Noisy power supply

[Colas LeGrippa]

Hola amigos, in order to supply 12.6 vdc to the tube  of my overdrive pedal, I have modified my regulated power supply made with a 7812 regulator, swapping it for a 2N3055 coupled to a 14 V zener diode.  Once connected to the 12au7, the voltage dropped to 13,2V. One common diode at the output dropped the  voltage to 12.7 aprox. , which voltage I used for heaters and anode supply. Is it normal that this new power supp. generates more hiss / shhhh than the only 7812 ? 
The reason I swapped thev7812 was because I was getting max 12 V, with no load connected.
Thanxx
Colas

[shooter]

more hiss / shhhh

is the supply "remote" like a battery eliminator or is it build right next to a very sensitive pre-amp tube?
"sounds" like you have some sort of coupling noise by your description

[sluckey]

Go back to the 7812 and put a 1n4007 between the ground lead and ground. Then you will have 12.6V output.

[Colas LeGrippa]

Interesting !  i'll try the diode to gnd trick.


Thanx

[sluckey]

Oops! I forgot. You need a resistor too. See attached...

[Colas LeGrippa]

Just at the moment where I was prepairing to finalize it     thamxxx

[PRR]

These tubes WILL run on 12.00 Volts. It is even in spec. Dunno why I would change it.

The resistor "may" not be necessary. I see where he is going, but the LM7812 GND pin current will bring-up a Si diode well.

[Colas LeGrippa]

As a matter of fact it was working WELL before my anxiety tells me : Jack, the heaters are starving , raise the voltage !!!!

[sluckey]

OK Colas. What's the verdict?

[Colas LeGrippa]

Oops sorry for keep you waiting , I wasn' t around.
Your P S is very quiet. I think the zener diode that I used in conjunction with the 2n3055 transistor makes output noisy. I read something on that in my researches.  The  casing of TO3 voltage regulator is the ground connection so no need to use mica, paste, isolating washers. The 2n3055 was getting so hot I couldn t even touch it and it would have needed a heat sink while the 7812 stays dead cold. Less work, less components, less noise.  Love it. The small 500 mA trannies 120V / 16 V dont yield  enough power and they tend to develop noise as well.
I used  a  5A tranny that I had in stock . Overkill but it works. I guess 1 A tranny will be small enough and reliable for one tube if we want things quiet and reliable. Anyway my little 12AU7 preamp is very happy with her new mama feeding him.

[Colas LeGrippa]

I have modded things as well in my preamp. Lowered the plate resistors from 100k to 47k.
On the second half of the tube I put a cold clipper  of 10k, first section 1k5 with .68uF.
Lowered the grid stopper to 1k , thats about it.
I get clean sustain, feedback and overtones in an ultra simple tube pedal without any  IC.
Resistors and caps




Thanx Sluckey  for schemati, PRR for advice and the others.
I keep up tweaking my gear with great help


Colas

[Colas LeGrippa]

Hi,


More tests at higher volume showed that the diode to ground in order to gain extra .6V  was noisy. Removed that diode and the 680R as well. The 1000uF at the output is not necessary as the 7812 gives 1.5A. Lowered the value of that output cap to 1 mF which is less costly and does the job perfectly. So the new mother feeds the baby silently in order to hear the guitar without farts nor burps  . I built another power supply with a 24V tranny which was a bad idea as the dc voltage to the 7812 input was reaching a couple of volts over the maximum input voltage of 35V , by reference  to the 7812 specs.

[Colas LeGrippa]

.....and turned out to be noisy too. So a 16V trany for a 12V regulated supply is a oerfect choice. I 'm keeping on working on power supplies trying to eliminate unwanted noise, though there will remain a certain amount of noise coming from the high gain tube preamp itself.


So after a couple of days of trial an errors, here's the score:


PRR 2, Sluckey 1 .

[sluckey]

PRR 2, Sluckey 1

Is that hits or strikes?   

[Colas LeGrippa]

Dont try to save yourself, it s the score at the end of the 9th inning