Search found 22 matches

by N9AOK
Mon Aug 25, 2003 10:37 am
Forum: General Discussion
Topic: Reverse Polarity on 555 timer???
Replies: 16
Views: 6113

Re: Reverse Polarity on 555 timer???

Here's my circuit. I was going to resize everything (bigger cap, smaller divider) so I could use a cheaper pot that the 2 meg one I would need with this.<p>http://www.homefires.us/bluemarble/PAGE ... STROBE.jpg<p>UV LED strobe<p>Other comments welcomed.<p>Todd Snyder
N9AOK
by N9AOK
Mon Aug 25, 2003 10:28 am
Forum: General Discussion
Topic: Reverse Polarity on 555 timer???
Replies: 16
Views: 6113

Re: Reverse Polarity on 555 timer???

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by Chris Foley: The brief answer to your question is, try the 1N5817 schottky rectifier diode if you're worried about voltage drop. <p>I'll check that diode out. Your basic problem, though, has to do ...
by N9AOK
Sun Aug 24, 2003 6:05 pm
Forum: General Discussion
Topic: Reverse Polarity on 555 timer???
Replies: 16
Views: 6113

Re: Reverse Polarity on 555 timer???

Chris, Actually, I've decided to use a lm317 now to keep a steady voltage for my circuit. I'll be pulling pulses of up to 500ma at times.<p>So, now I guess the question is will the 317 handle reverse 10V for short times and if not then can the schottky diode you describe handle those kind of current...
by N9AOK
Fri Aug 22, 2003 4:12 pm
Forum: General Discussion
Topic: Reverse Polarity on 555 timer???
Replies: 16
Views: 6113

Re: Reverse Polarity on 555 timer???

I just hate to loose that 0.7volts since this is running off a 9V battery and as it drops voltage through out its life it will just end circuit functionality that much sooner.<p>My worries are only about inadvertant touching of the 9v battery backwards on there.<p>Thanks for you help....I think I ma...
by N9AOK
Fri Aug 22, 2003 8:17 am
Forum: General Discussion
Topic: Reverse Polarity on 555 timer???
Replies: 16
Views: 6113

Reverse Polarity on 555 timer???

Can a 555 timer take 10V reverse on its power/Grnd pins?<p>I'm building something and need to know if I have to include a protection diode?<p>I cant tell from the data sheet but it looks like it will be OK as long as the transistors inside can take it.<p>thanks for any help
Todd Snyder
by N9AOK
Mon Aug 18, 2003 9:47 am
Forum: General Discussion
Topic: Getting more current from power supply
Replies: 24
Views: 5366

Re: Getting more current from power supply

Grant, did you use the circuit on page 15 of the PDF?<p>Todd
by N9AOK
Mon Aug 18, 2003 9:42 am
Forum: General Discussion
Topic: Getting more current from power supply
Replies: 24
Views: 5366

Re: Getting more current from power supply

Grant, I tried the same thing with a 4amp rated transformer and could only get about 1.5amps out before its voltage dropped too low. <p>I assume you tapped your feedback from the base of your drive transistor? I made the mistake of trying to feedback from the output of the drive tansistor...the 317 ...