Search found 6 matches

by gatoruss
Thu Dec 18, 2008 3:54 am
Forum: General Discussion
Topic: Flash Light Project (Feb 08 N&V)
Replies: 29
Views: 7255

Thanks. This is very helpful. BTW, the BOM on page 36 indicates that R1 is 100K ohms. This gives a current of 0.0382 mA. This seems like too much resistor? In the 1N914 data sheet (if I am reading it correctly), at 0.0383 mA the Vf is around 450mV? Wouldn't a 1000 ohm resistor be more appropriate? T...
by gatoruss
Wed Dec 17, 2008 6:36 pm
Forum: General Discussion
Topic: Flash Light Project (Feb 08 N&V)
Replies: 29
Views: 7255

Revisiting the LED Flash Light Circuit

I know that this thread is dated, but I have been revisiting this article. Can someone point me toward - or provide me with :) - an explanation of D1's purpose in this circuit and how it works. I gather that it sets Vr to 0.6V, but I am having trouble understanding how that is accomplished.

Thanks.
by gatoruss
Tue Dec 16, 2008 4:32 am
Forum: General Discussion
Topic: Dec08 N&V Q&A - Blinking Lamp Schematic
Replies: 1
Views: 749

Dec08 N&V Q&A - Blinking Lamp Schematic

I do not have a lot of experience with circuits, so forgive me if this is a stupid question :) I have been reading thru the above material in the Dec08 N&V Q&A Section. The schematic appears to have C1 in parallel with R1 & R2. Is this correct? Not knowing anything about how a 555 timer, I have been...
by gatoruss
Wed Feb 27, 2008 6:01 pm
Forum: General Discussion
Topic: Flash Light Project (Feb 08 N&V)
Replies: 29
Views: 7255

Thanks to everyone. This has been very helpful. I gather from the responses that if less than 9 LEDs are used with the circuit in question (and with no feedback control), a "ballast resistor" would likely be required. What had kind of confused me was the following observation by the author: In other...
by gatoruss
Wed Feb 27, 2008 4:11 am
Forum: General Discussion
Topic: Flash Light Project (Feb 08 N&V)
Replies: 29
Views: 7255

Re: Flash Light Project (Feb 08 N&V)

Greetings (No Name Supplied) Sorry...the name is Russ :) The uC controlled charge pump circuit presented in the article is energy limited, meaning that it can't produce enough energy at its output to harm the long string of LEDs. Normally an LED is protected by a series "ballast" resistor. So now t...
by gatoruss
Tue Feb 26, 2008 8:46 pm
Forum: General Discussion
Topic: Flash Light Project (Feb 08 N&V)
Replies: 29
Views: 7255

Flash Light Project (Feb 08 N&V)

I have been reading the Flash Light Project article in N&V Feb08, and am wondering if someone else who might have read same could field a question? I am a total newbie, so this may be a dumb question, but here goes. The author states that if 5-10 LEDs are used that R2 is not longer needed. I am havi...