A few months ago I came across a 7 Year Joule Thief video from Xee2vids on YouTube (link below). It’s a conventional Joule Thief except that the resistor has been increased to 2 megohms, and a 100 pF capacitor has been added from the resistor to ground. He calculates that the LED should run for
(Read More…)
I took apart a “Type R” LED light, which is a substitute for a wedge base auto light used in instrument panels and dome lights. This light has an 8 mm diameter LED and a 560 ohm, 1/8 watt resistor in the wedge base. Assuming that the LED drops 3.2 volts and the auto’s battery
(Read More…)
The coin cells are insanely priced. I get five of them on a card from the dollar store for a dollar or $1.50, I forget which. Then I walk into Radio Shaft and I see them for something like $4 apiece! I hardly ever go into Radio Shack any more. About the only thing I
(Read More…)
My recent two blogs on powering a flasher with four red LEDs used a flasher made by modifying a Joule Thief. It works fine, but it requires a toroid core and wire; the flasher I blogged earlier does not require any inductor. It is a switched capacitor or charge pump,. and it works okay with
(Read More…)
A lady at work brought in a solar garden light for me to look at. The problem was that it wasn’t working. It consisted of a string of LEDs, all colored orange, just like a Xmas tree light string. On the end was a small box that fit in the palm of my hand. The
(Read More…)
One Joule Thief I have not built (at least not in the same JT) is the low power JT with the CdS photocell. Almost all of my JTs with daylight shutoff used a LED as a light sensing diode, and then most were flashers. I have a bunch of CdS photocells but I haven’t really
(Read More…)
I was reading some of the thread over at OU about transistor behavior. The discussion was about the BC337-25 and the 13003, which is often found in CFL bulbs. One poster said the 13003 was rated at 1 amp, and the BC337-25 was rated at 0.8 amps. But in the Joule Thief the BC337-25 drew
(Read More…)
I found these Fair-Rite toroid cores on eBay for $3.49 (U.S.) and $2.07 shipping. The quantity is eight, so it works out to about 70 cents apiece. This is nowhere as cheap as Mouser, but for a small quantity it seems like a fair price. These should make adequate Joule Thief cores with about 12
(Read More…)
Paul discussed buying LEDs and I decided to write about some of my experiences with buying LEDs in this blog. I bought some LED assortments from an eBay seller, I think he’s from Canada. He’s still selling stuff. Most of the LEDs had bubbles in them. I dealt with him through email, and I said
(Read More…)
A common circuit such as a night light may use a CdS photocell to turn it off during daylight hours and on during night time. The photocell is connected to a circuit that senses the voltage and turns the rest of the circuit on and off at a threshold point. The photocell is in series
(Read More…)
