Simple UHF Preamplifier Circuit

This circuit is designed for UHF Preamplifier circuit. This circuit is designed for working at UHF frequencies in range 450-800MHz. The circuit has a gain of around 10dB and is suitable for boosting weak TV signals. This is a simple design circuit. This is the figure of the circuit.


Operation of the circuit is description in beside. First, the coil is half a turn of 18-20 SWG copper wire bent around a half inch drill bit. This ensures a low Q and therefore broad tuning. High frequency work requires special construction techniques to avoid instability (unwanted oscillations) caused by feedback from output to input. Vero board is not suitable for this project as the capacitance between tracks is around 0.2pF. A better approach is to use tag-strip or a PCB. The circuitry should be enclosed in a metal case and a screen made between input and output. As the transistor is used in common base mode, its low input impedance is a good match for 50-75 ohm coax cable, whilst at the same time providing full voltage gain to the upper frequency limit of the device. The 15nH inductor load, having almost a short circuit impedance at DC, has an impedance of 56ohms at 600MHz. This inductance and 2.2pF capacitor form a tank circuit at the transistors collector, providing maximum gain at resonance. Note however that the voltage gain will be reduced under load, when the circuit is connected to the input of a TV set or a very long piece of coaxial cable for example.

Simple Fuse Monitor and Indicator Circuit

This is a simple design for fuse monitoring circuit. This circuit is work for to check if a fuse has blown without removing it from its holder. This is the figure of the circuit.


The simplicity of this circuit uses just two components, but with just one resistor and an LED this circuit gives visual indication of when a fuse has blown. LED1 is normally off, being "short circuited" by the fuse, F1. Should the inevitable "big-bang" happen in your workshop then LED1 will illuminate and led you know all about it. Please note that the LED will only illuminate under fault conditions, i.e. with a short circuit or shunt on the load. In this case the current is reduced to a safe level by R1.

The Simple Converting CD-ROM Drive to Audio CD Player

This is the simplest design circuit for converting a CD ROM drive of your computer to a Audio CD player. The minimum requirement for the player is that, it should have a audio output and skip button. Luckily most of the CD ROMs are equipped with both of these. This is the figure of the circuit.


The operation od the circuit is when CD ROM drive needs two voltages, 12V & 5V for its operation. So the main objective is to build a suitable power supply for the CD ROM drive. The IC1 (7812) together with associated components produce a regulated 12V DC. The IC2 (7805) together with associated components produce a regulated 5V DC. These voltages as well as ground can be connected to the corresponding voltage pins of the CD ROM drive using a male type CD ROM drive power connector. The 12V can be connected to the yellow wire of connector, 5V to red wire and GND to black wire as shown in figure1.Now the power supply is ready.

Power up the circuit after connecting the power connector to the CD ROM drive. Now the power LED of the drive will glow. Insert the audio CD. Now the music will be available at the audio output socket of the drive. It can be heared using a head phone. The skip button of the drive can be used to play next song. For car stereo applications you don’t need the transformer, rectifier and the 7812 regulator.12V will be available from battery. You just need to produce a 5V from it using a 7805 based regulator. Connect the corresponding voltages to the connector as shown in figure 1 and connect the connector to drive. The amplifier for the car audio CD player must be one operating from 12V.

Simple Voltage Booster Using Transistor

This is a design simple voltage booster circuit. This circuit is used for boosting 12 V DC to 24 V DC .The circuit is designed straight forward and uses few components. With few modifications the circuit can be used to boost any voltages. This circuit is work with based on operation of the transistor. This is the figure of the circuit.


The transistor Q1 and Q2 (D1616) essentially drives the primary of the transformer. The component values are not very specific here. We can use any NPN power transistors like D1616, 2N 3055, C2236, SL 100, etc for Q1 and Q2. The diode rectifies the output of transformer to obtain a 24V DC at the output load (here a fan). The diodes can be 1N 914 ones. The capacitors filter away noise and harmonics away from the output. For high current (around 5A) games use 2N 3055 transistor or more powerful Darlington pairs for Q1 and Q2. The transformer can be any center tapped 5A transformer with a 7:1 winding ratio. By experimenting on the transformer winding you can get different boost ratios.

Simple Two Flasher Circuit

This is a design of simple flasher circuit, but there is two flasher in the circuit. This circuit can be used to flash two Christmas stars alternatively. This circuit is using 555 IC for the operation. This is the figure of the circuit.


