problem with grounds

L

lerameur

Guest
Hello

I posted a simple circuit up on
http://www3.sympatico.ca/captoro/motor/design1.gif
I am having difficulty seperating the grounds. My final circuit is
much more complex, it may look trivial at first, but I absolutely need
to seperate the grounds. IN the simulator they are the same ground.
But my 30 v source comes from a separate circuit, therefore do not
activate the N-mosfet (no common ground). I need to figure out a way
to put 30v on the mosfet so that the rest of the circuit shown sees it
and operate the way it is showing.
I thought about adding opto couplers, but I will still have the
problem of finding 30v on the other side of the circuit to activate
the mosfets,( where the maximum volt is 24v). And no I cannot combine
the 24v and 12v.
anyone has any ideas?

thank you

K
 
On 2008-09-21, lerameur <lerameur@yahoo.com> wrote:
Hello

I posted a simple circuit up on
http://www3.sympatico.ca/captoro/motor/design1.gif
I am having difficulty seperating the grounds. My final circuit is
much more complex, it may look trivial at first, but I absolutely need
to seperate the grounds.
Click to expand...
If you do that what you have drawn will not work. (but then what you
have drawn makes no sense whatsoever) - possibly some of the MOSFETs are
backwards?

redraw your circuit so that it is understandable.

put the the parts that are referenced to one ground on one side and
those referenced to the other on the other side , and make a line down
the middle that indicates where you want isolate it.

IN the simulator they are the same ground.
But my 30 v source comes from a separate circuit, therefore do not
activate the N-mosfet (no common ground). I need to figure out a way
to put 30v on the mosfet so that the rest of the circuit shown sees it
and operate the way it is showing.
Click to expand...
M2 and M8 appear to be backwards,
only 6v of gate drive is available on M8 is that enough?

I thought about adding opto couplers, but I will still have the
problem of finding 30v on the other side of the circuit to activate
the mosfets,( where the maximum volt is 24v). And no I cannot combine
the 24v and 12v.
anyone has any ideas?
Click to expand...
To get +30V where you have only +24V stand an isolated 6V supply on top
of the 24V supply.


look at using mosfet drivers.

Bye.
Jasen
 
On Sun, 21 Sep 2008 06:49:56 -0700 (PDT), lerameur <lerameur@yahoo.com>
wrote:

If you do that what you have drawn will not work. (but then what you
have drawn makes no sense whatsoever) - possibly some of the MOSFETs are
backwards?
NO not backward, I need them this way. As you can see they are in saturation mode,
they can conduct both ways, It works in the simulation.
Click to expand...
---
If they conduct both ways, how do you turn them off? ;)
---

redraw your circuit so that it is understandable.


I dont know how much simpler I can put it. I clearly put the two
isolation part 'ground 1 and ground 2'

unless I do not understand exactly what you mean.
Click to expand...
---
I think he means that your circuit makes no sense. It makes no sense to
me either.

What are you trying to do, exactly?
---

Also the ground two should not even be there in practice, I just need
it in the simulation.
I think the HT04 might work, it is driving at high voltage and it has
a second output for forcing a reference point.
I will try this
Click to expand...
---
Good luck.

JF
 
On Sun, 21 Sep 2008 08:13:20 -0700 (PDT), lerameur <lerameur@yahoo.com>
wrote:

On Sep 21, 10:39 am, John Fields <jfie...@austininstruments.com
wrote:
On Sun, 21 Sep 2008 06:49:56 -0700 (PDT), lerameur <leram...@yahoo.com
wrote:



If you do that what you have drawn will not work. (but then what you
have drawn makes no sense whatsoever) - possibly some of the MOSFETs are
backwards?
NO not backward, I need them this way. As you can see they are in saturation mode,
they can conduct both ways, It works in the simulation.

---
If they conduct both ways, how do you turn them off? ;)
---

redraw your circuit so that it is understandable.

I dont know how much simpler I can put it.  I clearly put the two
isolation part 'ground 1 and ground 2'

unless I do not understand exactly what you mean.

---
I think he means that your circuit makes no sense.  It makes no sense to
me either.

What are you trying to do, exactly?
---

Also the ground two should not even be there in practice, I just need
it in the simulation.
I think the HT04  might work, it is driving at high voltage and it has
a second output for forcing a reference point.
I will try this

---
Good luck.

