Tube tester transformer saturates at 50 Hz - tips?
Tube tester transformer saturates at 50 Hz - tips?
(OP)
I have a Precision Model 10-12 tube tester. It works in every respect, but I have a problem when I try to calibrate it to show 100% instead of the close to 95% that I can run it without popping the fuse*.
I have found a way around that problem. It is not exactly what I wanted, but it works. It involves standard passive components, but is bulky.
I think that my "solution" is quite interesting but I am interested in hearing what other ideas there may be.
*You calibrate it by adjusting a series resistor in the primary of the transformer (yes, crude - it was like 60 or 70 years ago) and then the 50 Hz/20 ms saturates the transformer core while the 60 Hz/16.7 ms does not.
I have found a way around that problem. It is not exactly what I wanted, but it works. It involves standard passive components, but is bulky.
I think that my "solution" is quite interesting but I am interested in hearing what other ideas there may be.
*You calibrate it by adjusting a series resistor in the primary of the transformer (yes, crude - it was like 60 or 70 years ago) and then the 50 Hz/20 ms saturates the transformer core while the 60 Hz/16.7 ms does not.
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.





RE: Tube tester transformer saturates at 50 Hz - tips?
My first experience with 50HZ was at a power plant being constructed in Japan. Yup one of those hit by a big wave. I was just a kid when it was being constructed. Even then I was telling people that this was a disaster waiting to happen. This had an alarm panel filled with 50 transformers all in saturation. Plant hadn't even gone to startup and half the units had failed. Strangly the IC's failed, not the transformers and the units were labeled to work on 50HZ. Dropping the voltage solved that.
RE: Tube tester transformer saturates at 50 Hz - tips?
http://bama.edebris.com/manuals/paco/dat10_12/
RE: Tube tester transformer saturates at 50 Hz - tips?
The reason that the transformer core saturates is that the volt-seconds (the area under the sine) are higher when the frequency gets lower.
That, in combination with the "Grid Adjust" function that was used to calibrate the unit so that it delivers the right results even if the grid voltage is off, makes the use of a buck transformer impossible since you will still get back to the same V/turn ratio when the adjustment is made.
What you need to do is to reduce period time, which seems to be impossible without adjusting frequency.
It isn't. I put a triac with a fixed firing delay in series with the primary so that the voltseconds are reduced without lowering the peak voltage. Works wonderfully.
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Tube tester transformer saturates at 50 Hz - tips?
The Triac alternative is much neater and not bulky at all.
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Tube tester transformer saturates at 50 Hz - tips?
IR51H420 - SELF-OSCILLATING HALF-BRIDGE