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Little Dot Tube Amps: Vacuum Tube Rolling Guide
Jun 4, 2014 at 6:56 PM Post #6,376 of 13,434
trolldragon said:
Now if one were to run the heaters in series you could use the 12 volts from the PC power supply and no regulators would be required...
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I have never taken a very accurate voltage reading of the PC power supplies 12 votes is it exactly 12 votes or is it more like 12.6? Whatever it is would it be right as you explain? A few more words please! 
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Jun 4, 2014 at 7:42 PM Post #6,377 of 13,434
 It all depends on Desktop PS i do have few of them and the voltage out put varies some have(schiit ones/no name brand)11.something volts i've even saw one that only out put 10 something volts but this one on the picture out put 12.15V(according to my IDEAL Multi metre).One thing to be aware of these type of power supplies some have annoying fan noise and some of them it makes your tube hum but not these one on the picture these one is very quiet fan and all and it's heavier than any desktop PS i have on hand.If the fan is noisy you can just replaced them with quieter model or install a fan speed controller.

 
Jun 4, 2014 at 7:52 PM Post #6,378 of 13,434
bbmiller said:
I have never taken a very accurate voltage reading of the PC power supplies 12 votes is it exactly 12 votes or is it more like 12.6? Whatever it is would it be right as you explain? A few more words please! :eek:
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A decent PC power supply with a load attached should put out very close to 12V and be useful for heater supply of the same tubes in a series configuration. The reason I say the same tubes is if you decide to try a tube that draws 2.5 amps with a tube that draws 0.6 amps you will most likely burn out the lesser filament from the bigger tube drawing too much current through it. Best to series the filaments on the same current draw tubes.

You will have to measure the 12 volt line on your power supplies with a load connected such as a hard drive to see if the output would be suitable.

You don't need exactly 12.6 volts, 12V will work fine and the tubes will last a little longer in the process.
 
Jun 4, 2014 at 8:08 PM Post #6,379 of 13,434
Hi TD,
   Since we are on PS topic how important it is to put a dummy load resistor in the PS?What i did is i installed a 18R 5W resistor (white ceramic resistor don't know what you call them) on 5V rail, and since i tied the 2 12V rails(V1 and V2)does it mean i double up the current?THANKS! 
 
Jun 4, 2014 at 8:41 PM Post #6,380 of 13,434
Well ILM2...

I don't really know if you parallel both rails if you'll get double the current. Most of the stuff in this thread is unorthodox so it hasn't been tested before as PC power supplies are made for PC's... Utilizing the 3, 5 & 12 rails all at once. So I can't really say if the resistor is needed for the 5V rail or not as well. I'd say take it out and see if it still works, why generate heat when you don't have to?

All the tube amplifiers out there have transformers designed and spec'd to run the HV and Filament supplies and that's it there are no other sources like those from a multivolt switching power supply to deal with.

The best thing would be to find a 12V 8A power supply if anyone wants to run the 6AS7 filaments in series...
 
Jun 4, 2014 at 9:46 PM Post #6,381 of 13,434
trolldragon said:
The best thing would be to find a 12V 8A power supply if anyone wants to run the 6AS7 filaments in series...
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Or for those who don't have a suitable 12V desktop PC power supply.....
 
I am using this laptop power supply, adequate to power the heaters of two 6AS7's connected either in series or parallel.
 
19V 4.74A AC Adapter Charger For Samsung Laptop for about $9.50 (includes AC power cord).
 
http://www.ebay.com/itm/151235154803?
 
And I believe this regulator is similar to the one that Hypnos1 is using:
 
AC/DC 12-45V to 0.7-21V 8A Step-Down Voltage Regulator for about $8.25
 
http://www.ebay.com/itm/300839166993?
 
Jun 4, 2014 at 10:32 PM Post #6,382 of 13,434
Yes indeed gibosi,
That setup works like a charm, I was just simplifying it a little for those who do not want to mess with regulators. :)
 
Jun 5, 2014 at 11:53 AM Post #6,383 of 13,434
gibosi said:
   
Or for those who don't have a suitable 12V desktop PC power supply.....
 
I am using this laptop power supply, adequate to power the heaters of two 6AS7's connected either in series or parallel.
 
19V 4.74A AC Adapter Charger For Samsung Laptop for about $9.50 (includes AC power cord).
 
http://www.ebay.com/itm/151235154803?
 
And I believe this regulator is similar to the one that Hypnos1 is using:
 
AC/DC 12-45V to 0.7-21V 8A Step-Down Voltage Regulator for about $8.25
 
http://www.ebay.com/itm/300839166993?
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Hi gibosi and bb.
 
I have now gone for a higher-rated regulator, which looks a little better made (not a lot!)...
http://www.amazon.com/VvW-4-5-30V-0-8-30V-Converter-Regulator-4-5-30V/dp/B00IOT2TPI/ref=sr_1_2?
 
 
 
trolldragon said:
Yes indeed gibosi,
That setup works like a charm, I was just simplifying it a little for those who do not want to mess with regulators.
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Sure does work like a charm, TD...
 
ps. With protection circuits built into the regulator - especially the one I mentioned above - will this give added safety?...can't be too careful...or am I being my usual paranoid self, lol?!
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.
 
Jun 5, 2014 at 5:45 PM Post #6,384 of 13,434
trolldragon said:
Well ILM2...

I don't really know if you parallel both rails if you'll get double the current. Most of the stuff in this thread is unorthodox so it hasn't been tested before as PC power supplies are made for PC's... Utilizing the 3, 5 & 12 rails all at once. So I can't really say if the resistor is needed for the 5V rail or not as well. I'd say take it out and see if it still works, why generate heat when you don't have to?

All the tube amplifiers out there have transformers designed and spec'd to run the HV and Filament supplies and that's it there are no other sources like those from a multivolt switching power supply to deal with.

The best thing would be to find a 12V 8A power supply if anyone wants to run the 6AS7 filaments in series...
Click to expand...

Without the dummy load on 5V rail if  i plug-in 2 6AS7 on 12V rail the voltage will drop significantly then it goes back up to 12V and with the dummy load i can plugin the tubes and the voltage just dropped a few millivolts does this mean that with the dummy load the PS is more stable?Thanks!
 
Jun 5, 2014 at 5:56 PM Post #6,385 of 13,434
No what it means is that a PC power supply is designed to provide multiple voltages all at once and it gets a little wonky when put into service out of its design specifications.

So you'll have to leave the 5V load resistor in place to use the 12V lines. :)
 
Jun 5, 2014 at 6:03 PM Post #6,386 of 13,434
hypnos1 said:
ps. With protection circuits built into the regulator - especially the one I mentioned above - will this give added safety?...can't be too careful...or am I being my usual paranoid self, lol?! :blink: .
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With most inexpensive protection circuits, IF they are designed and working properly will crowbar the output to Zero volts in the event of failure. These ones on your board I believe also disable the regulator chip in the event of a short on the output lines as well.

So you should be alright as far as one can trust inexpensive Chi-Nee products...
:beerchug:
 
Jun 5, 2014 at 8:38 PM Post #6,389 of 13,434
Wow! Just got my 6HM5s... SO much better than stock... How many hours are they rated at? Might pick up another set at this price.  Thanks for the suggestions, this amp just got 5x better ^.^
 
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