Small Dc-Dc converter

P

Paul Jones

Guest
Hi everyone,

I'm trying to build a high voltage (170v) H bridge motor driver but I've
run into a bit of bother trying to reduce the voltage to something that
the opto coupler and mosfets can handle. I don't want to use a
transformer because it's too big, and I only need enough current to
drive two opto isolators and two mosfets at the same time (50mA?).
Everything I have come up with wants to consume more power than 1w
resistors and zenner diodes can handle.

Any suggestions?


Paul.
 
On Wed, 09 Feb 2005 15:43:45 +1100, Paul Jones <wiseguy@iinet.net.au>
wrote:

Hi everyone,

I'm trying to build a high voltage (170v) H bridge motor driver but I've
run into a bit of bother trying to reduce the voltage to something that
the opto coupler and mosfets can handle. I don't want to use a
transformer because it's too big, and I only need enough current to
drive two opto isolators and two mosfets at the same time (50mA?).
Everything I have come up with wants to consume more power than 1w
resistors and zenner diodes can handle.

Any suggestions?


Paul.
Click to expand...
Hello Paul,
I am guessing that you are looking for small isolated supplies
where the output of the DC supply can be tied to the two high
side fets of the H bridge.
Are these small DC to DC convertors at several dollars each
the sort of thing you are looking for.
http://www.computronics.com.au/meanwell/srs/

Just out of curiosity, can you tell us about your project?

Regards,
John Crighton
Hornsby
 
Paul Jones <wiseguy@iinet.net.au> wrote:
Hi everyone,

I'm trying to build a high voltage (170v) H bridge motor driver but I've
run into a bit of bother trying to reduce the voltage to something that
the opto coupler and mosfets can handle. I don't want to use a
transformer because it's too big, and I only need enough current to
drive two opto isolators and two mosfets at the same time (50mA?).
Everything I have come up with wants to consume more power than 1w
resistors and zenner diodes can handle.

Any suggestions?


Paul.
Click to expand...
A SMPS? Linear Technology make some great chips in which you can build
around. Throw in a few passives and two mosfets and you have a PS.

I've used them in many projects myself.

--

Wing Wong.
Webpage: http://wing.ucc.asn.au
 
John Crighton wrote:
On Wed, 09 Feb 2005 15:43:45 +1100, Paul Jones <wiseguy@iinet.net.au
wrote:

Hi everyone,

I'm trying to build a high voltage (170v) H bridge motor driver but
I've run into a bit of bother trying to reduce the voltage to
something that the opto coupler and mosfets can handle. I don't want
to use a transformer because it's too big, and I only need enough
current to drive two opto isolators and two mosfets at the same time
(50mA?). Everything I have come up with wants to consume more power
than 1w resistors and zenner diodes can handle.

Any suggestions?


Paul.

Hello Paul,
I am guessing that you are looking for small isolated supplies
where the output of the DC supply can be tied to the two high
side fets of the H bridge.
Are these small DC to DC convertors at several dollars each
the sort of thing you are looking for.
http://www.computronics.com.au/meanwell/srs/

Just out of curiosity, can you tell us about your project?
Click to expand...
170v DC? Killer Robot for sure.
 
John Crighton wrote:

Hello Paul,
I am guessing that you are looking for small isolated supplies
where the output of the DC supply can be tied to the two high
side fets of the H bridge.
Are these small DC to DC convertors at several dollars each
the sort of thing you are looking for.
http://www.computronics.com.au/meanwell/srs/

Just out of curiosity, can you tell us about your project?
Click to expand...
It's an industrial DC motor controller for a water pipe rolling-up
machine. The motor is used to move a swinging arm back and forward to
make the pipe roll up evenly on the reel.


Thanks everyone for your suggestions!
 
"Paul Jones"
It's an industrial DC motor controller for a water pipe rolling-up
machine. The motor is used to move a swinging arm back and forward to make
the pipe roll up evenly on the reel.
Click to expand...
** So what makes a 1 or 2 VA transformer too big ?

Quote: " I don't want to use a transformer because it's too big, ... "

Farnell have a range of them - a 1 VA is 32 x 27 x 22 mm , weighs 72
gms and costs $9.91 + gst.






.............. Phil
 
Phil Allison wrote:
"Paul Jones"

It's an industrial DC motor controller for a water pipe rolling-up
machine. The motor is used to move a swinging arm back and forward to make
the pipe roll up evenly on the reel.



