Re: Using a Device with Transformer


mea305 wrote:
Hi Chris and all others -- that respectively responded to my posts. I
want to first say that I am extremely grateful for your assistance. The
second thing I must say (although not specifically to the group, but
to, perhaps, Radio Shack....) is, ummm, ya know, they took me for being
stupid. I should have known better; but, like most others will agree,
hind sight is what it is ...

On the other side of the coin, however, even before I read any of the
second posts concerning this quagmire in which I have embedded myself,
the macerator does work. "I got to thinking...," and I already had an
"automotive jump starter/DC power supply," a unit that I purchased
while I was swimming beneath the currents of my scooter battery
"problem," (for lack of a better term). This 'little thing here' looks
like something that one would need to start a car. But, it is
relatively small. Charging it takes about a day; but, when I connected
it (while also holding my breath) to the macerator -- here, I was about
to, effectively, by-pass a small 20 Amp fuse that is attached to
swith/handle/trigger mechanism -- and.....it works! The information
that comes with the macerator suggests that one should not operate it
outside of its nornal environment, which would be -- water. Apparently,
it can get hot fast. But, it does work; and I can use this little thing
to connect to the macerator.

There is but one question -- and I am assuming that I might be correct.
I would not think that this little thing (although it weighs in at
almost 20 lbs. and I cannot lift it because if I did, two things would
happen -- pain and my doc would kill me) does not or cannot produce
more than 20 Amps, correct?

Aside from that, I'm OK. I will await a response before I use it.

Thanks -- to "all of you!"

Mark
Chris wrote:
mea305 wrote:
Again, Mr. J.D., et al:

Now, with the box in which the transformer was packaged in front of me,
it is a "13.8VDC, 25 Amp, 'switching power supply.'" The additional
nomenclature that is on the front of the package lists the following:

"Accepts 90 to 135VAC input and converts to 13.8VDC up to 25 amps."
And, it also states that it is a "low RFI unit," whatever that means.
The picture of the unit is also on the box, which matches the unit
itself. There is a power switch, "on and off," and the nomenclature is
again repeated on the front panel of the unit, "switchable power
supply, 25 Amp, 13.8VDC."

On the back of the package, the following is read: "With this Radio
Shack switching power supply, you can bench-test or power CB and HAM
radio sets, scanners, car stereos and radar detectors. You can also use
it with your faster 12VDC car chargers to re-charge wireless phones,
camcorders and re-chargeable flashlights and cordless tools."

There are five numbered elements listed on the back panel as well:
(1) lighted power on/off switch
(2) non-skid rubber feet
(3) 6 foot grounded AC cord
(4) cooling fan
(5) color coded terminal post outputs

On one side of the box, it states that it comes complete with a "short
circuit and overload protection."

We purchased the unit on the Internet at the following URL:

http://www.radioshack.com/entry.jsp?source=PE&entry=2103961

Thanks,

Mark
Mr. J D wrote:
mea305 wrote:
Recently, I sent a message to the group concerning a device that I will
be using with our RV. It requires at least 20 Amp, 12 VDC. To operate
it, we bought a 25 Amp, 12 V Transfomer. When I recently attempted to
operate it, it would run for almost an entire second and then, in order
to get it going again, the transfomer had to be shut down and
re-started; but the same problem recurs.

On the side of our RV, there is the fuse box; there are four fuses
(triggers), ranging from 15 Amp to 30 Amp. I do know that if I turn off
one or more of the lower fuses, only part of the RVs electricity goes
out; but it I turn off the 30 Amp, it shuts down the entire facility.

My first thought was that there might be something wrong with either
the transformer or the unit. But, then I "got to thinking." I would
presume that "most" of the outlets in the RV are hooked up to the 15
Amp fuses, whereas the 30 Amp fuse operates the entire electrical
system.

Would I be correct to assume, therefore, that if I am using an outlet
in the RV, it is most likely pulling only 15 Amps, and this would be
the reason the transformer is not able to handle the needs of the unit?

It's raining outside (here in the Sunshine State), so I am not about to
go outside, let alone "play around the fuse box." But, adjacent to
where we are situated rests a building where I know the outlets have at
least 20 Amps (or more). Should I try using one of those outlets first?

