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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 346

post #5176 of 6943

I was thinking of bypassing the regulator (as I don't have it yet) altogether and powering the 6SN7 tube directly with the 6v 600ma power adapter?

post #5177 of 6943

Hi mab1376,

 

Since i use a receiver, I just plug the voltage regulator adapter into a switched outlet on the back of the receiver. When the receiver is on, the heater is on, and when I shut it off, it's off.

 

However, I don't see any problem inserting a little push button or similar on off switch in one of the leads from the adapter (many times lamp cords have these little switches for table lights).

post #5178 of 6943
Quote:
Originally Posted by mordy View Post
 

Hi mab1376,

 

Since i use a receiver, I just plug the voltage regulator adapter into a switched outlet on the back of the receiver. When the receiver is on, the heater is on, and when I shut it off, it's off.

 

However, I don't see any problem inserting a little push button or similar on off switch in one of the leads from the adapter (many times lamp cords have these little switches for table lights).

 

I'm sure i can find something, I can probably scrounge up one at work since I work in an electronics factory. Right now I just have a Wii PSU plugged into my UPS.

 

Quote:
Originally Posted by samtheman View Post
 

I was thinking of bypassing the regulator (as I don't have it yet) altogether and powering the 6SN7 tube directly with the 6v 600ma power adapter?

 

As long as that's whats being outputted it should work. Spec is technically 6.3v but 6.0v will probably work fine.

 

http://www.alibaba.com/product-detail/6-3v-600ma-dc-adapter_487037164.html


Edited by mab1376 - 2/28/14 at 10:36am
post #5179 of 6943
Quote:
Originally Posted by mab1376 View Post
 

 

I'm sure i can find something, I can probably scrounge up one at work since I work in an electronics factory. Right now I just have a Wii PSU plugged into my UPS.

 

 

As long as that's whats being outputted it should work. Spec is technically 6.3v but 6.0v will probably work fine.

 

http://www.alibaba.com/product-detail/6-3v-600ma-dc-adapter_487037164.html


Thanks for the advice. Just tried it and its working :)

 Will post impressions once I've had a chance to have a proper listen.

post #5180 of 6943
Quote:
Originally Posted by samtheman View Post
 

I was thinking of bypassing the regulator (as I don't have it yet) altogether and powering the 6SN7 tube directly with the 6v 600ma power adapter?

 

It would be a good idea to check the output of this adapter with a voltmeter. I have a 24V adapter that is actually putting out 33V! So your 6V adapter might be putting out more than 6V. If is is less than 7V, then I think you can get by for awhile. But if it is more than 7V, it mght be better to wait...

post #5181 of 6943

Good point let me measure mine...

post #5182 of 6943
Quote:
Originally Posted by gibosi View Post
 

 

It would be a good idea to check the output of this adapter with a voltmeter. I have a 24V adapter that is actually putting out 33V! So your 6V adapter might be putting out more than 6V. If is is less than 7V, then I think you can get by for awhile. But if it is more than 7V, it mght be better to wait...


 Gibosi - you are a legend! Always so helpful and wise.

 

The power adapter is one where you can select the output voltage - 5,6,7 etc. I checked the 6V setting with a Multimeter and just as you warned it was indeed outputting a high voltage (7.5 Volts). Just for interest's sake I selected 5volts and checked again. What would you know - the actual reading on the multimeter came out as 6.3 Volts exactly :) I'm going to stick with the 5 volt setting until the step-down converter arrives.

 

Thank you so much Gibosi and everyone else who has been advising me. It's helpful people like you all who re-new my faith in Humanity :)

post #5183 of 6943

I just measured mine(24V) SPERRY Meter readout is 24.82V and IDEAL meter readout is 23.97V on the output side it read 6.39V on board LED Display but on my IDEAL Meter it read 6.34V.

post #5184 of 6943
Quote:
Originally Posted by samtheman View Post
 


 Gibosi - you are a legend! Always so helpful and wise.