The IC1 NE 555 is wired as an astable multi vibrator here. When there is a positive pulse from the output of IC1, the transistor Q1 conducts and the relay K1 gets activated. The lamp L2 connected via the N/O contact of the relay glows. When the output pulse of the IC goes low, the Q1 goes OFF and the relay gets deactivated. Now the lamp L2 extinguishes and the lamp L1 connected via the N/C contact of the relay glows. This cycle continues as long as there is power supply for the circuit. The timing of the lamps can be adjusted by varying the preset R2. The preset R2 can be used to vary the timing of lights. Power the circuit is from a 9V DC power supply.

Simple Single Transistor Radio

This is a design simple circuit diagram of radio. This circuit radio is uses single transistor and few other passive components. In this circuit transistor that using is BC547. This is the figure of the circuit.


The operation and principle work of this circuit is when C6 and L1 forms a tank circuit which picks up the signal from your desired radio station. Diode D1, capacitor C2 and resistor R1 does the detection of the picked signal. The detected signal is coupled to the base of Q1 through capacitor C3.The Q1 gives required amplification to the signal. The resistor R2 is used to bias Q1.R3 limits the collector current of Q1.The audio output will be available at the collector of Q1 and it can be heard by using a high impedance head phone. This radio will work only at places where there is reasonable radio signal strength.

The circuit can be powered by a 3V battery. The antenna for this circuit can be use a 1 M long wire. The headphone must be a high impedance (2 to 3K) type. If diode AA121 is not available you can use AA112, AA116 or 1N34. The inductor L1 must be a 0.35mH, center tapped one. The radio can be tuned by adjusting the variable capacitor C6.

Simple Shock Alarm Circuit Using LM358

This is a simple design circuit for shock sensitive alarm circuit that has many applications fro home to automobiles. The main application of this circuit is to use it as an anti theft alarm in automobiles. A peizo electric sensor is used as the shock sensor which has to mounted on the door which you have to protect. This is the figure of the circuit.


The operation of the circuit is based on the LM358 as the controller. The IC1 LM 3558 is wired as an inverting Schmitt Trigger. The POT R1 sets the threshold voltage of the circuit.R1 is used as a feed back resistor. When not activated the out put from the piezo sensor will be low and so do the output of the IC. When the piezo sensor is activated its output voltage goes high and triggers the Schmitt trigger. This results the beeping of the buzzer. The buzzer remains beeping for some time even if the vibration is removed. This is because the increase in the inverting input has little effect when the IC is triggered and the state can’t be easily reversed. Fix the sensor firmly to the surface, where ever you place it. It is always good to place the sensor near to the door knob. The circuit is powered by a 3 V battery can be used as power supply. Adjust R2 to obtain the required sensitivity.

Simple Saw Tooth Wave Generator Circuit Using NE555 IC

This is a simple design circuit for generating a saw tooth wave form using a NE555 IC. The frequency of the wave form can be varied by using a POT. This is the figure of the circuit.


The operation of the circuit is if the capacitor C, resistor R and zener diode forms a constant current source for charging of the capacitor. When the voltage across capacitor reaches 2/3 Vcc the internal comparator inside 555 goes on and capacitor discharges. When the voltage across the capacitor goes below 1/3 Vcc the internal comparator goes off and now capacitor starts charging. As a result the capacitor will be switched between 2/3 Vcc and 1/3 Vcc, resulting in a saw tooth wave form across the capacitor. The diode make the output voltage to zero during the discharge phase. The frequency of the output voltage can be given by the equation,

f = (Vcc-2.7)/(R*C*Vpp).

Where Vcc is the supply voltage and Vpp is the peak voltage of the output required.

Simple Remote Control Tester Circuit

This is a simple design circuit for remote controller tester circuit. This circuit is based on infrared sensor IC TSOP 1738. This is the figure of the circuit.


Operation of the remote control tester circuit is begin from the IR waves fall on the sensor it output changes to low state. This makes the transistor Q1 ON and LED will blink according to the code contained in the signal. So for press of each button the LED blinks in different ways. This is a good indication of the working of remote. The diode D1drops 0.7 V to give the IC ~ 5V supply from the available 6V .R2 is a current limiting resistance. This circuit is use power supply a 6V battery to power up the circuit. This circuit can be used to test remotes operating in the 38 Khz carrier frequency. Almost all remotes fall into this category so no problem.

Simple Remote Control Using Infrared Circuit

This is a simple design circuit of remote control. In this circuit is using infrared for controlling. Besides the infrared, this IC have core of operation that is used NE555 IC. This is the figure of the infrared remote control circuit.


