Circuit Project: Heat Detector Alarm using UM3561

A very simple heat detector alarm electronic project can be designed using the UM3561 sound
generator circuit and some other common electronic parts . This heat detector electronic circuit
project uses a complementary pair comprising npn and pnp transistor to detect heat Collector of
T1 transistor is connected to the base of the T2 transistor , while the collector of T2 transistor is
connected to RL1 relay T3 and T4 transistors connected in darlington configuration are used to
amplify the audio signal from the UM3561 ic.

When the temperature close to the T1 transistor is hot , the resistance to the emitter –collector
goes low and it starts conducting . In same time T2 transistor conducts , because its base is
connected to the collector of T1 transistor and the RL1 relay energized and switches on the siren
which produce a fire engine alarm sound. This electronic circuit project must be powered from a
6 volts DC power supply , but the UM3561 IC is powered using a 3 volt zener diode , because
the alarm sound require a 3 volts dc power supply. The relay used in this project must be a 6 volt
/ 100 ohms relay and the speaker must have a 8 ohms load and 1 watt power.

Automatic changeover circuit

Description.
 The circuit diagram shown here is of a automatic changeover switch using IC LTC4412 from Linear Technologies. This circuit can be used for the automatic switchover of a load between a battery and a wall adapter.LTC4412 controls an external P-channel MOSFET to create a near ideal diode function for power switch over and load sharing. This makes the LT4412 an ideal replacement for power supply ORing diodes. A wide range of MOSFETs can be driven using the IC and this gives much flexibility in terms of load current. The LT4412 also has a bunch of good features like reverse battery protection, manual control input, MOSFET gate protection clamp etc. The diode D1 prevents the reverse flow of current to the wall adapter when there is no mains supply. Capacitor C1 is the output filter capacitor. Pin 4 of the IC is called the status output. When wall adapter input is present the status output pin will be high and this can be used to enable another auxiliary P-channel MOSFET (not shown in the circuit diagram).

Circuit diagram.

12 Volt to 230 Volt Inverter Circuit Diagram Using IC 555 Description

Description
Circuit showing a 12 volt to 230 volt inverter. Here we have used a astable multivariate for
making square wave pulse. The frequency of the square wave signal is high
and the voltage is 9v.There for the primary output voltage is almost equal to 230 volt. Here need a 12
volt power supply. Click here for the power supply circuit

Components Required

Resistor 10 k, 47k,1k 2W
Capacitor 103 pf -2
Transistor SL 100
IC NE 555
Transformer 9-0,230 VOLT PRIMARY

40 Channels of Programmable Voltage with Excellent Temperature Drift Performance Using the AD5380 DAC

CIRCUIT FUNCTION AND BENEFITS
 This circuit is a multichannel DAC configuration with excellent temperature drift performance. It provides 40 individual output voltage channels with 14 bits of resolution and a temperature stability of typically less than 3 ppm/°C.

CIRCUIT DESCRIPTION
Figure 1 shows a typical configuration for the AD5380-5 when configured for use with an external reference. In the circuit shown, all AGND, SIGNAL_GND, and DAC_GND pins are tied together to a common AGND. AGND and DGND are connected together at the AD5380 device. On power-up, the AD5380 defaults to external reference operation. This design uses two separate 5.0 V power supplies—one to power the voltage reference and the analog portion of the AD5380 (AVDD) and the other to power the digital portion of the AD5380 (DVDD). For best performance, a linear regulator should always be used to power the analog portion of the circuit. If a switching regulator is used to power the digital portion, care should be taken to minimize switching noise at the DVDD supply pins. Additional decoupling using a series connected ferrite bead may be required. The AD5380 digital (DVDD) power supply can operate from a 3 V or 5 V supply, which provides for maximum flexibility when interfacing to digital components. Both supplies can be tied together to a common 5 V supply; it is derived from a linear regulator. Refer to the ADIsimPower™ design tool for guidance on the power supply designs.

