Efficiency Finding and Parallel Connected Transistor

[Khatandeee]

Hello, I have two questions about this circuit.
1- What is the efficiency of the circuit and how to find it?
2- What is the purpose of connecting two transistors in parallel?
Thank you for your time

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[betwixt]

That is a strange circuit!
I can't tell what is supposed to do, maybe an FM transmitter, maybe a direct conversion receiver, regardless, the component values are odd and as it can't consume more than 1.2uA I wouldn't worry about efficiency.
I've no idea why two transistors are used, why a 1W resistor is needed or what the two incorrectly drawn diodes are for.


Brian.

 

[BigBoss]

It's a "Base Grounded Colpitts" Oscillator ,nothing special.
The purpose of using two transistors may be to increase the Collector Current in order to obtain more power OR to satisfy the Oscillation Conditions. It ought be well examined.
But using this configuration IMHO has no sense because it will also increase the Noise.
The main principle is to design a Silent Oscillator even at low power then amplify this obtained signal in a appropriate way.

 

[vfone]

Whatever power is about, connecting two BJTs pin to pin in parallel without using ballast resistors in emitter (or in base), is wrong.