I'm in over my head, would someone kinly throw me a life rin

[Greg Postma]

I don't know enough about electronics/electicity to know if I am in the
correct place to seek some help, but if not, please pardon my intrusion.

In the past, I have help clients locate many diverse (read obscure)
devices,products, vendors, technologies,etc.......

Today,I was asked by a client to help him find an inverter that would
convert a 76vDc input to a 110vAc out put. The current draw would be
about 500ma. I know just enough about electricity to know what an
inverter does, but I've never sourced them before. Thie client has an
EAU of 3-5000 units. I've googled (76vdc invert,etc) and found great
sources for inverters to run the coffemanker while you are driving,
however the device I seek has not been found.

 

[Tom MacIntyre]

On Thu, 28 Apr 2005 17:09:08 -0500, Greg Postma
<gjpostma@comcast.nospam.net> wrote:

I don't know enough about electronics/electicity to know if I am in the
correct place to seek some help, but if not, please pardon my intrusion.

In the past, I have help clients locate many diverse (read obscure)
devices,products, vendors, technologies,etc.......

Today,I was asked by a client to help him find an inverter that would
convert a 76vDc input to a 110vAc out put. The current draw would be
about 500ma. I know just enough about electricity to know what an
inverter does, but I've never sourced them before. Thie client has an
EAU of 3-5000 units. I've googled (76vdc invert,etc) and found great
sources for inverters to run the coffemanker while you are driving,
however the device I seek has not been found.

Did you find this one?

Tom

 

[Norman Webb]

Intrigues me what situation would use 76Vdc (not a multiple of 6, 12, 24
etc)
Is it possible to tap a lower DC voltage and use an off the shelf 12vdc to
110vac inverter.

Regards
Norman

Greg Postma wrote in message ...

I don't know enough about electronics/electicity to know if I am in the
correct place to seek some help, but if not, please pardon my intrusion.

In the past, I have help clients locate many diverse (read obscure)
devices,products, vendors, technologies,etc.......

Today,I was asked by a client to help him find an inverter that would
convert a 76vDc input to a 110vAc out put. The current draw would be
about 500ma. I know just enough about electricity to know what an
inverter does, but I've never sourced them before. Thie client has an
EAU of 3-5000 units. I've googled (76vdc invert,etc) and found great
sources for inverters to run the coffemanker while you are driving,
however the device I seek has not been found.

 

[Tom MacIntyre]

On Thu, 28 Apr 2005 23:52:48 GMT, Tom MacIntyre
<tom__macintyre@hotmail.com> wrote:

On Thu, 28 Apr 2005 17:09:08 -0500, Greg Postma
gjpostma@comcast.nospam.net> wrote:

I don't know enough about electronics/electicity to know if I am in the
correct place to seek some help, but if not, please pardon my intrusion.

In the past, I have help clients locate many diverse (read obscure)
devices,products, vendors, technologies,etc.......

Today,I was asked by a client to help him find an inverter that would
convert a 76vDc input to a 110vAc out put. The current draw would be
about 500ma. I know just enough about electricity to know what an
inverter does, but I've never sourced them before. Thie client has an
EAU of 3-5000 units. I've googled (76vdc invert,etc) and found great
sources for inverters to run the coffemanker while you are driving,
however the device I seek has not been found.

Did you find this one?

Tom

Oops...http://energy.sourceguides.com/businesses/byP/invert/invert.shtml.


Tom

 

[Greg Postma]

Norman Webb wrote:

Intrigues me what situation would use 76Vdc (not a multiple of 6, 12, 24
etc)
Is it possible to tap a lower DC voltage and use an off the shelf 12vdc to
110vac inverter.

Regards
Norman
Ya know, the numbers didn't add up, (but what do I know) so after dinner

I called the guy to get more information. The source of the DC power is
6-12v batteries (in series) so the voltage could be anywhere from 72vDC
(6x12) up to 79.2vDC (6x13.2). He picked 76 volts "cuz it's in the middle".

