I am looking for info regarding a simple power supply with a full wave
rectifier (I got a 6X5).
Mainly I need to know the 'to be expected output voltage' (capacitor
filter)for any input. I don't have info on that.
Do the formulas for solid state rectifiers apply??

73 Uwe

Behold, Uwe signalled from keyed 4-1000A filament:

I am looking for info regarding a simple power supply with a full wave
rectifier (I got a 6X5).
Mainly I need to know the 'to be expected output voltage' (capacitor
filter)for any input. I don't have info on that. Do the formulas for
solid state rectifiers apply??

Yup! However tube rectifiers don't like large caps. 10-20uF should be
enough.

If you need better regulation or hum reduction, use a higher tranny
voltage and a choke-input filter.

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
http://geek.scorpiorising.ca

Behold, Uwe signalled from keyed 4-1000A filament:

I am looking for info regarding a simple power supply with a full wave
rectifier (I got a 6X5).
Mainly I need to know the 'to be expected output voltage' (capacitor
filter)for any input. I don't have info on that. Do the formulas for
solid state rectifiers apply??

Yup! However tube rectifiers don't like large caps. 10-20uF should be
enough.

If you need better regulation or hum reduction, use a higher tranny
voltage and a choke-input filter.

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
http://geek.scorpiorising.ca

"Uwe" wrote in message
...
I am looking for info regarding a simple power supply with a full wave
rectifier (I got a 6X5).
Mainly I need to know the 'to be expected output voltage' (capacitor
filter)for any input. I don't have info on that.
Do the formulas for solid state rectifiers apply??

See http://www.hanssummers.com/radio/glowbug/psu/index.htm

I use a GZ33 rectifier valve, followed by pi-filter containing a 16uF
capacitor, 5H choke, and 400uF capacitor.

I am no expert but from what I have learnt the following points are
important:

1. The first capacitor should be relatively low value (my 16uF seemed about
right). This capacitor should also be a very sturdy type, so that it is
unlikely to fail. A less robust electrolytic in this location might fail and
short out, destroying the rectifier valve in the process. Therefore I use an
overspecified bipolar capacitor in this location.

2. Don't forget a bleeder resistor across the output, essential for your
safety! This will discharge the capacitors within some seconds of switching
off, making it safe to work on your equipment.

3. Small resistors (I use 55 ohm) in series with the rectifier anodes are
needed to protect the valve from switch-on surge currents.

I also use a VR150/30 gas filled regulator valve to produce a 150V regulated
output in addition to the 350V HT.

73

Hans G0UPL
http://www.HansSummers.com

"Uwe" wrote in message
...
I am looking for info regarding a simple power supply with a full wave
rectifier (I got a 6X5).
Mainly I need to know the 'to be expected output voltage' (capacitor
filter)for any input. I don't have info on that.
Do the formulas for solid state rectifiers apply??

See http://www.hanssummers.com/radio/glowbug/psu/index.htm

I use a GZ33 rectifier valve, followed by pi-filter containing a 16uF
capacitor, 5H choke, and 400uF capacitor.

I am no expert but from what I have learnt the following points are
important:

1. The first capacitor should be relatively low value (my 16uF seemed about
right). This capacitor should also be a very sturdy type, so that it is
unlikely to fail. A less robust electrolytic in this location might fail and
short out, destroying the rectifier valve in the process. Therefore I use an
overspecified bipolar capacitor in this location.

2. Don't forget a bleeder resistor across the output, essential for your
safety! This will discharge the capacitors within some seconds of switching
off, making it safe to work on your equipment.

3. Small resistors (I use 55 ohm) in series with the rectifier anodes are
needed to protect the valve from switch-on surge currents.

I also use a VR150/30 gas filled regulator valve to produce a 150V regulated
output in addition to the 350V HT.

73

Hans G0UPL
http://www.HansSummers.com

In article , Uwe
writes:

I am looking for info regarding a simple power supply with a full wave
rectifier (I got a 6X5).
Mainly I need to know the 'to be expected output voltage' (capacitor
filter)for any input. I don't have info on that.
Do the formulas for solid state rectifiers apply??

Not quite. The voltage drop across vacuum diodes is
considerably higher and varies with different rectifier diodes,
typically 40 to as much as 100 Volts. You can find some
representative curves of DC output voltages versus AC input
for capacitor-input circuits in older texts of 40 to 50 years
ago. Some old vacuum tube data manuals give 'typical'
voltage drop values.

You can get an approximation for the peak DC output by
taking 1.4 times the AC RMS input, subtracting about 50
volts from that to begin a rectifier circuit for a 50 to 100 mA
HV supply. From there on you can pin down more exact
values with rectifier tube data.

