duncanamps.com

[Gubbe]

Hello everybody!
I want to simulate an output transformer in LT-Spice, but i have very little info on the thing. All i know is that it says on Hammonds website that primary impedance is 2.5 kOhm and that it can handle 30 "audio watts" (this is an example, I want to simulate different transformers, but you got to start somewhere). I guess that this is the aproximate impedance reflected by a load connected to the appropriate secondary winding (8 Ohm resitance connected to the winding marked 8 Ohm), my question is this; How do I calculate the parameters that I need to simulate this transformer? I don't have any inductance figures, just an impedance ratio. Is it possible to do some kind of approxmate guesses about the primary inductance and then work out the turns ratio to get the secondary inductance?
I mailed Hammond, but the answer I got was that they didn't have any additional information on this range of transformers! I find this strange, because they are used for building electronics, so people would have to have good specifications on them to be able to predict how they will function, rigth? Since no additional information is availble I can only assume that everything I need to know is in the information I already got, now I need someone to tell me how to use this informartion....

Please help.....

[Suusi M-B]

Hiya Gubbe


I guess that you could do a lot worse that start with the downloadable EL34 optput transformer here its on the LT spice page.

There is some help in the LT spice pages help files on transformers.

I guess that the best way of doing it would be to ask what the turns ratio for the transformer is. if you cant get that info, then put a low voltage ac bell transformer, say 6 volts) on the 8 ohm winding and measure the output voltage on the anode (plate) leads. (I am assuming that its a push pull output transformer)

WARNING The output voltage may be about 10 times higher so be careful.

The output voltage / input voltage is equel to the turns ratio. According to the LT spice help file the inductance ratio is equel to the square of the turns ratio.
_________________
Suusi M-B

Eight words the Wicca Rede fulfill, "An it harm none, Do as you will"