So knowing what I now know, I'm looking for an inverter that can handle
72-79.2vDC input and 110vAC output. The output current will be about 10
amps @ 110vAC. I hope this cleared this matter up.

Some times a client will ask me for a mouse, so I find him a mouse, ship
him a mouse, bill him for a mouse and then I get a nasty email calling
me names, telling me that I shipped the smallest moose the client has
ever seen. I guess today,I've been looking for mouse when the client
wanted a moose.
Thaks
Greg

 

[Greg Postma]

Tom MacIntyre wrote:

On Thu, 28 Apr 2005 23:52:48 GMT, Tom MacIntyre

Did you find this one?

Tom
Oops...http://energy.sourceguides.com/businesses/byP/invert/invert.shtml.


Tom

Thanks for clarification, Tom. I looking under my keyboard, behind the
monitor , I even looked in the little cup holder that came in the
computer and I couldn't find. <G> But I bet I can now.....

Thanks
Greg

 

[John Smith]

"Greg Postma" <gjpostma@comcast.nospam.net> wrote in message
news:N6SdnYdwMYzQHezfRVn-pw@comcast.com...

Norman Webb wrote:
Intrigues me what situation would use 76Vdc (not a multiple of 6, 12, 24
etc)
Is it possible to tap a lower DC voltage and use an off the shelf 12vdc
to
110vac inverter.

Regards
Norman
Ya know, the numbers didn't add up, (but what do I know) so after dinner
I called the guy to get more information. The source of the DC power is
6-12v batteries (in series) so the voltage could be anywhere from 72vDC
(6x12) up to 79.2vDC (6x13.2). He picked 76 volts "cuz it's in the
middle".

So knowing what I now know, I'm looking for an inverter that can handle
72-79.2vDC input and 110vAC output. The output current will be about 10
amps @ 110vAC. I hope this cleared this matter up.

Some times a client will ask me for a mouse, so I find him a mouse, ship
him a mouse, bill him for a mouse and then I get a nasty email calling
me names, telling me that I shipped the smallest moose the client has
ever seen. I guess today,I've been looking for mouse when the client
wanted a moose.
Thaks
Greg


You said "The current draw would be about 500ma. " and now you're saying

"The output current will be about 10 amps @ 110vAC.". This obviously
doesn't add up.

Besides your spec being ambiguous, just do as others have suggested, and use
one of those 12v batteries: why go from 72V?

 

[John G]

"John Smith" <bill.gates@microsoft.com> wrote in message
news:d4sp53$6n8$1@newstree.wise.edt.ericsson.se...

"Greg Postma" <gjpostma@comcast.nospam.net> wrote in message
news:N6SdnYdwMYzQHezfRVn-pw@comcast.com...
Norman Webb wrote:
Intrigues me what situation would use 76Vdc (not a multiple of 6,
12, 24
etc)
Is it possible to tap a lower DC voltage and use an off the shelf
12vdc
to
110vac inverter.

Regards
Norman
Ya know, the numbers didn't add up, (but what do I know) so after
dinner
I called the guy to get more information. The source of the DC power
is
6-12v batteries (in series) so the voltage could be anywhere from
72vDC
(6x12) up to 79.2vDC (6x13.2). He picked 76 volts "cuz it's in the
middle".

So knowing what I now know, I'm looking for an inverter that can
handle
72-79.2vDC input and 110vAC output. The output current will be about
10
amps @ 110vAC. I hope this cleared this matter up.

Some times a client will ask me for a mouse, so I find him a mouse,
ship
him a mouse, bill him for a mouse and then I get a nasty email
calling
me names, telling me that I shipped the smallest moose the client has
ever seen. I guess today,I've been looking for mouse when the client
wanted a moose.
Thaks
Greg


You said "The current draw would be about 500ma. " and now you're
saying
"The output current will be about 10 amps @ 110vAC.". This obviously
doesn't add up.

Besides your spec being ambiguous, just do as others have suggested,
and use
one of those 12v batteries: why go from 72V?


There was a thread not long ago similar to this.

Is it a need to boil a coffee pot in a train engine that prompts this
requirement.
--
John G

Wot's Your Real Problem?