JF

John,

here is a circuit with reverse mosfet:
http://www3.sympatico.ca/captoro/motor/design2.gif
as you can see, they can conduct both ways

here is a circuit when it is turned off
http://www3.sympatico.ca/captoro/motor/design3.gif

Those 30 volt supplies on the diagram are actually coming from a
separate circuit
so it is a circuit like this one:
http://www3.sympatico.ca/captoro/motor/design4.gif.

hope this is clearer
Click to expand...
---
Not really.

What I meant by: "What are you trying to do, exactly?"

was more like "What's your application?" It sounds like you're trying
to PWM a motor in both the forward and reverse directions. Am I right?

If not, what is it you want to do?

JF
 
If you do that what you have drawn will not work. (but then what you
have drawn makes no sense whatsoever) - possibly some of the MOSFETs are
backwards?
NO not backward, I need them this way. As you can see they are in saturation mode, they can conduct both ways, It works in the simulation

redraw your circuit so that it is understandable.
Click to expand...
I dont know how much simpler I can put it. I clearly put the two
isolation part 'ground 1 and ground 2'

unless I do not understand exactly what you mean.

Also the ground two should not even be there in practice, I just need
it in the simulation.
I think the HT04 might work, it is driving at high voltage and it has
a second output for forcing a reference point.
I will try this

K
 
On Sep 21, 10:39 am, John Fields <jfie...@austininstruments.com>
wrote:
On Sun, 21 Sep 2008 06:49:56 -0700 (PDT), lerameur <leram...@yahoo.com
wrote:



If you do that what you have drawn will not work. (but then what you
have drawn makes no sense whatsoever) - possibly some of the MOSFETs are
backwards?
NO not backward, I need them this way. As you can see they are in saturation mode,
they can conduct both ways, It works in the simulation.

---
If they conduct both ways, how do you turn them off? ;)
---

redraw your circuit so that it is understandable.

I dont know how much simpler I can put it.  I clearly put the two
isolation part 'ground 1 and ground 2'

unless I do not understand exactly what you mean.

---
I think he means that your circuit makes no sense.  It makes no sense to
me either.

What are you trying to do, exactly?
---

Also the ground two should not even be there in practice, I just need
it in the simulation.
I think the HT04  might work, it is driving at high voltage and it has
a second output for forcing a reference point.
I will try this

---
Good luck.

JF
Click to expand...
John,

here is a circuit with reverse mosfet:
http://www3.sympatico.ca/captoro/motor/design2.gif
as you can see, they can conduct both ways

here is a circuit when it is turned off
http://www3.sympatico.ca/captoro/motor/design3.gif

Those 30 volt supplies on the diagram are actually coming from a
separate circuit
so it is a circuit like this one:
http://www3.sympatico.ca/captoro/motor/design4.gif.

hope this is clearer

k
 
On Sun, 21 Sep 2008 09:32:10 -0700 (PDT), lerameur <lerameur@yahoo.com>
wrote:

On Sep 21, 11:42 am, John Fields <jfie...@austininstruments.com
wrote:

What I meant by: "What are you trying to do, exactly?"

was more like "What's your application?"  It sounds like you're trying
to PWM a motor in both the forward and reverse directions.  Am I right?

If not, what is it you want to do?

JF

Hi John,

I want to use the mosfet as relays. Once they are switch, the current
can flow in either direction.
Click to expand...
---
That's not true.

For an "N" channel enhancement mode MOSFET, the gate voltage must be
positive with respect to the source voltage in order for the channel to
be enhanced. What you're seeing if you're reversing the polarity of the
supply is charge flowing anode-to-cathode through the internal Zener.
---

I have a solar panel array with multiple
batteries, I am trying to come up with a way with a microcontroller
can change only the batteries that are the at their lowest. The whole
project is huge, I reduced it down to this circuit, if I can do it on
this circuit then what want to do will work.
Click to expand...
---
"Change" or "charge?"

I still don't fully understand what you want to do or how you want to do
it.

Instead of a schematic, can you sketch a block diagram of how many
batteries you have and how you want to connect/disconnect them from the
load(s) and the solar array?

