PLL For Induction Heating

[marcbarker]

Yes, I dont really know the best way to design the charge pump, do you know of any schematics?

It's just the "LPF" I mentioned earlier. Follow it with a unity-gain buffer, which drives (via a pot-down) the base of the transistor. The transitor that replaced R1 in the SG chip.

Open-loop condition for testing...The added transistor base circuit: you want the VCO to vary over your total expected range of frequencies plus a 'bit extra in case', according to a 1 V to 4V DC signal, that comes from the UG buffer. If you add a series resistor under the emitter, VCO be more linear and controllable.

 

[Alexsgarage]

Here is the phase detector with a LPF.

 

[marcbarker]

put a var. resistor in series with C14 and make R13 a var. res. too.

5K, 0.1 uF, 100K

the ohmage in series with the cap deliberately creates phase jitter. You'll need some phase jitter, or your loop will resonate too much

 

[tcmtech]

Seems like an overcomplicated way of doing something simple. Did someone not understand their electrical physics 101 class work?

 

[Alexsgarage]

Here is the updated schematic, I added the two variable resistors. Can I connect W16 to the base of my transistor on the oscillator now?

 

[Alloush1980]

Dear sir
i am trying to make induction heater using cd4046,but i have a question regarding the cutoff freq,how to determine it? for example if my fmax is 70KHZ and center freq is 60KHZ,and min freq is 50KHZ,what will be the cutoff frequency according to it, so I can design my low pass filter, any excel sheet any one did? or any formula,plz i need ur help in this issue
i appreciate ur answer.
Best Regards
Alloush