PRC as a amplifier in GPS question.

[Glenn Pure]

I think you have answered my question. Problem relates to a motor
(that I haven't seen... only been told about) that blows a 10 amp fuse
when it starts. Inrush current obviously high enough to do this.

Sounds like the trick is to protect the circuit with a circuit
breaker, not a fuse.

Cheers
Glenn

KLR <kreed@bigpond.net.au> wrote:

On Mon, 25 Aug 2003 12:01:06 GMT,
Glenn.Pure*delete_this_for_reply*@pcug.org.au (Glenn Pure) wrote:

What is the recommended method for controlling large surge currents
when 240V AC motors are switched on?

Cheers
Glenn



I have seen applications where a large wire wound resistor is used.
(on a drive motor for a commercial film projector) Usually though
nothing is done and there doesn't seem to be a problem. For example
my old simpson washing machine would slightly dim all the lights in
the house for a fraction of a second when its motor started.

Nameplate rating was 5amp @ 240v AC and I would imagine that 99% of
this current would have been used for the motor. Never blew the fuse
wire (15a) household circuit - or tripped a breaker (updated the
fuseboard later on to breakers) and didnt seem to bother any other
appliances

As far as I know - circuit breakers have a delay time at a given
overcurrent before they will trip. you could probably get a data
sheet through haymans on these for the common household/industrial
mains ones. (farnell may have them too)

 

[Rheilly Phoull]

Think "minature wine rack", 25mm mesh ??

--
Regards ............... Rheilly Phoull

"bemw" <queriesNOSPAM@bigpond.com> wrote in message
news:wJA2b.63646$bo1.46754@news-server.bigpond.net.au...

I have hundreds of tubes of ICs in a box, and everytime I need a
particular
IC, I have to sort through them all to find the tube I need. Can anyone
suggest a simple storage method for the tubes that will make finding the
right part simpler.

 

[budgie]

On Tue, 26 Aug 2003 10:48:11 GMT, "Alan"
<alanmac@nospambigpond.net.au> wrote:

"Mike Harding" <mike_harding1@hotmail.com> wrote in message
news:bh1lkvch7ii07o369ienfdbbl15nptbe6a@4ax.com...
On Mon, 25 Aug 2003 14:18:55 GMT, "Alan"
alanmac@nospambigpond.net.au> wrote:

I am trying to use my Palmpilot as a portable terminal to access some
servers. Command line access. PDA quicker to boot then lugging around a
laptop and waiting for it to boot. The problem is that the com port of
the
server requires more current than the palm can supply before it will open
the port. I am simply looking for a simple circuit take the low voltage
levels from the palm and boost them to the equivalent of a standard PC
com
port. Preferably battery powered. 9V would be good.

I doubt that is the problem. RS232 should operate from
3V to 15V and requires very little current - I cannot imagine
the Palmpilot designers making such an error - and no one
else has noticed?

Do you have a null modem in circuit, are both ports at the
same baud rate and parity settings, are all the handshake
lines doing what they should?

Mike Harding

Nope no null modem. The serial cable for the Palm is designed for data sync
to a PC. This works well, and I can set up a terminal session on the PC and
talk between the two. However I doubt that the Palm meets RS232 standards as
it is only running on two AAA batteries. Hard to meet the 3V minimum.

Depends on what chipset they are using, and whether it cranks up the
voltages a la MAX232. Put it this way, IMHO a manufacturer would be a
fool to turn loose an appliance with serial connectivity if it used
marginal drive voltages.

 

[Brian Goldsmith]

"Mainlander" <*@*.*> wrote


I seem to recall there are differing ways of implementing RS232, some
work on +/- 5Volts which doesn't meet standard.

*** RS232 is THE standard.Any protocol that does not meet the
requirements of this written standard is NOT RS232 but some other
variant with perhaps,as we have read,differing voltage levels etc.
Brian Goldsmith.

 

[Phil Pierotti]

I have a device I bought while in the US which requires an input of
9VAC@1.5A. The US being the center of the known universe (and also for
the sake of minimizing costs, I assume) the wall-wart it came with only
takes 110V input.

If I tried to plug in a wall-wart with 16VAC@1.5A output, I assume one
part or another in my device will fry quite nicely.

Phil P


In article <MPG.19b5f2172f1a1739989bc4@news.paradise.net.nz>, *@*.*
says...

In article <biebbm$896gf$1@ID-69072.news.uni-berlin.de>,
rod_speed@yahoo.com says...