JF
 
On Sep 21, 11:42 am, John Fields <jfie...@austininstruments.com>
wrote:
On Sun, 21 Sep 2008 08:13:20 -0700 (PDT), lerameur <leram...@yahoo.com
wrote:



On Sep 21, 10:39 am, John Fields <jfie...@austininstruments.com
wrote:
On Sun, 21 Sep 2008 06:49:56 -0700 (PDT), lerameur <leram...@yahoo.com
wrote:

If you do that what you have drawn will not work. (but then what you
have drawn makes no sense whatsoever) - possibly some of the MOSFETs are
backwards?
NO not backward, I need them this way. As you can see they are in saturation mode,
they can conduct both ways, It works in the simulation.

---
If they conduct both ways, how do you turn them off? ;)
---

redraw your circuit so that it is understandable.

I dont know how much simpler I can put it.  I clearly put the two
isolation part 'ground 1 and ground 2'

unless I do not understand exactly what you mean.

---
I think he means that your circuit makes no sense.  It makes no sense to
me either.

What are you trying to do, exactly?
---

Also the ground two should not even be there in practice, I just need
it in the simulation.
I think the HT04  might work, it is driving at high voltage and it has
a second output for forcing a reference point.
I will try this

---
Good luck.

JF

John,

here is a circuit with reverse mosfet:
http://www3.sympatico.ca/captoro/motor/design2.gif
as you can see, they can conduct both ways

here is a circuit when it is turned off
http://www3.sympatico.ca/captoro/motor/design3.gif

Those 30 volt supplies on the diagram are actually coming from a
separate circuit
so it is a circuit like this one:
http://www3.sympatico.ca/captoro/motor/design4.gif.

hope this is clearer

---
Not really.

What I meant by: "What are you trying to do, exactly?"

was more like "What's your application?"  It sounds like you're trying
to PWM a motor in both the forward and reverse directions.  Am I right?

If not, what is it you want to do?

JF
Click to expand...
Hi John,

I want to use the mosfet as relays. Once they are switch, the current
can flow in either direction. I have a solar panel array with multiple
batteries, I am trying to come up with a way with a microcontroller
can change only the batteries that are the at their lowest. The whole
project is huge, I reduced it down to this circuit, if I can do it on
this circuit then what want to do will work.

k
 
On Sep 21, 1:14 pm, John Fields <jfie...@austininstruments.com> wrote:
On Sun, 21 Sep 2008 09:32:10 -0700 (PDT), lerameur <leram...@yahoo.com
wrote:

On Sep 21, 11:42 am, John Fields <jfie...@austininstruments.com
wrote:
What I meant by: "What are you trying to do, exactly?"

was more like "What's your application?"  It sounds like you're trying
to PWM a motor in both the forward and reverse directions.  Am I right?

If not, what is it you want to do?

JF

Hi John,

I want to use the mosfet as relays. Once they are switch, the current
can flow in either direction.

---
That's not true.

For an "N" channel enhancement mode MOSFET, the gate voltage must be
positive with respect to the source voltage in order for the channel to
be enhanced.  What you're seeing if you're reversing the polarity of the
supply is charge flowing anode-to-cathode through the internal Zener.
---

I have a solar panel array with multiple
batteries, I am trying to come up with a way with a microcontroller
can change only the batteries that are the at their lowest. The whole
project is huge, I reduced it down to this circuit, if I can do it on
this circuit then what want to do will work.

---
"Change" or "charge?"

I still don't fully understand what you want to do or how you want to do
it.

Instead of a schematic, can you sketch a block diagram of how many
batteries you have and how you want to connect/disconnect them from the
load(s) and the solar array?

JF
Click to expand...
I will make one by hand, but I will need to be at work to scan and put
it in a pdf.

but if you look at design1 Vs design2, I reversed the drain and source
and it proves that I am able to conduct both ways, I guess because
the mosfet are in saturation in both conditions with the gate at 30v.

wouldn<t the HT0440 work?
what do you think about this chip?

k
 
On 2008-09-21, lerameur <lerameur@yahoo.com> wrote:
here is a circuit with reverse mosfet:
http://www3.sympatico.ca/captoro/motor/design2.gif
as you can see, they can conduct both ways

here is a circuit when it is turned off
http://www3.sympatico.ca/captoro/motor/design3.gif
Click to expand...
but that one's forwards.

Those 30 volt supplies on the diagram are actually coming from a
separate circuit
so it is a circuit like this one:
http://www3.sympatico.ca/captoro/motor/design4.gif.
Click to expand...
no. that image doesn't display.

