basic question(s) about cmos clocks

[jean-louise]

hello!

though i did some diy stuff before like making a little quad NAND / vactrol noise machine and a baby-8 sequencer, i haven't really got a background in electronics.
so from time to time (quite often actually ) i come across something basic i can't figure out myself. despite searching this exremely helpful forum and googling i don't know how to solve this question:

i got a baby-8 running on 9 volts and want to feed its 40106 clock to another circuit based on the "fun with seamoss"-sequencer (4040, 4051) running on 3 Volts.
is it necessary to step down the clock voltage to 3 Volts?
and if so how do i do that - does it suffice to hook up a simple voltage divider with say 10k and 20k resistors?

(i'd like to keep that second circuit at 3 to max 4,5 Volts in order to avoid using an 7805 regulator for a third circuit getting it's power from the same battery.)

thanks for your help!!

greetings
jan

[fluxmonkey]

all of the circuits on the fun w/ sea moss page are designed to run on 9v... i run lots of 4000 cmos stuff on 15 volts no problem, tho you might have to tweek the R/C values a bit. go for it!

[Cynosure]

CMOS clock signals shouldn't exceed the supply voltage.

It will need to be stepped down the same voltage that the chip receiving the clock is running at.

I'm a noob, so I have no idea how to safely do that without using a 78xx

[jean-louise]

hey fluxmonkey,

thanks for your answer!

--but it's not really what i meant!
the problem is this:

i'd really like to use this circuit with 3 Volts (so another circuit can share the same battery without the need for a voltage regulator) but want to have the possibility to feed it a 9 Volt clock pulse.
and i am afraid i'll damage the ICs with that voltage.

how to process the clock if necessary?
just a voltage divider?

it's kind of a stupid question, but i didn't come across this situation before, because in the past i just used 9 Volts for everything.
jan

[jean-louise]

[jean-louise]

[Blue Hell]

You could use a 2.7 V zener diode to ground over the 3 V input, then feed the 9 V signal into that through a resistor, of say like 10 k.

[jean-louise]

Hey Jan,

thanks for your help!

Is this solution preferable to the voltage divider - and why?

greetings
Jan

[Blue Hell]

Yeah, it would always clip around 2.7 V whereas a resistive thing would depend on the ingoing voltage. Of course when that ingoing voltage is fixed always a resistor would do the job as well, and a bit cheaper.

[jean-louise]

Aaah, now I get it!

Thanks again!

j