Electric noob question(s)

[Cherryman]

Hi all,

Being a noob in electronics, i'm trying to make a start.

I have a hard time understanding a lot around here, so time for improvement.
The language barrier, especially of technical terms, and my complete lack of electronic education make it a real challenge.

When I think of electronics and get suck, i usually replace the current for "air" and compare it to some sort of pneumatics.

They say there are no stupid questions, only stupid answers.. So lets give it a try:

I "built" or better , reconnected, my donor (a solar one led garden garbage toy)this little with an extra battery, and started to do some basic testing.

I think the circuit in there is already some kind of joule thief. Although It does not have a toroid. The Fan is an old PSU fan, rated at 12V 0,26A The four tiny blue LED's in the corners are hardwired with the fan. It spins nicely around (not full speed)

Now my first question is:

Do I understand it correctly that this thing: the fan and 4 tiny led's run on only 0,007A x 3,92V = 0,02744W

Does this run on 0,02744 watt ? That seems a little low.. do I measure incorrect?




Second:

Unconnected i get around 9V connected it drops to 3.9V is that normal? Can I see Voltage as "Pressure" what will get less when it is set free?

Cheers.

[LetsReplicate]

Hi all,

Being a noob in electronics, i'm trying to make a start.

I have a hard time understanding a lot around here, so time for improvement.
The language barrier, especially of technical terms, and my complete lack of electronic education make it a real challenge.

When I think of electronics and get suck, i usually replace the current for "air" and compare it to some sort of pneumatics.

They say there are no stupid questions, only stupid answers.. So lets give it a try:

I "built" or better , reconnected, my donor (a solar one led garden garbage toy)this little with an extra battery, and started to do some basic testing.

I think the circuit in there is already some kind of joule thief. Although It does not have a toroid. The Fan is an old PSU fan, rated at 12V 0,26A The four tiny blue LED's in the corners are hardwired with the fan. It spins nicely around (not full speed)

Now my first question is:

Do I understand it correctly that this thing: the fan and 4 tiny led's run on only 0,007A x 3,92V = 0,02744W

Does this run on 0,02744 watt ? That seems a little low.. do I measure incorrect?

Second:

Unconnected i get around 9V connected it drops to 3.9V is that normal? Can I see Voltage as "Pressure" what will get less when it is set free

Cheers.

I don't understand how you've connected the circuit together from your pictures, and I don't know where you have the meter connected in this circuit, but I can explain the meter readings.

In the first picture, you have 7 micro amps (0.000007 amps). 7uA * 3.92V = 27.44 micro watts (0.00002744 watts).

When it comes to measuring: current needs to be measured in series with the circuit (the meter has 1000 ohms resistance or less in this mode depending on setting), voltage needs to measured in parallel (the meter has about 10 000 000 ohms resistance in this mode). In this circuit you will probably have to change the position of the meter in the circuit to measure each because it has a load.

It is normal for the voltage to drop significantly when there is current being drawn. The static voltage converts into current when there is a path for it to travel.

[Cherryman]

I don't understand how you've connected the circuit together from your pictures, and I don't know where you have the meter connected in this circuit, but I can explain the meter readings.

In the first picture, you have 7 micro amps (0.000007 amps). 7uA * 3.92V = 27.44 micro watts (0.00002744 watts).

Wow that is even less (and impossible I think ;- )

I measured the Voltage by placing the two probes from the MM at the connector from the fan. (In simple: The circuit running, and touching the wires leading to the fan with the MM probes)

When it comes to measuring: current needs to be measured in series with the circuit (the meter has 1000 ohms resistance or less in this mode depending on setting), voltage needs to measured in parallel (the meter has about 10 000 000 ohms resistance in this mode). In this circuit you will probably have to change the position of the meter in the circuit to measure each because it has a load.

I measured the Amps by removing the positive from the fan connector and putting the MM in between, so it runs trough the MM and then into the fan connector.
I hope I make sense.

Should I measure the Amps straight from the battery, does that make a difference?

It is normal for the voltage to drop significantly when there is current being drawn. The static voltage converts into current when there is a path for it to travel.

Tnx!

[Cherryman]

Remeasured After two+ hours running : (Used the same way of measuring )

6uA Measured at the fan connector positive lead by placing MM in series.
3,75V measured at fan connector while running
2,44V measured at batteries while running

Batteries are non rechargeable AA penlights, laying around, probably already used sometime.