Infrared remote controls are using a 32-56 kHz modulated square wave for communication. These circuits are used to transmit a 1-4 kHz digital signal (OOK modulation) through infra light (this is the maximum attainable speed, 1000-4000 bits per sec). The transmitter oscillator runs with adjustable frequency in the 32-56kHz range, and is being turned ON/OFF with the modulating signal, a TTL voltage on the MOD input. On the receiver side a photodiode takes up the signal. The integrated circuit inside the chip is sensitive only around a specified frequency in the 32-56 kHz range. The output is the demodulated digital input (but usually inverted), just what we used to drive the transmitter. When the carrier is present, this output is usually low. When no carrier is detected, the output is usually high.

Part Component:
R1 = 1k, R2 = 15-22k use a 15k resistor series with a 10k potmeter to adjust frequency in the 32-40kHz range, R3 = 15 @5VDC, 200 mA peak/35 @9VDC, 200 mA peak/50 @12VDC, 200 mA peak, C1 = 1n, C2 = 47n

Simple Power Supply System

This is the simple circuit diagram of a simple Unit Power Supply. This circuit can deliver 12V unregulated and 5V regulated DC. This circuit is based on voltage regulator IC LM7805. This is the simple figure of the circuit.

The operation of this circuit is begin from the transformer T1 steps down the mains voltage to 12V AC and then the bridge B1 rectifies it. The transformer T1 can be a 230V AC primary, 12V secondary,3A step-down transformer. The bridge B1 can be a 2A bridge. If such a bridge is not available, make one using four 1N4007 diodes. The rectified signal is smoothed by the capacitor C1.When the mains supply is available the battery will be charged via diode D3 and the regulator IC gets supply via diode D5. 12V and 5V DC will be available at the output terminals.

When mains supply is not available the battery supplies current to the regulator IC and to the 12V DC terminal through diode D4.Also, the diode D3 blocks reverse flow of current during battery mode. The capacitors C2 and C3 acts as filters. The capacitor C1 must be rated at least 25V.

Simple Mini Night Lamp Circuit Using Battery

This is the simple circuit of mini night lamp. This is a circuit with low power LED night lamp. This circuit will automatically switch OFF at day time. This circuit is based on CMOS IC in the operation. This is the figure of the circuit.


The CMOS timer IC TS555CN is wired as a square wave generator operating at around 5Hz. The IC1 must be CMOS type because other types won’t operate at low voltages like 1.5V. The output voltage from the IC1 is doubled using the combination of capacitor C2 and diode D2 in order to drive the LED. The LED can be a bright white LED. At day time the resistance of LDR drops to few K Ohms and inhibits the IC from producing oscillations. The circuit can be powered from a single 1.5V cell. An optional switch can be added in series with the battery to provide a manual ON/OFF. Any diode can be used in place of D2, but Schottky diode like 1N5819 will give more brightness.

Simple Micro Flasher Circuit Using CD4093

This is the design for simple micro flasher circuit. This circuit is continuously emits flashing light with the consumption of very less power. The circuit is work with based on CD4093, for the operation. The circuit can run for a very long time for four 1.5 V torch cells. This is the figure of the circuit.


For operation of the circuit, a low power CMOS IC CD4093 (IC1) is used to produce sharp pulses of 20 ms from a red LED. The LED appears to be glowing continuously due to persistence of vision, and lot of power is saved. The IC1 is quad NAND gate whose one gate is used for producing oscillations. The unused inputs are kept to logic 1 by connecting it to the positive. The value of R1 determines the charging current of C1. All capacitors must be rated 10V. For power supply of the circuit, a 6V DC adapter can be also used to power the circuit or using 6V battery.

Simple Main Operated LED Lamp Circuit

This is design a very simple and cost effective mains operated LED lamp. This circuit is gives a very bright white light. This circuit is need twelve of LED for the operation. This is the figure of the circuit.


Since no transformer is used, the circuit is very compact and light weight. The mains supply is given to the bridge rectifier via the parallel network formed between R1 and C1.The bridge rectifies the mains supply. The resistor R2 limits the current through the LEDs. The capacitor C2 acts as a filter. The bridge D1 can be made by using four 1N 4007 diodes. D2 to D13 can be bright white LEDs.

Simple Light to Frequency Converter

This is a design circuit diagram of a simple effective light to frequency converter circuit. This circuit can be used for variety of applications such as light intensity measurement, fun etc. The circuit is based on TLC555, the CMOS version of famous timer IC NE 555. A photo diode is used for sensing the light intensity.

