Help with a 9v Sample and Hold circuit

[Oz32]

Hello everyone, this is my first post and I came after a long and confusing search through the web.
I'd like to build a simple (if possible) 9v sample and hold circuit. I saw different schematics but most of them are eurorack modules so +12/-12 powered. I also know the Maestro FSH filter but I'm looking for something simpler than that. Does anybody know some verified project that can suit me?
Thank you all.

Oz

[antonis]

Hi & Welcome,, 

One diode and one capacitor (in conjunction with a high impedance device) should be OK..

[Mark Hammer]

Funny you should ask.  Here's a wonderful contribution on the forum from the ever-helpful and industrious Kevin Mitchell:  https://www.diystompboxes.com/smfforum/index.php?topic=122371.msg1154322#msg1154322

I've built it a few times, and added a few bells and whistles, demonstrated here.  Kevin essentially distilled the Maestro circuit down to its essentials, and incorporated a charge pump so it runs nicely off +9VDC.

[DIY Bass]

https://www.pedalpcb.com/product/pcb367/

[Mark Hammer]

The toggle in the Youtube demo is a nifty mod I came up with, that I call a "droop" feature.  True S&H units hang on to a sampled noise voltage, until clocked to move on to another sample.  The "droop" option places a resistance in parallel with the capacitor holding on to the sampled voltage, such that it bleeds off, leading to the "pyew, pyew, pyew" sound, rather than discrete steps, heard at the start.  That build only includes one bleed-off resistor value, leading to an interaction with the sampling speed.  Ideally, one might use a 3-way toggle to select one resistor value optimal for slow clock rates, and another for faster clock rates.  But either way, it's a nice effect.

[ElectricDruid]

Another option you could try (if I might blow my own trumpet for a moment...):

https://electricdruid.net/filterfx-lp-bp-hp-lfo-filter/

The last two waveforms available from the StompLFO are a "random steps" (which is the Sample+Hold you're after and gives you that FSH-1 sound) and a "random slopes" which is a similar thing, but which slews from one level to another instead of just jumping there and staying there until the next level. The filter itself is an vactrol-based SVF like the Mutron or others, rather than an OTA-based SVF like the Maestro, but it's the same filter topology and very similar. The advantage of the vactrols in the FilterFX circuit are simplicity (especially when used with the StompLFO's PDM output) and the better signal to noise ratio. OTA-based filters like the Maestro one respond quicker so allow higher LFO rates (even up into audio rates) so they have other strong points.

HTH,
Tom

[Mark Hammer]

If the trumpet is sweet, and the player skilled, blow it as often and as loudly as you like!