"Mainlander" <*@*.*> wrote in message news:MPG.19b56a419e201dd3989bc0@news.paradise.net.nz...
In article <MPG.19b545a190ffaf4a989686@news.swiftdsl.com.au>,
Phil.dot.Pierotti@SoftHome.dot.NET says...
Anyone know where I can buy a

input = 240V AC
output = 9V AC @ 1.5A

Plugpack/wall-wart ?

I found this at JayCar, but it's only 1A.
http://www1.jaycar.com.au/productView.asp?ID=MP3027


DSE sell the following
M2156 taps to 8.5 & 9,5 VAC 2A
M2165 taps to 9V 6.6A

Those arent in plugpack/wallwart format tho.

He asks for a transformer first and a wallwart later.

 

[Fat Crack Ho]

You could try a parrallel combination of power resister and relay. Start the
motor with the resister in series. Once the motor is magnetised and spinning,
close the relay. I've used this as a "softstarter" so a household refrigerator
can be run by a gernerator without stalling the gen from large startup current.
Once cold, our fridge only draws 0.7amp. On startup, the peak current is
8.5amp.

R
240ac--/\/\--Motor
--relay-

What is the recommended method for controlling large surge currents
when 240V AC motors are switched on?

Cheers
Glenn

 

[Just Allan]

On Mon, 25 Aug 2003 12:58:28 GMT, "Brian Goldsmith"
<brian.goldsmith@nospamecho1.com.au> wrote:

***** How can they look it up if it is not there??Or is this respondent
a liar?

How convenient, since this fellow posted his HELPFUL info *after*
your ala rod speed comment. The simple truth is, you were being a
jerk and you know it.

 

[Rob Judd]

Brian Goldsmith wrote:

"Mainlander" <*@*.*> wrote

I seem to recall there are differing ways of implementing RS232, some
work on +/- 5Volts which doesn't meet standard.

*** RS232 is THE standard.Any protocol that does not meet the
requirements of this written standard is NOT RS232 but some other
variant with perhaps,as we have read,differing voltage levels etc.
Brian Goldsmith.

The rot set in with Japanese printers, where they started dropping lines
and using small plugs. 9-pin RS-232 ain't RS-232 either, no matter what
voltage is present.

Rob

 

[Sir Charles W. Shults III]

"Miem Chan" <miemchan@yahoo.com> wrote in message
news:3f4b79fe$1_1@news.iprimus.com.au...

I have some solar cells with 1.5v and 2volt outputs.
How can I use these cells to charge 4.8v or 9v NiCd batteries (without
connecting solar cells serially to produce higher voltages)?

You would use a boost regulator or switching regulator to produce the
required charging voltage.

Cheers!

Chip Shults
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip

 

[Mike Harding]

On Tue, 26 Aug 2003 14:45:01 +1000, jrobbo
<jrobboSPAMSUCKS@jrobbo.com> wrote:

I think you would have better off using Dannii for that, as she is a
qualified elecution teacher. That way, you could free up Kylie for
other things

Oh yeeesss pllleeeaaassseee

Mike Harding

 

[Gerry Schneider]

"Sir Charles W. Shults III" wrote:

"Miem Chan" <miemchan@yahoo.com> wrote in message
news:3f4b79fe$1_1@news.iprimus.com.au...
I have some solar cells with 1.5v and 2volt outputs.
How can I use these cells to charge 4.8v or 9v NiCd batteries (without
connecting solar cells serially to produce higher voltages)?

You would use a boost regulator or switching regulator to produce the
required charging voltage.

Cheers!

Chip Shults
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip

Actually, he'd need a boost/switching current source, at least C/20 to
produce an effective charging action. The regulator should follow a standard
NiCd charging profile for the current produced (anything from "don't care"
for C/10 to one of the "delta" profiles for higher currents). An MPPT action
in the switcher would give him maximum efficiency under all solar conditions,
but from his description of the cells, I'm guessing that he'll be happy with
just an uncontrolled boost design that dumps enough current into the batts to
eventually get the job done )

Regards,

Gerry

 

[Rod Speed]

Rob Judd <judd@ob-wan.com> wrote in message
news:3F4B871C.D091B9C@ob-wan.com...

Brian Goldsmith wrote:
Mainlander <*@*.*> wrote

I seem to recall there are differing ways of implementing RS232,
some work on +/- 5Volts which doesn't meet standard.

RS232 is THE standard.Any protocol that does not meet the
requirements of this written standard is NOT RS232 but some other
variant with perhaps,as we have read,differing voltage levels etc.

The rot set in with Japanese printers, where they
started dropping lines and using small plugs.

Nope, DEC started using a minimum number of lines
LONG before Jap serial printers ever showed up.

9-pin RS-232 ain't RS-232 either,
no matter what voltage is present.

