L-Adapter

[savvas]

Mine too, it slowly decreases till it settles below 1mV

The transformer unfortunately has one 8VAC and one 16VAC primary. It is useful at this stage, nonetheless.

Using the Tinker box (which acts as heatsink) I'm forced to use those micro-usb cables which are thin and it's hard to find a really short one in my city. I'm thinking of building one myself.

 

[Salas]

Anyways, if you will suspect end of line voltage drop in peaks due to cabling add 0.1V to 0.2V on 5V output if its acceptable by the Tinker box when idling.

 

[savvas]

Will do that, thanks

 

[Nikos]

Here is my L adapter in a small edition for my filaments feed tube vs Lm317 CCS.
Big improvements in sound more bass and more details realy
Big improvements certify the very good waveform on my scope against waveform of the lm317...

 

[Salas]

Nice custom size home etch work. Congratulations. What type of diodes and what amperage F1 you used? Transformer VA? Those reservoir capacitors are high mF and there should be substantial inrush current at the power on moment. Any significant temperature on the naked bridge diodes? That's the 6V6 line preamp, so 0.45A heater current for each tube. Not much, but constant.

 

[Nikos]

Hi Nick
i use 1A fuse fast and MUR860 ,it is the main transformer with the specs that you gave us
2 X 10V/2A at the first post 6V6 line preamp ,the L adapter it very stable no high temperature on the naked bridge diodes at all.
Yes not much curent but realy stable .

 

[Salas]

I see your fuse is located after the single reservoir cap in this case. Safeguarding the main electronics section. Does not "feel" any inrush or ripple current.

 

[Nikos]

With the eye i dont saw anything in red.. at 610-620ma load 10Ω voltage 6.200

 

[Salas]

No, it wouldn't glow. Its located after the reservoir capacitor's charge path. So 1A fast is good choice for your purpose. In case of a shorted filament tube failure it owes to blow.

 

[Salas]

P.S. Forgot to mention, in post #35 there's a turn on event capture. You may notice it takes about 220mS to reach 6V+ Vout. That's a kind of soft start. No over voltage peak or wiggles there as well.
Such behavior helps with heaters because they tend to pull harder the moment you first apply voltage on them. Because of their significantly lower cold state resistance. Consequently a softer climb to Vout is good for their longevity.

 

[Nikos]

 

[Salas]

Remember how Incandescent light bulbs tend to more often go the moment we switch them on but less likely when already at work as they age? Something like that.

 

[savvas]

One supply to rule them all ...
from PCs to Tubes

 

[Bigun]

- We many times wonder what if that SMPS brick that feeds the Raspberry Pi or the mini PC or the MiniDSP or the Squ

- I will be editing & enhancing post #1 in later installments.

The implementation looks superb. But your DIY bench is very tidy, this is quite disturbing

 

[Salas]

I don't have much space. It's both my desk and a bench. So I have to deploy things and then remove them. If it was a bench only, the experimental leftovers would have stayed there forever.

 

[Salas]

One supply to rule them all ...
from PCs to Tubes

Did you find time to apply on the Tinker Box by now?

 

[Bigun]

I'd love a switch mode (aka modern) power supply suitable for a tube amp - it can provide high voltage for B+, high current for filaments. It has to be one supply because separate SMPS will 'talk' with each other.

 

[savvas]

Did you find time to apply on the Tinker Box by now?

No, I'm finishing a mic preamp in between, ordering and etching will take couple of days.
Today I was looking something better for phantom power (48V) other than plain LM317.
Most of the time is spend on decisions.
- "Decisions, decisions...."

 

[jackinnj]

I'd love a switch mode (aka modern) power supply suitable for a tube amp - it can provide high voltage for B+, high current for filaments. It has to be one supply because separate SMPS will 'talk' with each other.

I think that I post a link to this excellent application note every couple of weeks:
https://www.analog.com/media/en/technical-documentation/application-notes/AN118fb.pdf

 

[jayce996]

hi there, following you and very interested in a GB if this comes. (for my RPi3+Kali+Piano thinking to move to digiOne)