Building the Sample and Hold + Noise

BOM:

Qty
Value
Device
Package
Description
Other
2100kR-US_R0805R0805RESISTOR
4100nC-EUC0603C0603CAPACITOR
1100nCAPACITOR_NPOL-0805C805CAPACITOR
510kR-US_R0805R0805RESISTOR
110nC-EUC0805C0805CAPACITOR
110nCAPACITOR_NPOL-0805C805CAPACITOR
11MR-US_R0805R0805RESISTORDO NOT INSTALL
21kR-US_R0805R0805RESISTOR
11nCAPACITOR_NPOL-0805C805CAPACITOR
21n4148DIODESIGNALSOD80C
31uCAPACITOR_NPOL-0805C805CAPACITOR
122kR-US_R0805R0805RESISTOR
22N3904MMBT3904LT1-NPN-SOT23-BECSOT23-BECNPN Transistror
2470KR-US_R0805R0805RESISTOR
147nC-EUC0805C0805CAPACITOR
24k7R-US_R0805R0805RESISTOR
43.5mm 3.5MM SOCKETTHONKICONN-MOD3.5mm socket for Eurorack modular synths
1Tile TailTILE-POWER-FUTABA-SMALL1U Tile Power Connector
1MMBF5457MMBF5457SOT23N-Channel RF AmplifierReplaces J111
2M7DIODEPOWERDO214AC
2TL072IC-TL072SMTSO08OP AMP

Assembly:

  1. Clean the PCB with Isopropyl Alcohol.
  2. Solder the surface-mount components to the PCB.
    1. The two diodes on the top left are M7 or 1N4007 rectifier diodes. Make sure the polarity is correct.
    2. The four small unlabelled footprints (0603 size) are 100n bypass capacitors.
    3. Pin 1 for the TL072 IC is by the large white dot.
  3. If using hot-air or an oven to solder the surface-mount components then do this now.
  4. Inspect all of the soldered components for solder bridges between pins and components, especially around the OpAmps.
  5. Solder the Tile-Tail power cable. The lead should be inserted on the component side of the PCB and soldered on the side with the jacks.
  6. Solder the jacks to the front of the PCB.
  7. Attach the front panel.

Testing

  1. Inspect PCB for solder bridges between components, loose solder balls, tombstones, etc.
  2. Before powering the module for the first time ensure there are no power shorts. Check that there is no continuity between the pins on the power cable, and across the opamp bypass capacitors (unlabelled 0603 components).
  3. The “NOISE” output should make noise when plugged into an audio system or viewed on an oscilloscope.
  4. To test the Sample and Hold plug a 0-5V square wave into “HOLD” and a sine or triangle wave into “IN” and watch “OUT” on an oscilloscope or plug into an oscillator and listen. The output should follow the input whenever the “HOLD” signal is low (around 0V), and stay at one level “HOLD” is high (around 5V).