Notes.

• Before wiring the circuit make sure that the carrier frequency  of the TV remote you have is 38 KHz.For that wire the sensor part only ,point your remote to the TSOP1738 and press any switch.If  out put of TSOP1738  goes  low them ok, your remote is of 38Khz type.Nothing to worry almost all TV remote are of this type.
• You can use any switch because for any switch the code only changes,the carrier frequency remains same.We need this carrier frequency only.
• Assemble the circuit on a good quality PCB or common board.
• The appliance can be connected through NO or NC  and contacts of the relay

 

• Assemble the circuit on a good quality PCB.
• Use 9V PP3 battery for powering the circuit.
• The Mic M1 can be condenser micro phone.
•  Use push to ON type push button switch for S2.
• Use a slide switch for switch S1.S1 can be used to power the circuit

• Assemble the circuit on a good quality PCB or common board.
• The LDR can be general purpose LDR.
• The light sensitivity can be adjusted using the preset R6.
• The IC1 must be mounted on an IC holder

• Power the circuit from a 3V battery.
• Two metal wires 10 cm long and 5cm apart driven into the soil will do the job for probes.
• The probes are to be connected at the terminals A and B shown in circuit.
• Capacitors C1 and C2 must be polyester type.
• The IC U1 is a quad two input Schmitt NAND IC 4093.
• The sensitivity can be adjusted by varying the preset R2.
• Mount the IC on a holder.

• The circuit can be assembled on a general purpose PCB.
• The transistor Q3 must be fitted with a heat sink.
• The elements L1 to L3 can be 10W heating coils.
• The switches S1 and S2 must be able to withstand at least 5A.
• The circuit can be powered from a 12V battery.
• The LED D1 gives a visual indication of the duty cycle of the circuit

• Assemble the circuit on a general purpose PCB.
• The circuit can be powered from 12V DC.
• The buzzer can be any general purpose piezo buzzer.
• The IC1 must be mounted on a holder

• Assemble the circuit on a general purpose PCB.
• The IC must be mounted on a holder.
• The circuit can be powered from two torch cells connected in series.
• The capacitors C1 and C2 must be Tantalum type.
• The diodes D1 to D3 must be of 1N4148

Components

1. The components needed for the connection are
2. Flashlight bulb and socket [1]
3. Dry cell lantern battery/D-cell battery [2]
4. Wire [About 15 to 17 inches and another one 2 inches]
5. Spring [1]
6. Wire Clippers [A pair]
7. A typical spring can be obtained from a widow roll up. You can even get to buy one at a cheap rate.

Procedure

• Connect the two Dry cell lantern/D-cell batteries tail-to-tail, so that the positive polarity of one battery is connected to the negative polarity of the other.
• Using a wire cutter, cut the wire in equal lengths. One wire should be at least 8 centimetres long.
• Connect the wires onto the open ends of both the batteries.
• The end of one wire must be connected to the bulb socket with the bulb in it.
• Connect the second wire to one end of the long spring.
• Connect the free end of one wire to one terminal of the light socket.
• Connect the other free wire to one end of the spring.
• Take the two inch wire and connect it to the second terminal of bulb socket.
• Connect the other end of the two inch wire onto the other end of the spring.

How to make a Rheostat

What happens?

Water level controller circuit.

Description.

A simple but very reliable and effective water level controller circuit diagram is shown here. The circuit uses 6 transistors, 1 NE555 timer IC, a relay and few passive components. The circuit is completely automatic which starts the pump motor when the water level in the over head tank goes below a preset level and switchess OFF the pump when the water level in the over head tank goes above the full level.

Probe D is positioned at the bottom level of the tank while probes A, B and C are placed at full, half and medium levels of the tank respectively. The level sensing part of the circuit is built around transistors Q1, Q2 and Q3. When water level is below the quarter level probes A, B and C are open and the transistor Q1, Q2 and Q3 remains OFF. When the water level rises and touches the probes the corresponding transistors gets biased and switches ON. Resistors R1, R2, R3 limit the bases current of corresponding transistors while resistors R4, R5, R6 limit their collector current. LEDs D1, D2 and D3 provide a visible indication of the current water level.

When the water level goes below medium, transistor Q2 gets switches OFF and its collector goes positive. Collector of Q2 is connected to the base of transistor Q6 and as result transistor Q6 gets switched ON. Transistor Q5 will be also ON because its base in connected to the collector of Q4 which is presently OFF. As a result when the water level goes below medium relay K1 gets energised and the pump is driven. The relay is wired in the latching mode so that even if the water level goes above medium level the pump remains ON so that the tank gets completely filled. For wiring the relay in latching mode one set  of N/O contacts is used. When relay is activated these contacs close which forms a short across collector and emitter of Q6. This makes the state of Q6 irrelevant to the opertion of the relay and the relay remains ON as long as the transistor Q5 is ON. The only way to make the relay OFF is by switching OFF Q5 and it is done automatically when the water level reaches the full level.

Collector of transistor Q1 is connected to the trigger pin (pin2) of IC1. When the water level reaches full level the transistor Q1 gets switched ON. As a result its collector goes to ground level which triggers the IC1 which is wired as a monostable. The output of IC1 goes high for about 1S. This makes the transistor Q4 ON for the same time and transistor Q5 whose base is connected to the collector of Q4 is switched OFF cutting the supply to the relay. This makes the motor OFF and it remains OFF until the water level again goes below the medium level.

