Presently, production of
robots of different types and functions are rapidly created to help
people make their life easier. We can even imagine how the world would
look like on the next decade to come. That is – robots do most of the
work that people used to do.
Most of the bots in the market are not controlled by Bluetooth
except this bot. It’s amazing how this bot dances while controlling the
Bluetooth keyboard and a lot of fun to watch for robot fanatics.
In spite the advantages of bots, it can shut down if operation failed
therefore failure on its task. Then back to basics must always be a
How do you want to have
your wipers become more intelligent? In this way, they could remember
how frequent you need to use them. But of course, this will need the
help of an ATmega8L microcontroller.
When you need to activate the wiper, you just press the button and
it will run in one course. There is a 45 seconds waiting time that if
you do not press the button, it will go on standby while telling itself
that only one course is needed. The system will activate the wiper again
if the button is pressed before 45 seconds. The good thing is that it
will remember the interval when you pressed the button.
We have all seen the commercial on TV ………. CLAP – ON – CLAP – OFF – THE – CLAPPER ………… well here is a circuit that will perform that same function.
Circuit operation is as follows. A single hand clap will be picked
up by the electric mic which is coupled through C1 into the op amp IC1.
The output of IC1 triggers the 555 IC timer IC2 which is configured as a
monostable multivibrater. The trigger pulse is stretched by IC2 and
outputs a pulse to IC3 a D type flip flop. Because of the three state
counter arrangement of IC3, two sharp claps are required before IC3 will
output a high to Q1 which will turn on K1 relay and any device
connected to K1’s switch contacts. Two more claps will clock IC3 again
and will turn off Q1 and any device connected to the K1’s contacts. I
had my unit connected to my xmas tree lights so that I wouldn’t have to
crawl behind the tree to turn the lights on and off. Sensitivity for the
circuit is R3 and should be adjusted so that the circuit ignores normal
The fan runs constantly
in many PCs, which may not even be necessary. A simple controller
circuit can regulate the fan speed according to demand. This not only
saves energy, it also reduces irritation from the fan noise. Only three
components are needed to allow the fan speed to be controlled according
to the actual demand: one adjustable voltage regulator and two resistors
that form a voltage divider. One of the resistors is a NTC
thermistor (temperature-sensitive resistor), while the other is a
normal resistor. If the 12-V power supply is not located close to the
regulator, a decoupling capacitor is also required (see Figure 1).
Circuit diagram with LM317
The thermistor has a rated value of 470 Ω. It sets the output
voltage of the LM317T to approximately 7 V at 25 ºC. This should ensure
reliable starting of the fan. If the temperature rises to roughly 40°C,
the output voltage of the regulator reaches its maximum value and the
fan runs at its maximum speed. The voltage drop across the regulator is
at least 1.75 V for a motor current of (for example) 300mA, and in any
case 2V at the maximum current level of 1 A. You thus might want to
consider using a low-drop regulator, such as the National Semiconductor
Circuit diagram with LM2941
To be sure, this increases the size of the circuit to a full five
components, which are arranged as shown in Figure 2. However, this
approach reduces the voltage drop to 0.2 V at 300 mA or 0.5 V at 1 A. By
the way, low-drop voltage regulators are not available in a three-lead
package. The circuit can be constructed as a well-insulated
‘free-standing’ assembly, or it can be built on a small piece of
prototyping board. In either case, it should be fixed to one of the
mounting holes of the fan body (via the cooling tab of the TO-220
regulator package for the free-standing construction). The circuit board
should be mounted out of the air stream, but the NTC thermistor must extend into the air stream.
This circuit is ideal to
control the cooling fan of heat generated electronic gadgets like power
amplifiers. The circuit switches on a fan if it senses a temperature
above the set level. The fan automatically turns off when the
temperature returns to normal.
