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  • LTC1660CN-ND Octal 10 bit DAC ($11.38/1, $7.55/25, $5.70/100)
    • May be replaced by less expensive quad DAC, if one is found. AD5318?
  • ATMega32-16PI microcontroller ($8.28/1, $5.20/25, $4.81/100)
    • To be replaced with ATMega48V-10MI ($2.69/1, $1.69/25, $1.56/100)
    • Requires an external crystal, and 2 caps in the 20pf range (or ceramic oscillator)
  • Each SMU uses 12 resistors, 3 opamps, and 2 MOSFETs (the MOSFETs select current vs. voltage mode)
    • 6 NJM062D dual op-amps for SMUs (each SMU uses 3 opamps) ($0.35/1 from Mouser)
      • May be replaced with quad version, NJM064 ($0.61 from Mouser, $0.365 in large quantities)
      • Should be replaced with rail-to-rail op-amp, for greater signal swing range. Any op-amp that uses a 5V rail is acceptable, but FET-input ones are preferable.
    • We use the excessively expensive ZVN3306 ($0.84/1, $0.63/10, $0.42/100, down to $0.17/25000), but any FET will do. We can also replace all 8 MOSFETs in all 4 SMUs with a single MAX4702 ($1/1000, can be ordered from for $1.52/1, $1.43/25, $1.35/100, $1.15/500 from https://shop.maxim-ic.com/Image Removed, MAX4702eue. Maxim apparently considers itself too good for normal distributors) (Other parts to look at: MAX395, MAX4702).
  • We use the USBMOD3 module, for $33, which consists of:
    • The FT232BM ($5/1, $3.86/100, $2.87/5000, from parallax.com)
    • 6MHz crystal (we should be able to share crystals with the microcontroller)
    • 93LC66B EEPROM (not necessary – $0.56-$0.33 from Digikey. It contains the USB serial number of the device).
    • USB type B connector ($1.23/1, $1.04/10, $0.85/100, $0.63/500, $0.53/1000, $0.49/10000)
    • Ferrite bead, 2x10nf, 3x100nf, 2x27pf caps, 27K, 2.2K, 10K, 470ohm resistors (27pF not necessary if we share crystals)
  • We built a power regulator out of an NJM062D (listed above) a 2N3904, a 2N3906, and a pair of resistors. This can obviously be simplified
  • We will need a 5 pin header connector, for programming the microcontroller. We also use 4 1k resistors, to make sure we cannot fry anything, and a 10k pullup on one pin.
  • Assorted power supply bypass capacitors
  • We currently use a $100 prototyping board, but this will obviously be replaced with a PCB.

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