A slight advantage of vacuum tubes in capacitor-input rectifier
circuits was that the very high initial turn-on surge isn't there;
a vacuum tube diode literally turns on slowly as the filament
warms up. In cheaper tube designs that was offset by the
higher heat dissipation of tube rectifiers creating a local hot
spot much higher than with semiconductor rectifier diodes.
[typical heat dissipation of a 5Y3 common dual-diode in 100
Watt units was 15 to 20 Watts all by itself]

Len Anderson
retired (from regular hours) electronic engineer person

In article , Uwe
writes:

I am looking for info regarding a simple power supply with a full wave
rectifier (I got a 6X5).
Mainly I need to know the 'to be expected output voltage' (capacitor
filter)for any input. I don't have info on that.
Do the formulas for solid state rectifiers apply??

Not quite. The voltage drop across vacuum diodes is
considerably higher and varies with different rectifier diodes,
typically 40 to as much as 100 Volts. You can find some
representative curves of DC output voltages versus AC input
for capacitor-input circuits in older texts of 40 to 50 years
ago. Some old vacuum tube data manuals give 'typical'
voltage drop values.

You can get an approximation for the peak DC output by
taking 1.4 times the AC RMS input, subtracting about 50
volts from that to begin a rectifier circuit for a 50 to 100 mA
HV supply. From there on you can pin down more exact
values with rectifier tube data.

A slight advantage of vacuum tubes in capacitor-input rectifier
circuits was that the very high initial turn-on surge isn't there;
a vacuum tube diode literally turns on slowly as the filament
warms up. In cheaper tube designs that was offset by the
higher heat dissipation of tube rectifiers creating a local hot
spot much higher than with semiconductor rectifier diodes.
[typical heat dissipation of a 5Y3 common dual-diode in 100
Watt units was 15 to 20 Watts all by itself]

Len Anderson
retired (from regular hours) electronic engineer person

Uwe wrote in message ...
I am looking for info regarding a simple power supply with a full wave
rectifier (I got a 6X5).
Mainly I need to know the 'to be expected output voltage' (capacitor
filter)for any input. I don't have info on that.

Check out the tube data sheets, available on several websites. If you
need urls, I can dig them up. The RCA HB-3 books are online for sure.

Do the formulas for solid state rectifiers apply??

Not directly, because tube rectifiers tend to have more drop than
silicon. Different types have different drop, too, and it depends on
the current load. An important concern in setups where the current
draw varies (such as CW transmitters) is the voltage regulation of the
supply from minimum to maximum load. Different types of rectifier tube
have different regulation performance.

As a limiting case, with a full wave center tap rectifier using a
transformer giving Vt volts on either side of center tap, the
*maximum* voltage you will get is:

1.4 * Vt (capacitor input filter)
0.9 * Vt (choke input filter)

In real-life applications, the output voltage will be less.

The 6X5 is good up to 70 mA, but has relatively high voltage drop and
relatively poor regulation. The 5Y3 is better, the 5V4 better still,
and the 5U4 even better. The ultimate in tube rectifiers are the
mercury vapor types, but that's a subject for another post.

What transformer do you have available, and what is the application?

btw, I have found that an input capacitor of 40uf is fine with the 5Y3
and larger rectifiers.

73 de Jim, N2EY

Uwe wrote in message ...
I am looking for info regarding a simple power supply with a full wave
rectifier (I got a 6X5).
Mainly I need to know the 'to be expected output voltage' (capacitor
filter)for any input. I don't have info on that.

Check out the tube data sheets, available on several websites. If you
need urls, I can dig them up. The RCA HB-3 books are online for sure.

Do the formulas for solid state rectifiers apply??

Not directly, because tube rectifiers tend to have more drop than
silicon. Different types have different drop, too, and it depends on
the current load. An important concern in setups where the current
draw varies (such as CW transmitters) is the voltage regulation of the
supply from minimum to maximum load. Different types of rectifier tube
have different regulation performance.

As a limiting case, with a full wave center tap rectifier using a
transformer giving Vt volts on either side of center tap, the
*maximum* voltage you will get is:

1.4 * Vt (capacitor input filter)
0.9 * Vt (choke input filter)

In real-life applications, the output voltage will be less.

The 6X5 is good up to 70 mA, but has relatively high voltage drop and
relatively poor regulation. The 5Y3 is better, the 5V4 better still,
and the 5U4 even better. The ultimate in tube rectifiers are the
mercury vapor types, but that's a subject for another post.

What transformer do you have available, and what is the application?

btw, I have found that an input capacitor of 40uf is fine with the 5Y3
and larger rectifiers.

73 de Jim, N2EY

Avery Fineman wrote:

A slight advantage of vacuum tubes in capacitor-input rectifier
circuits was that the very high initial turn-on surge isn't there;
a vacuum tube diode literally turns on slowly as the filament
warms up. In cheaper tube designs that was offset by the
higher heat dissipation of tube rectifiers creating a local hot
spot much higher than with semiconductor rectifier diodes.
[typical heat dissipation of a 5Y3 common dual-diode in 100
Watt units was 15 to 20 Watts all by itself]

I seem to remember the 5Y3 as directly heated which means it warms up
before the rest of the valves in the set so producing high HT value
intitially. Need to take this into account with electrolytics.

Peter

Len Anderson
retired (from regular hours) electronic engineer person