Will this new circuit work for a solar light?

Thread Starter

dameo182

Joined Nov 12, 2022
35
The circuit in post #16 will handle the 170 ma.

Is your charger/protection board the same as that shown in post #14? I can add that to the circuit if you like.

Your comment about how complex the circuit looks reminds me of when a senior engineer gave the schematic of a groundplane video board he wanted wired up. I looked at it and complained "Why does it have so many parts?!" His answer "Because it takes that many parts to make it work!" We were friends for years after that.
Yes it's the same, it's that board that I was trying to add into Clive's original circuit to protect the battery, before I knew it wasn't substantial enough for what I wanted to do. What worries me about the circuit you gave me, is that I have no idea how it works, or how to change it for different loads, sometimes I might want to increase or decrease the amount of light sources for different outdoor projects. So that coupled with the many parts makes me feel like I did when I first started designing speakers and crossovers. Now I'm capable of making really good speakers with crossovers measured and designed by myself, it took me years to learn though, when it comes to diodes and transistors it's all new to me.

These are the parts I have,
 

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Ya’akov

Joined Jan 27, 2019
9,070
Yes it's the same, it's that board that I was trying to add into Clive's original circuit to protect the battery, before I knew it wasn't substantial enough for what I wanted to do. What worries me about the circuit you gave me, is that I have no idea how it works, or how to change it for different loads, sometimes I might want to increase or decrease the amount of light sources for different outdoor projects. So that coupled with the many parts makes me feel like I did when I first started designing speakers and crossovers. Now I'm capable of making really good speakers with crossovers measured and designed by myself, it took me years to learn though, when it comes to diodes and transistors it's all new to me.

These are the parts I have,
Just a thought, for only a couple of bucks you can become a Patreon patron for Big Clive. There are discussion threads there, which he participates in—you could literally ask him about this. He is very accessible and answers DMs as well.

He’s a really nice guy, why not go to the source?
 

DickCappels

Joined Aug 21, 2008
10,152
NIGHTLIGHT CORRECTED 1N5819.jpg

I don't have the eye for detail that I used to have. Sitting down to explain this circuit I noticed that the 4.7k resistor was connected to the anode of the diode rather than the cathode. NOW it should work.

You can change the current by changing the resistor in series with the LED. The rest of the stuff is a switch that grounds the led-resistor combination when the voltage from the panel gets low enough.

It is all pretty simple: The left-most transistor holds the base of the middle transistor to near ground until voltage out of the panel drops. This threshold can be adjusted by changing the value of the 1k resistor.

When the left-most transistor turns off (from lack of base current from the panel) the base of the middle transistor is pulled toward your battery voltage this middle transistor and the transistor following make a high current gain switch, which when the base of the middle transistor is pulled high grounds the collector of the right-most transistor.

This should be good for over 200 milliamps without the right-most transistor getting too hot. If you need more than 200 milliamps you should probably move up to a higher powered transistor.

Warning: I have not built this (or I would have caught the misconnected 4.7k resistor) and you might want to adjust the value of that 1k resistor to get the light to turn on at your desired darkness.
 

Thread Starter

dameo182

Joined Nov 12, 2022
35
Just a thought, for only a couple of bucks you can become a Patreon patron for Big Clive. There are discussion threads there, which he participates in—you could literally ask him about this. He is very accessible and answers DMs as well.

He’s a really nice guy, why not go to the source?
Yeah that is a good idea, thank you
 

Thread Starter

dameo182

Joined Nov 12, 2022
35
@DickCappels

I would have to read that a few times lol thank you for the explanation though, I was told on a previous thread that the LED strip I'm using has the current limiting resistors built into it so I didn't need a resistor before the strip, is that not the case in your circuit?

I was under the impression an LED strip only draws what it needs from the source as long as it's not massively overpowering them, can't remember who told me that though, and it could be that I misunderstood
 

DickCappels

Joined Aug 21, 2008
10,152
The resistors I drew in series with the LEDs are representative of the resistors already in your LED strip.

