[jaap[_3_]]

Hi all,

Looking for a simple voltage regulator I came across this 1993 Sound
Practices article by Mike Vans Evers:
http://www.enjoythemusic.com/magazin..._regulator.htm

It's ment for feeding one channel of a SE Piccolo amp (ECL86 triode
connected, 29mA HT current). While my power supply has no more than 32mV
AC ripple I noticed that after the regulator AC ripple is over 200mV at
100Hz. Lacking a 33uF capacitor for C1 I used 22uF instead but this
won't hurt. Can someone explain this phenomenon?

Regards, Jaap

[Ian Bell[_2_]]

jaap wrote:
Hi all,

Looking for a simple voltage regulator I came across this 1993 Sound
Practices article by Mike Vans Evers:
http://www.enjoythemusic.com/magazin..._regulator.htm


It's ment for feeding one channel of a SE Piccolo amp (ECL86 triode
connected, 29mA HT current). While my power supply has no more than 32mV
AC ripple I noticed that after the regulator AC ripple is over 200mV at
100Hz. Lacking a 33uF capacitor for C1 I used 22uF instead but this
won't hurt. Can someone explain this phenomenon?

Regards, Jaap


Seems odd. The regulator should reduce ripple if correctly built. Are
you sure you have sufficient voltage drop across the regulating valve?

Cheers

ian

[jaap[_3_]]

jaap wrote:
Hi all,

Looking for a simple voltage regulator I came across this 1993 Sound
Practices article by Mike Vans Evers:
http://www.enjoythemusic.com/magazin..._regulator.htm


It's ment for feeding one channel of a SE Piccolo amp (ECL86 triode
connected, 29mA HT current). While my power supply has no more than
32mV AC ripple I noticed that after the regulator AC ripple is over
200mV at 100Hz. Lacking a 33uF capacitor for C1 I used 22uF instead
but this won't hurt. Can someone explain this phenomenon?

Regards, Jaap


Seems odd. The regulator should reduce ripple if correctly built. Are
you sure you have sufficient voltage drop across the regulating valve?

Cheers

ian

Voltage drop is 75 volts. When I turn down the output voltage -so
voltage drop is higher- there's only marginal less ripple.
Will check the connections again.

[jaap[_3_]]

jaap wrote:
Hi all,

Looking for a simple voltage regulator I came across this 1993 Sound
Practices article by Mike Vans Evers:
http://www.enjoythemusic.com/magazin..._regulator.htm


It's ment for feeding one channel of a SE Piccolo amp (ECL86 triode
connected, 29mA HT current). While my power supply has no more than
32mV AC ripple I noticed that after the regulator AC ripple is over
200mV at 100Hz. Lacking a 33uF capacitor for C1 I used 22uF instead
but this won't hurt. Can someone explain this phenomenon?

Regards, Jaap


Seems odd. The regulator should reduce ripple if correctly built. Are
you sure you have sufficient voltage drop across the regulating valve?

Cheers

ian

Voltage drop is 75 volts. When I turn down the output voltage -so
voltage drop is higher- there's only marginal less ripple.
Will check the connections again.

Sorry, ripple was 50Hz and heater related. Glowing with DC removes
ripple completely.
Still, it's bizarre. The heater bias is bypassed with a rather large C1
to ground and should not introduce humm... Will up C1 to 100uF and see
what happens.

[jaap[_3_]]

jaap wrote:
Hi all,

Looking for a simple voltage regulator I came across this 1993 Sound
Practices article by Mike Vans Evers:
http://www.enjoythemusic.com/magazin..._regulator.htm


It's ment for feeding one channel of a SE Piccolo amp (ECL86 triode
connected, 29mA HT current). While my power supply has no more than
32mV AC ripple I noticed that after the regulator AC ripple is over
200mV at 100Hz. Lacking a 33uF capacitor for C1 I used 22uF instead
but this won't hurt. Can someone explain this phenomenon?

Regards, Jaap


Seems odd. The regulator should reduce ripple if correctly built. Are
you sure you have sufficient voltage drop across the regulating valve?

Cheers

ian

Voltage drop is 75 volts. When I turn down the output voltage -so
voltage drop is higher- there's only marginal less ripple.
Will check the connections again.

Sorry, ripple was 50Hz and heater related. Glowing with DC removes
ripple completely.
Still, it's bizarre. The heater bias is bypassed with a rather large C1
to ground and should not introduce humm... Will up C1 to 100uF and see
what happens.

Where are my spectacles 8)
The voltage devider R8/R4 which forms the voltage devider is not
bypassed to ground. A flaw in the design? Would it be wise to place a
10uF bipolar to ground from the bias point?

[jaap[_3_]]

jaap wrote:
Hi all,

Looking for a simple voltage regulator I came across this 1993 Sound
Practices article by Mike Vans Evers:
http://www.enjoythemusic.com/magazin..._regulator.htm


It's ment for feeding one channel of a SE Piccolo amp (ECL86 triode
connected, 29mA HT current). While my power supply has no more than
32mV AC ripple I noticed that after the regulator AC ripple is over
200mV at 100Hz. Lacking a 33uF capacitor for C1 I used 22uF instead
but this won't hurt. Can someone explain this phenomenon?

