Re: Heads Up for Power Supply deal...

Bertho,
Good point.... best to simplyt get the correct PSU to begin with... but 36V @8.5Amps for $30 is a deal...
Those 2 extra diods will not cost more than $2....

so let me modify my connections descritption to include the diodes

Connections would be like this

Positive from Supply #1 Cathode of Diode#1 ( the end with the stripe ). Become the 36 Volt connection

Negative from Supply #1 Anode of Diode#1 never consider this as ground !
| connect together
Positive from Supply #2 Cathode of Diode#2 ( the end with the stripe )

Negative from Supply #1 Anode of Diode#2. Becomes the 0V connection

Any diode able to handle 8-10 amps will do the trick, or two 5 Amp diodes in parallel is OK also.
Remember these diodes will only be used IF one of the power supplies fails, otherwise they are doing almost nothing, maybe catching a
little back emf from the motors when the unit is switched off, and that is just a plus anyway.

Still looks like a deal to me... the point about Isolation of the one supply still applies.

It would be easier to insert a small diagram, does this list allow that ?

hansw

Bertho Boman wrote:

> From: Bertho Boman <boman@...>
>
> That is usually OK but it is also an easy way to kill power supplies if they are not designed correctly. For example, if the fuse
> blows in one supply the other one will feed power backwards into the one that is not turned on and often kill it.
>
> One way to protect them is to put a power diode (that can handle the max current) backwards across each output. That will limit
> the reverse voltage to one diode drop.
> Bertho Boman
> ==================================================
>
> > From: hansw <hansw@...>
> >
> > Hi Carlos,
> > Good question, and I think that should be possible.
> > It is a switch mode supply, which means it has 100% isolation from the input, so that's the first thing solved.
> >
> > When you do connect in series, you will have one of the power supplies (negative) connection effectively at half voltage, and
> > only need to make sure you never "ground" it...
> >
> > Connections would be like this
> >
> > Positive from Supply #1 become the 36 Volt connection
> >
> > Negative from Supply #1 never consider this as ground !
> > | connect together
> > Positive from Supply #2
> >
> > Negative from Supply #1 becomes the 0V connection
> >
> > I expect already know all of this. Also remember the negative is often also part of the circuit board screw mounting holes, and
> > you need to isolate that #1 supply,
> > for example mount it on Nylon spacer.
> >
> > It should work, no reason why it will not.
> >
> > regards
> > Hans Wedemeyer
> >
> > Carlos Guillermo wrote:
> >
> > > From: "Carlos Guillermo" <cnk@...>
> > >
> > > Hans -
> > >
> > > Any way to double those up effectively for 36V?
> > >
> > > Carlos Guillermo
>
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