Not clue what to make of it.
Is this extremely low? Or just normal?

Seeing the Voltage drops from 3.92 to 3.75 looks like a lot of loss, so could the Amp readings be wrong, or is this normal?.

[LetsReplicate]

Remeasured After two+ hours running : (Used the same way of measuring )

0.000006 A
3,75V

Batteries a non rechargeable AA penlights, laying around, probably already used sometime.

Not clue what to make of it.
Is this extremely low? Or just normal?

Oh, ok, I get it now. Yes, you measured correctly. The reason why current appears so low is because it's being compressed into pulses. These pulses have a low duty cycle, and your meter is averaging out the pulse's maximum.

If it were really running on so little current, the batteries shouldn't be draining that quickly.

Can you give a close up picture of the "solar card on led circuit"? I should be able to give you a good idea of how it works if I can see it up close. (you might need to take a picture of each side of the board)

[Cherryman]

Tnx for helping me on the road.

Here is the picture, unfortunately the Macro function of my Sony phone worked better in the advertisement.

I think I get were you going; because the circuit pulses very rapidly, the MM does not take an accurate reading.

Edit: I did a Amp measure at the positive of the battery: 012uA

So thats double, still not much. I guess here also influence from the frequency?

[LetsReplicate]

Tnx for helping me on the road.

Here is the picture, unfortunately the Macro function of my Sony phone worked better in the advertisement.

I think I get were you going; because the circuit pulses very rapidly, the MM does not take an accurate reading.

Edit: I did a Amp measure at the positive of the battery: 012uA

So thats double, still not much. I guess here also influence from the frequency?

No problem.

Hi,
JD1803 is functionally equivalent to QX5252. Go to www.qxmd.com/index.aspx, enter QX5252 into query box on top-right of screen under English and a new page will list all data PDFs. Only in Chinese so far as I can tell but still readable.
Regards,
Qdoc

JD1803 product description
QX5252 datasheet. -> Translated by By Google (the pictures of the internal workings are sill not translated, which is the main information I'd need )

I drew up the circuit from the IC, as best as I can see it. The connection wires are all on the left side with the LED output on the right:

[Cherryman]

Edit: Double post

[Cherryman]

I think I understand the circuit, TNX

I'm reading about the JD1803 now.


I did a little research of my own and have a few more questions:

There is this little photo diode, that works on lumen.. It functions to turn the led on when there is not enough light on the solar panel.

Key Features

0.5 lux to 10,000 lux range
1.8V to 3.3V supply range
Low supply current
Fast response time
Excellent linearity of output voltage vs light intensity
Close to human eye response
Good IR rejection
Internal temperature compensation
Operating temperature range -40°C to +85°C
Ultra-compact surface mount package
Pb-free (RoHS compliant)

Description

The ISL29101 is a low power ambient Light-to-Voltage optical sensor combining a photodiode array, a current amplifier and a micropower operational amplifier on a single monolithic IC. Similar to the human eye, the photodiode array has a peak response at 550nm and spans from 400nm to 600nm, rejecting UV light and IR light. The output voltage is proportional to the visible light intensity from 0.5 lux up to 10,000 lux. However, the input luminance range can go up to 30,000 lux with some compromise in linearity.

A dark current compensation circuit aids the photodiode array to minimize temperature dependent leakage currents in the absence of light, improving the light sensity at low lux levels.

Housed in an ultra-compact surface mount 2mmx2.1mm ODFN clear plastic package, this device is excellent for power saving control functions in cell phones, PDAs, and other handheld applications.

1. How can this works on lumen as it is normally in an enclosed casing? Does it "read" the voltage from the solar panel? How come they talk about lumen ? How does this thing "see" light?

2. If I remove that that, and replace it with a switch, will that function as the power switch on demand for the output?



3. Can i put a pot-meter somewhere to control the frequency (not voltage) of the output ?

(Remember, there are no stupid questions ;-)

[LetsReplicate]

1. A photo diode is pretty much the same as an LED, the casing lets light pass through it. If you take 2 of the same kind of LED, light one up and shine it into the other, voltage will be produced across the unlit one (not much current though). A photo diode is designed to only receive an not produce light.

