I'm working a project that needs a simple frequency divider (specifically by 2). It's just a DC square wave input, but it and the output will be at 12v, so the CMOS ics I usually use are out of the question.
I'm working a project that needs a simple frequency divider (specifically by 2). It's just a DC square wave input, but it and the output will be at 12v, so the CMOS ics I usually use are out of the question.
Anyway, all you need is a bistable multivibrator, you can easily built one with a couple of transistors - they were commonly used as computer elements in the pre-IC days, and are what is inside many CMOS and TTL logic chips.
Most manufacturers' CD4xxx-series ordinary Cmos ICs have a max voltage rating of 18V. The ones from Texas Instruments (their Cmos ICs were formerly Harris which was formerly RCA) have a max voltage rating of 22V. Many circuits use 15V. The higher the voltage, the faster they go and with more output current. RCA invented Cmos ICs and I still got some.
74HCxx high-speed Cmos ICs have a max voltage rating of only 7V.
I have some 74HCxx circuits that operate fine with a supply voltage below 1.24V, which is the lowest output from my LM317 variable supply. Ordinary Cmos runs into trouble with a supply voltage below 3V.
You can make a variable-frequency generator from a 74HCxx Schmitt-trigger input inverter oscillator. Vary its supply voltage and the frequency varies a lot.
That's interesting. I always though CMOS ICs were too sensitive to go over 5v. Whenever I drop in here with a quick question, I always learn something new.
That's interesting. I always though CMOS ICs were too sensitive to go over 5v. Whenever I drop in here with a quick question, I always learn something new.
74LS series have a high for a voltage: 4.75v to 5.25v. CMOS have a wider range of values for high up to about 15V I think. Conflict usually arises when you want to do a mixed logic design for example when you want to use a 74LS to drive a CMOS.