Regards, Jaap


Seems odd. The regulator should reduce ripple if correctly built. Are
you sure you have sufficient voltage drop across the regulating valve?

Cheers

ian

Voltage drop is 75 volts. When I turn down the output voltage -so
voltage drop is higher- there's only marginal less ripple.
Will check the connections again.

Sorry, ripple was 50Hz and heater related. Glowing with DC removes
ripple completely.
Still, it's bizarre. The heater bias is bypassed with a rather large C1
to ground and should not introduce humm... Will up C1 to 100uF and see
what happens.

Where are my spectacles 8)
The heater bias consisting of the voltage devider R8/R4 is not
bypassed to ground. A flaw in the design? Would it be wise to place a
10uF bipolar to ground from the bias point?

[Ian Bell[_2_]]

jaap wrote:
jaap wrote:
Hi all,

Looking for a simple voltage regulator I came across this 1993 Sound
Practices article by Mike Vans Evers:
http://www.enjoythemusic.com/magazin..._regulator.htm


It's ment for feeding one channel of a SE Piccolo amp (ECL86 triode
connected, 29mA HT current). While my power supply has no more than
32mV AC ripple I noticed that after the regulator AC ripple is over
200mV at 100Hz. Lacking a 33uF capacitor for C1 I used 22uF instead
but this won't hurt. Can someone explain this phenomenon?

Regards, Jaap


Seems odd. The regulator should reduce ripple if correctly built. Are
you sure you have sufficient voltage drop across the regulating valve?

Cheers

ian

Voltage drop is 75 volts. When I turn down the output voltage -so
voltage drop is higher- there's only marginal less ripple.
Will check the connections again.


That's about what the author recommends so it should be OK. Puzzling -
might be worth scoping around the circuit.

Cheers

Ian

[Ian Bell[_2_]]

jaap wrote:
jaap wrote:
Hi all,

Looking for a simple voltage regulator I came across this 1993 Sound
Practices article by Mike Vans Evers:
http://www.enjoythemusic.com/magazin..._regulator.htm


It's ment for feeding one channel of a SE Piccolo amp (ECL86 triode
connected, 29mA HT current). While my power supply has no more than
32mV AC ripple I noticed that after the regulator AC ripple is over
200mV at 100Hz. Lacking a 33uF capacitor for C1 I used 22uF instead
but this won't hurt. Can someone explain this phenomenon?

Regards, Jaap


Seems odd. The regulator should reduce ripple if correctly built. Are
you sure you have sufficient voltage drop across the regulating valve?

Cheers

ian

Voltage drop is 75 volts. When I turn down the output voltage -so
voltage drop is higher- there's only marginal less ripple.
Will check the connections again.

Sorry, ripple was 50Hz and heater related. Glowing with DC removes
ripple completely.
Still, it's bizarre. The heater bias is bypassed with a rather large C1
to ground and should not introduce humm... Will up C1 to 100uF and see
what happens.


Looking at the circuit, C1 bypasses zener noise rather than heater hum.
No mention is made of using a raised heater voltage buit he does say '
the maximum heater to cathode voltage is only 100 V, so the maximum
output voltage should be limited to the zener voltage plus 200 V.' Since
the pentode cathode is higher than the triode cathode this implies top
me that the heater should be connected to the cathode of the triode.
Obviously a separate heater supply for this valve is needed to do this.
If you heater is referenced to 0V then the heater/cathode volts of the
pentode could easily be exceed and this would explain why you get to
much hum.

HTH

Cheers

ian

[Ian Bell[_2_]]

jaap wrote:
jaap wrote:
Hi all,

Looking for a simple voltage regulator I came across this 1993
Sound Practices article by Mike Vans Evers:
http://www.enjoythemusic.com/magazin..._regulator.htm


It's ment for feeding one channel of a SE Piccolo amp (ECL86 triode
connected, 29mA HT current). While my power supply has no more than
32mV AC ripple I noticed that after the regulator AC ripple is over
200mV at 100Hz. Lacking a 33uF capacitor for C1 I used 22uF instead
but this won't hurt. Can someone explain this phenomenon?

Regards, Jaap


Seems odd. The regulator should reduce ripple if correctly built.
Are you sure you have sufficient voltage drop across the regulating
valve?

Cheers

ian

Voltage drop is 75 volts. When I turn down the output voltage -so
voltage drop is higher- there's only marginal less ripple.
Will check the connections again.

Sorry, ripple was 50Hz and heater related. Glowing with DC removes
ripple completely.
Still, it's bizarre. The heater bias is bypassed with a rather large
C1 to ground and should not introduce humm... Will up C1 to 100uF and
see what happens.