A lumen is a unit of light like "candle power", it is the proper units to describe the brightness of a light source. LEDs take electrical energy in and emit lumens of light, and photo diodes convert lumens of light into electrical energy.

2. Possibly, depending on how it's connected you'll either be able to replace it with a switch, or a switch connected to a "pull up"/"pull down" resistor.

3. Probably not. I think the frequency is being controlled by the solar panel.

[Cherryman]

1. A photo diode is pretty much the same as an LED, the casing lets light pass through it. If you take 2 of the same kind of LED, light one up and shine it into the other, voltage will be produced across the unlit one (not much current though). A photo diode is designed to only receive an not produce light.

A lumen is a unit of light like "candle power", it is the proper units to describe the brightness of a light source. LEDs take electrical energy in and emit lumens of light, and photo diodes convert lumens of light into electrical energy.

2. Possibly, depending on how it's connected you'll either be able to replace it with a switch, or a switch connected to a "pull up"/"pull down" resistor.

3. Probably not. I think the frequency is being controlled by the solar panel.

1. I understand the (photo)diode, but this was INSIDE the black watertight casing of the whole garden unit, and still detects light (sunlight, but also inside the house a lamp) As soon as the solar panel does not receive light, the led goes on. But the light sensitive diode is INSIDE ?? To me it looks more like a simple device just takes the input voltage and convert it to output according to the value of input of Voltage instead of lumen (does that makes sense?)

2. Tnx, will try that.

3. Hmm okay, more research i do for that.


Tnx, this simple session tonight made much basics clear for me!
Now I start experimenting ;-)

Note: This is fun! Even more as i bought those solar garden gadgets for 1 Euro: I bought 10 units to start my electronics course ;-)

So now I have 10 of each:

- A small solar panel
- Two RVS tubes
- A rechargeable penlight AA (Not used in this experiment! The ones with comes with the unit a very light-weighted and soon depleted when used in the unit)
- A RGB led
- a photosensitive diode
- JD1803 aka QX5252
- A battery holder
- A power-switch
- A capacitor
- Waterproof casing

Edit update: 6 hours , fan still running, leds still burning, voltage at fan connector 3.6V

[Cherryman]

Eleven hours

Fan still running nicely, leds still on
3.26V At fan connector

Let's see if it still spins around when i wake up.

[LetsReplicate]

If it was not being exposed to any light at all, then it was not a photo diode. Which wires was it connected to on the board? Do you mean the 1N5804 that is on the board? That is just a high speed silicon diode.

[Slider2732]

Been doing a lot with these circuits myself. I must say, as a stock unit you're getting even better results than the USA K-Mart ones i've been dinking around with.
The inductor on your board (resistor looking jobby) is a 470uH. It's your coil, the toroid replacement in some ways that you expected to see on this Joule Thief type circuit. Now, in time and you may wish to do this, you can change that out for others. Or, as i have done, change it for an old AM radio loopstick. The current draw goes even lower ! Loopsticks normally have a ferrite piece in the middle and that is often rated at around 680uH...in other words, more induction.
I found that if you put a 1K variable pot and a small capacitor over the contacts to that (parallel) and fit those in series with the inductor, then you can change the current draw/alter the output strength.
Finally, if you connect a 1.5V rechargeable battery after the Positive output to the LED's in series with the LED's, then you can recharge it while running the circuit, for seemingly no penalty

I have a test going on at the moment that's been running for nearly a week.
It's got a 1.2V Ni-MH on the input, 1 on the output. I can explain the double loopstick energy scavenging if you like, but basically it's a route forward with this sort of thing for efficiency.
The red ultrabright LED I have on the output is always on and yet only now is it starting to use anything. For the first couple of days I was seeing voltage increases of a couple of mV. Up to now, it has used 34mV over 6 days, to run the circuit and light the LED.
Good fun these solar light circuits

[Cherryman]

@ Letsreplicate

This is all i can read, mabe there are letter on the bottom-side.
It is small cylinder shaped thing, with two pins. the positive pin arrives from the second coming from the transistor and according to the qx5252, the BAT connector. The other (the negative) is going to the capacitor and led out.
But is ok, i will test it and we know.

I woke up this morning, leds still on and it is still spinning.

14 hours running

Voltage has dropped to 3.2V at the fan connector.