USB IR Toy v1.1 update

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Contents

Development

Prototypes

REV 4

Irtoy-v4.jpg

REV 3

Irtoy-v3.jpg

REV 2

Irtoy-v1.1-3leds-output.jpgIrtoy-v1.1-3leds.jpg

REV1

Irtoy11-pcb-frequencydetector.jpg Irtoy11-pcb.jpg Irtoy11-pcb-back.jpgIrtoy-pcb-new-board.jpg

Latest Schematic

Usb-irtoyv2-cct.png

Early schematic

Usb-ir-toy-v2-cct.pngIrtoyv2-cct.pngIrtoy11-cct.png

Latest PCB

Usb-irtoyv2-board.png

Early PCB

Usb-ir-toy-v2-brd.pngIrtoyv2-brd.pngIrtoy-brd.png

Partlist

partlist
PartQuantityValuePackage
C1 1 0.1uf C603
C2,C4,C7 3 0.22uf C603
C5,C6 2 27pf C603
C8 1 1.0uF C603
D1 1 SOD2514X100N
D2,D3 2 DO323
I 1 LED CHIP-LED0805
IC1 1 PIC18F2550_28W SO28W
ICSP 1 1X05
J1 1 CON-USB-MINI-BUSB1 CONN_USB_MINI-B
JP1 1 2X06
Q1 1 20Mhz HC49UP
R1 1 10k R603
R2 1 2K7 R603
R3,R6 2 390R R603
R4 1 7R M1206
R5 1 3K6 R603
RX 1 TSOP34838 TSOP18XX
RX2 1 QSE159 QSE15X
S1 1 SMD_TACT_SMALL TACT_SWITCH_SMALL
T1 1 BC81840MTF SOT23-BEC
TX 1 100mA IR LED LED5MM
UART 1 1X04


PartValue
C1 0.1uF capacitor (0805)
C2, C4, C7 0.22uF capacitor (0805)
C5,C6 27pF capacitor (0805)
C8 1.0uF capacitor (0805)
D1 Small signal diode (DO323)
IC1 PIC 18F2550-i/so (SOIC28W)
J1 USB MINI-B jack (SMD)
Q1 20MHz crystal (SMD/HC49UP)
R1, R6 10,000 ohm resistor (0805)
R2 2700 ohm resistor (0805)
R3 390 ohm resistor (0805)
R4 TX current limiting resistor, see table below (0805)
R5 1000 ohm resistor (0805)
T1 NPN transistor, hfe 40+, 1A+ (SOT23)
I indicator LED (0805)
RX 5volt 38kHz IR receiver (eg: TSOP38238)
RX2 QSE159 IR photosensor
TX [60degree+ infrared emitter/LED] see table below (5mm)
Pin headers 0.1" pin header (optional)
S1 small tactile switch (optional)

Transmitter circuit

We really want to get the transmitter section perfect on this version. Here's some optional LEDs:

Most IR LEDs seem to have a continuous current of 100mA and a pulse current of 200mA, and a voltage drop between 1.6 and 1.3.

  • For 100mA - 39ohms, 0.34watts
  • For 200mA - 18ohms, 0.68watts

Resistors

Most 0805 resistors are only good to .125 or .1 watts, so a way to have more power without a bigger resistor is to use more LEDs:

  • For 100mA x 2 - 18R, 0.18watts
  • For 100mA x 3 - 2R, 0.02watts
  • For 200mA x 2 - 10R, 0.36watts
  • For 200mA x 3 - 1R, 0.04watts

Another alternative is to use several resistors in parallel to increase the power rating. This should be cheaper - both in parts and board space.

Constant current

Ir-led-cct.png

Ir-led.png

Calculations for a constant current LED driver. Spreadsheet.

Frequency measurement

Irfreq-tests.png

Links

QSE159 frequency counter