mstechca
New Member
No, I'm not showing you one.
I mentioned in Walter's 3-page thread about capacitors that I discovered that there is a band-pass and a band-reject filter.
If I'm not mistaken, a band-reject filter connected in a certain way will be a band-pass filter. The same is true for a band-reject filter. right?
So anyways, what I intend to do is convert these "filters" into tank circuits and control them both at the same time, so that hopefully two band-pass filters will see the frequency, and my equation stress will stop.
my varactor is the design Audioguru showed me, a diode and a capacitor in series. The center point is the voltage control point. I will be using two varactors now.
Because I want both varactor values to be the same at all times, do I need to use two DAC's to digitally control each one independantly, or can I use one DAC, and deliever the output to both at the same time?
I would rather use one, but I'm not sure what effect it will have on the entire circuit if any.
My DAC is an R-2R ladder connected to a 4024 counter.
Also, Does anyone know where I can find a list of diodes or transistors that work as perfect varactors? I want to obtain a wide range. I use 0.1uH inductors in my circuit.
So far, the best transistors that work as a varactor are the 2N2222, and the 2N3904.
Actually, if there is a large database that tells me the junction capacitance of many BJT transistors without having to download hundreds of datasheets, I would like you to tell me where to find the database.
thanks.
I mentioned in Walter's 3-page thread about capacitors that I discovered that there is a band-pass and a band-reject filter.
If I'm not mistaken, a band-reject filter connected in a certain way will be a band-pass filter. The same is true for a band-reject filter. right?
So anyways, what I intend to do is convert these "filters" into tank circuits and control them both at the same time, so that hopefully two band-pass filters will see the frequency, and my equation stress will stop.
my varactor is the design Audioguru showed me, a diode and a capacitor in series. The center point is the voltage control point. I will be using two varactors now.
Because I want both varactor values to be the same at all times, do I need to use two DAC's to digitally control each one independantly, or can I use one DAC, and deliever the output to both at the same time?
I would rather use one, but I'm not sure what effect it will have on the entire circuit if any.
My DAC is an R-2R ladder connected to a 4024 counter.
Also, Does anyone know where I can find a list of diodes or transistors that work as perfect varactors? I want to obtain a wide range. I use 0.1uH inductors in my circuit.
So far, the best transistors that work as a varactor are the 2N2222, and the 2N3904.
Actually, if there is a large database that tells me the junction capacitance of many BJT transistors without having to download hundreds of datasheets, I would like you to tell me where to find the database.
thanks.