Joule Thief

[stprue]

@stprue

Don't forget to try removing some turns on the x2 , i think you maybe losing 10 to 15 volts now, but only testing will tell ...

Mark

Yes I will do that and also try a basic MK set up for those to see what happens.  Last time you told me to remove a few turns I did and I gianed lost of extra voltage. 

Thanks...Stew

[xee2]

@ jeanna

OK,
Then what I want to know is at what point in this circuit of yours does the battery get declared dead by the fluoro light.

(I know when mine does, I am asking you for similar info)
I suspect you have not tried this.
I am surprised by your response.
You are an experimenter, and you know that the only way to find out is to try it.

thanks,

jeanna

You are correct. I have not tried this because I do not want to sit around for 2 days watching a light.

But since you have. What battery were you using, what was your initial battery drain mA, and how long did the tube stay lit. The battery mAh rating is from 1.5 volts to 0.8 volts. So the JT should run longer than the calculation. Probably about 50% longer since the battery drain current will drop as the battery voltage drops and a JT can run with battery as low as 0.5 volts. Perhaps we can improve the calculation to give more accurate times for the JT.

[resonanceman]

@Gary,
What I meant about getting the fixtures right is finding fixtures that offer the right amount of light diffusion. I have found the perfect kind of glass. It is lighter in whiteness than the one I showed last night. It looks more translucent. I have 2 of these and another that is close. All 3 were made to be candle holders. I turn them over and put the led up into them and they are really great. Maybe I will show you later with a yellow led candle... or I could put it over that array I just showed.

Jeanna

The   right  kind of diffusor is   a good thing but it  is not what I was  trying to ask about

You said you were planning on  swiching  the lights in your house over to LEDs ......  how are  you powering them ?
Are  you planning on  changing  batterys   every few days ?
Or  using  stepped down AC?


I  am  still thinking that   a a coil can be used to step  down  the  voltage  being used .....   I have  decided  it is time to  work on that  today .

gary

[xee2]

Connecting either side of pickup coil to negative side of battery will make it easier to light the tube. This is not needed with 200 ohm base resistor, but I found that when using a 400 ohm base resistor the tube would not light without touching it unless the connection from one side of pickup coil (either side works) is made to the negative side of battery.

[jeanna]

@ jeanna

You are correct. I have not tried this because I do not want to sit around for 2 days watching a light.

But since you have. What battery were you using, what was your initial battery drain mA, and how long did the tube stay lit. The battery mAh rating is from 1.5 volts to 0.8 volts. So the JT should run longer than the calculation. Probably about 50% longer since the battery drain current will drop as the battery voltage drops and a JT can run with battery as low as 0.5 volts. Perhaps we can improve the calculation to give more accurate times for the JT.

I am sure you will not be sitting around for 2 days.

I used a NiMH AA rated at 2500mAH
The fully charged battery was able to light the light for 5 1/4 hours one way but only 4 1/2 hours 2 other ways.
The "dead" voltage as far as the fluoro light was concerned was 1.12v.

I think I am seeing that the joule thief and the joule thief with pickup have different tolerances. The bjt can drain the battery very deeply. the jt with pickup cannot run the show off the pickup when the battery is down "some".

The "some" is something I think we could look at. It may hold more clues than a timeline.

ergo my question to you.

oops and edit add
The mA draw before the fluoro light was on was 75mA. The light extinguished when I had the volts/10ohm resistor at the battery, -- of course, this took away too many volts.

thanks,

jeanna