I need a 45 volt DC power supply for a tube regenerative radio, but
don't like the idea of using 5 9 volt batteries. I found a
transformer I was thinking of using two in series, but I'm not sure
how safe 45 volts is at 500 mA. The transformers are AC/AC so I'll
also have to use some 1N4007 rectifiers.
Transformer is Cat# M2860 at http://www.dse.com.au
I'm going to use the 30 volt tap on one and 15 volt tap on the other
and wire in series. If I also use a 4.5 or 6 volt transformer for the
tube filament, what resistor value would I need to get it down to 2
volts. The tube is a # 30 type with 60 mA filament.

"Dave.H" <the1930s@googlemail.com> wrote in message
news:c77babaf-2e2d-41a1-aacc-0b0604092080@s37g2000prg.googlegroups.com...
>I need a 45 volt DC power supply for a tube regenerative radio, but
> don't like the idea of using 5 9 volt batteries. I found a
> transformer I was thinking of using two in series, but I'm not sure
> how safe 45 volts is at 500 mA. The transformers are AC/AC so I'll
> also have to use some 1N4007 rectifiers.
> Transformer is Cat# M2860 at http://www.dse.com.au
> I'm going to use the 30 volt tap on one and 15 volt tap on the other
> and wire in series. If I also use a 4.5 or 6 volt transformer for the
> tube filament, what resistor value would I need to get it down to 2
> volts. The tube is a # 30 type with 60 mA filament.

For the filament, as I recall the LM317 will go down to 1.5v, for your HT
why not use a voltage doubler cct with the 30vac tranny ? Since the upper
limit for the 317 would be above 30v you could use the one tranny.

Cheers ............. Rheilly

On Mar 16, 9:50 pm, "Rheilly Phoull" <rhei...@bigpong.com> wrote:
> "Dave.H" <the19...@googlemail.com> wrote in message
>
> news:c77babaf-2e2d-41a1-aacc-0b0604092080@s37g2000prg.googlegroups.com...
>
> >I need a 45 volt DC power supply for a tube regenerative radio, but
> > don't like the idea of using 5 9 volt batteries. I found a
> > transformer I was thinking of using two in series, but I'm not sure
> > how safe 45 volts is at 500 mA. The transformers are AC/AC so I'll
> > also have to use some 1N4007 rectifiers.
> > Transformer is Cat# M2860 atwww.dse.com.au
> > I'm going to use the 30 volt tap on one and 15 volt tap on the other
> > and wire in series. If I also use a 4.5 or 6 volt transformer for the
> > tube filament, what resistor value would I need to get it down to 2
> > volts. The tube is a # 30 type with 60 mA filament.
>
> For the filament, as I recall the LM317 will go down to 1.5v, for your HT
> why not use a voltage doubler cct with the 30vac tranny ? Since the upper
> limit for the 317 would be above 30v you could use the one tranny.
>
> Cheers ............. Rheilly

I would like more info on this voltage doubler. As for the filament,
will probably run it on one or two D cells, don't mind replacing them,
and with only 60 mA current draw, will probably last quite a bit.

On Mar 16, 9:50 pm, "Rheilly Phoull" <rhei...@bigpong.com> wrote:
> "Dave.H" <the19...@googlemail.com> wrote in message
>
> news:c77babaf-2e2d-41a1-aacc-0b0604092080@s37g2000prg.googlegroups.com...
>
> >I need a 45 volt DC power supply for a tube regenerative radio, but
> > don't like the idea of using 5 9 volt batteries. I found a
> > transformer I was thinking of using two in series, but I'm not sure
> > how safe 45 volts is at 500 mA. The transformers are AC/AC so I'll
> > also have to use some 1N4007 rectifiers.
> > Transformer is Cat# M2860 atwww.dse.com.au
> > I'm going to use the 30 volt tap on one and 15 volt tap on the other
> > and wire in series. If I also use a 4.5 or 6 volt transformer for the
> > tube filament, what resistor value would I need to get it down to 2
> > volts. The tube is a # 30 type with 60 mA filament.
>
> For the filament, as I recall the LM317 will go down to 1.5v, for your HT
> why not use a voltage doubler cct with the 30vac tranny ? Since the upper
> limit for the 317 would be above 30v you could use the one tranny.
>
> Cheers ............. Rheilly

