Minimal Solar Night Light Circuit

This is a simple Joule Thief like circuit that works as a solar night light.

Category:

Education

Tags:

• Joule Theif
• circuit
• jeri ellsworth
• electronics
• solar
• tutorial
• instructional video
• experimental
• tips & tricks
• diy
• arts
• educational

[vk2zay]

You can burn a bit less current keeping the switcher off by reducing it's base bias needs, it need only be biased enough to start up if the oscillator bootstraps itself. Maybe bypass part of the bias resistor with capacitance?

[jeriellsworth]

@vk2zay Interesting idea. Wonder if it would start.

[MrPieChee]

aren't joule thief's incredible inefficient?

[jeriellsworth]

@MrPieChee Yes. That is what I'm saying in the video.

[mikeselectricstuff]

Jeri - what's with the 21K ? Let me guess - you have an E96 resistor kit & already used up all the normal values...?

I think Linear tech have a similar problem - all their appnotes use wacky resistor values.

[jeriellsworth]

@mikeselectricstuff Hehe.  I do have big kits of 1% resistor I feed from.

[Claude77]

@Orthosonic

Hi yes that would work, I think this is the solution PNP as a switch to the center tap, with the base of the transistor on the anode of the schottky, through a resistor of course.. Try it out Jeri :) And Thanks for all the cool videos..

[frac]

I always hit "Like" before the video even starts, and you haven't made a liar out of me yet. Another gem.

[acmefixer1]

Yes, shunting the base bias to negative is not the most efficient way to turn off the JT. I do it several ways in my recent blog. You may have never thought that a red LED could turn off the JT. It's at rustybolt dot info and click on the link to my blog.

[acmefixer1]

@MrPieChee

About 40 to 70 percent, from what I've measured; typically 50 percent.

[jayson01982]

what size is the wire on that joule?

[AKSoapy29]

Can't you add one of those coil things to the solar cell to boost the charging power to?

[PoirierMike]

Very well detailed, Intelligent, Well explained. I like it.

[Pirate88179]

@jeriellsworth

Nice project. Actually a correctly built JT circuit is very efficient. Some of mine run for months 24/7 on an AA. Dr. Jones has measured possibly COP 8 with his circuit on oudotcom. Others in our group have circuits that will run for a year. Very efficient and flexible little circuit. You can really get the amp draw very low with a little effort. Very nice video.

Bill

[ltkipras]

can you charge your phone with this?



[MrThomassss]

Use a darington transistor to reduce the waste of the current.

[SniperPIKACHU]

@vk2zay Thanks for the tips. I have a similiar circuit in one of my projects and what I did to kick start the oscillator is to use an CR integrator to trigger a pulse on the gate of an SCR. The SCR keeps the load to turn on as long as the PV cell is blocked. Once the load current drops below the holding current of the SCR (light is on) the entire circuit shuts off and no leakage is measured. Im not sure will it help, Jeriellsowrth. Anyway, I will also try to play with vk2zay's idea. Thanks!