as seen in picture below, when i hook up the oscilloscope to outA and gnd, I can get about 1Hz, but when I connect it to OutB, I somehow get a Sine wave, what could be wrong? I am guessing one of the NAND gate is tossed?

I should get a 22kHz square + 1HZ square wave on OutB.

note: In is always high, and the OutA on the second one should be labeled OutB

 

My guess is you are beating the two frequencies together, which would create a sine wave. Just a guess though. Try each oscillator separately and see what it does.

 

What's the value of the resistor at the bottom? 220 or 22k or something else?

 

sorry about my writing, it's 22k

What's the value of the resistor at the bottom? 220 or 22k or something else?

 

I should get a 22kHz square + 1HZ square wave on OutB.

What's the sinewave frequency you see on the CRO - maybe it's 50Hz due to CRO signal grounding oversight.

I'm assuming you have actually built the circuit.

The output should be a gated pulse train at the nominal conditions - if the primary astable is indeed 1Hz then you would expect approx 500ms bursts at the second astable frequency [22kHz?]. However, I'd check your values do actually give those stated frequencies.

 

Sorry, the second should be around 2kHz, my mistake.

the circuit was built, I will need to go back to school to check the frequency tomorrow.

maybe it's 50Hz due to CRO signal grounding

And can you explain a bit more on this one, I think I get your idea, but I am not sure if I got right idea tho.

And another thing, how robust is a NAND gate, I am thinking I might tossed one of the NAND gate, as connect the positive to the wrong when I first hooked it up to the scope.

What's the sinewave frequency you see on the CRO - maybe it's 50Hz due to CRO signal grounding oversight.

I'm assuming you have actually built the circuit.

The output should be a gated pulse train at the nominal conditions - if the primary astable is indeed 1Hz then you would expect approx 500ms bursts at the second astable frequency [22kHz?]. However, I'd check your values do actually give those stated frequencies.

 

Then the wave should look something like the attached....

Top = Out_A
bottom = Out_B

Allen

 

Sorry, the second should be around 2kHz, my mistake.

the circuit was built, I will need to go back to school to check the frequency tomorrow.

And can you explain a bit more on this one, I think I get your idea, but I am not sure if I got right idea tho.

And another thing, how robust is a NAND gate, I am thinking I might tossed one of the NAND gate, as connect the positive to the wrong when I first hooked it up to the scope.

If you leave the signal ground off the circuit connection [by mistake or due to a connection fault] often you will see 50Hz [or 60Hz] mains 'noise' picked up on the CRO active. I would see 50Hz here in Australia.

If you have a spare chip it might be worth checking the problem is elsewhere rather than with a damaged gate(s).

 

I can only get 1Hz with my physical connection, but I can't even get 1Hz in multisim, is it the right connection below???

 

I've not used Multisim but I note your sim schematic has no ground node.

 

What's the sinewave frequency you see on the CRO - maybe it's 50Hz due to CRO signal grounding oversight.

I have checked it, it is exactly what you said, thanks