Hi everyone,
Iam attaching an image. just check it. what is that symbol?

Iam also attaching a pdf file. How can the frequency of the output can be decided?

 

Must be AND component with schmitt trigger on each input and inverted output...

 

Since one input is always high, it is an inverter with a schmitt-trigger input.
It is one gate of a CD4093 quad 2-input NAND Schmitt trigger IC.

 

okm thank you.

How can i control the frequency with that IC?

 

Look up CMOS oscillators that use the inverter function. Fairchild Semi AN-118 is a nice source. It can be done with a single resistor, capacitor, and gate.

John

 

As AudioGuru suggests, it's likely a 4093 quad NAND Schmitt trigger; the Philips datasheet would be HEF4093B.

Schmitt triggers are generally used to "square up" signals. Just looking at that one gate, the threshold levels for the inputs would be 1/3 Vdd and 2/3 Vdd.

If the upper input were held high as shown, and the lower input started off low, the output would be high until the lower input exceeded 2/3 Vdd, or 8v. Then the output would go low until the lower input fell below 1/3 Vdd, or 4v.

The NE566 function generator is a discontinued part. You'd have to use a different timer/oscillator IC; a 555 timer might be a substitute - but you couldn't use the 3.3v Zener or the rest of the oscillator circuit as shown.