 

[John Smith]

"John G" <Greentest@ozemail.com.au> wrote in message
news:Ncnce.246$sd7.3635@nnrp1.ozemail.com.au...

"John Smith" <bill.gates@microsoft.com> wrote in message
news:d4sp53$6n8$1@newstree.wise.edt.ericsson.se...

"Greg Postma" <gjpostma@comcast.nospam.net> wrote in message
news:N6SdnYdwMYzQHezfRVn-pw@comcast.com...
Norman Webb wrote:
Intrigues me what situation would use 76Vdc (not a multiple of 6,
12, 24
etc)
Is it possible to tap a lower DC voltage and use an off the shelf
12vdc
to
110vac inverter.

Regards
Norman
Ya know, the numbers didn't add up, (but what do I know) so after
dinner
I called the guy to get more information. The source of the DC power
is
6-12v batteries (in series) so the voltage could be anywhere from
72vDC
(6x12) up to 79.2vDC (6x13.2). He picked 76 volts "cuz it's in the
middle".

So knowing what I now know, I'm looking for an inverter that can
handle
72-79.2vDC input and 110vAC output. The output current will be about
10
amps @ 110vAC. I hope this cleared this matter up.

Some times a client will ask me for a mouse, so I find him a mouse,
ship
him a mouse, bill him for a mouse and then I get a nasty email
calling
me names, telling me that I shipped the smallest moose the client has
ever seen. I guess today,I've been looking for mouse when the client
wanted a moose.
Thaks
Greg


You said "The current draw would be about 500ma. " and now you're
saying
"The output current will be about 10 amps @ 110vAC.". This obviously
doesn't add up.

Besides your spec being ambiguous, just do as others have suggested,
and use
one of those 12v batteries: why go from 72V?


There was a thread not long ago similar to this.
Is it a need to boil a coffee pot in a train engine that prompts this
requirement.
--
John G

Wot's Your Real Problem?

Then go back to steam engines, and just use the fire

 

[Greg Postma]

John Smith wrote:

"Greg Postma" <gjpostma@comcast.nospam.net> wrote in message
news:N6SdnYdwMYzQHezfRVn-pw@comcast.com...

Norman Webb wrote:

Intrigues me what situation would use 76Vdc (not a multiple of 6, 12, 24
etc)
Is it possible to tap a lower DC voltage and use an off the shelf 12vdc

to

110vac inverter.

Regards
Norman

Ya know, the numbers didn't add up, (but what do I know) so after dinner
I called the guy to get more information. The source of the DC power is
6-12v batteries (in series) so the voltage could be anywhere from 72vDC
(6x12) up to 79.2vDC (6x13.2). He picked 76 volts "cuz it's in the

middle".

So knowing what I now know, I'm looking for an inverter that can handle
72-79.2vDC input and 110vAC output. The output current will be about 10
amps @ 110vAC. I hope this cleared this matter up.

Some times a client will ask me for a mouse, so I find him a mouse, ship
him a mouse, bill him for a mouse and then I get a nasty email calling
me names, telling me that I shipped the smallest moose the client has
ever seen. I guess today,I've been looking for mouse when the client
wanted a moose.
Thaks
Greg



You said "The current draw would be about 500ma. " and now you're saying
"The output current will be about 10 amps @ 110vAC.". This obviously
doesn't add up.

Besides your spec being ambiguous, just do as others have suggested, and use
one of those 12v batteries: why go from 72V?

John,

The device I seek is not for me. One of my clients (who has employed my
services many times in the past) asked me to find a source for an
inverter using 76Vdc in and 110Vac out. He said he would need about
500ma. I sent my first plea for help shortly after I spoke with him.
In my second post, I said "Ya know, the numbers didn't add up, (but what
do I know) so after dinner I called the guy to get more information. The
source of the DC power is 6-12v batteries (in series) so the voltage
could be anywhere from 72vDC (6x12) up to 79.2vDC (6x13.2). He picked 76
volts "cuz it's in the middle". After speaking with him,and offering the
same suggestion I received "Just grab 12vDc off one of the batteries and
use a commercial inverter" I was informed that the ONLY source of power
was the 72Vdc. There is no access to any other power.

