Antenna Tuner series

This is a series of antenna-tuning circuit or circuits for transmitting antenna placement SW 3-30 MHz wave / short wave 3-30 Mhz. If the placement is just right then the maximum energy from the transmitter will send out all the antenna through sehinnga nothing is wasted. To get a clear picture of the circuit is click on the picture below.

This transmacth circuit function is to locate an appropriate impedance between the transmitting antenna that occurred in the ratio 1:1 SWR reading it, because in this placement is associated with a series of SWR / standing wave ratio. Thus the purpose of 1:1 is the one that came out was also one emitted by the antenna instead of just half saja.Impedansinya generally is 50 Ohm. With this circuit the maximum power that can pass this circuit is 50 Watt.

About SWR meter

The SWR meter or VSWR (voltage standing wave ratio) meter measures the standing wave ratio in a transmission line. This is an item of radio equipment used to check the quality of the match between the antenna and the transmission line.

The VSWR meter should be connected in the line as close as possible to the antenna. This is because all practical transmission lines have a certain amount of loss, causing the reflected power to be attenuated as it travels back along the cable, and producing an artificially low VSWR reading on the meter.

FM Radio Transmitter Antenna

Omnidirectional (all directions). This antenna radiates radio waves strong kesegala same direction.

bidirectional (both directions). This antenna radiates radio waves as strong to just two directions. The two parameters that need to be considered on an antenna is the polarization and penguatannya. Simply put, an antenna has a vertical polarization if the antenna is placed in a position perpendicular to the earth. Antenna with vertical polarization will produce radio waves with vertical polarization, too. In addition to vertical, there are also berpolarisasi horizontal antenna, the antenna plays when the field parallel to the earth.

One important factor in the FM antenna system installation is the antenna height. In the VHF band, provided that communication can take place is a LOS (Line Of Sight). So ideally communications on VHF, the antenna receiver and transmitter both have seen each other. So in between there must be no objects that can absorb radio energy.

So that radio amateurs in the VHF band is often stated that a better antenna has a small gain but higher than the antenna mounted with a large gain but low installed.

Simple circuit of elektronic buzzer

simple Electronic buzzer series is a series that only use 2 resistor, 3 capacitor , NE555 Chip, switch, and speaker. string up series of simple electronic buzzer is also very easy and simple. IC NE555 is the frequency of 1 kHz when the switch is pressed. This frequency can be set using the potensiometer 10 KOhm. Picture a series of simple electronic buzzer can be seen above:


IC NE555

555 timer IC provides practical solutions and relatively inexpensive for a variety of electronic applications related to the timing (timing). Especially two of the most popular application is a series of monostable and astable timing.

• Pin 1: Ground, is the input pin of the source of the negative DC voltage
• Pin 2: trigger, negative input from the lower comparators (comparator B) that maintain oscillation capacitor voltage in the lowest 1 / 3 Vcc and set RS flip-flop
• Pin 3: output, the output pin of the IC 555.
• Pin 4: reset, the pin that serves to reset the latch inside the IC to be influential to reset the IC work. This pin is connected to a PNP-type transistor gate, so the transistor will be active if given a logic low. Normally this pin is connected directly to Vcc to prevent reset
• Pin 5: control voltage, this pin serves to regulate the stability of the reference voltage negative input (comparator A). This pin can be left hanging, but to ensure the stability of the reference comparator A, usually associated with a capacitor of about 10nF to berorde pin groun
• Pin 6: threshold, this pin is connected to the positive input (comparator A) which will reset the RS flip-flop when the voltage on the capacitor from exceeding 2 / 3 Vc
• Pin 7: discharge, this pin is connected to an open collector transistor Q1 is connected to ground emitternya. Switching transistor serves to clamp the corresponding node to ground on the timing of certain
• Pin 8: vcc, pin it to receive a DC voltage supply. Usually will work optimally if given a 5-15V. the current supply can be seen in the datasheet, which is about 10-15mA.

Fire detection alarm circuit using LDR

In the rooms are vulnerable to fire, such as a storage material flammable, required a system of prevention of the occurrence of fire. For example, using a fire alarm, so that eg arise if a flame, can be quickly and by others that can immediately fire it does not cause a fire is greater.

