[sdiy] clock pulse to vtrig

rsdio at audiobanshee.com rsdio at audiobanshee.com
Fri Dec 28 02:16:26 CET 2018

R7 & R8 already form a voltage divider, making the output 68% of the CD4538’s V(OL). Looks like +Vcc is up to 15V. The CD4538 will output at least 14.95V when using a 15V supply, so that makes OUT around 10V or just slightly above that.

If you want to limit the OUT to 5V, you could take advantage of the fact that the CD4538 will run on any Vcc from 3V to 15V. Targeting exactly 5.0V OUT, you could probably just run +Vcc at 7.4V without changing anything in the circuit at all. There might be some component values that are tuned for 15V, but I assume they’ll all work fine on reduced voltage. There’s no harm in trying, especially not if you start by confirming proper operations at 15V and proceed from there.

Option 1) Build the circuit and try running it on 7.5V or less. If it works fine, and your OUT doesn’t exceed 5V, then you’re done.

Option 2) If there is trouble above, then just change R7 & R8 values without adding any resistors.

As far as varying the Gate size, it looks like there are already controls for Pulse Delay and Pulse Width. I don’t see how R8 as a pot would change the “size” of anything. If you’re talking about changing the Gate Voltage with a pot, I’d be more inclined to vary Vcc and leave the circuit alone, especially since the CD4000 series is so flexible about power supply voltages.


On Dec 27, 2018, at 7:21 AM, Joe Frey <frey at radioles.com> wrote:
> Thanks for the help. I am wondering if I wanted to limit the output of the yusynth pulse delay to 5V would I make a voltage divider by adding a 5k resistor after R7 and change R8 to 5k from 10k?
> If I wanted to vary the gate size could I do the above and change R8 to a 5k pot?
> Please refer to
> http://www.yusynth.net/Modular/Commun/PULSEDELAY/pulsedelay-sch.gif
> at
> http://www.yusynth.net/Modular/EN/PULSEDELAY/index.html
> Thanks. JoeF.
> Sent from TypeApp
> On Dec 17, 2018, at 2:03 PM, Joe Frey <frey at radioles.com> wrote:
> Hello all, this is a follow-up to an email from 2 weeks ago some may remember. Anyway, I am using a clock out from my EHX 8-step sequencer to trigger my Lyra-8. The Lyra-8 plays for as long as the clock pulse. I want to be able to create a longer and variable pulse using a circuit. I am not interested in tackling programming a microcontroller, yet.
> Can anyone point me in the direction of some circuitry that can do this? Thanks. JoeF.

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