the centre tap, and then hits the fork in the road.. initially it picks the path of least resistance, then it flip flops back and forth from there onward

[Allen Burgess]

Flip Flop

Radio Shack has a simple LED flip flop circuit; The resistors in that circuit are tiny variable trim pots. You really need low value variable resistors to prevent the one sided transistor overheating problem.

[boguslaw]

What is the purpose of two diodes in schematic ?

[SkyWatcher]

Hi folks, Hi kcarring, thanks for reply and kind words, though that circuit i just copied and redrew.
Hi boguslaw, without the diodes, my circuit would not oscillate, so I'm guessing they prevent interference of oscillation of circuit due to coils operation.
peace love light
tyson

[boguslaw]

Hi folks, Hi kcarring, thanks for reply and kind words, though that circuit i just copied and redrew.
Hi boguslaw, without the diodes, my circuit would not oscillate, so I'm guessing they prevent interference of oscillation of circuit due to coils operation.
peace love light
tyson

Ah,that's the problem. I have to understand it better because my plan was to set switching to resonant frequency of primary coils and caps.

[AhuraMazda]

Royer oscillator

This looks very much like a Royer Oscillator.

[shawnnweed]

This looks very much like a Royer Oscillator.

It is probably the precurssor.

[totoalas]

Hi folks, I have been trying to power some series leds, like christmas leds with the bare bones flip flop inverter and this one seems to be working well.
The idea was to be able to adjust the frequency and have a more true ac output on a secondary to play around with resonance to achieve higher efficiencies.
I'm using 3 AA nimh in series for around 3.8 volts for input and it is drawing 120 milliamps when powering a string of colored leds to about 85% of full brightness, though if i lower the 1.5 kohm resistors to increase frequency, I'm sure i can get full output of leds for a little more input.
Though just under 1/2 watt is pretty good for the light I'm getting and any possible resonance tuning may increase efficiency further.
You thoughts welcome.
Here is a circuit drawing.


Uploaded with ImageShack.us
peace love light
tyson

Hi tyson maybe just post my results here since its similar to the flip flop function .... Im thinkking of using two parallel 2n3055 or mje121194 just to dissipate the heat ?????



My joule ringer failed - cooked all the transistors
Hi to all,
Tested my joule ringer in the Philippines

4 circuits all failed heating up the transistor 2n3055 and mje121194
base trigger
1. 1 M 5 k pot with .082 cap - 200 ma max with 50 % brightness worked for a month and still ok till i changed to the following

a. 220 ohm 5 w series with 5 k and diode 1n4007 to transistor current from 170 to 1.5 amperes full brightness but only lasted 1 hr and transistor fried

b. 10 k pot 1/4 w series with diode in4007 - fried right away
c 1 m resistor series with 10 k and diode - no resonance
d 220 ohm R series with 10 k series with diode fried after 1 hour

my supply voltage 13 v dc 7ah sla battery charged by 5 watt solar
load parallel 5 220 v ac led lamps 5 w ea

last connection
battery to inverter 500 w 220 v ac output I in dc 1.5 A Iac out 2.5 A

I think the 1st one will be adopted but 50 % brightness only and can last from 6 pm to 6 am duration

Dont know what happened since b. was tested in China for 2 weeks w/o any glitches

Hope others can share their results also

thanks

totoalas

[Dave45]

I believe the 2N3055 is npn unless Im mistaken