Here is a simple fire alarm circuit based on a LDR and lamp pair for sensing the fire.The alarm works by sensing the smoke produced during fire.The circuit produces an audible alarm when the fire breaks out with smoke.

Note:

    The speaker can be a 8Ω tweeter.
    POT R4 can be used to adjust the sensitivity of the alarm.
    POT R3 can be used for varying the volume of the alarm.
    Any general purpose NPN transistor( BC548,BC148,2N222) can be used for Q1.
    The circuit can be powered from a 9V battery or a 9V DC power supply.
    Instead of bulb you can use a bright LED with a 1K resistor series to it.


When there is no smoke the light from the bulb will be directly falling on the LDR.The LDR resistance will be low and so the voltage across it (below .6V).The transistor will be OFF and nothing happens.When there is sufficient smoke to mask the light from falling on LDR, the LDR resistance increases and so do the voltage across it.Now the transistor will switch to ON.This gives power to the IC1 and it outputs 5V.This powers the tone generator IC UM66 (IC2) to play a music.This music will be amplified by IC3 (TDA 2002) to drive the speaker.

The diode D1 and D2 in combination drops 1.4 V to give the rated voltage (3.5V ) to UM66 .UM 66 cannot withstand more than 4V.

Melody generator circuit | Musical Toys

Circuit of musik|melody generator you can make using an IC.The UM66 series are CMOS IC’s designed for using in calling bell, phone and toys. It has a built in ROM programmed for playing music. The device has very low power consumption.Thanks for the CMOS technology.The melody will be available at pin3 of UM66 and here it is amplified by using transistor Q1 dan Q2 to drive the speaker.

UM66 is a pleasing music generator IC which works on a supply voltage of 3V. the required 3V supply is given through a zener regulator. its out put is taken from the pin no1 and is given to a push pull amplifier to drive the low impedance lowd speker. A clss A amplifier before pushpull amplifier can be used to decrese the noise and improve out put. UM66 is a 3 pin IC pakage just looks like a BC 547 transistor.

Notes

    Power supply must be between 6V - 15V .
    Melody begins from the first note if power is reseted.
    Assemble the circuit on a good quality common board.



IC UM66 Description
The U66 series is a CMOS LSI designed melody generator IC for use in telephones and toys application. It has an on-chip ROM programmed for musical performance. Produced by CMOS technology, the device results in very low power consumption. And with built-in RC oscillator, a compact melody module can be constructed with only a few additional components.

Pin No Designation Description

-1. Out put Melody out put

-2. +Vdd Positive power supply

-3. -Vss Negative Power supply

Features of UM66T series

-62 Note ROM Memory

-Voltage rating: 1.3V to 3.3 V

-Power on reset

-

Anti-theft alarm circuit LDR

Anti-theft alarm circuit it produces an audible alarm when fridge is left open for a preset time.Rangkaian This versatile alarm is based on two 555 timer IC's. Both ICS are wired as astable Multivibrators.An LDR is connected in parallel to the timing capacitor
C1 of IC 1.When is completely close door there will be no light inside the fridge and offers high resistance LDR R1 keeping fully charged.When door is left open, the lamp inside the fridge will remain glown, LDR will be illuminated, and its falls.This resistance makes
C1 stops charging and starts to discharge (In simple words, this is because at low resistance LDR bye passes much of the current in the parrallel path and capacitor gets less current). Now IC 1 starts oscillating slightly and after a preset time of 25 ( time T1) seconds high.This its output goes out put makes the Ic 2 to produce oscillations and results in a beeping sound for next 20 (time T2) seconds and cycle is repeated till door is closed.

List Component alarm anti maling:

    R1: 10K 1/4W Resistance
    R3: 2.2 M 1/4W Resistance
    R4: 1M 1/4W Resistance
    C1: 10µF/25V Electrolytic Capacitance
    C2: 100nF/63V Polyester Capacitance
    D1: 1N4001 Diode
    IC1,IC2: NE 555 Timer ICs
    BZ1: Piezo Buzzer
    B1: 3V Cell


Note:
Assemble the circuit on a good quality PCB .Time T1 & T2 can be adjusted by varying C1, C2, R1, R4 etc (Refer data sheet of 555). Place the LDR close enough to the lamp inside the fridge.