The circuit uses an NTC (Negative Temperature Coefficient) Thermister to sense heat. NTC
Thermister reduces its resistance when the temperature in its vicinity
increases.IC1 is used as a voltage comparator with two potential
dividers in its inputs. Resistor R1 and VR1 forms one potential divider
connected to the non inverting input of IC1 and another potential
divider comprising R2 and the 4.7K Thermister supplying a variable
voltage to the inverting input of IC1. VR1 is adjusted so as to give
slightly lesser voltage at the non inverting input than the inverting
input at room temperature.
DC Fan Controller Circuit
In this state, output of IC1 will be low and the Fan remains off.
When the temperature near the Thermister increases, its resistance
decreases and conducts. This drops the voltage at pin 2 of IC1 and its
output becomes high. T1 then triggers and fan turn on. Red LED
indicates that fan is running. Capacitor C1 gives a short lag before T1
turns on to avoid false triggering and to give proper bias to T1.DC fan
can be the one used in Computer SMPS.
Keep the Thermistor near the heat sink of the Amplifier PCB
and switch on the amplifier for 10 minutes. Then adjust VR1 till the
Fan stop running.When the temperature rises, Fan will automatically
This rotative speed
regulator circuit schematic allows to control the holing speed of your
borer or driller machine. This project is based on the fact that if the
load grows, the voltage decrease and current increase. Use this circuit
to control the speed of revolutions of your drilling mill or bench
Driller controller circuit schematic
Exhaust fan is an
important component in kitchens. Here is a simple circuit to control
kitchen fans by monitoring the ambient temperature. It is built around
the renowned precision integrated temperature sensor chip LM35 (IC1).
Rest of the circuit is a non-traditional electromagnetic relay driver
wired around the popular LED driver LM3914
(IC2). User can switch three presetted temperature levels using a
jumper/slide switch (JP1), which determines the heat level to activate
the relay and hence the electric exhaust fan wired through the relay
contacts. It works off 12V DC power supply.
Kitchen Fan Controller Circuit Schematic
Only one adjustment is required in this kitchen exhaust fan
controller circuit. After construction, set jumper point in its first
position, ie base terminal of T1 is connected to pin 13 of IC2 and
adjust the preset P1 carefully so that relay RL1 is energised when
ambient temperature level reaches near 29oC. However this is not very
critical as you can select any threshold level by connecting the jumper
points to other unused output pins of IC2 (here only 3 outputs are
Minuscule circuit of the
electronic heater controller presented here is built around the
renowned 3-Pin Integrated Temperature Sensor LM35 (IC1) from NSC.
Besides, a popular Bi Mos Op-amp CA3140 (IC2) is used to sense the
status of the temperature sensor IC1, which also controls a solid-state
switch formed by a high power Triac BT136. Resistive type electric heater at the output of T1 turns to ON and to OFF states as instructed by the control circuit.
This gadget can be used as an efficient and safe heater in living
rooms, incubators, heavy electric/electronic instrument etc. Normally,
when the temperature is below a set value (Decided by multi-turn preset
pot P1), voltage at the inverting input (pin2) of IC1 is lower than the
level at the non-inverting terminal (pin3). So, the comparator output
(at pin 6) of IC1 goes high and T1 is triggered to supply mains power to
the desired heater element.
Electronic Heater Controller Circuit Schematic.
Note: CA3140 (IC2) is highly sensitive to electrostatic discharge (ESD). Please follow proper IC Handling Procedures.
When the temperature increases above the set value, say 50-60 degree
centigrade, the inverting pin of IC1 also goes above the non-inverting
pin and hence the comparator output falls. This stops triggering of T1
preventing the mains supply from reaching the heater element.
Fortunately, the threshold value is user-controllable and can be set
anywhere between 0 to 100 Degree centigrade.
The circuit works off stable 9Volt dc supply, which may be derived
from the mains supply using a standard ac mains adaptor (100mA at 9V) or
using a traditional capacitive voltage divider assembly. You can find
such power circuits elsewhere in this website.