--

Bye.
Jasen
 
On Sun, 21 Sep 2008 11:29:13 -0700 (PDT), lerameur <lerameur@yahoo.com>
wrote:

On Sep 21, 1:14 pm, John Fields <jfie...@austininstruments.com> wrote:
On Sun, 21 Sep 2008 09:32:10 -0700 (PDT), lerameur <leram...@yahoo.com
wrote:

On Sep 21, 11:42 am, John Fields <jfie...@austininstruments.com
wrote:
What I meant by: "What are you trying to do, exactly?"

was more like "What's your application?"  It sounds like you're trying
to PWM a motor in both the forward and reverse directions.  Am I right?

If not, what is it you want to do?

JF

Hi John,

I want to use the mosfet as relays. Once they are switch, the current
can flow in either direction.

---
That's not true.

For an "N" channel enhancement mode MOSFET, the gate voltage must be
positive with respect to the source voltage in order for the channel to
be enhanced.  What you're seeing if you're reversing the polarity of the
supply is charge flowing anode-to-cathode through the internal Zener.
---

I have a solar panel array with multiple
batteries, I am trying to come up with a way with a microcontroller
can change only the batteries that are the at their lowest. The whole
project is huge, I reduced it down to this circuit, if I can do it on
this circuit then what want to do will work.

---
"Change" or "charge?"

I still don't fully understand what you want to do or how you want to do
it.

Instead of a schematic, can you sketch a block diagram of how many
batteries you have and how you want to connect/disconnect them from the
load(s) and the solar array?

JF

I will make one by hand, but I will need to be at work to scan and put
it in a pdf.

but if you look at design1 Vs design2, I reversed the drain and source
and it proves that I am able to conduct both ways, I guess because
the mosfet are in saturation in both conditions with the gate at 30v.

wouldn<t the HT0440 work?
what do you think about this chip?
Click to expand...
---
Looks interesting, but I'll reserve judgment until I see your block
diagram. :)

JF
 
On Sun, 21 Sep 2008 09:32:10 -0700 (PDT), lerameur
<lerameur@yahoo.com> wrote:


Hi John,

I want to use the mosfet as relays. Once they are switch, the current
can flow in either direction. I have a solar panel array with multiple
batteries, I am trying to come up with a way with a microcontroller
can change only the batteries that are the at their lowest. The whole
project is huge, I reduced it down to this circuit, if I can do it on
this circuit then what want to do will work.

k
Click to expand...
Why do you want to do this? Why not just connect all the batteries in
parallel - this will minimised depth-of-discharge on all batteries,
and remove a lot of unneeded complexity. Then all batteries will be
charged and discharged simultaneously. There is no law requiring you
to disconnect all loads from a battery while you are charging it.

--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca
 
On 2008-09-21, lerameur <lerameur@yahoo.com> wrote:
On Sep 21, 5:25 pm, Jasen Betts <ja...@xnet.co.nz> wrote:
On 2008-09-21, lerameur <leram...@yahoo.com> wrote:

here is a circuit with reverse mosfet:
http://www3.sympatico.ca/captoro/motor/design2.gif
as you can see, they can conduct both ways

here is a circuit when it is turned off
http://www3.sympatico.ca/captoro/motor/design3.gif

but that one's forwards.

Those 30 volt supplies on the diagram are actually coming from a
separate circuit
so it is a circuit like this one:
http://www3.sympatico.ca/captoro/motor/design4.gif.

no. that image doesn't display.

--

Bye.
   Jasen

I just tried the link now, it works, Tell me if its still do not work.
Click to expand...
no. still doesnt work, but I figured out why:.

why do you want 30V on the M6 and M2 gates, 22V should be enough on M6
and 10V on M2

why do you need M8 at all? can you move it?
 
On Sep 21, 5:25 pm, Jasen Betts <ja...@xnet.co.nz> wrote:
On 2008-09-21, lerameur <leram...@yahoo.com> wrote:

here is a circuit with reverse mosfet:
http://www3.sympatico.ca/captoro/motor/design2.gif
as you can see, they can conduct both ways

here is a circuit when it is turned off
http://www3.sympatico.ca/captoro/motor/design3.gif

but that one's forwards.

Those 30 volt supplies on the diagram are actually coming from a
separate circuit
so it is a circuit like this one:
http://www3.sympatico.ca/captoro/motor/design4.gif.

no. that image doesn't display.