The timer IC is wired in astable mode. The leakage current of the reverse biased photo diode is proportional to the light intensity falling on it. This leakage current charges the capacitance C1. This is the figure of the circuit.


The operation is beginning when the capacitor voltage reaches 2/3 of the supply voltage the out put (pin 3) goes low. As a result the capacitor discharges through photo diode .When the capacitor voltage reaches 1/3 the supply voltage the out put (pin 3) of IC goes high. This cycling continues and we get a frequency at pin 3 proportional to the light intensity falling on the photo diode. With the given components the frequency varies from 1 KHz is a complete darkness to 24 KHz a bright sunlight. The frequency range can be changed by using different values for C1.

Simple LED Torch Circuit

This is a design for simple LED torch circuit. This circuit is based on IC MAX660 from MAXIM semiconductors. The MAX 660 is a CMOS type monolithic type voltage converter IC. The IC can easily drive three extra bright white LEDs. This is the figure of the circuit.


The LEDs are connected in parallel to the output pin 8 of the IC. The circuit has good battery life. The switch S1 can be a push to ON switch. For operation, the IC must be mounted on a holder. The capacitors C1 and C2 must be Tantalum type. The diodes D1 to D3 must be of 1N4148. The circuit can be powered from two torch cells connected in series.

Simple Electronic Fuse Circuit

This is a design of simple electronic fuse circuit one that can make. The circuit uses only one transistor, one SCR, one push button switch and two resistors. The working of the circuit is very simple. This is the figure of the circuit.


The first operation is beginning with initially the load current flows through SCR and resistor R1.The value of R1 is so selected that, the maximum load current multiplied by the resistance of R1 is equal to 0.7 volts. When the load current exceeds the maximum value the voltage drop across R1 becomes more than 0.7V and switches transistor Q1 ON. Now the transistor completely bye passes the load current and the current through triac falls below the holding current. This makes the triac OFF. When SCR is OFF there will not be any current flow through R1 and so the voltage across it falls to 0.This makes the transistor OFF, completely isolating the load circuit. The fuse can be reset by pressing S1.When S1 is pressed the SCR is again triggered and remains latched to conduct the load current.

Simple Car Reverse Horn Circuit With Music Generator

This is a simple design circuit to produce a musical horn when ever your car is in reverse gear. This circuit is using two ICs for the operation, voltage regulator 7805 (IC1) and musical tone generator UM66 (IC2). This is the figure of the circuit.


The operation of the circuit is beginning when the IC1 reduces the car battery voltage to 5V. The diodes D1 & D2 in combination produces an additional drop of 1.4 V to give a 3.6 V supply for the UM66. The supply voltage of UM 66 should not be more than 4V. When ever the car is in reverse gear, the reverse gear switch of the car gets activated and the circuit gets connected to the car battery. The UM66 starts playing the music tone. The transistor T1 amplifies the output of UM66 to drive the loudspeaker.

Before attempting the circuit, have a good idea about the electrical wiring of your car. A wrong connection may damage your car’s electrical system. The transistor Q1 is not very specific. Any medium power NPN audio transistor will do the job. You could easily find one from your electronics junk box. The switch S1 is the reverse gear switch of the car. Don’t forget to place in waterproof dashboard in the car.

Simple 8 Watt Amplifier Circuit Using IC LM386

This is a simple design for 8 watt audio amplifier circuit using IC LM 386. This amplifier is much suitable for small game amplifying applications. This is the figure of the circuit.


The circuit has few components and works of a 12 Volt power supply. You can increase the supply voltage up to 18V for a bit more power, with out changing the components. But I would say 12V is OK. A 4 Ohm speaker can be used as load. Volume can be controlled by connecting a 10k pot at the audio input to the IC.

This is the Parts list:
C1 1 10uf Electrolytic Capacitor
C2 1 470uf Electrolytic Capacitor
C3 1 0.1uF Disc Capacitor
C4 1 2000uf Electrolytic Capacitor 2200uF
R1 1 2.2 Ohm Resistance (Anything Within 10% tolerance)
R3 1 220 Ohm Resistance (Anything Within 10% tolerance)
IC1 1 LM383 IC

Simple Lamp Flasher Circuit Using Relay

This is a design for very simple lamp flasher circuit. The circuit is use only three components (a capacitor, relay and one resistor) other than the lamp. This is the figure of the circuit.


