Recent content by anstxfw

hi,Jim.Thank you for your help.I solved my problem.I just put a wire into the cleaning barrel,which filled with ionized water.And the wire connected to the GND of the machine.The voltage of VCOin can be stable. I think the wire bypass the interference. Thank you again. If you visit to China, I...

I try 200pf,but the PLL can unlock.the VCOin is 5V. And Impolite to ask a question,why to Series a capacitor,i don't understand.

If the power supply systems of some customers don't connect to the earth,it can be an problem.So i must solve it without the earth. How to improve the response time, if the use of 1uF capacitors(C18).

Sorry about that,because i put the ground of the machine to the earth.

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no,i don't solve my problem.using 0.1uf (C18) ,the VCOin can not be stable, the frequency of the hash is 50HZ,you can watch the figure 4 at 3# where I posted.If using 1uf,the VCOin have no hash,but the rising time will be 5 times before. It is unacceptable. It looks like Figure a,attached in...

it may be better to connect the sensor across the timing capacitor C18,you mean connect the neddle to the C18? what is the sensor?

Thank you a lot.Figure 5.1 shows the neddle connects to the circuit and the tube. The gnd of circuit is connected to the gnd of machine. Today I try to change C18(the low pass filter cap) from 0.1uf to 1uf.The waveform of VCOin can be stable,as shown in Figure 5.2,the figure 5.2 shows that...

Jim Hardy,Thank you so much. I'm trying to lock to HEF4024 Q3,the frequency is 375khz. But if the needles are filled with ionized water,the PLL can not lock, as shown in figure. It is strange that if I put the ground of the machine to the earth(the real ground),no any changes,the PLL can lock...

I just want the VCOin to be DC Voltage. I don't understand why this voltage could fluctuate? (PS:my AC power is 50 HZ).

First,I illustrate the application of this circuit,as shown in Figure 1.It is called capacitive liquid level detection.When the needle touches the liquid level,the capacitance value will become larger.So using phase locked loop to detect the change of capacitance.My schematic diagram is...

The voltage waveform of the PLL circuit VCOin is shown(The PLL can lock).I need to get the stable voltage.If I change C18 from 0.1uF to 10uF, PLL cann't lock phase,the VCOin is always 5V,How to select C18/R5/R6 of the filter.How to calculate?