Search found 106 matches

by ecerfoglio
Fri Sep 07, 2007 5:58 am
Forum: General Discussion
Topic: Charging While Wall-Warting
Replies: 45
Views: 8963

I've seen much more complicated circuits that isolate the cells of the battery and charge them in turn. I don't think something like that makes sense for this application Those systems are used when you want to get a charge into the battery ASAP - some charges seem to promise to get a full charge i...
by ecerfoglio
Thu Aug 23, 2007 2:58 pm
Forum: General Discussion
Topic: ceiling fan speed controls
Replies: 13
Views: 2889

Dimmers, especially older ones were notoriuos for failing after an incandescant light bulb blows . I forget the exact mechanism but it causes a voltage spike that blows the SCR. Not sure if newer models are also susceptable but if you buy a heavy duty one with a high current rating, it is less like...
by ecerfoglio
Wed Jul 25, 2007 6:58 pm
Forum: General Discussion
Topic: Regulate to 13.8 Volts
Replies: 23
Views: 3751

It will be a 3 phase motor and I will update my schematic to show that. There are two ways to wire it up thou... STAR or DELTA.. I believe you find more Star configurations for Windmill applications.. so I will try that first. Alternators are (almost) allways wired in a STAR configuration. There is...
by ecerfoglio
Fri Jun 29, 2007 7:34 am
Forum: General Discussion
Topic: The impending death of incandescent bulbs
Replies: 100
Views: 18466

The hot bulb will receive about 90 percent of the power and the cold bulb about 10 percent. This might be a stable condition, but I don't know how to analyze it. The cold bulb, receiving some power will probably heat up slowly . As its filament't temperature raises so does its resistance and the po...
by ecerfoglio
Tue Jun 26, 2007 5:49 am
Forum: General Discussion
Topic: Measuring 220 AC with an ADC
Replies: 21
Views: 5307

It's US 240 if you know what I mean. It's coming off of a stepdown transformer with a center tap and so from the two lines two the center tap (ground) is 120VAC. So I don't know how I should measure th voltage with the method I just described. Just use a small transformer with a 220 (or 240) V prim...
by ecerfoglio
Thu Jun 21, 2007 3:11 pm
Forum: General Discussion
Topic: Measuring 220 AC with an ADC
Replies: 21
Views: 5307

:shock: :shock: SAFETY WARNING :shock: :shock: If your ADC has its reference voltage (aka ground) tied to one side of the 220 V supply, you can use a voltage divider as was sugested. In that case, your entire circuit should be enclosed so it is not accesible to anyone. You shoult treat it as a hot c...
by ecerfoglio
Fri Jun 08, 2007 3:36 pm
Forum: General Discussion
Topic: 36 volt to 12 regulator capable of 30 watts
Replies: 29
Views: 4243

i have tried something like this before. especially with chriastmas lights..lol results weren't good .. the lower wattage lamp lights up way faster , and after a few times of doing this, the lower wattage lamp failed .. it lit up super bright. and then the higher wattage lamp glowed a bit..but they...
by ecerfoglio
Fri Jun 08, 2007 5:41 am
Forum: General Discussion
Topic: Compressed Air Car
Replies: 145
Views: 26603

haklesup said: Batteries don't last as long as air tanks. Weigh a lot more too. I'm sure he was referring to the lifetime of the storage tanks vs the replacement rate of depleated batteries. ------------ Barring a puncture , the tank should last the life of the vehicle . In Argentina we have lots of...
by ecerfoglio
Mon Jun 04, 2007 12:48 pm
Forum: General Discussion
Topic: Compressed Air Car
Replies: 145
Views: 26603

I see this as similar to a flywheel. A way to temporarily store mechanical energy without the losses associated with conversion to and from electric. I think it is more like a very BIG spring than a flywheel. It just stores mechanical work (force x distance = pressure x volume) In ideal (=isothermi...
by ecerfoglio
Mon May 21, 2007 5:22 am
Forum: General Discussion
Topic: To run a stepper motor on starving diet...
Replies: 9
Views: 2058

Dale: 30 mA the IC alone. Not bad, but still a waste 98% of the time when running on batteries: http://www.datasheetcatalog.com/datasheets_pdf/U/C/N/5/UCN5804.shtml The datasheet says Supply current Idd ( 2 outputs ON ) typ 20 mA max 30 mA A good part of that current should go to the output transis...
by ecerfoglio
Fri Apr 27, 2007 1:03 pm
Forum: General Discussion
Topic: Transformer energy consumption
Replies: 7
Views: 1540

you should invest in a "Kill-A Watt" meter ($24 ebay w/ free ship, multiple vendors). ..........especially if those warts feel warm at any time loaded or not. A very "quick and dirty" way to find if it is drawing much power is to feel (or meassure) the wall wart's temperature after a few hours of b...
by ecerfoglio
Fri Apr 13, 2007 5:35 am
Forum: General Discussion
Topic: new question
Replies: 9
Views: 2070

A synchronous motor might well draw mmore current at a lower voltage in order to maintain the load at synchronous speed A motor with tachometer feedback would probably draw more current with decreasing input voltage in order to maintain the output power of the motor constant. As I posted yesterday,...
by ecerfoglio
Thu Apr 12, 2007 6:39 am
Forum: General Discussion
Topic: new question
Replies: 9
Views: 2070

An ac motor has a running amperage of 10 amps and the measured voltage is 120volts ac. If the voltage drops to 110volts An AC (induction) motor's current depends on the speed it is rotating. When the input voltage is decreased, il lowers its speed (** only slightly **) and increases its current (an...
by ecerfoglio
Fri Mar 23, 2007 3:15 pm
Forum: General Discussion
Topic: Audible continuity tester...
Replies: 27
Views: 5785

to find if the TO-92 device is a UJT, JFET, mosfet, bipolar transistor, or what I would say that it's only a "garden variety" NPN bipolar transistor (ie BC548 or PN2222 or whatever you vave at hand) Colector to +V (bottom), emiter to the transformer's "primary" (top), base to the secondary (right) ...
by ecerfoglio
Wed Mar 21, 2007 6:52 am
Forum: General Discussion
Topic: Powering a cordless tool from a plug-in supply?
Replies: 24
Views: 4877

It occured to me that startup and possibly braking of the blade would demand the largest current but only for a short period of time. I think you'll find that motor braking is provided by short-circuiting the motor rather than using the power supply in some incredible way. A shorted PM motor that's...