Solar Joule thief problems - Page 1
Forum section: electronics / projects

author: GadgetBoy
author_rank: Regular Contributor
timestamp: August 15, 2018, 02:07:40 am
content: I'm trying to integrate a solar panel and dusk sensor into a bigclive style Joule thief, but I'm running into some issues. To my knowledge (which is admittedly limited), this *should* work, but it isn't. The parentheses on the schematic are the second set of values I tried.Sent from my ONEPLUS A3000 using TapatalkEdit: I'm not integrating a 'dollar' panel. Stupid autocorrect.

author: oPossum
author_rank: Super Contributor
timestamp: August 15, 2018, 05:54:20 am
content: It requires a fast rise time of the power supply voltage to start oscillating. Your circuit will increase the voltage gradually, so it won't start oscillating.

author: GadgetBoy
author_rank: Regular Contributor
timestamp: August 15, 2018, 06:00:50 am
content: Quote from: oPossum on August 15, 2018, 05:54:20 amWell, the Joule thief part works just fine. When I add in the dusk sensor, it doesn't work.Sent from my ONEPLUS A3000 using Tapatalk

author: oPossum
author_rank: Super Contributor
timestamp: August 15, 2018, 06:08:12 am
content: It doesn't work with the dusk sensor because the voltage rises slowly. When you connect the battery directly the voltage immediately rises to the battery voltage.

author: oPossum
author_rank: Super Contributor
timestamp: August 15, 2018, 06:09:58 am
content: A Schmitt trigger implemented with a PNP & NPN transistor may work. The positive feedback will cause the voltage to rise quickly.

author: GadgetBoy
author_rank: Regular Contributor
timestamp: August 15, 2018, 06:12:11 am
content: Quote from: oPossum on August 15, 2018, 06:09:58 amOhh. I get what you're saying. I'll try this.Sent from my ONEPLUS A3000 using Tapatalk

author: oPossum
author_rank: Super Contributor
timestamp: August 15, 2018, 06:25:58 am
content: This may work. R3 provides positive feedback that should make it turn on quickly.

author: GadgetBoy
author_rank: Regular Contributor
timestamp: August 15, 2018, 06:28:01 am
content: Quote from: oPossum on August 15, 2018, 06:25:58 amOoh, nice schematic. I'll whip it up and let you know.Sent from my ONEPLUS A3000 using Tapatalk

author: GadgetBoy
author_rank: Regular Contributor
timestamp: August 15, 2018, 07:26:54 am
content: Quote from: oPossum on August 15, 2018, 06:25:58 amWell, the Joule thief turns on, but it doesn't shut off when the solar panel is illuminated. My mind is mush, though, I might have buggered something. I'll check it over in the morning.Sent from my ONEPLUS A3000 using Tapatalk

author: Zero999
author_rank: Super Contributor
timestamp: August 15, 2018, 10:14:23 am
content: Quote from: GadgetBoy on August 15, 2018, 07:26:54 amHave you checked the solar panel is actually working?What open circuit voltage does it produce, when fully illuminated?

author: Wolfgang
author_rank: Super Contributor
timestamp: August 15, 2018, 08:27:37 pm
content: Hi,some time ago I made a competion for different Joule thieves. Look here:https://electronicprojectsforfun.wordpress.com/energy-harvesting/Maybe you can use some results.

author: GadgetBoy
author_rank: Regular Contributor
timestamp: August 15, 2018, 11:24:48 pm
content: Ok, after a good night's sleep, I figured out where I was messing up the wiring. It works perfectly, thanks!https://youtu.be/j_PFQ7iaptQ/\| Video of it in action.

author: oPossum
author_rank: Super Contributor
timestamp: August 16, 2018, 01:01:36 am
content: Excellent! Thanks for letting us know it works.You may be able to reduce power consumption a little by increasing the value of R1 and R3. It is important that the R1:R3 ratio be about 1:2 to have the proper turn on / turn off thresholds. So R1=2k2 R3=4k7, R1=4k7 R3=10k, etc...