How to determine the type of VT1?

S

synapse_people2021-04-19 20:09:00

Electronics

synapse_people, 2021-04-19 20:09:00

Hello!
I found the amplifier circuit, tell me, the VT1 type is missing ...
What should it be?
And is it true that this circuit is capable of delivering 10 watts, working from 9v? How long will it run on 3x16850 x 3500mah batteries?

Reply

Answer the question

In order to leave comments, you need to log in

1 answer(s)

V

Viktor, 2021-04-19
@nehrung

missing type VT1... What should it be?

Yes, almost any low power PNP with a coefficient. current gain 100...300. But since it stands at the entrance, it is highly desirable that it be the so-called. "low noise". Low-noise is one whose datasheet specifically says that it is low-noise. Or, if there is nothing written about this, then the coefficient must be indicated. noise, and its value should be small in comparison with similar ones.

And is it true that this circuit is capable of delivering 10 watts, working from 9v?

This is easy to see by eye. When powered by 9 volts, the output sine wave is unlikely to exceed 7 volts (if without clipping). So the amplitude is 3.5, and eff. about 2.5 volts. We divide your required 10 watts by 2.5 volts, we get a current of 4 amperes. If 2.5 volts is divided by 4 amperes, then according to Ohm's law, the load resistance should be 0.625 ohms - a little more than half a ohm .
If you find a loudspeaker with such an impedance, then you can get 10 watts.
Please note that I did not use any parameters specifically for your circuit in this estimate. So the same will apply to any other circuit that you want to power from 9 volts. Except class D (pulse) amplifiers.

How long will it run on 3x16850 x 3500mah batteries?

Three elements, presumably, are connected in series - otherwise the voltage of 9 volts cannot be obtained. This means that the required current of 4 amperes should be provided by any of these elements. A capacity of 3500 mAh means that such an element is ideally capable of delivering 3.5 amperes for one hour. But we have, firstly, the current is more than 3.5, and secondly, the batteries are not ideal. Well, they will give you such a current for 30 ... 40 minutes. Hardly any longer.