Into HSMM-MESH big time and wanted a way to see where my antennas or other devices really were spectrum wise.
Therefore, I am building my own poor man's spectrum analyzer.
I actually have one running now but I recognize that it needs to be better.
Not being very smart on these things and not an engineer but having been exposed to such things enough to be encouraged I have put together a 2.4 gig VCO swept by a 555 generated constant current charged saw tooth.
Running between 1/3 and 2/3 VCC, which is not what I wanted, I need 2 volts to 15 volts P/P. Or 2 to 17 volts depending on which VCO you get.
Since the VCC spec on the 555 is 18 volts max I am taking a risk with running it at 24 volts VCC in order to get the 2/3 VCC top rail of 16 volts so I cringe every time I apply power.
I don't like taking the sweep voltage from the charging CAP because it has to feed both the VCO and the horizontal input of the scope.
　
　
So I need some advice on how best to amplify, split, match the sawtooth.
My first impression is to add an OP AMP but that is where the problem is.
　
　
Thanks, Joe )

 

You can use the control input to change the voltage divider away from the 1/3 and 2/3 points.

If you have a good sawtooth and it just isn't between the desired endpoints voltage-wise, then I would recommend passing it through a little opamp circuit that provides the needed gain and offset correction to get what you want.

 

That is interesting, the only thing I have used pin 5 for is to FM the oscilator with audio.
Joe )