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Raspberry Pi 3 Self Learning Kit
Pi 3 + bunch of goodies = super fun learning!
Manual buzzers used for quiz competitions in schools and colleges create a lot of confusion in identifying the first respondent. Although there are circuits using PCs and discrete ICs, they are either too expensive or limited to only a few number of players. The School/College Buzzer is a circuit that can be used for up to eight players.It uses the IC 74LS373 (which is an octal latch) and a few passive components to implement the quiz buzzer mechanism.
Things Which you will learn:
*Application of the octal latch IC 74LS3737.
*Use of SCRs in logic circuits.
*Application of transistors as switches.
Quiz competition are integral part of our learning and as the world advances towards technological advancement , there should be some changes in the way we conduct quiz. So with this kit , you can build yourself an digital quiz buzzer supporting upto eigth players and ejoy playing quiz without any confusion.
At the heart of the School/College Quiz Buzzer is the IC 74LS373 which transfers the logic state at data input pins (D0 through D7) to the corresponding outputs (Q0 through Q7). Data pins D0 through D7 are normally pulled low by resistors. One terminal of eight push-to-on switches (S1 through S8) is connected to +5V, while the other terminal is connected to the respective data input pins. The switches are to be extended to the players through cord wire.
The torch bulbs (BL1 through BL8) can be housed in boxes with the front side of the boxes covered with a white paper having the name or number of the contestant written over it for easy identification. When the power is switched on using switch S9 (provided terminals ‘A’ and ‘B’ of both the power supply and quiz buzzer sections are interconnected), the circuit is ready to be used.
Now all the switches (S1 through S8) are open and Q0 through Q7 outputs of IC 74LS373 (IC2) are low. As a result, the gates of silicon-controlled rectifiers (SCR1 through SCR8) are also low. As soon as a contestant momentarily presses his respective switch, the corresponding output data pin goes high.
This triggers the corresponding SCR and the respective bulb glows. At the same time, the piezoelectric buzzer (PZ1) sounds as transistor BC548 (T1) conducts. Simultaneously, the base of transistor BC548 (T2) becomes high to make it conduct. Latch-enable (LE) pin 11 of IC2 is tied to ground to latch all the Q0 through Q7 outputs. This restricts further change in the output state due to any change in the state of switches S1 through S8 by any other contestant.
Only one of the eight torch bulbs glows until the circuit is reset by on/off switch S9.
Download PDF for this project.
FM booster is a low cost circuit that can be fed between an FM receiver and antenna to listen to distant commercial FM stations clearly.The main components of the circuit comprises of CS2570 transistor,trimmers and inductor coils.
Things which you can learn:
*Application of C2570 transistor.
*Working of trimmers.
*Maximum Power Transmission
*RF pre amplifier setup
The FM booster can be used to listen to programs from distant FM stations clearly It basically extents the range by which distant channels can be recieved.
The circuit comprises a common-emitter tuned RF preamplifier wired around VHF/UHF transistor 2SC2570.
The input/output trimmers (VC1/VC2) for set for maximum gain. An input coil L1 consisting of four turns of 20SWG enameled copper wire (slightly space wound) over 5mm diameter former, is tapped at the first turn from ground lead side. Coil L2 is similar to L1, but has only three turns.
Some of the mosquito repellents available in the market use a toxic liquid to generate poisonous vapors in order to repel mosquitoes out of the room. Due to the continuous release of poisonous vapors into the room, after midnight the natural balance of the air composition for good health reaches or exceeds the critical level. Mostly, these vapors attack the brain through the lungs and exert an anesthetic effect on mosquitoes as well as other living beings by small or greater percentage. Long exposure to these toxic vapors may cause neurological or related problems.Here is a circuit that automatically switches on and off the mosquito repellent after a preset time interval, thus controlling the release of toxic vapors into the room.
Things which you can learn:
*Application of NE 555 timer.
*Application of TRIAC BT136.
*Application of Zener diode as voltage regulator
Here is a circuit that automatically switches on and off the mosquito repellent after preset time interval, thus controlling the release of toxic vapours into the room. The circuit turns the mosquito repellent ‘on’ for approximately 20 minutes then process of 'on' and 'off' occurs repeatedly.So if you leave the mosquito repellent switched on from 10 pm to 6 am (eight hours), it will be ‘on’ for four hours and ‘off’ for four hours of the total duration. During ‘off’ time, the room air tries to balance its natural composition.
Another important feature is that the circuit switches to ‘on’/‘off’ operation without producing any noise or a sound click as in a relay and hence doesn’t disturb your sleep.
The circuit consists of a timer section built around IC 555 (IC1) and an automatic switching section using triac BT136 (triac1). Power supply to the circuit is derived from the AC mains by stepping it down to a required level and rectifying it. The elimination of the transformer saves on space as well as money. Zener diode ZD1 and capacitor C2 provide regulated 9V DC power supply to timer IC1.The timer section comprises resistors R1 and R2 and capacitor C1. The output of timer IC 555 is fed to the gate terminal of BT136 through series LED1 and resistor R4. When the timer output goes high, it triggers the gate of triac 1 and LED1 shows the ‘on’ period. During ‘off’ time, the output of IC1 goes low and hence triac 1 is not fired and LED1 doesn’t glow. The circuit is very compact and can be assembled on a general-purpose PCB. Use an 8-pin IC base for timer IC LM555. After assembly, fit the unit inside the housing electric board where you plug in the mosquito repellent.
This is a simple Automatic water controller Kit which the users can assemble in minutes and starting experimenting with it. The circuit is built around a TIMER555 and a inverting buffer CD4049. Circuit works on a 12V DC supply. Three sensors are installed with the kit to indicate lower level, higher level and VCC. At bottom of the tank VCC is placed,lower level L is placed above the VCC and higher level H is placed at the top.
Get the kit now and build yourself a reliable water controller and get amazed by how this tiny little device takes care of water level in the tank!!
Things Which you can learn:
*Application of NE555 timer.
*Application of CD4069 as inverter.
*Application and connection of relay switches to control the on/off of appliances.
Water-level controllers are common nowadays and have become essential device in conserving water which otherwise would get wasted as the tank gets full up to its brim. The one described here is built around timer NE555 and inverter buffer CMOS IC CD4049. It uses readily-available, low-cost components, and is easy to build and install on the over-head tank (OHT) to prevent wastage of water.
The circuit works off a 12V battery or 230V AC mains using a 12V adaptor. Since Vcc terminal is at the bottom of the tank, when the water level falls below sensor L, timer IC2 is triggered at pin 2 via inverters N1 and N2 and its output goes high. As a result, the output of timer IC2 goes high. Relay RL1 energises and the motor starts filling water in the tank. The motor remains ‘on’ even when the water level crosses sensor L.
As water in the tank rises to touch sensor H, timer IC2 is retriggered at pin 6 via inverters N3 and N4 and as a result, its outputgoes low. The relay de-energises and
the motor stops filling water in the tank. The motor remains ‘off’ even when the water level falls below sensor H. As water is consumed and its level falls below sensor L, the motor restarts.Thereafter, the cycle repeats.
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