Thanks,

Mark
The fuses are rated at amperages (ie, 30 Amps). This only means that
they blow when a load tries to grab more than 30 Amps from the line
that the fuse is connected to.
You say you bought a 25 Amp, 12V Transformer. By this do you mean a
wall/table top transformer, or an actuall transformer? If you just say
transformer, then we all assume the transformer is putting out AC. What
kind of device are you using that requires 25 Amps of 12V? Thats a huge
load, or you sure you dont mean more like 250 mA, or a 2.5 A? Descirbe
in total what you are actually doing.

Hi, Mark. The Radio Shack switching power supply is basically meant to
power up mongo car stereos on a bench. They're really not made for
motor loads. You should look into returning the product -- it works,
but it's not made for the job.

On the prior thread, someone mentioned using a car battery with a
charger rated for 25 amps. Although it's clunky, that might be your
best bet to get things going quickly (again, assuming the macerator
works -- test as above). You should be able to scrounge a battery, and
possibly borrow a charger. Be sure to use an inline fuse, put a shield
around the battery to protect everyone's eyes in case of accidental
acid discharge, and keep things well-ventilated. A working car battery
produces hydrogen gas and acid fumes. Possibly you could ask your
electrician friend for advice.

Longer term, you'll probably want to find a 12VDC power supply that can
do the job. Look for a linear supply (they're a lot heavier, because
they've got a 60Hz transformer rated for the output power). Actually,
a non-technical person should just evaluate by weight -- if the 12VDC,
25 amp power supply is light like the Radio Shack power supply, it's a
switcher, and won't do the job. Your electrician friend might be able
to help you here, too.

Of course, hoping for the best for you and your family. This is the
worst part of being stuck -- that you have to spend inordinate amounts
of time and money over something that wouldn't even be a problem if you
weren't stuck. If you were renting, you'd let the landlord worry about
the septic tank stuff. The harder you work, the behinder you get.
You're not alone in seeing the irony in spending all this time fiddling
around with something that does what a macerator does.

Good luck
Chris

Hi, Mark. I'm glad to hear you're getting a bit closer to having your
setup work.

Here's the thing. The battery charger provides rectified AC, which
probably isn't too good for your motor by itself. The way it works, is
that the charger sends pulses of current into the battery when the
charger voltage goes above the battery voltage (120 times a second).
The rest of the time, the load is carried by the battery.

You really should put an automotive battery in parallel with your
macerator, so the battery can help shoulder the load and even the
voltage out. Even an older or marginal battery will be a lot better
than none. This will help your motor to survive. Also, be sure to get
a battery charger which shows more than 20 amps output on the
nameplate. If you pick one that's too small, you'll probably fry the
charger.

As a bit of a sidenote, please bottom post if you have future
questions. Read Google Groups Help Topic "What's good 'netiquette'
when posting to Usenet?"

http://groups.google.com/support/bin/answer.py?answer=12348&topic=250

I hope things are looking up for you soon. It seems like you've been
handed more than your share of macerator grist recently!

Cheers
Chris

.

Relevant Pages

  • Re: Does the power supply limit the actual power of a tube amp?
    ... I rebias the amp (perhaps ... you'll blow your power transformer." ... ALL current from the power transformer's collective secondary windings, ... Any increase in current draw from ANY one of the secondaries, ...
    (alt.guitar.amps)
  • Re: really dumb question re direct line powering and safety
    ... transformer, powered by a small cheap DC supply? ... Many amps especially the cheap beginner amp we used to get from ... This thing is a 3 tube afair, 35W4 rectifier, 12AX7 ... No power transformer. ...
    (alt.guitar.amps)
  • Re: really dumb question re direct line powering and safety
    ... transformer, powered by a small cheap DC supply? ... Many amps especially the cheap beginner amp we used to get from ... This thing is a 3 tube afair, 35W4 rectifier, 12AX7 ... No power transformer. ...
    (alt.guitar.amps)
  • Re: Which university produces good analog EEs?
    ... I remember dropping a tool into my 2nd shortwave power amp. ... 5kV on the plates and an oil-cooled transformer the size of a shoe box. ... The amp before that was built when I head no money for luxuries such as transformers so I rigged up a tripler from 230VAC to around 900VDC. ... Tons of caps, lots of power. ...
    (sci.electronics.design)
  • Re: Using a Device with Transformer
    ... Now, with the box in which the transformer was packaged in front of me, ... it is a "13.8VDC, 25 Amp, 'switching power supply.'" The additional ... There is a power switch, "on and off," and the nomenclature is ... Shack switching power supply, you can bench-test or power CB and HAM ...
    (sci.electronics.basics)