 

[Franc Zabkar]

On Wed, 27 Aug 2003 00:03:03 +1000, "Phil Allison"
<philallison@optusnet.com.au> put finger to keyboard and composed:

"Fat Crack Ho" <s363281@student.uq.edu.au> wrote in message
news:bifosb$9qm$1@bunyip.cc.uq.edu.au...

You could try a parrallel combination of power resister and relay.


** That power resistor may need to be a whopper.



Start the
motor with the resister in series. Once the motor is magnetised and
spinning,
close the relay. I've used this as a "softstarter" so a household
refrigerator
can be run by a gernerator without stalling the gen from large startup
current.
Once cold, our fridge only draws 0.7amp. On startup, the peak current is
8.5amp.



** Peanuts. A PC plus monitor peaks at 100 + amps.

Chalk and cheese. 100A for a split second is nothing compared to 8A
over several seconds.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

 

[Fat Crack Ho]

Though I havn't tried it, could use a series cap instead of a resister. The
50Hz impedance of the cap would serve as the current limiter. Just need a cap
capable of surviving the startup current through it.

"Fat Crack Ho" <s363281@student.uq.edu.au> wrote in message
news:bifosb$9qm$1@bunyip.cc.uq.edu.au...

You could try a parrallel combination of power resister and relay.


** That power resistor may need to be a whopper.



Start the
motor with the resister in series. Once the motor is magnetised and
spinning,
close the relay. I've used this as a "softstarter" so a household
refrigerator
can be run by a gernerator without stalling the gen from large startup
current.
Once cold, our fridge only draws 0.7amp. On startup, the peak current is
8.5amp.



** Peanuts. A PC plus monitor peaks at 100 + amps.




........... Phil

 

[N. Thornton]

"Miem Chan" <miemchan@yahoo.com> wrote in message
news:3f4b79fe$1_1@news.iprimus.com.au...
I have some solar cells with 1.5v and 2volt outputs.
How can I use these cells to charge 4.8v or 9v NiCd batteries (without
connecting solar cells serially to produce higher voltages)?

Simplest is a 2 tr oscillator driving a miniature transformer with rectifier..

Regards, NT

 

[Paul Bealing]

bemw wrote:

I have hundreds of tubes of ICs in a box, and everytime I need a particular
IC, I have to sort through them all to find the tube I need. Can anyone
suggest a simple storage method for the tubes that will make finding the
right part simpler.



Years ago were I worked we made a tube storage rack out of plastic

electrical conduit.

cut conduit into lengths a 10mm longer than the longest IC tubes
glue together flat (forms a square raft)
make as many rafts as needed
glue rafts together in a stack

We rotated the rafts when gluing together so that all 4 sides were used
for different IC families (linear, cmos, ttl, etc).
Rubber corks (stoppers) are tied onto the end of each IC tube with a
colour coded label stuck to the cork.
The IC's stay in the anti-static tubes and the tubes slide into the
conduit rack.
The rack was mounted on a rotary base and sat on a filing cabinet in the
workshop.
The IC tubes were stored in numerical order by the labels were colour coded.

It worked realy well but you need to get the conduit at a good price.
It was probably 20mm conduit.

Regards
Paul Bealing
www.pmb.co.nz

 

[Steve]

"amstereo - matt2" <amstereo@optusINTERnetDOT.comDOT.auSTRALIA> wrote in message news:<3f4a039c$0$28121$afc38c87@news.optusnet.com.au>...

what about a real big capacitor ?

GREAT IDEA! Then it's a simple task to work out a way to run a 240VAC
motor from a charged capacitor, limit the inrush to the "real big"
cpacitor when you start to charge it and you're all sorted!

can't wait to see the circuit!

 

[Rod Speed]

Phil Pierotti <Phil.dot.Pierotti@SoftHome.dot.NET> wrote in message news:MPG.19b6a52f13bdada5989689@news.swiftdsl.com.au...

I guess then I'm essentially SOL looking for an existing
wall-wart, and therefore need to assemble my own.

Yep.

Not knowing anything about assembling power transformer
circuits (or any caveats therein), is it as simple as:

240V wall Socket-> OZ power plug -> cable -
transformer -> cable with appropriate plug for my device?

Yep. Best to use a plastic box so you dont
have to bother with earthing a metal box.

pack it in a project box of suitable size (with ventilation)

That last isnt really necessary.

and have fun?

You forgot the tune for minimum smoke step.

Have fun when ready, Gridly.

In article <bifvoe$8raoo$1@ID-69072.news.uni-berlin.de>,
rod_speed@yahoo.com says...

Phil Pierotti <Phil.dot.Pierotti@SoftHome.dot.NET> wrote in message news:MPG.19b5fa29baa0eec7989688@news.swiftdsl.com.au...

