Hey, I'm attempting to build a high frequency variable oscillator on a range of 18 MHz to 48 MHz(preferably 48, but 42 would work if 48 is too high) using the 4011 quad NAND. I want it to work on the circuit that I'm posting, and I just need the values for C1, R1(pot), and R2(pot). Id like it if only one of the resistors was a Potentiometer, but if it cant cover the entire range, I would use 2. Can anybody help me out?
Sebi,
How did you make a 4011 oscillator go so high? With only 27pF and both resistors 1K with a 12V supply mine barely reached 2MHz.
I have heard that a 4049 high current buffer can reach 6MHz without the input resistor.
Do I dare try using a 74HC00 high-speed Cmos IC for 15MHz or do you think it might melt?
V1 is the 5 volt power supply but supply voltage is not critical. L1 is 7 turns #20 enameled wire on a 1/4 inch form (a standard pencil will do). The turns should be close and don't forget that the leads are part of the inductor, so keep them short.
Thanks. I have changed the pic a bit. Would this still work? Also, what is the difference between the 2 outputs? Could Q1 be substituted for any other transistor? Why does L1 say 275nH (what does it mean)? Did I mention, "Thank You"?
I had used this circuit as a crystal checker (substitute the crystal for L1, C3 & C4). Out_2 was a 50 ohm drive to my frequency counter. 275 nano-henries is 275*10^-9 henries. Any transistor with Ft greater than 100 mHz should work, eg: 2N3904.
Does anybody know a cheap circuit that I can add on to one of the outputs to compare that clock to an existing one and light an LED when they are the same?