CROSSING LIGHTS

Description A magnet on the train activates the TRIGGER reed switch to turn on the amber LED for a time determined by the value of the first 10u and 47k. When the first 555 IC turns off, the 100n is uncharged because both ends are at rail voltage and it pulses pin 2 of the middle 555 LOW. This activates the 555 and pin 3 goes HIGH. This pin supplies rail voltage to the third 555 and the two red LEDs are alternately flashed. When the train passes the CANCEL reed switch, pin 4 of the middle 555 is taken LOW and the red LEDs stop flashing. Circuit Diagram

MERCURY SWITCH DETECTOR

Description
 This circuit is a LATCH CIRCUIT and it detects when the mercury switch is tilted. But it is consuming 10mA while it is sitting around waiting for the mercury switch to make contact. By replacing the 555 with two transistors, the circuit will consume zero current when waiting for the switch to close. Sometimes a 555 is not the ideal choice.

 Circuit Diagram

Remote control using telephone

Description Here is a teleremote circuit which enables switching ‘on’ and ‘off’ of appliances through telephone lines. It can be used to switch appliances from any distance, overcoming the limited range of infrared and radio remote controls. The circuit described here can be used to switch up to nine appliances (corresponding to the digits 1 through 9 of the telephone key-pad). The DTMF signals on telephone instrument are used as control signals. The digit ‘0’ in DTMF mode is used to toggle between the appliance mode and normal telephone operation mode. Thus the telephone can be used to switch on or switch off the appliances also while being used for normal conversation. The circuit uses IC KT3170 (DTMF-to-BCD converter), 74154 (4-to-16-line demultiplexer), and five CD4013 (D flip-flop) ICs. The working of the circuit is as follows. Once a call is established (after hearing ring-back tone), dial ‘0’ in DTMF mode. IC1 decodes this as ‘1010,’ which is further demultiplexed by IC2 as output O10 (at pin 11) of IC2 (74154). The active low output of IC2, after inversion by an inverter gate of IC3 (CD4049), becomes logic 1. This is used to toggle flip-flop-1 (F/F-1) and relay RL1 is energised. Relay RL1 has two changeover contacts, RL1(a) and RL1(b). The energised RL1(a) contacts provide a 220-ohm loop across the telephone line while RL1(b) contacts inject a 10kHz tone on the line, which indicates to the caller that appliance mode has been selected. The 220-ohm loop on telephone line disconnects the ringer from the telephone line in the exchange. The line is now connected for appliance mode of operation. If digit ‘0’ is not dialed (in DTMF) after establishing the call, the ring continues and the telephone can be used for normal conversation. After selection of the appliance mode of operation, if digit ‘1’ is dialed, it is decoded by IC1 and its output is ‘0001’. This BCD code is then demultiplexed by 4-to-16-line demultiplexer IC2 whose corresponding output, after inversion by a CD4049 inverter gate, goes to logic 1 state. This pulse toggles the corresponding flip-flop to alternate state. The flip-flop output is used to drive a relay (RL2) which can switch on or switch off the appliance connected through its contacts. By dialing other digits in a similar way, other appliances can also be switched ‘on’ or ‘off.’ Once the switching operation is over, the 220-ohm loop resistance and 10kHz tone needs to be removed from the telephone line. To achieve this, digit ‘0’ (in DTMF mode) is dialed again to toggle flip-flop-1 to de-energise relay RL1, which terminates the loop on line and the 10kHz tone is also disconnected. The telephone line is thus again set free to receive normal calls.This circuit is to be connected in parallel to the telephone instrument

