- transcranial magnetic stimulation
Concept for the electronics (pdf)
Right now I am concentrating on the control software and the 0.9 version of the electronics. The V0.9 is basically the signal generator combined with the low-power backend. In this version I had the split between the microcontroller and DAC + amplifiers. In V1.0 the DAC is together with the microcontroller, because it is more likely that the amplifiers will be replaced than the DACs.
Generator_V0.9.sch
Generator_V0.9.brd
The following list provides the required material to build one mainboard and one addon board with two channels.
| 2 | 1 nF, 0603 | Capacitor, AD converter |
| 2 | 10 nF, 0603 | Capacitor, USB power filter and reset signal filter |
| 12 | 100 nF, 0603 | Capacitor as current spike filter next to every IC |
| 2 | 10 uF, MLCC, 0603 | Capacitor for Voltage stabilisation |
| 1 | NFE61PT | Noise filter, maybe not necessary, replace by a piece of wire? |
| 1 | P8X32A, VQ44 | Parallax Propeller |
| 1 | 24LC256, SO-08 | One I2C EEprom stores the program. The other one seemed to be a good idea, when I designed the board. But I think it is not needed right now. |
| 1 | FT232RL, SSOP28 | FTDI USB to serial converter: talking to the PC & getting programmed |
| 1 | LT1117-3.3, SOT223 | 800mA and 1A Low Dropout (LDO) Positive Regulator |
| 2 | LM339D | Low Power Low Offset Voltage Quad Comparators |
| 3 | LED, 0603 | RX, TX, and status, choose any color You like ... |
| 1 | MCP4922-SN | 12-Bit DAC with SPI Interface |
| 1 | AD8644 | Quad 18 V R2R Operational Amplifiers |
| 1 | Crystal CTS406, 5 MHz | Anything that says "5.000 MHz" on the housing |
| 2 | 82 Ohm, 0603 | Resistors, horizontal and vertical sync signal |
| 5 | 270 Ohm, 0603 | Resistors for the LEDs and PS2 |
| 3 | 430 Ohm, 0603 | Resistor, RGB voltage DAC |
| 3 | 820 Ohm, 0603 | Resistor, RGB voltage DAC |
| 2 | 4k7 Ohm, 0603 | Resistor, reference voltage stabilizer in add-on boards |
| 20 | 10k Ohm, 0603 | Pull-up / pull-down resistors for every occasion |
| 1 | 33k Ohm, 0603 | Resistor, voltage divider for comparator, replace with 10k to get voltage right. (see below) |
| 1 | 100k Ohm, 0603 | Resistor, AD converter |
| 2 | 270k Ohm, 0603 | Resistor, AD converter |
| 1 | BC847, SOT23 | NPN Transistor, any NPN from the "TUN TUP DUS DUG" tables works |
| 1 | PN61729-S | USB connector (Berg) |
| 1 | MDSSV-BC06 | PS2 connector |
| 1 | F15HDH | Sub-D, VGA connector (15 pol) |
| 1 | WAGO 233-104 | Wago connector, or solder the wires directly onto the board |
| 1 | SW-SCHURER | Reset button |
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