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Schematic of Walkie-Talkie circuit
I decided to create a simple 2 way radio transmitter as I am very interested in ...
M

michaelkd

I decided to create a simple 2 way radio transmitter as I am very interested in learning more about communication protocols and radio technology. I found it very helpful whenever the parts I needed were already in the parts library, however, I found the component creator very unintuitive coming from Fusion 360. I really liked playing around with Copilot and the extent of what it knew and could solve really surprised me. I found the layout rules a little confusing at first, but once I started to understand it I appreciated being able to edit all of the properties in one place. I really like how simple the webapp is to run as well!
2y
2
please explain what Q2 does.
M

michaelkd

@copilot please explain what Q2 does.
2y

copilot

The Q2 designator represents a 2N3904 NPN Bipolar Junction Transistor (BJT). In this walkie-talkie circuit, Q2 is functioning as a voltage amplifier. The electrical signal from the microphone (MK1) is quite small and not sufficient to drive the radio transmitter (U1).
This is where Q2 comes in: it takes the small input voltage from the microphone (MK1), applied between its base (B) and emitter (E), amplifies it and reproduces it across its collector (C) and emitter (E). This amplified signal is then ready to be input into the radio transmitter.
The Q2 base-emitter junction is forward-biased by capacitor C4 and R4, allowing AC signals to pass through while blocking DC. The collector-emitter junction is reverse-biased by the power supply (+9V). The amplification level is largely determined by the values of R3 and R4.
In short, Q2 is used as the amplifier part of the walkie-talkie to enhance the audio signal coming from the microphone (MK1) before being sent to the NRF24L01 transceiver for transmission.
2y
4
J1
C1
Capacitance
100uF
U3
C2
Capacitance
100uF
R1
Resistance
10KΩ
U2

Walkie-Talkie circuit