Then use a high supply voltage and a low-value emitter resistor to get more power output. Adding an RF power amplifier will also extend its range. Adding a multiple-stage RF power amplifier will extend its range a lot (and put you in jail).mstechca said:Lets take a simple FM transmitter.
What components should I deal with and how should I change them? I want to optimize it for distance
What tone? Are you modulating it with an audio tone?but I also want to hear the transmitted tone on the receiver as well. I don't care if the tone changes frequency, but I still want to hear it when the transmitter and receiver are far away.
mstechca said:how did you figure 100Mhz?
Lets say the oscillator comes with the emitter resistor. What equation can I use to determine the frequency?
mstechca said:if you say LC determines the frequency of the output tone, then why is it that when I change any component shown in my oscillator diagram, the frequency changes?
Are you telling me that I can just change those values around, and the tone frequency doesnt change? I dont think so.
What I have learned from experience is that two frequencies exist in a transmitter, the Radio frequency, and the audio (tone or voice) frequency.
And in a radio transmitter, the audio or voice gets passed through the radio frequency. The simple LC equation would reveal the radio frequency, and I understand that. But, what I need is the equation for the audio frequency with the feedback capacitor. For a simple oscillator, I can just do R * C, but here, it doesn't exactly work that way because of the feedback capacitor.
I need an equation for the audio frequency.
Me: if you say LC determines the frequency of the output tone, then why is it that when I change any component shown in my oscillator diagram, the frequency changes?
Nigel: Because you are altering L or C (most probably C), changing any component around the oscillator will affect these.
Uhh, I built and tested the circuit, so I do know what I am talking about.Me: Are you telling me that I can just change those values around, and the tone frequency doesnt change? I dont think so.
Nigel: Having finally realised what you are on about, there IS NO TONE.
How about a tracking transmitter. How can it transmit to a receiver if a tone isn't passed?Me: What I have learned from experience is that two frequencies exist in a transmitter, the Radio frequency, and the audio (tone or voice) frequency.
Nigel: That's not really true, you need to 'learn' some more 8)
A transmitter has a carrier (RF) and 'may' include modulation at a lower frequency, but this is seperate to the RF transmitter part.
Me: And in a radio transmitter, the audio or voice gets passed through the radio frequency. The simple LC equation would reveal the radio frequency, and I understand that. But, what I need is the equation for the audio frequency with the feedback capacitor. For a simple oscillator, I can just do R * C, but here, it doesn't exactly work that way because of the feedback capacitor.
I need an equation for the audio frequency.
Nigel: There is NO AUDIO FREQUENCY, just an RF carrier signal, modulated by any input fed to it - if you want an audio tone you need to build an audio oscillator and feed it to the input.
mstechca said:Me: if you say LC determines the frequency of the output tone, then why is it that when I change any component shown in my oscillator diagram, the frequency changes?
Nigel: Because you are altering L or C (most probably C), changing any component around the oscillator will affect these.
in my original circuit, there is no L.
Uhh, I built and tested the circuit, so I do know what I am talking about.Me: Are you telling me that I can just change those values around, and the tone frequency doesnt change? I dont think so.
Nigel: Having finally realised what you are on about, there IS NO TONE.
How about a tracking transmitter. How can it transmit to a receiver if a tone isn't passed?Me: What I have learned from experience is that two frequencies exist in a transmitter, the Radio frequency, and the audio (tone or voice) frequency.
Nigel: That's not really true, you need to 'learn' some more 8)
A transmitter has a carrier (RF) and 'may' include modulation at a lower frequency, but this is seperate to the RF transmitter part.
Me: And in a radio transmitter, the audio or voice gets passed through the radio frequency. The simple LC equation would reveal the radio frequency, and I understand that. But, what I need is the equation for the audio frequency with the feedback capacitor. For a simple oscillator, I can just do R * C, but here, it doesn't exactly work that way because of the feedback capacitor.
I need an equation for the audio frequency.
Nigel: There is NO AUDIO FREQUENCY, just an RF carrier signal, modulated by any input fed to it - if you want an audio tone you need to build an audio oscillator and feed it to the input.
Now you are really throwing me off. If I could just get AN EQUATION, maybe I wouldn't be in need of help right now.
mstechca said:audioguru is now starting to understand me.
I hope everyone understands this:
1. I want to make an FM transmitter using only transistors as the semiconductor devices.
2. I want the transmitter to transmit a continuous audio tone.
3. I want equations relating to every component in the circuit.
It transmits a weak signal on the FM band.
It transmits AM and FM when modulated with a tone.
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