The working of the circuit is very straight forward. When the power is switched ON, the capacitor C1 will charge through the resistor. When the voltage across the capacitor is sufficient, the relay switches ON and the lamp connected via the normally open contact of the relay glows. The relay remains energized until the capacitor discharges and then the lamp extinguishes. The charging and discharging cycle of the capacitor gives a flashing effect to the lamp. The relay L1 can be a 12V SPDT relay. The lamp L2 can be a 12V, 5W lamp. The frequency of flashing can be varied by changing the value of C1 and R1.

Simple IR to RF Converter Circuit

This is the design for the infrared transmitter circuit, but it is a simple design. The IR to RF transmitter circuit given here can convert the IR signals from your remote to RF signals to long distances. The circuit given here is a good one for extending the range of your IR remote. Also such system does not need a line of sight since RF signals are used. This is the figure of the circuit.


The transmitter is based on a St-TX 01 ASK transmitter IC (IC2).The IR signals falling on IC 1 (TSOP 1738) will be converted to RF signals by IC2 and transmitted through antenna. The transmitter has a power output of 16dBm at 5V supply. The receiver is based on a ST-RX04 ASK receiver IC (IC3).The IC3 receives the transmitted code, decodes it to the original IR code and re transmits through IR LED (D1). The transistor Q1 is used to drive the D1 from the output of the IC3 (pin2). For the antenna, it use 20 cm long copper wire for each antenna. Ranges up to 200m are possible with matching antenna. All of the capacitor C1 must be rated 10V. It is use a 6V battery with a 1N 4007 series(forward biased) with its positive terminal as power supply for each circuit.

Simple Field Strength Meter

This is a design for simple handy field strength meter that can be used to check the strength of AM radio signals. The circuit is a very useful for those who assemble radio transmitters (especially in the tuning of the final stage for maximum range). This operation of the circuit is based on a transistor. This is the figure of the circuit.


The circuit is essentially some sort of an AM receiver it self. The capacitor C3 and inductor L1 forms a tuned circuit to receive a particular frequency (the frequency of your transmitter). The diode D1 detects the signal and applies to the base of transistor Q1 (MPSA 18). The collector current of the Q1 will be proportional to the strength of this signal and will be shown in the meter M1. In result the meter reading will be a measure of the strength of the signal (of the tuned frequency) falling on the antenna.

The C3 must be varied to tune in to the frequency of your transmitter. For that, keep the antenna of meter circuit close to the antenna of your transmitter and adjust C3 to get a maximum reading on meter M1. In order to tune your transmitter for a maximum range, place the meter circuit some place near to the transmitter and adjust the transmitters tuning elements. Maximum range setting will at the point where the meter shows full deflection. The transistor Q1 can be any high gain NPN RF transistor. Switch S1 is used as a power switch. Keep this switch OFF when circuit is not in use to save battery life. The antenna can be a 15 cm long Copper wire. Power the circuit using a 9v battery.

Simple Emergency Light Circuit

This is a design for simple emergency light. This circuit is work automatically. The circuit is work based on power failure. This is the figure of the circuit.


Operation of the circuit is the circuit remains OFF when the mains power is available and switches ON when there is a power failure. When mains power is available, it is stepped down by transformer T1, rectified by diodes D1&D2, filtered by the capacitor C2 and regulated by the 9V regulator IC 7809 to produce 9V DC. The transformer T1 can be a 230V AC primary, 12 – 0 - 12V secondary, 500mA transformer. This 9V DC is used for charging the battery. While the battery is charging the diode D3 is forward biased and this makes the emitter potential of transistor Q1 lower than the base potential and this makes the transistor OFF. The lamp will not glow.

When AC mains is not available, the diode D3 will be reverse biased and this makes the emitter potential of transistor Q1 higher than base potential and Q1 becomes ON. The lamp glows and continues to glow as long as there is no mains supply. The capacitors C1 and C3 act as decoupling capacitors. Battery B1 can be a 6V lead acid battery or five 1.2V Ni-Cd cells in series. The fuse F1 can be a 0.5A one.

Simple Delayed ON LED Circuit

This is design for a very simple delay ON LED circuit. In the circuit, LED becomes ON only after a preset time the power supply is switched ON. This circuit is need low and inexpensive components. This is the figure of the circuit.


When the power supply is switched on the transistor will be OFF. The capacitor now charges via the preset R3 and when the voltage across C1 is sufficient, the transistor switches ON and LED glows. The ON delay depends on the value of POT R3. You can increase the time delay by increasing the resistance of POT R3. This circuit alone may not have much practical applications but this can be used in many other projects where a delayed ON indication is required. The circuit can be powered from a 10V DC power supply. Anyway you can use from 6 to 18V for powering this circuit, but you need to adjust the POT R3 for getting the required delay.