I have a device I bought while in the US which requires
an input of 9VAC@1.5A. The US being the center of the
known universe (and also for the sake of minimizing costs,
I assume) the wall-wart it came with only takes 110V input.

If I tried to plug in a wall-wart with 16VAC@1.5A output, I
assume one part or another in my device will fry quite nicely.

Really depends on the device.

AC wall warts are usually used when the device needs to generate
more than one DC supply internally, like with modems etc.

As such they may not care about the higher AC input, but if its got
a 5V DC internal rail, the regulator to 5V may well get pretty hot
just because its dropping rather more voltage down to 5V.

You may well have to use a 2A transformer in a
small project box with a pair of cables coming out
of it, one for the 240VAC and the other for the 9VAC.

There are a few wallwart style cases around but
they wont usually take a 2A output transformer.

I basically did a quick and dirty myself in that situation,
put the transformer in a pretty solid cardboard box just
to get something working quickly and it ended up like
that for 10 years or something. For just that situation,
an imported modem.


In article <MPG.19b5f2172f1a1739989bc4@news.paradise.net.nz>, *@*.*
says...
In article <biebbm$896gf$1@ID-69072.news.uni-berlin.de>,
rod_speed@yahoo.com says...

"Mainlander" <*@*.*> wrote in message news:MPG.19b56a419e201dd3989bc0@news.paradise.net.nz...
In article <MPG.19b545a190ffaf4a989686@news.swiftdsl.com.au>,
Phil.dot.Pierotti@SoftHome.dot.NET says...
Anyone know where I can buy a

input = 240V AC
output = 9V AC @ 1.5A

Plugpack/wall-wart ?

I found this at JayCar, but it's only 1A.

 

[Phil Pierotti]

Tune for minimum smoke?

Also, one last question - so far I've been unable to source even a naked
transformer which produces exactly 9VAC@1.5A output.

So I'm wondering which way I should lean?

Exactly the correct output voltage but higher AMPs (and assume the
internal electronics will only draw what's needed), or vice-versa?

Thanks.

In article <bigu91$99dp5$1@ID-69072.news.uni-berlin.de>,
rod_speed@yahoo.com says...

Phil Pierotti <Phil.dot.Pierotti@SoftHome.dot.NET> wrote in message news:MPG.19b6a52f13bdada5989689@news.swiftdsl.com.au...

I guess then I'm essentially SOL looking for an existing
wall-wart, and therefore need to assemble my own.

Yep.

Not knowing anything about assembling power transformer
circuits (or any caveats therein), is it as simple as:

240V wall Socket-> OZ power plug -> cable -
transformer -> cable with appropriate plug for my device?

Yep. Best to use a plastic box so you dont
have to bother with earthing a metal box.

pack it in a project box of suitable size (with ventilation)

That last isnt really necessary.

and have fun?

You forgot the tune for minimum smoke step.

Have fun when ready, Gridly.


In article <bifvoe$8raoo$1@ID-69072.news.uni-berlin.de>,
rod_speed@yahoo.com says...

Phil Pierotti <Phil.dot.Pierotti@SoftHome.dot.NET> wrote in message news:MPG.19b5fa29baa0eec7989688@news.swiftdsl.com.au...

I have a device I bought while in the US which requires
an input of 9VAC@1.5A. The US being the center of the
known universe (and also for the sake of minimizing costs,
I assume) the wall-wart it came with only takes 110V input.

If I tried to plug in a wall-wart with 16VAC@1.5A output, I
assume one part or another in my device will fry quite nicely.

Really depends on the device.

AC wall warts are usually used when the device needs to generate
more than one DC supply internally, like with modems etc.

As such they may not care about the higher AC input, but if its got
a 5V DC internal rail, the regulator to 5V may well get pretty hot
just because its dropping rather more voltage down to 5V.

 

[Duane C. Johnson]

Hi Mien;

Miem Chan <miemchan@yahoo.com> wrote:

I have some solar cells with 1.5v and 2volt outputs.
How can I use these cells to charge 4.8v or 9v NiCd
batteries (without connecting solar cells serially
to produce higher voltages)?

I have never seen normal PV cells with this much
voltage. Usually the silicon cells are about 0.55 volts.
OK, some very exotic semiconductors can but I doubt
that's what you have.

Or maybe you really have a small panel of cells
strung in series already.

Anyway, I have made an inverter that works on single
PV cells. See:
http://www.redrok.com/images/pvcellinv01.gif

Miem Chan
nospam_miemchan@yahoo.com

Duane

--
Home of the $35 Solar Tracker Receiver
http://www.redrok.com/electron.htm#led3X [*]
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