08-08-2012, 01:32 PM
Wiper Speed Controller
[attachment=30571]
Acontinuously working wiper in
a car may prove to be a nuisance,
especially when it is not
raining heavily. By using the circuit described
here one can vary sweeping rate
of the wiper from once a second to once
in ten seconds.
The circuit comprises two timer
NE555 ICs, one CD4017 decade counter,
Which advances
by one count on each successive
clock pulse or the push of switch S1.
Ten presets (VR1 through VR10),
set for different values by trial and error,
are used at the ten outputs of IC2.
But since only one output of IC2 is high
at a time, only one preset (at selected
output) effectively comes in series with
timing resistors R4 and R5 connected in
the circuit of timer IC3 which functions
in astable mode.
As presets VR1 through VR10 are
set for different values, different time
periods (or frequencies) for astable
multivibrator IC3 can be selected. The
output of IC3 is applied to pnp driver
transistor T1 (TIP32) for driving the final
power transistor T2 (2N3055) which
in turn drives the wiper motor at the
selected sweep speed. The power supply
for the wiper motor as well as the circuit
is tapped from the vehicle’s battery itself.
The duration of monostable
multivibrator IC1 is set for a nearly one
second period.
[attachment=30571]
Acontinuously working wiper in
a car may prove to be a nuisance,
especially when it is not
raining heavily. By using the circuit described
here one can vary sweeping rate
of the wiper from once a second to once
in ten seconds.
The circuit comprises two timer
NE555 ICs, one CD4017 decade counter,
Which advances
by one count on each successive
clock pulse or the push of switch S1.
Ten presets (VR1 through VR10),
set for different values by trial and error,
are used at the ten outputs of IC2.
But since only one output of IC2 is high
at a time, only one preset (at selected
output) effectively comes in series with
timing resistors R4 and R5 connected in
the circuit of timer IC3 which functions
in astable mode.
As presets VR1 through VR10 are
set for different values, different time
periods (or frequencies) for astable
multivibrator IC3 can be selected. The
output of IC3 is applied to pnp driver
transistor T1 (TIP32) for driving the final
power transistor T2 (2N3055) which
in turn drives the wiper motor at the
selected sweep speed. The power supply
for the wiper motor as well as the circuit
is tapped from the vehicle’s battery itself.
The duration of monostable
multivibrator IC1 is set for a nearly one
second period.