 

The power adapter is one where you can select the output voltage - 5,6,7 etc. I checked the 6V setting with a Multimeter and just as you warned it was indeed outputting a high voltage (7.5 Volts). Just for interest's sake I selected 5volts and checked again. What would you know - the actual reading on the multimeter came out as 6.3 Volts exactly :) I'm going to stick with the 5 volt setting until the step-down converter arrives.

 

Thank you so much Gibosi and everyone else who has been advising me. It's helpful people like you all who re-new my faith in Humanity :)

 

Good catch Gibosi!

post #5185 of 6943
Quote:
Originally Posted by samtheman View Post


 The power adapter is one where you can select the output voltage - 5,6,7 etc. I checked the 6V setting with a Multimeter and just as you warned it was indeed outputting a high voltage (7.5 Volts). Just for interest's sake I selected 5volts and checked again. What would you know - the actual reading on the multimeter came out as 6.3 Volts exactly smily_headphones1.gif I'm going to stick with the 5 volt setting until the step-down converter arrives.
You need to measure the voltage under load for a proper reading, You will probably find on most non switching unregulated power supplies / adapters that measuring voltage without a load will give higher readings than advertised since the minimal regulation circuitry requires a load to work.

Test it again with the 6V setting connected to a tube filament.
post #5186 of 6943
Quote:
Originally Posted by TrollDragon View Post


You need to measure the voltage under load for a proper reading, You will probably find on most non switching unregulated power supplies / adapters that measuring voltage without a load will give higher readings than advertised since the minimal regulation circuitry requires a load to work.

Test it again with the 6V setting connected to a tube filament.

 

I have a question. Measuring my 24V adapter at the input to the voltage regulator shows 33V with no load. But still, I am able to dial in more than 25V. So, it certainly seems that my 24V adapter is actually putting out more than 24V into a load. But perhaps, since its intended use is as a battery charger for an 19.2V drill/driver, the load presented by a tube is somewhat different than it was spec'd for?  And perhaps this explains to some degree why it is delivering more than it's rated voltage?

post #5187 of 6943
Quote:
Originally Posted by gibosi View Post
 

 

I have a question. Measuring my 24V adapter at the input to the voltage regulator shows 33V with no load. But still, I am able to dial in more than 25V. So, it certainly seems that my 24V adapter is actually putting out more than 24V into a load. But perhaps, since its intended use is as a battery charger for an 19.2V drill/driver, the load presented by a tube is somewhat different than it was spec'd for?  And perhaps this explains to some degree why it is delivering more than it's rated voltage?

NiCad batteries require a constant current for charging, the voltage has to be higher than the battery voltage to allow this to happen. If you plugged in a battery pack and measured the voltage from the charger you will find it to be between 19.2 and 24V depending on the charge state of the batteries.

 

You are able to dial in more than 25V as the no load output of the charger is 33V and the current draw from the regulator / tube is minimal compared to charging a battery.

:beerchug: 

post #5188 of 6943

Thanks for clarifying this. It all makes sense. :)

post #5189 of 6943
Quote:
Originally Posted by TrollDragon View Post


You need to measure the voltage under load for a proper reading, You will probably find on most non switching unregulated power supplies / adapters that measuring voltage without a load will give higher readings than advertised since the minimal regulation circuitry requires a load to work.

Test it again with the 6V setting connected to a tube filament.


Thank you - great advice.

 

Power supply was connected to the tube when I tested it - more by luck than design though :)

post #5190 of 6943
Quote:
Originally Posted by samtheman View Post


Thank you - great advice.

Power supply was connected to the tube when I tested it - more by luck than design though smily_headphones1.gif
You are most welcome.

I couldn't tell by your post if it was connected or not, since it is under load that you get 6.3V on the 5V setting then that is good and will work great until your reglulator arrives on the slow boat from China. smily_headphones1.gif
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