INFRARED TOY CAR MOTOR CONTROLLER

This add-on circuit enables remote
switching on/off of battery-operated
toy cars with the help of a TV/
video remote control handset operating at
30–40 kHz.
When the circuit is energised
from a 6V battery, the decade
counter CD4017 (IC2), which is
configured as a toggle flip-flop, is
immediately reset by the power-onreset
combination of capacitor C3
and resistor R6. LED1 connected
to pin 3 (Q0) of IC2 via resistor R5
glows to indicate the standby condition.
In standby condition, data
output pin of the integrated infrared
receiver/demodulator
(SFH505A or TSOP1738) is at a
high level (about 5 volts) and transistor
T1 is ‘off’ (reverse biased).
The monostable wired around IC1
is inactive in this condition.
When any key on the remote
control handset is depressed, the
output of the IR receiver momentarily
transits through low state and
transistor T1 conducts. As a result,
the monostable is triggered and a
short pulse is applied to the clock
input (pin 14) of IC2, which takes Q1 output
(pin 2) of IC2 high to switch on motor
driver transistor T2 via base bias resistor
R7 and the motor starts rotating
continously (car starts running). Resistor
R8 limits the starting current.
When any key on the handset is