** So what makes a 1 or 2 VA transformer too big ?

Quote: " I don't want to use a transformer because it's too big, ... "

Farnell have a range of them - a 1 VA is 32 x 27 x 22 mm , weighs 72
gms and costs $9.91 + gst.
Click to expand...
Sounds fine to me. I've never seen one that small before.
 
"Paul Jones"
Phil Allison wrote:
"Paul Jones"

It's an industrial DC motor controller for a water pipe rolling-up
machine. The motor is used to move a swinging arm back and forward to
make the pipe roll up evenly on the reel.



** So what makes a 1 or 2 VA transformer too big ?

Quote: " I don't want to use a transformer because it's too big, ... "

Farnell have a range of them - a 1 VA is 32 x 27 x 22 mm , weighs 72
gms and costs $9.91 + gst.

Sounds fine to me. I've never seen one that small before.
Click to expand...


** Pays to check the odd catalogue once in few years.

1 VA trannies have been on sale for decades.





............. Phil
 
Sure you dont mean KVA?

David

Phil Allison wrote:

"Paul Jones"

It's an industrial DC motor controller for a water pipe rolling-up
machine. The motor is used to move a swinging arm back and forward to make
the pipe roll up evenly on the reel.


** So what makes a 1 or 2 VA transformer too big ?

Quote: " I don't want to use a transformer because it's too big, ... "

Farnell have a range of them - a 1 VA is 32 x 27 x 22 mm , weighs 72
gms and costs $9.91 + gst.

............. Phil
Click to expand...
 
"quietguy" ...
Sure you dont mean KVA?
Click to expand...

** Someone did not read the thread or the heading.

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


David

Phil Allison wrote:

"Paul Jones"

It's an industrial DC motor controller for a water pipe rolling-up
machine. The motor is used to move a swinging arm back and forward to
make
the pipe roll up evenly on the reel.


** So what makes a 1 or 2 VA transformer too big ?

Quote: " I don't want to use a transformer because it's too big, ... "

Farnell have a range of them - a 1 VA is 32 x 27 x 22 mm , weighs 72
gms and costs $9.91 + gst.

............. Phil
Click to expand...
 
The guy asked for advice. Not intimidation.
"Phil Allison" <philallison@tpg.com.au> wrote in message
news:370lt5F55a4jnU1@individual.net...
"Paul Jones"
Phil Allison wrote:
"Paul Jones"

It's an industrial DC motor controller for a water pipe rolling-up
machine. The motor is used to move a swinging arm back and forward to
make the pipe roll up evenly on the reel.



** So what makes a 1 or 2 VA transformer too big ?

Quote: " I don't want to use a transformer because it's too big, ...
"

Farnell have a range of them - a 1 VA is 32 x 27 x 22 mm , weighs
72 gms and costs $9.91 + gst.

Sounds fine to me. I've never seen one that small before.



** Pays to check the odd catalogue once in few years.

1 VA trannies have been on sale for decades.





............ Phil
Click to expand...
 
"thegoons" <thegoons@bigpond.com> wrote in message
news:377gv7F598qteU1@individual.net...
The guy asked for advice. Not intimidation.
Click to expand...

** Nobody needs top posting shithead like you.

Piss off.

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


"Phil Allison" <philallison@tpg.com.au> wrote in message
news:370lt5F55a4jnU1@individual.net...

"Paul Jones"
Phil Allison wrote:
"Paul Jones"

It's an industrial DC motor controller for a water pipe rolling-up
machine. The motor is used to move a swinging arm back and forward to
make the pipe roll up evenly on the reel.



** So what makes a 1 or 2 VA transformer too big ?

Quote: " I don't want to use a transformer because it's too big, ...
"

Farnell have a range of them - a 1 VA is 32 x 27 x 22 mm , weighs
72 gms and costs $9.91 + gst.

Sounds fine to me. I've never seen one that small before.



** Pays to check the odd catalogue once in few years.

1 VA trannies have been on sale for decades.





............ Phil
Click to expand...
 
"Matthew Gunn" <matthewgunn_au@hotmail.com
Hey, I may get shot down for this but what is wrong with posting at the
top of the other messages?
Click to expand...


** Use "top posting" as a Google search heading - then read what it
finds.

Grow up anytime.





............... Phil
 
"Matthew Gunn" <matthewgunn_au@hotmail.com
Phil Allison wrote:

Hey, I may get shot down for this but what is wrong with posting at the
top of the other messages?



** Use "top posting" as a Google search heading - then read what it
finds.

Grow up anytime.



Why send me looking elsewhere for an answer?
Click to expand...