IC 555 Pin No Designation Description

1. Ground, is the input pin of the source of the negative DC voltage
2. Trigger, negative input from the lower comparators (comparator B) that maintain oscillation capacitor voltage in the lowest 1 / 3 Vcc and set RS flip-flop
3. Output, the output pin of the IC 555.
4. Reset, the pin that serves to reset the latch inside the IC to be influential to reset the IC work. This pin is connected to a PNP-type transistor gate, so the transistor will be active if given a logic low. Normally this pin is connected directly to Vcc to prevent reset
5. Control voltage, this pin serves to regulate the stability of the reference voltage negative input (comparator A). This pin can be left hanging, but to ensure the stability of the reference comparator A, usually associated with a capacitor of about 10nF to berorde pin groun
6. Threshold, this pin is connected to the positive input (comparator A) which will reset the RS flip-flop when the voltage on the capacitor from exceeding 2 / 3 Vc
7. Discharge, this pin is connected to an open collector transistor Q1 is connected to ground emitternya. Switching transistor serves to clamp the corresponding node to ground on the timing of certain
8.  Vcc, pin it to receive a DC voltage supply. Usually will work optimally if given a 5-15V. the current supply can be seen in the datasheet, which is about 10-15mA.

Ding dong bell circuit house

This simple circuit an low cost ding dong bell suitable for calling bell purposes. It is made around IC 8021-2 . IC 8021 has an in-built circuitry to produce ding dong sound each time its pin 3 is pulled low. The sound is stored in a 4 bit ROM.a complementary-pair, two-transistor amplifier is used to amplify the sound to a fair level of audibility. A piezo tweeter or an 8-ohm, 500mW speaker can be used at the output.

List Component bel Rumah:
R1: 1K 1/4W Resistance
C1: 10µF/12-25V Electrolytic Capacitance
T1: BC548/c8050 NPN transistor
T2: BC557/C8550 PNP transistor
IC1: 8021-2 ding dong sound generator
Ls1: Speaker tweeter 500 Mwatt - 5 watt
S1: switch on/off
S2: Switch Normally close
B1: 3V Cell

Each time when switch S2 is pressed, ding dong sound is produced twice. If you try to press switch S2 a second time when the first ding dong sound is still being produed, it has no effect whatever and the two ding-dong bell sounds will be invariably produced.S1 is the ON- OFF switch.Assemble the circuit on a good quality all pupose PCB.Don’t forget to use an IC holder for IC 8021.

IC 8021 Description
The 8021-2 is a ding-dong sound effect generator IC produced by LSI CMOS technology. With built-in RC oscillator and digital envelope circuits, minimal external components are required. This IC simulates the mechanical ding-dong sound, and is ideal for door bell application.

IC 8021 Features
- 1.3V to 3.3V operating voltage and low power consumption
- One-shot mode of 2 ding-dong playing sequences
- Standard TO-92 package form
- Dynamic speaker can be driven with external NPN transistor


IC 8021 Absolute Maximum Ratings
DC Supply Voltage ........................................... -0.3V to +5.0V
Operating Ambient Temperature .................... -10°C to 60°C
Storage Temperature ....................................... -55°C to 125°C

The series Door Bell Home

This is a doorbell circuit use IC NE555.When some one presses switch S1 momentarily, the loud speaker sounds a bell tone as long as the time period of the monostable multivibrator (IC1). When the switch S1 pressed, IC1 is triggered at its pin 2 and output pin 3 goes high for a time period previously set by the values of POT R4 and POT R5.When the output of IC1 goes high it resets IC2 and it starts to oscillate to make a bell sound through the speaker.The IC2 is configured as an astable multivibrator whose oscillation frequency can be varied with the help of POT R5.By adjusting the values of R4 & R5, modifications on the tone are possible.

IC NE555 description

The NE555 monolithic timing circuit is a highly stable controller capable of producing accurate time delays or oscillation. In the time delay mode of operation, the time is precisely controlled by one external resistor and capacitor. For a stable operation as an oscillator, the free running frequency and the duty cycle are both accurately controlled with two external resistors and one capacitor. The circuit may be triggered and reset on falling waveforms, and the output structure can source or sink up to 200mA. The NE555 is available in plastic and ceramic minidip package and in a 8-lead micropackage and in metal can package version.

