on1aag said:pin 5 is not connected !
on1aag.
forever99482 said:pin 5(toko) is not connected?? but the circuit shows that it is connected to pin 5 of tca440. Please explain a bit more, I might be confused.
some more questions,
1. what frequency should I be looking at before the input to the lm386 (pin 3)?
2. What frequency should I be expecting on the mixer output of tca440, as I'm seeing frequency as high as 100MHz.....
Thank you
forever99482 said:As I'm not inputing any RF signals to it, so shouldn't the mixer output be around 3.5MHz? Unless my VFO is not working correctly....
electrocompo said:Hello,
Can anybody please help me out with oscillator configuration of the tca440.
the internal oscillator circuit can be controlled by pin 4 5 and 6. my questions are
1) how do you control the frequency of the signal produced by this internal oscillator by using this three pins?
2) am i suppose to build a whole new oscillator circuit to control the internal one?
3) how do i build an oscillator circuit that controls another oscillator circuit?
Thanking you i advance
electrocompo said:So there are many kinds of RF oscillator that I can use with the tca440?
Arent RF oscillator meant to be connected to the mixer directly... I mean if it is an RF oscillator and we are connecting it to another oscillator (the internal one) then its like two oscillator connected together? does that make sense?
I really need help with this topic
electrocompo said:So there are many kinds of RF oscillator that I can use with the tca440?
Arent RF oscillator meant to be connected to the mixer directly... I mean if it is an RF oscillator and we are connecting it to another oscillator (the internal one) then its like two oscillator connected together? does that make sense?
forever99482 said:pin 5(toko) is not connected?? but the circuit shows that it is connected to pin 5 of tca440. Please explain a bit more, I might be confused.
some more questions,
1. what frequency should I be looking at before the input to the lm386 (pin 3)?
2. What frequency should I be expecting on the mixer output of tca440, as I'm seeing frequency as high as 100MHz.....
Thank you
Nigel Goodwin said:Like on1aag says, there's only one oscillator circuit there, with the active part inside the chip, and the LC tuning part outside the chip - two halves make a whole.
You're making it far more complicated than it is!.
electrocompo said:Thanks for your help!... really appreciate it.
But just one more thing: about the "LC tuning part" outside chip as you mentioned above,
Is that the only configuration (in the circuit diagram above) that can be used with the TCA440?
If yes, how does this oscillator circuit works as there are both "trimmer capacitor" and "variable resistor" in the circuit. i would just like to know the separate function of this components cos i understand one of them is definitely responsible for tuning the circuit.
If there are other configuration out there, could you please point me in the right direction?
Also, could you please tell me the exact relationship between the internal osccillator (the 1st half) and the external oscillator (the second half). I mean do i not need to know this reationship to understand how the external oscillator controls the internal one?
and the three pins of the intena oscillator...are those the "base", "emitter" and "collector" pins?
I do not mean to bug you guys but i really need help on this topic
Thanks in advance... hope u having a nice festive season!
1. for LO to be on the High side- set it to 3.955 to 4.055MHzelectrocompo said:Thanks for your help!
so after building the ciruit above all i need to do to adjust the oscillator frequency is fiddle with the potmeter?
Just wanna clarify some points here:
I wanna use this to work with RF signals within the range 3.5MHz - 3.6MHz with 455KHz as the IF frequency.
1) What frequency should i set the oscillator frequency to?
2) Since there is no indicator or some kind of visual user interface for the oscillator, how do i check if the desired oscillator frequency have been achieved?
3) Also, as I have no real RF signals and I can only test this circuit in the lab. do u have an idea on how to go about simulating an RF signal within the range 3.5MHz - 3.6MHz and testing this circuit? i intend to use an oscilloscope to check the corresponding outut and not the audio aids as i am focusing on the front part of the circuit only.
Thank You.
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