Circuit Diagram

Remote control using VHF modules

Description A few designs for remote control switches, using VG40T and VG40R remote control pair, are shown here. The miniature transmitter module shown in Fig. 1, which just measures 34 mm x 29 mm x 10 mm, can be used to operate all remote control receiver-cum-switch combinations described in this project. A compact 9-volt PP3 battery can be used with the transmitter. It can transmit signals up to 15 metres without any aerial. The operating frequency of the transmitter is 300 MHz. The following circuits, using VG40R remote control receiver module measuring 45 mm x 21 mm x 13 mm, can be used to: (a) activate a relay momentarily, (b) activate a relay for a preset period, (c) switch on and switch off a load. To activate a relay momentarily (see Fig. 2), the switch on the transmitter unit is pressed, and so a positive voltage is obtained at output pin of VG40R module. This voltage is given to bias the relay driver transistor. The relay gets activated by just pressing push-toon micro switch on the transmitter unit. The relay remains energised as long as the switch remains pressed. When the switch is released, the relay gets deactivated. Any electrical/electronic load can be connected via N/O contacts of the relay. To activate a relay for a preset period (refer Fig. 3), the switch on the transmitter unit is pressed momentarily. The transistor gets base bias from VG40R module. As a result the transistor conducts and applies a trigger pulse to IC 555, which is wired as a monostable multivibrator. The relay remains activated till the preset time is over. Time delay can be varied from a few seconds to a few minutes by adjusting timing components. To switch on and switch off a load (refer Fig. 4), a 555 IC and a decade counter 4017 IC are used. Here the 4017 IC is wired as a flip-flop for toggle action. This is achieved by connecting Q2 output to reset terminal while Q1 output is unused. Q0 output is used for energising the relay. The relay is activated and deactivated by pressing the transmitter switch alternately. So, to activate the load, just press the transmitter switch once, momentarily. The relay will remain activated. To switch off the relay, press the transmitter switch again. This process can be repeated. Time delay of monostable multivibrator is set for about one second. Note: Short length of shielded wire should be used between VG40R receiver module output and the rest of the circuit. The transmitter with 9V battery must be housed inside a nonmetallic (say, plastic) cabinet for maximum range of operation.

 Circuit Diagram

BENCH POWER SUPPLY

Description
Here is a regulated power supply for you bench. The 100n capacitors are needed across the input and output of the regulator IC's to prevent high-frequency instability.

Circuit Diagram

ULTRASONIC REMOTE CONTROL

Description Here is a low cost, wireless switch controller. It uses ultrasonic sound waves for remote control of a switch. As with any other remote control, the system basically comprises a transmitter and a receiver circuit. Frequencies up to 20kHz are audible. Frequencies above 20kHz are not audible. The transmitter circuit generates an ultrasonic frequency between 40-50kHz. The receiver senses the ultrasonic sound and switches on a relay. The transmitter uses a 555 astable multivibrator. It oscillates at a frequency of 40-50kHz. An ultrasonic transducer is used to transmit the frequency. The transmitter runs on a 9v battery. The ultrasonic receiver uses a receiver transducer to sense ultrasonic signals. It uses a twostage amplifier, a rectifier stage and an operational amplifier in inverting mode. Output of the operational amplifier is connected to a relay through a driver stage. A 9v adapter can be used to power the receiver circuit. When switch S1 is pressed, it generates ultrasonic sound. The receiver amplifies the received signal via transistors Q3 and Q4. The amplified signal are then rectified and filtered. The filtered DC voltage is given to the inverting pin of operational amplifier 1C2. The non-inverting pin of 1C2 is connected to a DC voltage through VR2 that determines the threshold value of the signal received, for operation of relay RL1. The inverted output of 1C2 is used to bias transistor Q5. When transistor Q5 conducts, it supplies base bias to transistor Q6. When transistor Q6 conducts, it energises the relay RL1 . The relay can be used to control any electrical or electronic appliance. Frequency of the circuit can be varied by adjusting VR1. Adjust it for maximum performance. Ultrasonic sounds are highly directional. So when you are using the transmitter, the receiver should face towards the transmitter. The receiver is always kept on

Circuit Diagram