Resistor R8 is a pull up resistor for the trigger pin of the NE555. Capacitor C3 couples the collector of Q1 to the trigger pin of NE55 and facilitates edge triggering whenever the transistor Q1 goes ON. A monostable circuit can be made edge triggered by connecting the trigger signal to the trigger input pin through a capacitor. The capacitor blocks DC and passes sudden changes. The circuit used here is termed as negative edge triggered because the monostable is triggered when ever the trigger input signal falls. R10 and R12 limits the collector current of Q4 and Q5 respectively while R9 and R11 limits their base current. R13 limits the base current of Q6 while D4 is a freewheeling diode which protects the switching transistors from voltage transients.

Circuit diagram.

 

Water level controller circuit diagram

Probe arrangement diagram

The probes can be arranged as shown in the diagram above. Insulated Aluminium wires can be used as the probes. The probes can be binded on a plastic rod and should be erected vertically inside the tank. The length of the probes wires and the supporting plastic rod must be chosen according to the depth of the tank. Since DC is used in the level sensing section electrolysis will occur in the probes and so the probes require small maintinances in 1 or 2 month intervals. Using AC in the sensing section will completely eliminates the chance of electrolysis and I am presently working on such a circuit. You can expect it soon.

Notes.

• Use 12V DC for powering the water level controller circuit.
• The relay I used was a 5V/220 ohm relay and that’s why the current limits resistor R12 was added in the circuit. If you use a 12V relay then the R12 can be shorted.
• Do not use a relay that consumes 500mA. Maximum collector current PN2222 can handle is 600mA.
• Use insulated single strand aluminium wires for probe and they can be arranged in the tank as per the probe arrangement diagram.
• Use a holder for mounting NE555.
• The circuit can be assembled on a Perf board.
• K1 must be a double pole relay.
• The load current, voltage ratings of the relay must be selected according to the ratings of the pump motor.
• The type number of the transistors used here are not very critical and you can do suitable replacements if any type number is not availble.
• Most of the components required for this project can be found inside your scrap box.

Power supply for this circuit.

12V DC power supply

A classic 12V regulated DC supply based on 7812 is shown above. A power ON indicator LED is also added in the circuit.Resistor R13 limits the LED current. A small aluminium heatsink can be fitted to the 7812 for better saftey.Small Al heatsinks for TO-220 package are readily available in the market

• A 12V lead acid battery can be used for powering the circuit.
• TIP3055 must be mounted on a heat sink.
• T1 can be an EHT (extra high tension) transformer used in television sets.
• For an EHT from 20inch TV, the output voltage will be 8 to 10 KV @12V supply voltage.
• This circuit is not an efficient one and is not suitable for any serious applications.
• Once again, be very careful with this circuit!

• Assemble the circuit on a goos quality PCB or common board.
• If the matching is not satisfactory then change the values of L1,C1,C2&C3  to the next close value and tune again.
• Proper tuning requires some trial and error.
• The circuit can be enclosed in an aluminum casing for better performance

• The POT R2 can be used for frequency adjustments.
• POT R3 can be used for volume adjustments.
• The switch S1 can  be a Morse code key

Touch Switch Circuit using NE 555

Description

Notes.

Touch Switch Circuit Diagram

• Power up the circuit and adjust the presets (R6 to R 13) to get the desired tune at the  output for the press of corresponding push button.
• Preset R1 (5K)  can be used as a volume control.
• You can also try different values for C2 get the desired tunes.
• All capacitors are of ceramic type

• Switch S1 can be a pushbutton switch.
• Switch S2 can be a SPST switch.
• The circuit can be powered from a 9V battery or 9V DC power supply

• Assemble the circuit on a good quality PCB or common board.
• The ICs must be mounted on holders.
• The speed of the dancing LEDs can be adjusted by varying POT R2.
• The capacitor C1 must be rated 15V.
• Using different color LEDs could produce a better visual effect.

• The circuit can be powered from a 3V battery.
• The M1 can be a general purpose condenser microphone.
• The switch S1 can be push button switch.
• The circuit can be assembled on a good quality PCB or common board.
• Instead of the LED, you can also try a low power 3V bulb

• The circuit can be powered from 5 V DC.
• Switch S1 is a push button switch.
• The ICs must be mounted on holders.
• The circuit can be assembled on a general purpose PCB

• Assemble the circuit on a general purpose PCB.
• The switch S1 can be a slide type ON/OFF switch.
• The IC must be mounted on a holder.
• The POT R1 can be used to adjust the sensitivity of the circuit.

• Assemble the circuit on a general purpose PCB.
• The circuit can be powered from a 9V PP3 battery.
• The transformer T1 can be a audio output transformer like LT700.
• If LT700 is not available, try the audio output transformer used on you old transistor radio board.
• The speaker can be an 8 ohm tweeter.
• Switch S1 can be a push button switch.
• The chirping sound can be altered by changing the value of R1 and C1

Circuit diagram with Parts list.

• Switch S1 is the ON/OFF switch.
• Switch S2 can be a push button switch.
• Buzzer K1 is a piezo buzzer.
• The circuit can be powered from a 9V PP3 battery.
• The IC must be mounted on a holder

• Assemble the circuit on a good quality PCB.
• The circuit can be powered from a 3V battery.
• IC U1 is a CMOS CD4049 Hex inverter.
• M1 can be an electret microphone.
• B1 can be a 3V piezo buzzer.
• Mount the IC on a holder.
• The duration of beeping can be adjusted by varying the components C4 and R9

• The circuit can be powered from a 3V battery.
• Do not give more than 3.3V to the IC.
• K1 can be a 200mW/8 Ohm speaker.
• IC1 must be mounted on a holder.

• The circuit can be assembled on a Vero board.
• Do not give more than 4.5v to the circuit.
• Switches S1 to S4 can be miniature push button switches.
• S5 can be a miniature ON/OFF switch.
• K1 can be an 8 ohm speaker.
• IC1 and IC2 must be mounted on holders