"High Voltage" Tube pedal project suggestions

[box_maker_1]

This board is invaluable.  Thanks!

Hey, so I wasn't totally clear.  How do you get +12V out of the Power Supply? 
I only see the single output from the power supply (the +50-390V output that will feed the tubes).

The Power Supply link I'm talking about:
https://www.ebay.com/itm/384981437781?hash=item59a2ae8d55:g:QScAAOSwroVhsdRT&amdata=enc%3AAQAHAAAAoF110dfVmAwFsGZkz423hr5HxEuo1ECXrSjHSK9gKLI6LqVQSMt1N310Mf9WqZZtlWSWy3XU6B9NaSnVxoK5M59pyXejtKNLkPW3PISAXhzJZRppAL2p%2B9bkNyKMqHEqDf0Z9zv4sRBT1lMsNVmNhaiAAwqpG%2BkHxOZOhnUPo0verN4QGEEuqHqgHwwHUZMP9Mc22RcElL0oBmpvF2H8nWY%3D%7Ctkp%3ABk9SR4ji9uqJYQ

[puretube]

Look at the INput of that supply ...
(first you need 12V (8-32V), to make a HV out of it - and to heat the tubes).

[box_maker_1]

ahhh, I'm being a doofus. 

There will be a power adapter with 12V coming into the project. Split that power and send 12V to the heater pins of the tubes and 12V to its input of the Nixie Power Supply.

Simple as that?

[puretube]

ahhh, I'm being a doofus. 

There will be a power adapter with 12V coming into the project. Split that power and send 12V to the heater pins of the tubes and 12V to its input of the Nixie Power Supply.

Simple as that?

Yep.

[GibsonGM]

I think you can actually see that in the pic of mine that I posted.

Yup, with the electrical tape on it. Goes to the heaters w/dropping resistor, to the SMPS board, and to the LED up front.

[box_maker_1]

Ok guys, thanks for indulging my questions.  I'm learning!

So let's say I've got a 12V 1A power supply feeding this project.
Looking at this spec sheet for a 12AU7 tube: https://frank.pocnet.net/sheets/093/1/12AU7A.pdf
It looks like the heater will take 12V if wired in series but only 150mA current.

Would feeding a 1A straight from the power supply fry it?  That like 7x more current than it's asking for...

@GibsonGM -  What is the dropping resistor in front of the heaters doing in your project?  Was the power supply feeding your project >12 volts?  Or perhaps were you dropping to 6 Volts to wire in parallel?  How did you handle current differences?

[GibsonGM]

It's a common problem when you're new to not really understand current, so no worries!  Your logic is sound, and thinking ahead is a good thing.  And we here love answering questions if we can, lol

Whatever you're supplying current to, which we call the 'LOAD', DRAWS its own current ('load' and 'draws current' are on the test).  We don't push the current into it.   We need to think about how MUCH current our power supply can deliver, except in a few rare cases such as LEDs, which need an external resistor since they have so little of their own when "on" and oriented properly that they will fry themselves, as you're imagining!   

The load for the GTFO is the 2 tube heaters (so, about 300mA), and whatever current they'll need to operate (probably like 3mA each triode, just say 15mA; very little).   The SMPS will require power too, of course, but not much.   1A 'ampacity' (ability to deliver current) is fine.   

I'm using a 13.5V 1A supply myself.   Because it's "13.5" and not 12, I put a dropping resistor in series, yes.   

Its value is found by "R = Ed/I "    Resistance = voltage drop / current       wanted to drop 1.5v/300mA = 5 ohms
I used a 10 ohm because I had it lying around, and the power supply was putting out a bit more than 13.5V anyway.  So the measured voltage on the heaters is good. 

It's a 10 watt resistor (large size), because it has to dissipate POWER (watts). It gets warm.   About 1 watt, anyway...

[box_maker_1]

Excellent! Many thanks.  All is clear now.  At least mostly clear

Gonna order me some parts and do some tinkering.  I imagine I'll have more semi-obvious questions sooner or later.

[GibsonGM]

Great. We all have questions, they just get more complicated, ha ha.  Let us know how it's working out.