Constructional difficulty: Easy.
The Sample and Hold module in a 1U panel.
The job of a Sample and Hold is to memorise the input voltage on command of a clock signal. The Oakley sample and hold module has two modes of operation. The first is the 'sample' mode. The clock signal is any signal input you like, but it is traditional to use a gate type pulse. If the clock signal is inserted into the 'Clock [rising]' input, then when the signal rises over 2V or so, the command is given to hold. The Hold output will then remain fixed no matter what the input signal is now doing. That is until the command to hold is given again.
Note, if the clock signal is connected to the 'Clock [falling]', then the hold command is given when the clock input falls below 2V or so.
The second mode is 'track'. This functions like the so-called 'sample and hold' module on the Korg MS-20. Here, the hold output actually follows the input signal slavishly, but only when the clock input is below 2V for the clock rising input (or above 2V for the clock falling input). But when the command to hold is given, the 'hold output' is fixed and unchanging.
The Restriction pot affects the way the hold output moves with respect to its input and the previously held output level. With the pot fully off the unit behaves just like any other S/H, but at full, the output is restricted to move only a little after each new sample. It'll still have the same range as the input, but will need more hold commands to get there.
The Slew generator can be accessed separately from the S/H section, but is normalised to the output of the S/H when it has no input connected. The slew generator smooths any sudden changes in the input signal. Thus a square wave becomes more like a triangle, and keyboard CVs start sliding between notes.
The 'clock' LED lights when the clock input is active. The output LED is a bicolour LED that gives a visual indication of the hold output voltage.
The issue 2 PCB set
The issue 2 Sample and Hold module features a two PCB set. Previously, many Oakley modules have had the sockets, switches and extra pots wired to the board by individual wires. The new issue module allows all the socket wiring to be done via an extra PCB and two MTA solderless connections. If you are building this module in the standard MOTM and Oakley format this new system will reduce assembly time and possible wiring errors.
Some people will wish to use this Oakley design in a non standard format, such as fitting it to a Analogue Solutions rack or one of their own invention. This is perfectly easy to do. Simply do not use the socket board and wire the main board to the sockets as per usual.
The main PCB is 10.5cm (high) x 7.3cm (deep). The two pots and LEDs are board mounted for easier construction.
As with all Oakley projects the PCB is double sided with through plated holes, has solder mask both sides, and has component legending for ease of construction.
The rear view of the issue 2 Sample and Slew module.
Prices
PCB Set ....................................... 19GBP
Pot Kit
............................................. 7GBP
Pot Bracket Kit
............................... 2GBP
PCB Set contains the two PCBs required to complete 1 module.
Pot Kit contains the correct type and quantity of Spectrol 248 potentiometers to complete 1 module.
Pot Bracket Kit contains the correct type and quantity of Oakley-Spectrol pot brackets and extra Spectrol nuts required to complete 1 module.
Click here for full price list and ordering details. All prices include VAT at UK rates. Shipping/postage is additional to these prices.
Project Downloads
User Guide Includes parts list and building instructions
Use 'save as...' button to download and view the files. IE users need to right hand mouse click and then choose 'save as'. Links to schematics are available to purchasers of the PCB or module and will be sent via e-mail when the board(s) are shipped.
Front Panel Design
The new MOTM compatible front panel database is here: S/H Panel. To read this file you will need a copy of 'Frontplatten designer' from Schaeffer. The program also features on-line ordering, so its now even easier to buy your panels from Scheaffer.
The company are based in Berlin in Germany and will send out panels to anywhere in the world. Delivery to the UK normally takes around ten days. For North American users you can also order your Schaeffer panels from Front Panel Express.
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Copyright: Tony Allgood.
Last revised: January 23, 2008.