I was under the impression an LED strip only draws what it needs from the source as long as it's not massively overpowering them, can't remember who told me that though, and it could be that I misunderstood
Electronics are like that. For the most part circuit are designed to work well when supplied by a power supply of the appropriate voltage. Your LED strips should work well when you apply the appropriate voltage. Too little voltage and they get dim. Too much voltage they get really bright...and maybe not for very long.
 

Thread Starter

dameo182

Joined Nov 12, 2022
35
This still seems too complicated for me to really understand, I'm looking at the circuit you drew and I can't seem to figure it out as it's drawn differently to crossover circuits that I'm used too, I'm not actually sure which resistors you are referring too in the diagram, I'm struggling to know which is in series and which is in parallel, I have everything but the transistors and the diodes, so to have a go at putting it together I will have to order those components. Would you use the boost converter board and the charge board in that circuit too?
 

DickCappels

Joined Aug 21, 2008
10,152
The resistors in series with the Eds are representative of the resistors already in you LED strip.

As for the series/parallel issue, you can probably figure it out by reading the internet.

Parallel components have their electrodes connected in parallel. Series connected components usually have the power supply voltage divided by them - 10 volts with two 1k resistors in series would have 5 volts across each resistor. It will take some time for this to become intuitive.
 

Thread Starter

dameo182

Joined Nov 12, 2022
35
Homestly though
The resistors in series with the Eds are representative of the resistors already in you LED strip.

As for the series/parallel issue, you can probably figure it out by reading the internet.

Parallel components have their electrodes connected in parallel. Series connected components usually have the power supply voltage divided by them - 10 volts with two 1k resistors in series would have 5 volts across each resistor. It will take some time for this to become intuitive.
Yeah thank you, I just have trouble with the way the circuit is drawn, I understand parralel vs series when it comes to speaker crossovers, and how the impedance/frequency response are all changed by the componants put into the crossover circuit, but for some reason I can't relate that to these circuits, probably becuase I have no understanding of how each component works. I'm useless at electronics and it really does annoy me that I find it so hard to understand, if you could show me a circuit with the charge board and boost converter added I'll order the parts and see if I can have a go at building it successfully, if you don't mind that is. But your help is appreciated.

I wonder if you could point me to a good book to learn the basics? It's how I learned speaker design so it might be something I should try doing in this circumstance
 

DickCappels

Joined Aug 21, 2008
10,152
Here is what I think you described. Make sure your solar panel does not deliver more than 7.5 volts (the charger chip is specified for 8.0 volts absolute maximum).
1669811170167.png
This time the LED string is drawn as a single LED and resistor representing the parts in the string.

When you order your 5 Volt boost converter be sure to check and see if it is one that support your 170 ma load.
 

Thread Starter

dameo182

Joined Nov 12, 2022
35
@DickCappels

Thank you for taking the time, I will do my best to put that together, it may take a while though as I have to order parts and fit it in to a busy work day and a two year old son lol but again thank you
 

Ya’akov

Joined Jan 27, 2019
9,070
Not to throw a wrench in here…

Since you are using a solar cell you should be sure your charger is an MPPT (Maximum Power Point Tracking) type. Solar cells can produce more net power with the right load on them, and an MPPT charger adapts to that.

One like this would be perfect except that max VIN on that one is only 6V.
 

Thread Starter

dameo182

Joined Nov 12, 2022
35
Not to throw a wrench in here…

Since you are using a solar cell you should be sure your charger is an MPPT (Maximum Power Point Tracking) type. Solar cells can produce more net power with the right load on them, and an MPPT charger adapts to that.

One like this would be perfect except that max VIN on that one is only 6V.
I have no idea what my charger is, but it probably is the wrong type, since it's the first I've heard about needing an MPPT, I just assumed it would be fine since it worked with the setup I had it in originally, but that was charging from a USB C lead, which I'm guessing doesn't fluctuate in the power it provides. But thanks for the input, I'll look at ordering one of those too
 
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