Gas Sensor detection- in this project we gas sensor will detect signal . it will provide signal to 555 timer.
Monthly Archives: February 2014
OR gate
Gas sensor alarm
Sensors Connections will according to type of Gas sensor Use-
Normally Gas sensor start from MQ2 to MQ15 . According to gas required
For Smoke- MQ2
LPG- MQ5
Alcohol – MQ3
Components Used:
Q3- BC548
Q4-BC558
D&- LED 5mm
R12- 10k variable resistor
R13- 1k
R14+R15- 1k
555 timer
LDR- 5mm- 50 ohm
Soldering wire
Soldering Iron
Multimeter
PCB-
light sensitive triggering
Electronic Eye
Electronics Eye
This circuit activates a speaker output detecting the absence of light on LDR (Light Dependent Resistor). It is particularly well suited to burglar alarm system.
Contrary its normal use as an astable or monostable multivibrator. The transistor BC 148 is an NPN type transistor, which is use as a audio preamplifier & transistor BEL 188 is a PNP type transistor, which is use as an amplifier.
These both transistors is working together as a Complimentary Pair Direct Coupled Amp. For oscillation of the circuit Feedback Amp. Transistor BEL 188 is collector giving of .02 mfd or 12K Resistor starts to pre transistor BC 148.
The LDR is placed between bases of the preamp. Or negative supply of the circuit.
There is only 3V DC supply is required for operating the circuit.
PART LIST:
RESISTORS:
R1 – 270K
R2 – 12K
CAPACITORS:
C1 – .02MFD
TRANSISTORS:
T1 – BC 148
T2 – BEL 188
MISC:
8E SPK. – 1
3V Battery Holder – 1
LDR – 1
clap switch
clap switch
Here is a circuit for electronics hobbyists that can switch on and off, a fan or a Radio etc. by the sound of a clap.
The sound of clap is received by a small microphone that is shown biased by resistor R1 in the circuit. The signal is further amplified by transistors Q1,Q2,Q3. The relay contact is connected to the power line and hence turns on/off any electrical device at output socket.
PARTS LIST:
RESISTORS:
R1 – 15K
R2,5,12 – 2M2
R3 – 270K
R4 – 3K3
R6,10 – 27K
R7,11 – 1K5
R8,9 – 10K
R13 – 2K2
MISC:
X1 – 12V / 300mA Transformer
NIC – Condenser Mic
RLY – 12V Single charge over relay
CAPACITORS:
C1 – 10KPF Disc
C2,3 – 47KPF Disc
C4 – 1000uF/16V
SEMICONDUCTORS:
Q1,2,3,4 – BC 149 B OR C
D1 – IN 4002
D2,3,4,5 – IN 4148
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FM transmitter
FM transmitter sensor
Several circuits for constructing FM transmitter have been published by EFY. The power output of most of these circuits were very low because no power amplifier stages were incorporated. The transmitter circuit described here has an extra RF power amplifier stage, after the oscillator stage, to raise the power output to 200-250 milli watts. With a good matching 50 ohm ground plane antenna or multi element yagi antenna, this transmitter can provide reasonably good signal strength up to a distance of about 2 kilometers. The circuit built around transistor T1 (BF494) is a basic low power variable frequency VHF oscillator. A varicap diode circuit is included to change the frequency of the transmitter and to provide frequency modulation by audio signals. The output of the oscillator is about 50 milliwatts. Transistor T2 forms a VHF class A power amplifier. It boosts the oscillator signal’s power is generated at the collector of transistor T2.
FM TRANSMITTER
Componet list:-
Resistances
R1 – 3.3K
R2 – 33K
R3 – 4.7K
R4 – 33K
R5 – 1K
R6 – 100ohm
TRANSISTORS
T1 – 548
T2 – 548
CAPACITORS
C1 – 10uf/50V
C2 – 473K
C3 – 224K
C4 – 474K
C5 – 4.7
C6 – 0.02
C7 –
OTHERS
L1 – Coil
BAT9V – DC Battery 9Volt
ANT – Antenna
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Battery connector
Electronic harmonium
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Electronics harmonium
ELECTRONIC HARMONIUM
So much is being said and done about electronic music now a days that you may be interested to have hands on experience in this field. To get you started here is am easy to make project.
This harmonium can generate 15 different notes of music (One at a time). It has a PCB with15 parallel copper strip. Each strip corresponds to one note. So as you put the probe on a strip, the instrument plays a corresponding note.
The heart of the circuit is a 555 timer IC. Here the IC is used as an oscillator ( or free running multivibrator, as it is technically called) which can produced square waves of different frequencies. The frequency produced depend on the note selected by the probe. A glance at the circuit diagram tells us that when we put the probe on different strips , we are effectively changing the resistance between pin 7 and pin 2 (and 6) of 555. For convenience we may denote this resistance by Rk.
Now let us have a look at the functioning of 555 as an oscillator. If we assume that 555 has been given a 9 volt power supply across pins 1 and 8, it exhibits the following properties:
- When voltage on pin 2 falls below 3V, output at pin 3 is switched to +9V and pin 7 acts as open circuited. Any change in voltage level at pin 2 will not change the state of IC now.
- When voltage on pin 6 goes above 6V then pin 3 switches to 0V level & pin 7 acts as if it has been short circuited to ground. Any change of pin 6 will not change the state now.
In our ckt. We have connected pin 2 and 6 together. So if we assume that output at pin 3 is 9V, at a particular instant the combination of R1 and RK (R2 to R16) charges capacitor C3 and voltage across the capacitor keeps on increasing. When it becomes slightly more than 6V, pin 6 senses it and changes output voltage at pin 3 to 0V and pin 7 starts acting as if it has shorted to the ground. So C3 starts discharging through RK. As soon as pin 2 senses that voltage across the capacitor is less than 3V, output is switched back to 9V, so the cycle repeats itself. This way we get square waves at pin 3 since capacitor c3 charges and discharges through RK, the charge and discharge times can be varies by changing values of RK and in turn the frequencyof square wave can be changed. The values of R2 to R16 (which present RK) have been calculated to give the correct ratio within 2 percent tolerance.
For a sweet musical sound, it is required to have symmetrical sqaure wave ( which is in high and low state for equal periods of time) Thus R1 is kept small compared to RK in order to achieve a nearly symmetrical waveform.
The types as speaker used is not critical, you can use almost any speaker. For a loud sound use at least 10 CM speakers. You may solder resistors R2 to R16 directly on the PCB of keyboard.
PARTS LIST:
RESITORS:
R1 – 10K
R2 – 82K
R3,R5 – 68K
R4,R10,R12 – 33K
R6,R7 – 47K
R8,R13,R14 – 22K
R9 – 39K
R11 – 18K
R15 – 12K
R16 – 180K
CAPACITORS:
C1 – 10uF/16V
C2 – .01 uF
C3 – .002Uf
SEMICONDUCTOR:
IC1 – 555
S1-S15- 2PIN PUSH ON SWITCH
9V BATTERY SNAP
SPEAKER 8E LS WT
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