YuSynth Boolean Logic Module
Introduction
A bare double sided PCB (no need for the wire jumper links shown on the PCB layout) for the Yusynth Boolean Logic Module synth module. These PCBs are manufactured by Soundtronics with a percentage of the sale going to the creator of the YuSynth - Yves Usson. These are early days for the YuSynth Modular Synth at Soundtronics, our plan is to stock PCBs for all of the projects as well as components, kits and front panels. This is going to take time but will eventually be as comprehensive as our MFOS range.
No components are included with the PCB but check out our Synth Components section where you should find what you need. We do suggest visiting the YuSynth Boolean Logic project page for detailed information including Yves panel layouts but a summary is shown below.
Description
This module provides very useful boolean logic function such as two logical AND gates that can be combined into a single three inputs AND gate; a logical OR gate and a simple NOT gate.
This utility module is very handy module in order to combine GATE signals to trigger conditional event. For example it can be used to combine the GATE signals from various sequencers.
Yves designed this module with discrete component only. He could have used CMOS logical ICs but thought it would be more fun to use transistors and diodes only ! Maybe a weird conception of having fun. Never mind... Anyway, each input is fed to a schmitt trigger. Therefore, one can also input analogue signals instead of pure GATE signal. In such a case, the negative part of the signal is ignored and considered as LOW, and as soon as the signal gets higher than 2V then it is considered as HIGH.
Here are the truth tables of this module : for the inputs, low means voltage lower than 2V and high voltage higher than 2V and for the outputs LOW means 0V and HIGH 10V (or 5V depending on the zener option, see notes in the part list)
| Logical AND (two inputs) | Logical OR | ||||||||||||||||||||||||||||||
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The PCB can accept a choice of three types of power connector, it can be either a Synthesizers.com 6 pins MTA connector, a MOTM 4 pins MTA96 connector or a 10-pin Eurorack connector.
Circuit
Click on the schematic thumbnail above for the circuit diagram.
Logical AND sections:
The input signals are applied to Schmitt triggers which convert these signals to proper logical levels (0V or 15V). For the first AND section, Q1-Q2 and Q4-Q5 are connected as classical discrete Schmitt triggers. R2,R3 and R7,R8 are large value resistors that insure high input impedances. Diodes D1 and D3 prevent the input transistors from negative voltages. The logical levels available at the collectors of Q2 and Q5 are applied to D2 and D4 which constitute with R12 (pull-up resistor) the actual logical AND operator. Q3 acts as a buffer and the output signal is available through R17. LD1 show the status of the output. With the values shown on the schematics the logical ON level is 10V. If a 5V level is preferred use the optional zener diode Z1 (5.1V), the PCB is provided with pads for soldering the optional zener.
Logical OR section:
The input signals are applied to Schmitt triggers which convert these signals to proper logical levels (0V or 15V). Transistors Q11-Q12 and Q14-Q15 are connected as classical discrete Schmitt triggers. The logical levels available at the collectors of Q12 and Q15 are applied to D10 and D12 which constitute the actual logical OR operator. Q13 acts as a buffer and the output signal is available through R47. LD3 show the status of the output. With the values shown on the schematics the logical ON level is 10V. If a 5V level is preferred use the optional zener diode Z3 (5.1V), the PCB is provided with pads for soldering the optional zener.
Logical NOT section:
The input signal is applied to a Schmitt trigger which converts the signal to a proper logical level (0V or 15V). Q16-Q17 are connected as a classical discrete Schmitt triggers. Q18 acts as an inverting buffer and the output signal is available through R55.
Wiring
The wiring schematic image in the above thumbnails show the panel wiring to the pots and sockets etc.
Setting and Trimming
No setting up or trimming required
Parts List
The parts list below is direct from the YuSynth website.
The parts list excludes knobs although we have standardised on the Cliff KM20B but it does include 1/4" jack sockets. All parts are available individually (use the part number in the search box above) or as a components kit that excludes sockets and knobs.
| Reference | Value | Part No. | Qty |
| Q1.....Q18 | BC547 | 7212-401 | 18 |
| D1.....D13 | 1N4148 | 7212-480 | 13 |
| Z1....Z3 | optional 5V zener diodes (see text) | 2101-502 | 3 |
| R1 | 10 ohm 5% | 7163-007 | 1 |
| R4,R9,R15,R20,R25,R31,R36,R41,R45 | 220 ohm 5% | 7163-035 | 9 |
| R50 | 330 ohm 5% | 7163-039 | 1 |
| R17,R33,R47,R55 | 1K 5% | 7163-051 | 4 |
| R16,R32,R46 | 1.5K 5% | 7163-055 | 3 |
| R13,R29,R44 | 4.7K 5% | 7163-067 | 3 |
| R5,R6,R10,R11,R12,R21,R22,R26,R27,R28 R37,R38,R42,R43,R51,R54 |
22K 5% | 7163-083 | 16 |
| R52 | 47K 5% | 7163-091 | 1 |
| R53 | 100K 5% | 7163-099 | 1 |
| R14,R30 | 220K 5% | 7163-107 | 2 |
| R2,R7,R18,R23,R34,R39,R48 | 1M 5% | 7163-122 | 7 |
| R3,R8,R19,R24,R35,R40,R49 | 1.2M 5% | 7163-128 | 7 |
| C2.....C8 | 100nF power filtering caps (not shown on schematic) | 7212-749 | 7 |
| C1 | 22µF/25V electro. | 7213-108 | 1 |
| LD1,LD2,LD3 | Panel Mount | 7213-900 | 3 |
| LD1,LD2,LD3 | Red LED | 7213-901 | 3 |
| Jk1...Jk11 | 6.5 mm jack socket | 7212-211 | 11 |