So I can use an LM317 chip powered from the 30 volts for the
filament? How do I wire this up? Closest I can find is the LM317t
which handling 1.5 amps. If I use a voltage doubler, the voltage would
be around 60 volts. This radio wasn't cheap to buy, and I don't want
to damage it with to much voltage. Perhaps my 1 amp 23 volt DC switch
mode wall wart would be better instead of the transformer. It would be
cheap, just install the voltage doubler circuit in a plastic box, with
a DC plug at one end, and binding posts at the other.

On Mar 16, 10:28 pm, "Dave.H" <the19...@googlemail.com> wrote:
> On Mar 16, 9:50 pm, "Rheilly Phoull" <rhei...@bigpong.com> wrote:
>
>
>
> > "Dave.H" <the19...@googlemail.com> wrote in message
>
> >news:c77babaf-2e2d-41a1-aacc-0b0604092080@s37g2000prg.googlegroups.com...
>
> > >I need a 45 volt DC power supply for a tube regenerative radio, but
> > > don't like the idea of using 5 9 volt batteries. I found a
> > > transformer I was thinking of using two in series, but I'm not sure
> > > how safe 45 volts is at 500 mA. The transformers are AC/AC so I'll
> > > also have to use some 1N4007 rectifiers.
> > > Transformer is Cat# M2860 atwww.dse.com.au
> > > I'm going to use the 30 volt tap on one and 15 volt tap on the other
> > > and wire in series. If I also use a 4.5 or 6 volt transformer for the
> > > tube filament, what resistor value would I need to get it down to 2
> > > volts. The tube is a # 30 type with 60 mA filament.
>
> > For the filament, as I recall the LM317 will go down to 1.5v, for your HT
> > why not use a voltage doubler cct with the 30vac tranny ? Since the upper
> > limit for the 317 would be above 30v you could use the one tranny.
>
> > Cheers ............. Rheilly
>
> So I can use an LM317 chip powered from the 30 volts for the
> filament? How do I wire this up? Closest I can find is the LM317t
> which handling 1.5 amps. If I use a voltage doubler, the voltage would
> be around 60 volts. This radio wasn't cheap to buy, and I don't want
> to damage it with to much voltage. Perhaps my 1 amp 23 volt DC switch
> mode wall wart would be better instead of the transformer. It would be
> cheap, just install the voltage doubler circuit in a plastic box, with
> a DC plug at one end, and binding posts at the other.

Perhaps I can get another switch mode wall wart and wire the two in
series, both set at 23 volts. That will provide 46 volts DC.
I believe the one I already have is category # M9926 @ http://www.dse.com.au
Would probably need some sort of filtering to remove hum. I seem to
remember this is done with a large value electrolytic cap across the
secondary output.

On Mar 16, 1:27=A0am, "Dave.H" <the19...@googlemail.com> wrote:
> I need a 45 volt DC power supply for a tube regenerative radio, but
> don't like the idea of using 5 9 volt batteries. =A0I found a
> transformer I was thinking of using two in series, but I'm not sure
> how safe 45 volts is at 500 mA. =A0The transformers are AC/AC so I'll
> also have to use some 1N4007 rectifiers.
> Transformer is Cat# M2860 atwww.dse.com.au
> I'm going to use the 30 volt tap on one and 15 volt tap on the other
> and wire in series. =A0If I also use a 4.5 or 6 volt transformer for the
> tube filament, what resistor value would I need to get it down to 2
> volts. =A0The tube is a # 30 type with 60 mA filament.

