Switching time of 7408 IC... >21MHz?

MM007 · Post by **MM007** » Wed Jan 10, 2007 12:38 pm

I'm trying to design an NES overclocking circuit, but part of the circuit design I am using requires a signal in excess of 21MHz to be fed through one input of a standard AND gate, spacifically a 7408 IC chip.

My question: Can the 7408 IC keep up with the clock signal and put out a signal of >21 MHz at its output?

codeman · Post by **codeman** » Wed Jan 10, 2007 2:48 pm

huh? Why are you using a 7808 to output a clock signal? What exactly are you trying to do?

I dont think the 7808 would be fast enough anyway...

Post by **marshallh** » Wed Jan 10, 2007 3:03 pm

I think you mean a 7408. Better to use a 74HCT08, the letters are for for "High-speed CMOS TTL compatible" so it runs at 5v. I'm pretty sure it can handle high frequencies, it's made for them.

Post by **gannon** » Wed Jan 10, 2007 3:04 pm

If nothing else, a switching transistor based gate should work I think.

codeman · Post by **codeman** » Wed Jan 10, 2007 4:50 pm

hahaha...that makes a lot more sense! I was wondering how you could make a clock signal with a 7808 regulator...

MM007 · Post by **MM007** » Wed Jan 10, 2007 5:16 pm

Hmm...I'm using an "NTE7408"...and I've corrected the original post.

I may have to make some alterations then...hmm...