I didn’t have any sample and hold module in my rack. At first I didn’t think I needed one. But seeing a few video’s of what you could do with them I just wanted to have one. A sample and hold basically takes a voltage and when triggered it send the voltages to the output and keeps it at that level until next trigger,in theory. But being in a analog realm the capacitors used to keep the level at the output steady lose there voltage slowly and the voltage keeps dropping. This can be overcome making a digital sample and hold or just to use a quantizer and hope the next trigger will come before the next note is quantized. In practice the last option fits most purposes. So I decided to build a analog sample and hold.
I have been looking at two designs to build upon. A design by Rene Schmitz and the design recently published by Skulls and Circuits. The design by Rene Schmitz is build by many eurorack diy people. Some make these on pref boards. I decided to make a pcb for both designs, they have a different approach. But I thought it would be fun to see the difference in action and maybe putting one (or both) in the shop for sale if Rene and/or S&C approve.
The design by Rene Schmitz came in first in the mail. This design is also known a YASH, Yet Another Sample and Hold. Like always there where a few error’s on the board. This seems to happen on every first run I put out to the manufacturer. This issues where easily overcome. I don’t know how but somewhere on the board two ground planes weren’t connected. A wire between two ground point was a easy fix for this. The second error and I seem to do this almost always on the first run, the potentiometers where reversed. For myself this isn’t a big issue. The potentiometers are used to set a internal trigger rate. I plan not to use this function very much and the leds are showing the rate of the trigger so I think I can get used to reversed potentiometers for this.
The design is made with Polystyrene capacitors but are pretty hard to come by. I found myself a batch and bought them. I still have to test the design with other caps. Rene Schmitz mentioned this on his website: Polystyrene caps are now difficult to source, so a polypropylene (PP), polycarbonate (PC) or polyphenylene sulfide (PPS) cap can be used instead. At least I know it should be possible. The schematic is quite small so I can be easily build on a pref board. This challenged me to do two of the YASH’s on one board or at least 4hp. I could not fit on one board (two YASH) but I at least stick to the 4hp.
The boards function quite nicely and will be putting them on GitHub if the owner of the schematics approves. First I’m going to fix the errors I found before uploading them.
Now waiting on the boards for the Skull and Circuits desing to compare both designs. There is more to come on Sample and Hold, hold it….