Joule Thief

[conradelektro]

Hi guruji !

Attached please see my basic Joule Thief circuit and the Toroid I used. This gives me about 400 Volt from an 1.5 Volt AAA battery (just barely lighting a small 4 Watt 220 Volt fluorescent tube). The power consumption is still very modest, about 90 mA on average.

You wrote that you got high voltage with a 1" toroid and a Slayer circuit.

Could you please post the Slayer circuit you used and the exact windings on your 1" toroid and how much voltage you got.

I rather agree with freepow that it takes a fairly big toroid (which then can have a high Al value of e.g. 10.000 nH/N2) in order to reach about 1000 Volts from a 1.5 Volt battery.

If a Slayer type circuit can do about 1000 Volts with a small toroid (with an Al value smaller than e.g. 3000 nH/N2), I would be very much interested in learning the details.

Greetings, Conrad

[innovation_station]

the best i have been able to get is 700v from a gold mine 1"  useing a basic jt configuration .. meaning equal length coils ..

the secondary was really fine wire ..  many turns

first you need to tune the core material ..

you can do this by  starting at a 6 turn jt .. and removeing turns till highest voltage is seen on 1 turn secondary .. then you have tuned to the best working range for the core ..

the best i have found is 2 to 4 turn jt .. this will yeild about 4 to 7 vdc per turn of secondary wire .. 

after the best results are attained for your core .. you can then add as many turn secondary as you desire .. KEEPING  THE TUNED JT

IST

eg ..   say you find that 4 turns yeilds 6 volts .. if you now dubble the other wire length ..  or use teslas method for 1/4 wave ... 

your results should be better ... as you just tuned to the core for best results then you dubbled the best  and it is your delay line ..   

so 4 turns .. and the second wire is 8 turns and if you multi lap it .. IT BECOMES  MY HF CONVERTOR ..

: )

[conradelektro]

To innovation_station !

Thank you for your very helpful reply, that clears up my recent experiments and offers a nice way to check my toroids. Will try to get a bit more out of my 1" toroid than 400 Volt, may be closer to the 700 Volt you mentioned. I do indeed have too many turns on L1 and L2. Some bigger toroids are on the way to me, but I want to get to the limits of each toroid type I have.

I would like to take advantage of your presence in this forum and dare to pose questions concerning air coils for a Joule Thief (since I am an inexperienced hobbyist and you seem to be a master of electronic wizzardtry):

Lately I have played with some air coils. See attached pictures and the following specifications:

Air Coil A (see specification next to the circuit, rather complicated attempt):
-------------------------------------------------------------------------
50 to 70 Volt on L3,  58 KHz
18 Volt over collector emitter
power consumption 40 mA (for 14 white LEDs)
transistor 2N3904 , base resistor 100 to 220 Ohm


Air coil B900 (the one on the photo):
-----------------------------------
160 Volt over small neon lamp on L3, 27 KHz
27 Volt over collector emitter
power consumption 60 mA on average (for small neon lamp, see attached scope shot)
transistor 2N3055 , base resistor 100 to 220 Ohm

L1 - first layer - 20 turns
enamelled copper wire 0,8 mm ~ AWG20
20 x 0,8 = 16 mm, 1 row

L2 - second layer - 90 turns
enamelled copper wire 0,3 mm ~ AWG28
45 x 0,3 ~ 16 mm, 2 rows

L3 - outermost layer - 900 turns
enamelled copper wire 0,3 mm ~ AWG28
45 x 0,3 ~ 16 mm, 20 rows

Now my questions:

1) Do you have a nice recipe for air coils (in connection with a Joule Thief)? I like air coils because one can build them from cardboard and wire salvaged from obsolete transformers or motors.

2) Is it true, that one can attain a higher frequency with an air coil in comparison to the frequency when using a toroid?

(I do not talk about a Slayer type coil and the Slayer circuit, still staying with the basic Joule Thief circuit. Later I want to progress to other circuits, but not now, because I do not yet understand the Joule Thief circuit well enough.)

Greetings, Conrad

[innovation_station]

i have found with air core coils ..

the bobbin makes a HUGE DIFF!

THANKS FOR YOUR KIND WORDS CONRAD!

this is true as if you look back to the formulas for electro magnetics ..  and examine the pancake coil ..

it is thin  this creates a much stronger electro feild ..

so basically use a min 1" center as i have seen ..  and thin maybe 3 turns .. then back and forth till spool is full bifillar min .. diffrent gages same length .. 

hit it 12vdc use 3055  and 270 ohm .. with a 1 " center i have reached extream voltages and it shoots plasma ..  useing 22 gage and 26 gage with the wire length of 38 to 40 feet ..

secondary does not matter ..  the longer the higher the voltage .. the more the draw from source the bigger the BITE !  : )

peace and all expairmenters keep up the great work !

ist

feel free to ask any questions you wish .. if i can answer truthfully i will so .. if i can not i wont !

: )

[giantkiller]

Yes, the bobbin creates a pancake but with depth like concentric canisters.