[Lowfer] need a circuit for DC to DC Boost converter

[Zack Widup]

Here's an example of the circuit I was talking about:

http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1042,C1036,P1313

The schematic is the "typical application." I have built dozens of versions
of this circuit. I've made several to power laptops that run off 22-24 volts
from a 12 volt source. I've made versions with output voltages as high as 45
volts. The input voltage is not critical as long as it's at least a volt or
so below the output voltage (hence "boost converter").

Although you don't need it, an LT1270 in the TO220-5 case in the same
circuit can give you up to 8 amps of output current.

73, Zack W9SZ


On Fri, Apr 9, 2010 at 9:58 AM, Andy - KU4XR <ku4xr at yahoo.com> wrote:

> I have saw pics of that setup !!! Probably a little bit Over-Kill
> for a lowFER PA power supply; hi - hi ::::
>
> I bought a lot of 3 - 32v/16v HP wall-wart SMPS off ebay. The are
> defective, although brand new. All 3 have the worst noise I have
> ever seen on a SMPS before. Connecting them to any of the LF gear
> and the noise is imposed onto the transmit. The linear transverter
> goes nuts !! and the PA can't handle the noise on the voltage.
> The convienience of the dual voltage supply is nice, but the same
> outcome can be accomplished with a single voltage, and regulated
> down.
>
> The 18 volt HP printer supply I have is at 1.5 Amps, plenty of " I "
> for a doubled voltage, but looks like I will be the same as building
> another supply to work with this one. Not worth the time, and money.
>
> Ralphs idea of series supplies might be the answer. 18 & 12 volts
> will put me at 30, and then use the adjustable regulator for the
> 25 volts I have been using on the PA, then tap off the 12 v side to
> run the transverter. That's probably what I'll do for now just to
> get running again.
>
> Hope everyone has a great weekend. Looks like the receive cndx have
> improved now.  73 to all :::
>
>
> Andy - KU4XR - EM75xr - Friendsville, TN. USA
> LOWfer Beacon " XR " @ 185.29875 KHz ( QRSS-60 )
> Coordinates:  N:  35º 43' 54" - W:  84º 3' 16"
> http://www.myspace.com/beaconxr
> http://webpages.charter.net/ku4xr/
>
>
> --- On Fri, 4/9/10, Mike.WE0H <we0h at gmx.com> wrote:
>
> > From: Mike.WE0H <we0h at gmx.com>
> > Subject: Re: [Lowfer] need a circuit for DC to DC Boost converter
> > To: "Discussion of the Lowfer (US, European, & UK) and MedFer bands" <
> lowfer at mailman.qth.net>
> > Date: Friday, April 9, 2010, 1:10 AM
>  > Build the Tower of Power. Ralph can
> > fill you in on what that is.
> >
> > 12 x 3 = 36 or 7 x 5 = 35
> >
> > Mike
> > WE0H
> >
> >
> >
> > Ralph-W5JGV wrote:
> > >> I have an 18 Volt DC supply. I want to convert the
> > voltage to
> > >> 36 Volts DC to power my lowFER PA. Will anyone
> > point me to a
> > >> circuit to do this ?? I suppose minimal parts
> > count, low ripple,
> > >> 500 mAmp power handling.
> > >
> > >
> > > Since you don't need a lot of current, here are a
> > couple of ideas:
> > >
> > > 1) Find another 18 volt power supply and connect the
> > two supplies in series.
> > >
> > > 2) Scrounge through the local thrift stores for some
> > used inkjet printer
> > > power supplies.  I have found several switching
> > power supplies rated at
> > > 30-40 volts DC @ 300-700 mA at my local thrift
> > store.  The HP inkjet
> > > printers commonly use power supplies in that range.
> > >
> > > Since all of the wall-wart and brick-style switching
> > power supplies have
> > > isolated outputs, you can easily connect them in
> > series.
> > >
> > > Good luck!
> > >
> > > 73,
> > >
> > > Ralph  W5JGV - WD2XSH/7
>
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