Search found 17 matches

by Carl Pugh
Thu Mar 23, 2006 6:45 pm
Forum: General Discussion
Topic: Using 240 volt transformer at 120 volts
Replies: 10
Views: 1973

Re: Using 240 volt transformer at 120 volts

Current rating will be the same as at 240 volt.
Voltage rating will be 1/2.
Power rating will be 1/2.
% sag will be twice what it was at 240 volt.
Sag probably will probably not be a problemill.
by Carl Pugh
Sat Dec 24, 2005 10:14 am
Forum: General Discussion
Topic: the best procedure to check ultra fast diode
Replies: 5
Views: 931

Re: the best procedure to check ultra fast diode

Robert A. Pease in his book Troubleshooting Analog Circuits, page 68 describes a low cost circuit for testing fast recovery rectifiers. This circuit requires a high speed oscilloscope and a few discreet components. Troubleshooting Analog Circuits is a good book and reasonably priced. I strongly reco...
by Carl Pugh
Mon Dec 05, 2005 10:21 am
Forum: General Discussion
Topic: "Perfect" LED current limiting challenge
Replies: 255
Views: 48552

Re: "Perfect" LED current limiting challenge

If you are trying to design a circuit with the highest efficiency then a resistor (or transistor biased as a resistor) cannot be used. An inductor is probably the best approach with a transistor duty cycle modulated to limit the current. You could search the web for boost or buck convertors. The cir...
by Carl Pugh
Fri Oct 07, 2005 9:23 am
Forum: General Discussion
Topic: Analog Electronics books?
Replies: 7
Views: 1608

Re: Analog Electronics books?

IC Op-Amp Cookbook by Walter G. Jung is the book you should get.
by Carl Pugh
Thu Jul 14, 2005 6:36 pm
Forum: General Discussion
Topic: Series Zeners
Replies: 8
Views: 1266

Re: Series Zeners

The best zeners are usually around 6 or 6.2 VDC. Comparing 1N5233 (6.0 V) and 1N5242 (12 V)<p>1N5233 Zzt=7.0 ohm/20mA, Zzt=1600 ohm/0.25mA, Temp Coef=+0.038<p>1N5242 Zzt=30 ohm/20mA, Zzt=600 ohm/0.25mA, Temp Coef=+0.077<p>So depending on the current operated at, two 6.0 volt zeners in series may be ...
by Carl Pugh
Fri Jan 21, 2005 7:49 am
Forum: General Discussion
Topic: relay oscillator
Replies: 21
Views: 3651

Re: relay oscillator

Chic, in my opinion, your question is totally acceptable.<p>If you have a function generator, you could set it to 1 hertz and drive relay with it.
by Carl Pugh
Fri Sep 24, 2004 7:16 am
Forum: General Discussion
Topic: Electronics Design Forum
Replies: 3
Views: 829

Re: Electronics Design Forum

Try www.eng-tips.com
This site is more for professional users than hobbyists.
by Carl Pugh
Sun Jun 06, 2004 12:01 pm
Forum: General Discussion
Topic: One Horse Power - Motor Starting Capacitor
Replies: 12
Views: 2340

Re: One Horse Power - Motor Starting Capacitor

Are you sure it's a motor start and not a motor run capacitor?
Anyway a good source for either of these capacitors is www.grainger.com
by Carl Pugh
Sat Jan 31, 2004 9:52 am
Forum: General Discussion
Topic: generator head variable load
Replies: 12
Views: 2124

Re: generator head variable load

Light bulbs sound like a good idea. If you can get to the generator field, then using a separate variable power supply for the field could be the way to go.
The separate variable power supply should not be operated off the generator output.
by Carl Pugh
Wed Dec 31, 2003 9:56 am
Forum: General Discussion
Topic: 480VAC Transformer
Replies: 11
Views: 2336

Re: 480VAC Transformer

For best solution search different manufactures products. Thomas Register has list of manufactures. www.thomasregister.com If unable to find standard product, I have used Signal Transformer www.signaltransformer.com 516-239-5777 and Stangenes Industries Inc www.stangenes.com 650-493-0814 for custom ...
by Carl Pugh
Sat Dec 20, 2003 8:26 am
Forum: General Discussion
Topic: 480VAC Transformer
Replies: 11
Views: 2336

Re: 480VAC Transformer

One solution, probably the cheapest, but not the best would be to use two transformers. Use transformers with 240 volt primaries and 8 volt secondaries. Series the primaries and parallel the secondaries.
Signal transformer DST-2-16 should work.
www.signaltransformer.com
Good Luck
Carl
by Carl Pugh
Tue Oct 07, 2003 7:09 am
Forum: General Discussion
Topic: Photo_Resistor
Replies: 8
Views: 1668

Re: Photo_Resistor

Optoelectronics section of Perkin-Elmer appears to have been discontinued?
When searched for VTL5C1 (Part number) got WWW.AIKENAMPS.COM and some other interesting sites.
by Carl Pugh
Sat Oct 04, 2003 10:38 am
Forum: General Discussion
Topic: Photo_Resistor
Replies: 8
Views: 1668

Re: Photo_Resistor

Google is a wonderful device isn't it. Except I can't find anything on it either. "EG&G OPTOELECTRONICS VACTEC, Optoelectronics Data Book, Photoconductive Cells and Analog Optoesolators (Vactrols) November 1997" has considerable information on this subject. Their address and phone number (1997) is 1...
by Carl Pugh
Thu Sep 04, 2003 9:11 am
Forum: General Discussion
Topic: toothbrush charger
Replies: 8
Views: 1172

Re: toothbrush charger

In the interest of preventing smoke, it might be advisable to put a electric light bulb in series with the coil that you have wound. When the light bulb does not glow, it could be removed. Maybe use a 60 watt light bulb.
by Carl Pugh
Sun May 04, 2003 7:49 am
Forum: General Discussion
Topic: in need of a capatior
Replies: 10
Views: 1770

Re: in need of a capatior

For motor-run capacitor try Grainger, www.grainger.com