So.... here we are. I'm still looking for a source of an inverter to go
from 72vDc to 110vAc at about 10 amps. As for the location of where this
is to used, I've got no idea. Could be for making coffee in a locomotive
or powering a microwave oven in the space shuttle for all I know. I
really don't know or care what my clients do with the products I locate,
design or manufacture. Like wise, I don't care what they do with
information I provide when I am doing basic research..... It's really
nunna my business.....

Hope I didn't sound ungrateful for the suggestions made by the group and
I also hope that I didn't sound snobbish or boorish. I just thought
that this project would be simple and it is starting to seem like the
wheel has to be re-invented<g>.

So if any of you kind, bright, energetic, good looking folks have any
ideas that might help locate this elusive "grail" I would be most thankful.

TIA
Greg

 

[John Fields]

On Fri, 29 Apr 2005 14:40:36 -0500, Greg Postma
<gjpostma@comcast.nospam.net> wrote:

The device I seek is not for me. One of my clients (who has employed my
services many times in the past) asked me to find a source for an
inverter using 76Vdc in and 110Vac out. He said he would need about
500ma. I sent my first plea for help shortly after I spoke with him.
In my second post, I said "Ya know, the numbers didn't add up, (but what
do I know) so after dinner I called the guy to get more information. The
source of the DC power is 6-12v batteries (in series) so the voltage
could be anywhere from 72vDC (6x12) up to 79.2vDC (6x13.2). He picked 76
volts "cuz it's in the middle". After speaking with him,and offering the
same suggestion I received "Just grab 12vDc off one of the batteries and
use a commercial inverter" I was informed that the ONLY source of power
was the 72Vdc. There is no access to any other power.

So.... here we are. I'm still looking for a source of an inverter to go
from 72vDc to 110vAc at about 10 amps. As for the location of where this
is to used, I've got no idea. Could be for making coffee in a locomotive
or powering a microwave oven in the space shuttle for all I know. I
really don't know or care what my clients do with the products I locate,
design or manufacture. Like wise, I don't care what they do with
information I provide when I am doing basic research..... It's really
nunna my business.....

Hope I didn't sound ungrateful for the suggestions made by the group and
I also hope that I didn't sound snobbish or boorish. I just thought
that this project would be simple and it is starting to seem like the
wheel has to be re-invented<g>.

So if any of you kind, bright, energetic, good looking folks have any
ideas that might help locate this elusive "grail" I would be most thankful.

---
What I find problematical is that you orginally asked for 500mA and
now it's up to 10 amps, and no mention has been made as to the output
frequency, frequency stability, or output waveform required.

--
John Fields
Professional Circuit Designer

 

[Greg Postma]

John Fields wrote:

What I find problematical is that you orginally asked for 500mA and
now it's up to 10 amps, and no mention has been made as to the output
frequency, frequency stability, or output waveform required.

John, You are correct, originally I asked for 500mA and then after
further questioning of my client, I learned that he misspoke. His
initial request for 500mA will not meet the needs of his project. After
discussion, he informed me that his needs are more like 5-6 amps and I
made the call for 10amps as a safety factor.

So the requirements for the device are nominal 72vDc in, nominal 110vAc
60hertz out, with a capacity of 10amps out. I hope that this clarifies
the needs of this project.

Thanks for your patience
Greg

 

[John Fields]

On Fri, 29 Apr 2005 18:21:25 -0500, Greg Postma
<gjpostma@comcast.nospam.net> wrote:

John Fields wrote:

What I find problematical is that you orginally asked for 500mA and
now it's up to 10 amps, and no mention has been made as to the output
frequency, frequency stability, or output waveform required.

John, You are correct, originally I asked for 500mA and then after
further questioning of my client, I learned that he misspoke. His
initial request for 500mA will not meet the needs of his project. After
discussion, he informed me that his needs are more like 5-6 amps and I
made the call for 10amps as a safety factor.