--

Bye.
   Jasen
Click to expand...
I just tried the link now, it works, Tell me if its still do not work.

k
 
On Sep 21, 8:42 pm, Peter Bennett <pete...@somewhere.invalid> wrote:
On Sun, 21 Sep 2008 09:32:10 -0700 (PDT), lerameur

leram...@yahoo.com> wrote:

Hi John,

I want to use the mosfet as relays. Once they are switch, the current
can flow in either direction. I have a solar panel array with multiple
batteries, I am trying to come up with a way with a microcontroller
can change only the batteries that are the at their lowest. The whole
project is huge, I reduced it down to this circuit, if I can do it on
this circuit then what want to do will work.

k

Why do you want to do this?  Why not just connect all the batteries in
parallel - this will minimised depth-of-discharge on all batteries,
and remove a lot of unneeded complexity.  Then all batteries will be
charged and discharged simultaneously.  There is no law requiring you
to disconnect all loads from a battery while you are charging it.

--
Peter Bennett, VE7CEI  
peterbb4 (at) interchange.ubc.ca  
GPS and NMEA info:http://vancouver-webpages.com/peter
Vancouver Power Squadron:http://vancouver.powersquadron.ca
Click to expand...
Hi all, John,

here is a working schematic with opto couplers. Basically this circuit
is not fully functional because it do not fully open the mosfet and
not allowing all the current to go through. I thought of adding the
tc4432 buffers instead of the opto coupler, but I had the grounding
problem.
With the optocoupler I was taking the voltage of the batteries as the
reference point, but it does not allow me for enough gate voltage.
so basically this circuit:
http://www3.sympatico.ca/captoro/motor/design5.gif
but a higher gate voltage.
is this more clear?

k
 
On 2008-09-22, lerameur <lerameur@yahoo.com> wrote:


here is a working schematic with opto couplers. Basically this circuit
is not fully functional because it do not fully open the mosfet and
not allowing all the current to go through. I thought of adding the
tc4432 buffers instead of the opto coupler, but I had the grounding
problem.
With the optocoupler I was taking the voltage of the batteries as the
reference point, but it does not allow me for enough gate voltage.
so basically this circuit:
http://www3.sympatico.ca/captoro/motor/design5.gif
but a higher gate voltage.
is this more clear?
Click to expand...
this looks like a circuit designed to destroy mosfets and/or optocouplers.

what current does your simulations suggest would be flowing.

I suggest you add some series resistors to the input side of the
optocouplers. about 220 ohms would be good I think.

the batteries are connected in what seems like an unusual setup,

the 5 ohm resistor you had in the loop last time is gone now.

Bye.
Jasen
 
On Sep 22, 12:57 am, Jasen Betts <ja...@xnet.co.nz> wrote:
On 2008-09-22, lerameur <leram...@yahoo.com> wrote:

here is a working schematic with opto couplers. Basically this circuit
is not fully functional because it do not fully open the mosfet and
not allowing all the current to go through. I thought of adding the
tc4432 buffers instead of the opto coupler, but I had the grounding
problem.
With the optocoupler I was taking the voltage of the batteries as the
reference point, but it does not allow me for enough gate voltage.
so basically this circuit:
http://www3.sympatico.ca/captoro/motor/design5.gif
but a higher gate voltage.
is this more clear?

this looks like a circuit designed to destroy mosfets and/or optocouplers..

what current does your simulations suggest would be flowing.

I suggest you add some series resistors to the input side of the
optocouplers. about 220 ohms would be good I think.

the batteries are connected in what seems like an unusual setup,

the 5 ohm resistor you had in the loop last time is gone now.

Bye.
   Jasen
Click to expand...
I did not put the resistor in the last circuit, I should of.

Ok here I have three circuit:
http://www3.sympatico.ca/captoro/motor/design6.gif
The first is with a 12v at the gate, then 20 and 25, the 30v circuit
was in my first link.
I noticed that beyond 30v the mosfet is already in saturation and will
not conduct more.
This is why I need 30v.
I just want to know how to put 30v on these gates when the ground is
NOT a common ground.
Is it possible? I am looking to redesign, unless someone tells me it
is impossible and really need to redesign.

thanks
k
 
On Sep 22, 12:57 am, Jasen Betts <ja...@xnet.co.nz> wrote:
On 2008-09-22, lerameur <leram...@yahoo.com> wrote:

here is a working schematic with opto couplers. Basically this circuit
is not fully functional because it do not fully open the mosfet and
not allowing all the current to go through. I thought of adding the
tc4432 buffers instead of the opto coupler, but I had the grounding
problem.
With the optocoupler I was taking the voltage of the batteries as the
reference point, but it does not allow me for enough gate voltage.
so basically this circuit:
http://www3.sympatico.ca/captoro/motor/design5.gif
but a higher gate voltage.
is this more clear?

this looks like a circuit designed to destroy mosfets and/or optocouplers..

what current does your simulations suggest would be flowing.