Simple Brightness Control Lamps Circuit

This circuit is a simple design for brightness control lamps circuit, which is the circuit is based on 7555 IC for core operation. This is the figure of the circuit.


The operation work to control light intensity from the four filament lamp (the ring illuminator) is supported by two AA or AAA battery, for close up pictures using digital camera. The circuit will be used in another ways. The principle work of the circuit is IC1 produce 150 Hz square wave of variable duty cycle. When the cursor from P1 is fully played against D1, the output pulse appears on the positive pin 3 of IC1 is very narrow. Bulb LP1, driven by Q1, is turned off in the lead as the voltage is too low. When the cursor is played from P1 to R2, the output pulse increases in width, they reach the maximum amplitude when the potentiometer is rotated in full clockwise. In the way the bulb reaches full brightness

Part Component:
P1 = 470K Pot, R1 = 10K, R2 = 47K, R3 = 1K5, C1 = 22nF, C2 = 100uF/25V, D1/D2 = 1N4148, IC1 = 7555 or TS555CN, Q1 = BD681, LP1 =1, 5V 200mA Bulb, SW1 = SPST Switch, B1 = 3V Battery

Simple Battery Charger Circuit

This is a simple design and straight forward battery charger circuit. That circuit can be used to charge all type of 12V rechargeable batteries including car batteries. This is the figure of the circuit.


The circuit is nothing but a 12V DC power supply with an ammeter for monitoring the charging current. The two diodes forms a centre tapped full wave rectifier .The capacitor filters the rectifier output to produce a clean 12V out put. Always be careful to connect the charger to the battery in correct polarity. Positive to positive and negative to negative. When the battery is fully charged the ammeter reading will be zero. As the battery is slowly charged the current slowly decreases. At initial stages of charging the ammeter will read about 1 to 3 amperes.

Simple Audio Wattmeter Circuit

This is a design circuit for simple audio wattmeter circuit. This is an easy trick to measure the output of an amplifier. In this circuit, resistor R2 acts as the load for the amp and it should be able to withstand twice the maximum power of the amp you are going to measure. The meter scale must be calibrated and with a little effort you can get good results. This is the figure of the circuit.


Operation of the circuit is if 1A bridges diode is not available, make one with four 1N 4007 diodes. The resistor R2 must be twice the power of amp you are going to measure. To calibrate the device, connect the output of amplifier to port 1. It also connects an AC voltmeter to port 1. Set R1 fully off. That means full counter clockwise direction if wired conventionally. Adjust the output of amp to read 20V rms on voltmeter. This is the equivalent of 50W on 8 Ohm load. Adjust R1 for a full scale deflection on meter M1. Now fix the wiper of preset R1 using some super glue. Reduce the voltage across the port 1 by reducing the output power of amplifier under test according to the table given below and mark the readings on the meter scale. The device is ready to measure.

Simple 10 Minute Timer Circuit Using 555 IC

This is a design for simple timer circuit. This circuit can giving 10 minute of the timer. This circuit is based on 555 IC for the operation. This circuit can connect with microcontroller for practicing the programming. This is the figure of the circuit.


When ever you need to get an alarm or intimation after ten minutes, the circuit shown below can be used. The circuit is nothing but a mono stable multi vibrator based on IC NE 555.When ever you press the reset push button the green LED D1 glows after 10 minutes. The time duration can be set by varying the POT R5. The switch S1 can be a push button switch. The IC1 must be mounted on an IC base.

Simple 4Watt Fluorescent Lamp Driver Circuit

This is a simple design for 4 Watt fluorescent lamp driver circuit. This circuit can be operated from a 12 V supply. This circuit is work with based on 555 IC. The first part of the circuit includes a NE555 timer IC wired as an astable multi vibrator. This is the figure of the circuit.


The output pulses from the IC are amplified by the transistor Q1. The transistor must use heat sink for transistor Q1. The transformer steps up the collector voltage to around 1KVto drive the fluorescent lamp. In the transformer is uses a 3 V primary, 230 V secondary, 5W transformer for T1. Before using the circuit, set the R2 at full resistance and switch on the supply, now adjust R2 so that the collector current is 300mA (use a multi meter) and this is the optimum setting for the lamp. Operating the lamp in this setting will give a better life. Power the circuit is from a 12V battery or 12V DC power supply. The L1 can be a 6 inch, 4W fluorescent lamp.