Where are my spectacles 8)
The heater bias consisting of the voltage devider R8/R4 is not
bypassed to ground. A flaw in the design? Would it be wise to place a
10uF bipolar to ground from the bias point?


Ah, ignore my earlier remarks about heaters, they are already elevated.
Yes the heater bias point ought to be decoupled. Don't know whether it
should be bipolar but an electrolytic should be OK.

Cheers

Ian

[Phil Allison]

"jaap"



Where are my spectacles 8)
The heater bias consisting of the voltage devider R8/R4 is not
bypassed to ground. A flaw in the design? Would it be wise to place a
10uF bipolar to ground from the bias point?


** Huh ?

All you need is a 0.1uF film cap of say 400 volts rating.

Cos all you need to do is bypass the stray primary to secondary capacitance
in the supply transformer - ie a few hundred pF at most.



....... Phil

[jaap[_3_]]

jaap wrote:
jaap wrote:
Hi all,

Looking for a simple voltage regulator I came across this 1993
Sound Practices article by Mike Vans Evers:
http://www.enjoythemusic.com/magazin..._regulator.htm


It's ment for feeding one channel of a SE Piccolo amp (ECL86
triode connected, 29mA HT current). While my power supply has no
more than 32mV AC ripple I noticed that after the regulator AC
ripple is over 200mV at 100Hz. Lacking a 33uF capacitor for C1 I
used 22uF instead but this won't hurt. Can someone explain this
phenomenon?

Regards, Jaap


Seems odd. The regulator should reduce ripple if correctly built.
Are you sure you have sufficient voltage drop across the regulating
valve?

Cheers

ian

Voltage drop is 75 volts. When I turn down the output voltage -so
voltage drop is higher- there's only marginal less ripple.
Will check the connections again.

Sorry, ripple was 50Hz and heater related. Glowing with DC removes
ripple completely.
Still, it's bizarre. The heater bias is bypassed with a rather large
C1 to ground and should not introduce humm... Will up C1 to 100uF and
see what happens.

Where are my spectacles 8)
The heater bias consisting of the voltage devider R8/R4 is not
bypassed to ground. A flaw in the design? Would it be wise to place a
10uF bipolar to ground from the bias point?


Ah, ignore my earlier remarks about heaters, they are already elevated.
Yes the heater bias point ought to be decoupled. Don't know whether it
should be bipolar but an electrolytic should be OK.

Cheers

Ian

Electrolytic seems OK to me too. Thanks for your input Ian.

[jaap[_3_]]

"jaap"


Where are my spectacles 8)
The heater bias consisting of the voltage devider R8/R4 is not
bypassed to ground. A flaw in the design? Would it be wise to place a
10uF bipolar to ground from the bias point?


** Huh ?

All you need is a 0.1uF film cap of say 400 volts rating.

Cos all you need to do is bypass the stray primary to secondary capacitance
in the supply transformer - ie a few hundred pF at most.



....... Phil


Seems you're right Phil. I just connected a seperate transformer to the
heater of the ECL82 and the rimple was nill.
I'm not quite sure what's going on. Is the stray capacitance between the
520V ct secondary interfering with the 6,3V seconday? Or is (as you
mentioned) the primary winding interfering with the 6,3V?
Would a capacitor from mains to the heater bias point pass mains pollution?

Regards, Jaap

[Iain Churches[_2_]]

"Phil Allison" wrote in message
...

"jaap"



Where are my spectacles 8)
The heater bias consisting of the voltage devider R8/R4 is not
bypassed to ground. A flaw in the design? Would it be wise to place a
10uF bipolar to ground from the bias point?


** Huh ?

All you need is a 0.1uF film cap of say 400 volts rating.


Yes. That's the value that Bruce Rozenblit gives in the circuit
in his book. I have used it often.

[jaap[_3_]]

"Phil Allison" wrote in message
...
"jaap"


Where are my spectacles 8)
The heater bias consisting of the voltage devider R8/R4 is not
bypassed to ground. A flaw in the design? Would it be wise to place a
10uF bipolar to ground from the bias point?

** Huh ?

All you need is a 0.1uF film cap of say 400 volts rating.


Yes. That's the value that Bruce Rozenblit gives in the circuit
in his book. I have used it often.


Ian, bypassing the heater bias does not lower AC ripple at the output. A
seperate transformer does.

[Ian Bell[_2_]]

jaap wrote:
"Phil Allison" wrote in message
...
"jaap"


Where are my spectacles 8)
The heater bias consisting of the voltage devider R8/R4 is not
bypassed to ground. A flaw in the design? Would it be wise to place a
10uF bipolar to ground from the bias point?

** Huh ?

All you need is a 0.1uF film cap of say 400 volts rating.


Yes. That's the value that Bruce Rozenblit gives in the circuit
in his book. I have used it often.


Ian, bypassing the heater bias does not lower AC ripple at the output. A
seperate transformer does.


That's interesting and perhaps a good reason for having a separte heater
transformer.

Cheers

Ian