Search found 59 matches

by dtief
Thu May 21, 2009 8:16 pm
Forum: General Discussion
Topic: LED /Low-voltage lighting in new home?
Replies: 16
Views: 2222

Re: LED /Low-voltage lighting in new home?

I've been experimenting with high power LEDs a bit. Some of the best current technology devices are comparable to flourescents for Lumens / Watt. They are better than the worst, but not quite as good as the best. Comparing to 48" T12 & T8 tubes. I just ordered a 3,500 Lumen :shock: RGBW LED to exper...
by dtief
Mon May 11, 2009 6:28 pm
Forum: General Discussion
Topic: Logic Analyzer Help~
Replies: 21
Views: 2382

Re: Logic Analyzer Help~

I've had good luck with this one:
http://www.pctestinstruments.com/index.htm

It is almost $400., but I had to analyze a DSP and other microcomputers.
by dtief
Sun May 03, 2009 4:43 pm
Forum: General Discussion
Topic: Capacitively driving a mosfet gate...
Replies: 4
Views: 601

Re: Capacitively driving a mosfet gate...

I suspect that by the time you have a cap big enough to keep the drive undistorted, it would be too big to prevent the failure. If the FET is on too long (10s of microseconds - depends greatly on the switcher frequency), the inductor saturates and the current spikes way up since there is only parasi...
by dtief
Sat May 02, 2009 8:49 pm
Forum: General Discussion
Topic: "Multitool", good?
Replies: 23
Views: 1817

Re: "Multitool", good?

I have found that for cutting metal or fibreglass, metal cutting blades desribed as "BI metal" last the longest. The term refers to hardend teeth on a tough steel backer. I Use them in my jig saw, sawsall, hacksaw & bandsaw. (also, all hole saws) My favorite for cutting PCBs? Bandsaw. A diamond blad...
by dtief
Tue Apr 21, 2009 6:43 pm
Forum: General Discussion
Topic: opnions wanted on battery reviving of NiCads
Replies: 31
Views: 4525

Re: opnions wanted on battery reviving of NiCads

That's why I don't bother with cheap tools. You're better off buy used quality tools.
by dtief
Fri Apr 17, 2009 7:56 pm
Forum: General Discussion
Topic: opnions wanted on battery reviving of NiCads
Replies: 31
Views: 4525

Re: opnions wanted on battery reviving of NiCads

I wouldn't change the battery type. The NiMH will cost a lot more. They have more capacity for the same case size. Higher self discharge rate. Lower cycle life. Deep cycles & high current aggravate this. What many times looks like memory effect is in fact the weakest cell dropping below 1V, and even...
by dtief
Thu Apr 16, 2009 5:41 pm
Forum: General Discussion
Topic: opnions wanted on battery reviving of NiCads
Replies: 31
Views: 4525

Re: opnions wanted on battery reviving of NiCads

BTDT Zapping the shorts out of dead NiCads works as a science experiment. For a short time. They will not be restored to new capacity. They will go bad again pretty quickly. I've rebuilt a few drill batteries over the years. Very short procedure: Open the case. Measure the cells. Look up the cells o...
by dtief
Sun Mar 29, 2009 4:58 pm
Forum: General Discussion
Topic: Is RadioShack that confused?
Replies: 73
Views: 9066

Re: Is RadioShack that confused?

I don't remeber if it was discovered during one of the testing steps of a production run, or an R&D project turned them up.

The error must have been made by a new hire. For the kind of high reliability devices they make, it would have been normal to test SAMPLES for incoming QC....
by dtief
Wed Mar 25, 2009 5:30 pm
Forum: General Discussion
Topic: This I did not know about variacs...
Replies: 17
Views: 2246

Re: This I did not know about variacs...

That looks exactly like the pair of 120V 2KVA theater dimmer variacs (actually Powerstat brand) I have. Mine don't have boost taps like "electronics" variacs often have.
by dtief
Wed Mar 25, 2009 5:24 pm
Forum: General Discussion
Topic: Is RadioShack that confused?
Replies: 73
Views: 9066

Re: Is RadioShack that confused?

This reminded me of the story told to me by an engineer from a large high technology company. - Seems someone in incoming QC inspection was testing all of the fuses. And yes, they all worked... And put the now tested, open fuses into the stock room.
by dtief
Sat Mar 07, 2009 5:35 pm
Forum: General Discussion
Topic: This I did not know about variacs...
Replies: 17
Views: 2246

Re: This I did not know about variacs...

Measure ing the resistance regarding the turns "shorted" by the brush isn't the whole story. This is a transformer, not a resistor / potentiometer. The turn/s shorted by the brush will have the ratio of the number of turns from the 2 terminals used for power input to 1. The brushes are low ohms, but...
by dtief
Tue Feb 10, 2009 7:37 pm
Forum: General Discussion
Topic: fast reaction circuit breaker
Replies: 6
Views: 807

Re: fast reaction circuit breaker

These are some DC circuit breakers... http://www.heinemannelectric.com.au/products_select.php?p=19 Probably not inexpensive. Sentron CSA-1V-SO is a current sensor IC. Just rout the wire carrying the current over the IC. Use a comparator to trip (open a relay? or a big FET?) at the desired current. h...
by dtief
Wed Feb 04, 2009 5:13 pm
Forum: General Discussion
Topic: Ice Storm
Replies: 28
Views: 2612

Re: Ice Storm

Part of the apparent HP discrepancy is due to the way engines are rated, and the power curve. IC engines are usually rated HP at maximum RPM. Turn the RPM down, the HP drops also. But it isn't linear. The HP drops faster than the RPM. My 3KW generator = approximately 4HP. It has an 11 HP engine. But...
by dtief
Tue Feb 03, 2009 5:55 pm
Forum: General Discussion
Topic: Ice Storm
Replies: 28
Views: 2612

Re: Ice Storm

I always make sure their is ventilation when running them. The small one I got from a ham radio friend, pretty much in operating condition. I added a remote start / stop / choke to it. The big one was in a field. One time a friend & I were riding by it, so we stopped to look at it. The owner told me...
by dtief
Mon Feb 02, 2009 7:07 pm
Forum: General Discussion
Topic: Ice Storm
Replies: 28
Views: 2612

Re: Ice Storm

My 1942 generators are pretty quiet.

1200RPM, and water cooled engines goes a long way to make them quiet.

http://home.comcast.net/~davidtief/gen.html

The small one you really have to listen for, even if it is running in the garage.
The only thing noisey about the big one is the radiator fan.