• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

wiring tubes in series

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#81
Aran Everitt said:
how do i work it out?
Click to expand...

The anode current is on the data sheet:
http://www.mif.pg.gda.pl/homepages/frank/sheets/106/1/12DU7.pdf

Look at typical operating conditions on the data sheet.
Plate means anode..

ie plate current is 12mA..so put the largest value in you can in and have it work.
Then measure the voltage across the resistor. Divide the voltage across the resistor by the resistor value that gives you the current. You can compare this to the 12mA and drop the value of resistor until you get 12mA

Its not much current.

Regards
M. Gregg
 
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#86
Aran Everitt said:
ok so i am left with 0.006A or 0.006mA
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The current through the resistor is the current through the Tube and also the current through the Output transformer

ie the current is in a circuit from supply through the output transformer then the tube then the resistor. So measure the cathode resistor and your measuring the value of the tube current which is anode current,,

😀 I'll give you a clue .5 A is 500mA..

Regards
M. Gregg
 
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#88
Aran Everitt said:
ok thanks, should i simply put 2 330ohm resistors in series to get me 12mA current? thanks

Aran
Click to expand...

If you reduce the resistance you increase the current.
If you increase the resistance you reduce the current.

Resistors in series is increasing resistance,

If .1A is 100mA what is .006A?
If .01A is 10mA..

Its just a bit of fun..😀

Regards
M. Gregg
 
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