I'd recommend that you do first try the 5 9V batteries, and some D
cells with a resistor for the filament. This will be the most hum-
free arrangement. Then when you build your supply you can compare the
level of hum with the battery arrangement to give you a performance
level to shoot for. One thing to make sure you do is put small (0.01
uF) capacitors across your rectifier diodes - otherwise when they go
into and out of conduction they can generate 120 Hz RF noise.

Mike

On Mar 16, 6:27=A0pm, "Dave.H" <the19...@googlemail.com> wrote:
> I need a 45 volt DC power supply for a tube regenerative radio, but
> don't like the idea of using 5 9 volt batteries. =A0I found a
> transformer I was thinking of using two in series, but I'm not sure
> how safe 45 volts is at 500 mA. =A0The transformers are AC/AC so I'll
> also have to use some 1N4007 rectifiers.
> Transformer is Cat# M2860 atwww.dse.com.au
> I'm going to use the 30 volt tap on one and 15 volt tap on the other
> and wire in series. =A0If I also use a 4.5 or 6 volt transformer for the
> tube filament, what resistor value would I need to get it down to 2
> volts. =A0The tube is a # 30 type with 60 mA filament.

Have you looked at the M0144
transformer? I don't think the taps you are proposing can be used in
series. Your filament current needs a separate transformer.

Cheers

On Mar 17, 4:39 am, Mike Silva <snarflem...@yahoo.com> wrote:
> On Mar 16, 1:27 am, "Dave.H" <the19...@googlemail.com> wrote:
>
> > I need a 45 volt DC power supply for a tube regenerative radio, but
> > don't like the idea of using 5 9 volt batteries. I found a
> > transformer I was thinking of using two in series, but I'm not sure
> > how safe 45 volts is at 500 mA. The transformers are AC/AC so I'll
> > also have to use some 1N4007 rectifiers.
> > Transformer is Cat# M2860 atwww.dse.com.au
> > I'm going to use the 30 volt tap on one and 15 volt tap on the other
> > and wire in series. If I also use a 4.5 or 6 volt transformer for the
> > tube filament, what resistor value would I need to get it down to 2
> > volts. The tube is a # 30 type with 60 mA filament.
>
> I'd recommend that you do first try the 5 9V batteries, and some D
> cells with a resistor for the filament. This will be the most hum-
> free arrangement. Then when you build your supply you can compare the
> level of hum with the battery arrangement to give you a performance
> level to shoot for. One thing to make sure you do is put small (0.01
> uF) capacitors across your rectifier diodes - otherwise when they go
> into and out of conduction they can generate 120 Hz RF noise.
>
> Mike

Might be the best way to go. Hell, if the batteries last long`enough,
I'll leave it like that. I can't see a one tube regen consuming too
much current anyway.

On Mar 17, 6:53 am, Varactor <Morefl...@gmail.com> wrote:
> On Mar 16, 6:27 pm, "Dave.H" <the19...@googlemail.com> wrote:
>
> > I need a 45 volt DC power supply for a tube regenerative radio, but
> > don't like the idea of using 5 9 volt batteries. I found a
> > transformer I was thinking of using two in series, but I'm not sure
> > how safe 45 volts is at 500 mA. The transformers are AC/AC so I'll
> > also have to use some 1N4007 rectifiers.
> > Transformer is Cat# M2860 atwww.dse.com.au
> > I'm going to use the 30 volt tap on one and 15 volt tap on the other
> > and wire in series. If I also use a 4.5 or 6 volt transformer for the
> > tube filament, what resistor value would I need to get it down to 2
> > volts. The tube is a # 30 type with 60 mA filament.
>
> Have you looked at the M0144
> transformer? I don't think the taps you are proposing can be used in
> series. Your filament current needs a separate transformer.
>
> Cheers

I did look at that one, but it's limited stock, not available at the
Shellharbour branch of DSE. I'll do what Mike said.