abbey road d enfer

Solar lights
« on: August 29, 2010, 01:47:49 PM »
Hi all,
I know it has nothing to do with audio, but it's electronics.
I have a solar yard lights acquisition syndrome.
Some of them are nearly 10 years old and still work, some are duff right out of the box (in typical chinese manner).
I have opened one and drawn a schematic
For the life of me, i can't figure out how it works!
I've checked the voltages: with the battery at a steady 1.32V, the Led anode is at 1.23V when lit, 1.32V when off.
I just don't get it. How can the LED be lit with 1.23V and off with 1.32?
I have drawn the schematic of an older discrete version - non-working so I couldn't take measurements, but I suspect it's the same basic circuit in the chip.
This second circuit, I could understand that the shunt transistor would turn of the LED by deriving current to ground, but that seems to me a waste of energy.
I've tried to google the subject, to no avail.
Anyone has an idea on this?

Thanks all.

ARdE
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.


Gus

Re: Solar lights
« Reply #1 on: August 29, 2010, 02:26:09 PM »
No inductors?

abbey road d enfer

Re: Solar lights
« Reply #2 on: August 29, 2010, 02:29:00 PM »
No!
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.


abbey road d enfer

Re: Solar lights
« Reply #4 on: August 29, 2010, 04:49:00 PM »
Thanks a lot. The first link is exactlu what I have.
When I said there were no inductors, I was completely wrong. They look like 1/2W resistors.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

johnR

Re: Solar lights
« Reply #5 on: August 29, 2010, 05:28:10 PM »
1.23V isn't enough to light a white LED. The supply must be pulsed at a higher voltage, and your meter is only reading the average. What's it look like on a scope?


abbey road d enfer

Re: Solar lights
« Reply #7 on: August 30, 2010, 12:53:29 PM »
Thanks to all who answered.
Now that I understand how it works, I tiink I'll be able to fix the ones that don't work.
Apparently the cause is one of the caps is missing!
That gives an idea of the alien conception of QC the Chinese have.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

detonator

Re: Solar lights
« Reply #8 on: August 30, 2010, 02:13:18 PM »
http://talkingelectronics.com/projects/SolarLight/SolarLight.html
The first circuit is the same as I have in my backyard.. Try to post a picture of it later.

 

Related Topics

  Subject / Started by Replies Last post
7 Replies
1742 Views
Last post May 06, 2008, 12:15:36 PM
by
3 Replies
1351 Views
Last post June 21, 2008, 10:21:43 PM
by Svart
17 Replies
2322 Views
Last post August 10, 2008, 02:35:30 PM
by hodad
2 Replies
286 Views
Last post January 10, 2019, 02:51:33 PM
by JohnRoberts