I suggest you add some series resistors to the input side of the
optocouplers. about 220 ohms would be good I think.

the batteries are connected in what seems like an unusual setup,

the 5 ohm resistor you had in the loop last time is gone now.

Bye.
   Jasen
Click to expand...
I did not put the resistor in the last circuit, I should of.

Ok here I have three circuit:
http://www3.sympatico.ca/captoro/motor/design6.gif
The first is with a 12v at the gate, then 20 and 25, the 30v circuit
was in my first link.
I noticed that beyond 30v the mosfet is already in saturation and will
not conduct more.
This is why I need 30v.
I just want to know how to put 30v on these gates when the ground is
NOT a common ground.
Is it possible? I am not looking to redesign, unless someone tells me
it
is impossible and really need to redesign.

(BTW, the ground in the simulation are there because they are need
during the simulation, otherwise pspice it will not run)
thanks
k
 
On 9/22/08 11:35 AM, in article Xns9B218A36CA926meadowmuffin@216.168.3.70,
"Kris Krieger" <me@dowmuff.in> wrote:

Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in
news:y1hBk.25806$PK.14621@newsfe04.iad:

lerameur wrote:

Hello

I posted a simple circuit up on
http://www3.sympatico.ca/captoro/motor/design1.gif
I am having difficulty seperating the grounds. My final circuit is
much more complex, it may look trivial at first, but I absolutely need
to seperate the grounds. IN the simulator they are the same ground.
But my 30 v source comes from a separate circuit, therefore do not
activate the N-mosfet (no common ground). I need to figure out a way
to put 30v on the mosfet so that the rest of the circuit shown sees it
and operate the way it is showing.
I thought about adding opto couplers, but I will still have the
problem of finding 30v on the other side of the circuit to activate
the mosfets,( where the maximum volt is 24v). And no I cannot combine
the 24v and 12v.
anyone has any ideas?

thank you

K
Optical isolation.

Look for optocouplers.

Below is a good component and many like it.

http://www.supertex.com/pdf/app_notes/AN-D26.pdf

the application notes should give you some lead way.

http://webpages.charter.net/jamie_5"



I'm gettign "file not found" - I also qwent to the site and searched D26, but
that didn't work. Could you post the component name, or another search term
I could use...?

Thanks!
Click to expand...
The link worked for me.
 
On Sep 22, 2:35 pm, Kris Krieger <m...@dowmuff.in> wrote:
Jamie <jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote innews:y1hBk.25806$PK.14621@newsfe04.iad:



lerameur wrote:

Hello

I posted a simple circuit up on
http://www3.sympatico.ca/captoro/motor/design1.gif
I am having difficulty seperating the grounds. My final circuit is
much more complex, it may look trivial at first, but I absolutely need
to seperate the grounds. IN the simulator they are the same ground.
But my 30 v source comes from a separate circuit, therefore do not
activate the N-mosfet (no common ground). I need to figure out a way
to put 30v on the mosfet so that the rest of the circuit shown sees it
and operate the way it is showing.
I thought about adding opto couplers, but I will still have the
problem of finding 30v on the other side of the circuit to activate
the mosfets,( where the maximum volt is 24v). And no I cannot combine
the 24v and 12v.
anyone has any ideas?

thank you

K
Optical isolation.

  Look for optocouplers.

Below is a good component and many like it.

http://www.supertex.com/pdf/app_notes/AN-D26.pdf

the application notes should give you some lead way.

http://webpages.charter.net/jamie_5"

I'm gettign "file not found" - I also qwent to the site and searched D26, but
that didn't work.  Could you post the component name, or another search term
I could use...?

Thanks!
Click to expand...

I just tried the 6 links, they all work well:
http://www3.sympatico.ca/captoro/motor/design1.gif
....
http://www3.sympatico.ca/captoro/motor/design6.gif


Anyhow I think I figured it out, I will try it tonight.
I am going to use my circuit as a reference point for the grounding of
my 30v gate voltage. It should work.
k
 
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