So the requirements for the device are nominal 72vDc in, nominal 110vAc
60hertz out, with a capacity of 10amps out. I hope that this clarifies
the needs of this project.

---
Almost. Does he need a sinewave output or can he settle for a modified
sinewave or a square wave?

Also, and I apologize for not asking earlier, does your client have
efficiency constraints?

--
John Fields
Professional Circuit Designer

 

[Wayne]

Another "gotcha" to consider. You should also find out if the DC supply
(battery bank) is big enough to power your inverter for the required amount
of time, whatever that is. This is a simplified version of a more
complicated question, but you need to know how long the AC device will
demand current. If the load is 1 Amp for 24 hours, this requires a minimum
24 Amp-hour set of batteries. In this scenario, 12 Amp-hour batteries would
not hold enough charge to power the system for the required time.

 

[Rich Grise]

On Fri, 29 Apr 2005 19:34:35 +1000, John G wrote:

"John Smith" <bill.gates@microsoft.com> wrote in message
"Greg Postma" <gjpostma@comcast.nospam.net> wrote in message
Norman Webb wrote:
Intrigues me what situation would use 76Vdc (not a multiple of 6,
12, 24
etc)
Is it possible to tap a lower DC voltage and use an off the shelf
12vdc
to
110vac inverter.

....
Besides your spec being ambiguous, just do as others have suggested,
and use
one of those 12v batteries: why go from 72V?

There was a thread not long ago similar to this.
Is it a need to boil a coffee pot in a train engine that prompts this
requirement.

Then either:
A: Hack the coffee pot to run off 72-79VDC
B: Get three more 12V batteries, put them in series, and in series
with the 72V, for 108-120 VDC and run the coffeepot on DC.

Cheers!
Rich

 

[Greg Postma]

Ya know, I think I like this group<G>
Very Innovative thinking........
I mentioned this idea to my client and after he stopped laughing like
fool, he said he thought that I'd come up with a solution like a 3000
milealong extension cord.....
But I like your idea better Rich
Thanks
Greg

There was a thread not long ago similar to this.
Is it a need to boil a coffee pot in a train engine that prompts this
requirement.


Then either:
A: Hack the coffee pot to run off 72-79VDC
B: Get three more 12V batteries, put them in series, and in series
with the 72V, for 108-120 VDC and run the coffeepot on DC.

Cheers!
Rich

 

[Dr Engelbert Buxbaum]

Greg Postma wrote:

Ya know, the numbers didn't add up, (but what do I know) so after dinner
I called the guy to get more information. The source of the DC power is
6-12v batteries (in series) so the voltage could be anywhere from 72vDC
(6x12) up to 79.2vDC (6x13.2). He picked 76 volts "cuz it's in the

Would it be possible to tab in between the battery pile and use a
standard 12 or 24 V converter. Probably a lot cheaper than something
crafted for a specific application.

In addition, 10 A at 110 V is quite a bit of power to sustain from batts
for any length of time. Even with 76 V input, taking into account the
inevitable losses (converters usually have efficiencies of 70-80%), he
will load the battery with almost 20 A. Your client will need rather
large batts and thick cable, too.

 

[Rich Grise]

On Sat, 07 May 2005 06:52:54 +0200, Dr Engelbert Buxbaum wrote:

Greg Postma wrote:

Ya know, the numbers didn't add up, (but what do I know) so after dinner
I called the guy to get more information. The source of the DC power is
6-12v batteries (in series) so the voltage could be anywhere from 72vDC
(6x12) up to 79.2vDC (6x13.2). He picked 76 volts "cuz it's in the

Would it be possible to tab in between the battery pile and use a
standard 12 or 24 V converter. Probably a lot cheaper than something
crafted for a specific application.

In addition, 10 A at 110 V is quite a bit of power to sustain from batts
for any length of time. Even with 76 V input, taking into account the
inevitable losses (converters usually have efficiencies of 70-80%), he
will load the battery with almost 20 A. Your client will need rather
large batts and thick cable, too.

It's a train.

Cheers!
Rich