555 timer Output

[pud3000]

Hi there,

i'm still building a 8 step sequencer out of a 555 Timer going into a 4017 binary counter going into a 4046 VCO. I wired the timer like this:

http://bp3.blogger.com/_BQac7gcHPK0/RlAC1GKBF2I/AAAAAAAAAY0/9n76jToy920/s1600-h/LED+Chaser+by+IC+4017+%2B+IC+555.jpg

(IC2 is the Timer)

So does anyone know where i can get information how much output (In Volt) the timer gives with this setup because my problem is the timer signal is to hot so the VCO is pitching up a little bit when the timer is giving its signal. So the sound is like a police-sirene in each step but my aim is to have nearly clear straight pitched tone. So does anyone know how to calm the timer signal down a little bit? (Im running allthe chips with a single 9V BLock)

thanks everyone, Tino.

[Uncle Krunkus]

The 555 is probably loading the supply a bit, which will make the VCO go up and down, like it's being starved.
Things I would try (in this order) : -
* The CMOS version of the 555 (LM7555) draws a lot less power.
* Increase the bypass cap across the battery, from 10uF to say 100uF 25V. Will help it hold up when the discharged timing cap goes across the supply.
* Smaller bypass caps across each chip's supply pins (as close as possible to the chip) say 100nF each. These should be standard practice on any circuit which uses digital signals for audio IMHO.

[pud3000]

Thanks very much, i'll definetly try that. I'm powering the Circuit with one single 9V Battery. So when i use the cmos version of the 555 do i have to change the power (9v) going to the timer or can i leave it with 9v and just the output of the cmos timer will be calmed down just by the characteristics of the cmos version....??

[JovianPyx]

For most circuits, a CMOS 7555 will work as a "drop in" replacement, but it will us far less current. 9 volts is fine for it. The spec for it is actually 2 volts to 18 volts. I think you're safe in just replacing the 555 with a 7555.

[Uncle Krunkus]