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- qs commented on qs's instructable The "Reverse Joule Thief" Battery Charger
- qs commented on qs's instructable A Solar Powered Reading LightView Instructable »
The most direct way is to start by calculating the power (V * I) of the LEDs, then match that to the capacity of the batteries and, finally to the solar batteries.For example, if you're using a white 1A LED, then its power requirement is 3.3W. - To run it for 3 hours, you'll need 10WHr. - So the batteries will need to be at least that capacity, while the capacity of solar cells will be 3/4 of that.Obviously, you will need to double if not triple the capacity of the batteries and solar power for rainy days.
- qs commented on qs's instructable Using AC With LEDs (Part 1)View Instructable »
Unless it's a misprint or a 240v transformer working on 110v, I can't explain it.If you are sure your readings are right, you can short out the 100-ohm (or so) resister over every third LED on the strip, it will now run at 10.5v, closer to the output of the xformer, and give you 85+% of full brightness
- qs commented on qs's instructable A High-power LED Torch Using a Single AA-batteryView Instructable »
Most general purpose transistors (BC3x7, 2N2222 etc) are available through sales channels as well as eBay. Then you would be sure of getting the correct performing components.Yes, larger inductors do build up a greater charge, but it also takes time to do so. Lessening the inductor may yield a lower charge, but it does it at a higher frequency, so the resulting light may be greater.
- qs commented on qs's instructable A High-power LED Torch Using a Single AA-batteryView Instructable »
NTE components tend to be much lower performers than their "equivalents". For example, if you're using the NTE-298, it only has less than half the gain of the "real" thing! To offset that you can try (1) reducing the 100k to 75k of 82k, or (2) reducing the coil to 28 or 30 turns. Change ONE element and test.
- qs commented on qs's instructable Adding 'Oomph' to the Garden Solar LightView Instructable »
Hi OldGuy, Very briefly, the circuit starts when the PNP begins conducting, which turns on the NPN, and this starts charging the coil. At the same time, current is drawn through the 150pF capacitor, which further increases the drive to the PNP and, subsequently, the NPN. When the capacitor is charged, the drive is cut off, and the magnetic field built up in the coil collapses and cause a voltage to appear across the ends. This voltage is placed in series with the NiCd battery to turn on the LED. Simultaneously, a small portion of this voltage is diverted through the diode (D2) to charge the 1uF cap. This provides about 3.5v to drive the PNP, which improves the brightness and efficiency. The cycle then restarts. As far as your circuit, double check the specs for the transistor you're usi…
see more » - qs commented on qs's instructable A High-power LED Torch Using a Single AA-batteryView Instructable »
No -- the resister is there to help the transistors work, and doesn't have a direct function in the LED's brightness. TO use a 1W LED, the transistors will also need to be changed to handle the current to 'charge' the coil.Also, most AA batteries will not support the 1000 mA draw to power the light.
- qs commented on qs's instructable Adding 'Oomph' to the Garden Solar LightView Instructable »
Any diode that can handle 150mA or more is suitable here. I've used the 1N4148 and they're still running after 5 years. If you can afford Schottky diodes they are even more efficient.
- qs commented on qs's instructable Build a low cost, scrolling LED display for your Arduino microprocessor.View Instructable »
Here is the image of the LED board shown in Step 5 with a bit more description. The resistors are hidden by Layer 2 but the green lines show where they connect.
- qs commented on qs's instructable Using AC with LEDs (Part 2) - and make this handy counter light.View Instructable »
Good point - if the wiring is exposed, a 4.7k 1/2w resistor across the capacitor will reduce chances of electrical shock, but since the circuit was intended to be hidden away in an enclosure, I did not include that.
- qs commented on qs's instructable Adding 'Oomph' to the Garden Solar LightView Instructable »
Hello there!It's always questionable whether a battery is being charged on overcast days. In the northern latitudes, even on sunny days, it is necessary to point the solar cell in a southerly direction, angled approximately 35-degrees to get the maximum exposure to sunlight. A good rule of thumb is that typical solar cell will produce about 50mA to charge the NiCad under full sunlight. So that translates to about the same operating time, since the JT here uses about 50mA while operating. So basically, you'll need 10 hours of sunlight to run the light through the night. Less sunlight? Less time.That's the reason I developed alternate circuits, notably the 'reverse' Joule Thief and the Blinking Joule Thief. Both are attempts to wring a bit more operating time out of whatever sunlight we see…
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LED1 and LED2 acts like a 3.6v zener, so you can replace the 2 with a Zener (anode pointing DOWN) to limit the charging voltage.
The circuit shown in part 1 is there to charge the battery, so that alone would be good enough for your use. Replace LED1 and LED2 with a 3.6v Zener (anode pointing DOWN) to limit the charging voltage to the proper one.