** Cos that is where the best answer is to be found.


And don't tell me to grow up,
Click to expand...

** Grow up.

I asked a perfectly valid question
Click to expand...

** And I posted a serious and valid reply.


and if you have a problem with "top posting" I would like to hear what it
is, from you personally.
Click to expand...

** Just keep holding your breath till you go blue in the face.

That's what brats usually do.





................ Phil
 
"Matthew Gunn" <matthewgunn_au@hotmail.com> wrote in message
news:421027fa@quokka.wn.com.au...
You are rude and ignorant.

Phil Allison wrote:
"Matthew Gunn" <matthewgunn_au@hotmail.com

Phil Allison wrote:


Hey, I may get shot down for this but what is wrong with posting at
the
top of the other messages?

** Use "top posting" as a Google search heading - then read what it
finds.

Grow up anytime.




Why send me looking elsewhere for an answer?



** Cos that is where the best answer is to be found.



And don't tell me to grow up,



** Grow up.


I asked a perfectly valid question



** And I posted a serious and valid reply.



and if you have a problem with "top posting" I would like to hear what
it
is, from you personally.



** Just keep holding your breath till you go blue in the face.

That's what brats usually do.





............... Phil
Click to expand...
Hi Matthew,

Welcome to aus.electronics and the oh so delightful and welcoming replies
and remarks from our resident newsgroup insulter extraordinaire Phil
Allison.

Phil doesn't know the meaning of the word "subtle", so expect numerous
caustic remarks from him. Regulars automatically put on our rhinoceros
hides and flame suits just in case PA drops by, which unfortunately is far
too frequently.

Stick around for a bit longer and before too long you will get to experience
a lot more of Phil's unique form of hospitality. Phil believes he is the
first and last word in newsgroup etiquette. For some choice samples of his
unique style visit
http://members.iinet.net.au/~rutlidge/alanindex.html

For a view of the T-shirt dedicated to PA look here
http://members.iinet.net.au/~rutlidge/PA.jpg

BTW it isn't Phil in the pic. Phil's way too old.

Cheers,
Alan
 
Matthew Gunn wrote:
I still don't get what the problem is with "top posting". To me, it
makes sense if you have already been following a thread you don't want
to have to scroll down to bottom of every message just to read what
someone has added.
Click to expand...
How does the reader know who you are replying to? If they come back to a
thread, having marked half of the messages read, bottom posting gives
them the sequence of conversation leading to your remark. Bottom posting
also encourages idiots to trim quoted text from their replies when it is
not needed and simply a waste of bandwidth!

Cheers,
Nicholas Sherlock
 
Hey, I may get shot down for this but what is wrong with posting at the
top of the other messages?

Phil Allison wrote:
"thegoons" <thegoons@bigpond.com> wrote in message
news:377gv7F598qteU1@individual.net...

The guy asked for advice. Not intimidation.



** Nobody needs top posting shithead like you.

Piss off.

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



"Phil Allison" <philallison@tpg.com.au> wrote in message
news:370lt5F55a4jnU1@individual.net...

"Paul Jones"

Phil Allison wrote:

"Paul Jones"


It's an industrial DC motor controller for a water pipe rolling-up
machine. The motor is used to move a swinging arm back and forward to
make the pipe roll up evenly on the reel.



** So what makes a 1 or 2 VA transformer too big ?

Quote: " I don't want to use a transformer because it's too big, ...
"

Farnell have a range of them - a 1 VA is 32 x 27 x 22 mm , weighs
72 gms and costs $9.91 + gst.

Sounds fine to me. I've never seen one that small before.



** Pays to check the odd catalogue once in few years.

1 VA trannies have been on sale for decades.





............ Phil
Click to expand...
 
"Wing Fong Wong" <wing@ta.com.au> wrote in message
news:cuppar$48a$1@enyo.uwa.edu.au...
"Alan Rutlidge" <rutlidge@ <No_Spam>.iinet.net.au> wrote:

BTW it isn't Phil in the pic. Phil's way too old.

So... is it you?
Click to expand...
No, I don't have Tourette's syndrome, and it isn't me either. :)

Surely you have been posting here long enough to see the humour? :)

Cheers,
Alan

--

Wing Wong.
Webpage: http://wing.ucc.asn.au
Click to expand...
 
"Alan Rutlidge" <rutlidge@ <No_Spam>.iinet.net.au> wrote:
BTW it isn't Phil in the pic. Phil's way too old.
Click to expand...
So... is it you?

--

Wing Wong.
Webpage: http://wing.ucc.asn.au
 
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