PAIA 9752 (01) PDF Document

The PAIA 9752 Sample and Hold monitors the input signal voltage and copies it to the output, synchronized to changes in an input control voltage (CV) or an input clock, or synchronized to an internal clock if there is no external input. The input may be an audio or control signal.

One typical application uses noise as an input signal and a variable rate clock to control sampling. This provides a random control voltage source from the PAIA 9752 output.

The PAIA 9752’s use with audio signals is enhanced by a switch option to change the function from “sample and hold” to “gate and hold”. In “gate and hold” mode, the output tracks the input signal as long as the control input voltage is above a threshold (or, if selected, the internal clock rises). After the control voltage drops, the output voltage freezes until the next high-going transition of the control voltage (or the internal clock rises again).

You’ll need a minimum of tools to assemble the kit:

• A small pair of diagonal wire cutters
• Pliers
• Screwdriver
• Soldering iron
• Solder

Use only a high quality electronic solder. The kit is compatible with lead-free and/or tin-lead flux-core solders made especially for electronic assembly. Plumbing solder will destroy your kit with its acid core. Jewelry solder (silver solder) will destroy your kit with its high working heat. Neither is for electronics work.

A proper solder joint has just enough solder to cover the soldering pad and about 1/16-inch of the lead passing through it.

Using too little solder will sometimes result in a connection which appears to be soldered when actually there is a thin layer of flux insulating the component lead from the solder bead. This situation can be cured by reheating the joint and applying more solder.

Too much solder may produce a conducting bridge of excess solder between adjacent pads causing a short-circuit. Continued feeding of solder into a hot joint can result in accumulation on the underside of the board and may cause bridges or impede the action of mechanical components. If you see this, position the board above the iron tip and the excess will flow to the tip.

Controls and connectors will be installed on the top side of the board with the placement designators as shown in the illustration.

The potentiometers have tabs extending from their body for stability. They have a snap-fit to the board. Align the tabs and pins with their holes and press them into place. There is no need to bend the tabs or terminals.

To ensure the best alignment with these parts with the front panel, begin by soldering only one of the multiple terminals associated with each of the following parts as it is installed. Then, if a part is tilted or crooked, it is only a matter of reheating the joint as the part is aligned.

The legs of the LED will be bent at a right angle so when it is installed, it will project through a hole on the front panel. This bend is about 1/8″ (2-3mm) from the back of the part, downwards with the shorter (marking cathode) leg to the right as viewed from the rear. Installation of this LED is a three-step process:

1. First the LED is inserted in its holes on on the board.

2. Next the board is mounted to the panel with the LED positioned in its panel hole.

3. Finally the joints for the LED legs are soldered.

Complete the module assembly by mounting the 9752 PCB sub-assembly to the front panel as follows:

1. Use the knurled phone jack nuts to secure the sub-assembly to the front panel.

2. Check for clearance of the potentiometer shafts to ensure they rotate freely.

3. Finger-tighten the phone jack nuts and then use the tips of the diagonal cutters to give them another quarter of a turn or so.

4. Complete the soldering of all multi-terminal parts. Take care the solder doesn’t run through to the opposite side of the board when soldering the mounting tabs. With practice, it is possible to flow solder to cover the opening; otherwise, just flow a bit to secure the tab to the pad ring.

1. Cut a 3/8″ (10mm) long shim sleeve for each pot from the length of polyethylene sleeve provided.

2. Set the shafts fully counter-clockwise.

3. Slip the shims over the pot control shafts.

4. Put the knob in place with the pointer aligned to about a 7:00 setting.

5. Use a small screwdriver to tighten the set-screw just enough that it grips.

Power to the circuit is via a four-circuit, dual-polarity DC power supply. A power connector cable matches the header for connection with one of the PAiA 977x supplies at 15v or more.

Connect the circuit labeled (+ to the positive DC source (V+), the circuit labeled (-) to the negative DC source (V-), the circuit labeled (G) to the power ground (G), and the circuit labeled (SG) to the signal ground (SG).

For other supplies without separate signal and power grounds, use two wires to join the two grounds (G and SG) to the one ground (aka GND, 0VDC or common) at the supply.

Use two-circuit, Tip-Sleeve (TS or mono), cords for patching in or out of the PAIA 9752 when connecting with external devices. Within a 9700-series system, either single conductor (Tip-only), or TS cords may be used. A regular mono cable will always work for most home studios. PAIA equipment allows tip-only connections for professional applications where star grounding is required.

Test operation by inputting a 0-10V Noise Source such as the 9751 or some other periodic signal such as an LFO or VCO to the Sample Input and patching the Output from this section to a VCO CV input so the control to the VCO can be heard. There should be a change controllable with the s/h Rate control, Output Offset control and Gate/Sample switch settings. Note that as the Offset is adjusted for a more positive CV output range, the glow will vary more brightly.

Offset adjustment helps match the output range attained for a range of input signal sources which don’t necessarily have to be a full 10V range (or DC, ie 0 to +10). Patching the Ctl Out, a copy of the sampling over to another devices trigger or clock input should elicit an action synchronized to the s/h Output. An external trigger or clock can be substituted for the internal one by making a patch into the Ctl In.

Offset adjustment on the PAIA 9752 helps match the output range attained for a range of input signal sources which don’t necessarily have to be a full 10V range (or DC, i.e., 0 to +10).

The PAIA 9752 power requirements are:

The heart of the PAIA 9752 module is based around the LF398 IC. Samples are taken from an input on Pin 3 when the (not)SH pin is pulled low and are stored in capacitor C3. When the (not)SH pin is pulled high, the sample is output from Pin 5 into U1A and U1B which provide output offset scaling as well as driving the S&H LED through U1D.

The (not)S&H pin is connected to switch SW1, which selects between sample-and-hold and track-and-hold operation.

S&H operation is driven from the U1C square wave oscillator, transistor switch T1 and monostable multivibrator. The oscillator output is normally connected to the T1 switch through the closed circuit jack, J1. The transistor circuit then drives the monostable multivibrator which limits the pulse width of the trigger signal to about 47uS.

If an external signal is plugged into J1, the oscillator is taken out of the circuit. T1 switches at about 1.5V minimum, so just about any signal can be used to control the sample and hold. When in trigger-and-hold mode, T1 and the 4538 are bypassed and the S&H IC is connected directly to the J1 input signal.

The PAIA 9752 Test Point Data is as follows:

DNI (Do Not Install) marking indicates designations where optional capacitors may be installed, parallel-connecting with capacitors associated with time constants: Cs1/12, 4/13 and 5/15.

Resistor R16 may be installed to parallel or replace on-board resistor R13 to match the current flow for a substitute LED (subtract the LED voltage from 10v and divide this result by the current (ie 0.01) for the resistance value).