Hi all
i found this circuit design
**broken link removed**
and i was wondering, what's going on with the 7404 ? The description says it is used as the clock, but i cant imagine that. Doesnt the circuit need a timer or a sin wave input?
If the link doesnt work, go to www.schematicsforfree.com then click on "show the files" and then go to the "clocks" section and u will find the design there.
A 74HC04 might melt if it is used instead of a 7404 in that oscillator circuit.
74HCxx inputs have a max 450ns spec'd amount of time that they are allowed to spend in the linear region. 74HCxx ICs with schmitt-trigger inputs are recommended for oscillators.
A 74HC04 might melt if it is used instead of a 7404 in that oscillator circuit.
74HCxx inputs have a max 450ns spec'd amount of time that they are allowed to spend in the linear region. 74HCxx ICs with schmitt-trigger inputs are recommended for oscillators.
My Ultra-bright LED Chaser projects use 74HCxx Schmitt trigger oscillators and work fine.
But your problem is: "the teacher says 74xx series, then 74xx series it is".
If I was doing it, I would build the 74xx circuit and power it from a car battery, and make another with 74HCxx and power it with a little battery.
The old 74xx ICs wasted a lot of power. The newer 74HCxx ICs use hardly any power.
I made circuits with LS all the time until I switched to Cmos. LS was fast and had a much lower supply current than ordinary TTL.
But Cmos can't be beat for low power consumption at low speeds: