good, affordable respiratory trainer

I am 73 years old. After a Quadrizepssehnenriss (and an OP, unfortunately no rehabilitation) I can not go over well and sit a lot. Long walks as before no longer exists therefore. I noticed that after a protracted bronchitis my breathing became more shallow. Countermeasures was announced. So buying an ergometer, more gymnastics and breathing exercises. In the instructions for breathing training by means of a CD I fell asleep on a regular basis immediately. Therefore, the purchase of the respiratory trainer TRI-ball, I use now times a day for a month about 3.
In layman's terms: breathing became deeper and calmer, the volume larger, I'm no longer constantly tired. Everything interacts well.
The respiratory trainer is certainly a very good addition. I do not want to miss him.