Pin connnections IC NE555

1 - GND

2 - Trigger

3 - Output

4 - Reset

5 - Control voltage

6 - Threshold

7 - Discharge

8 – VCC

Absolute maximum ratings

Supply Voltage: 18 V

Operating Free Air Temperature Range for NE555: 0 to 70 oC

Junction Temperature 150 oC

Storage Temperature Range –65 to 150 oC.

.

Bird Sound Generator circuit

This generate a sound like bird’s circuit. The trafo LT700 is a small audio transformer with primary is center tapped with an impedance of 1Kohms at 1KHz . The secondary has an impedance of 8 ohms.

The inclusion of R1 and C1 give this oscillator its characteristic “chirp”. As the 100u capacitor charges via the 4.7K resistor, R1 the bias for the transistor is cut off. This causes the oscillation to stop, the capacitor discharges through the base emitter circuit of the transistor and oscillations start again. Altering these components alters the frequency of the chirp. The chirp is also voltage dependent. When the push button switch is operated the 100u capacitor is charged. When its released, the oscillation decays and the chirp becomes faster.


Transistor BC177 description

NPN transistor in a TO-18; SOT18 metal package. PNP complement: BC177.

Data reverence Transistor BC177

    VCBO/ collector-base voltage open emitter: 30 V

    VCEO/ collector-emitter voltage open base: 20 V

    VEBO/ emitter-base voltage: 5 V

    ICM/ peak collector current - 200 mA

    Ptot/ total power dissipation Tamb £ 25 °C - 300 mW

    hFE DC current gain IC = 2 mA; VCE = 5 V: min 200 max 800

    fT transition frequency IC = 10 mA; VCE = 5 V; f = 100 MHz: min 100 MHz

    Tstg/ storage temperature: Min -65 max +150 °C

    Tj/ junction temperature max 175 °C

    Tamb/ operating ambient temperature min -65 max +150 °C

LT700 Tranformer is a small audio transformer with primary is center tapped with an impedance of 1Kohms at 1KHz . The secondary has an impedance of 8 ohms.

Siren series Simple 2 Transistor

This is a simple Siren circuit used 2 transistor . The siren circuit produced imitates the rise and fall of an American police siren. When first switched on the 10u capacitors is discharged and both transistors are off. When the push button switch is pressed to 10u capacitor will charge via 22k resistor. This voltage is applied to the base of the BC108B which will turn on slowly. When the switch is released the capacitor will discharge via the 100k and 47k base resistors and the transistor will slowly turn off. The change in voltage alters the frequency of the siren.

Current drain is fairly high in this circuit so a suitable power supply is required. The duration the tone takes to rise and fall is determined by the 10u and 22k resistor. These values may be varied for different effects.


Transistor 2N3702 description

This device designed for use as PNP general purpose amplifier and switches requiring collector currents to 300mA.

Absolute Maximum Ratings

    Collector-Emitter Voltage (VCEO ): -25 V.

    Collector-Base Voltage (VCBO ): -40 V.

    Emitter-Base Voltage (VEBO ): -5.0 V.

    Collector Current - Continuous (IC): -500 mA.

    Operating and Storage Junction Temperature Range (TJ, TST): -55 ~ +150 C.

    Current Gain (hFE DC ): 60 - 300.

Pin transistor BC 108

    Low current (max. 100 mA).

    Low voltage (max. 45 V).

    Current Gain (hFE DC) : 110 - 450.

The series of Sound Effects Generator

This is a sound effects generator circuit used IC HT2884. There are 8 different sound effect can be produced that are 2 lazer guns, 1 dual tone horn sound, 2 bomb sounds, 2 machine gun sounds and a rifle shot sound.

Power is a 3 Volt battery, but the IC will work with any voltage between 2.5 - 5 Volts. Switch S1 is the on / off switch. The output at pin 10 is amplified and drives a small 8 ohm loudspeaker. Pressing S3 once will generate all the sounds, one after another. S2 can be used to produce a single sound effect, next depression gives the next sound effect. Standby current is about 1 uA at 3 Volt, so battery life is very economical.


IC HT2844 Description

The IC HT2844 is a CMOS LSI chip designed for use in sound effect products. It is equipped with tone circuit, noise circuit, and other control logic to generate various sounds including rifle gun, machine gan, booming, door bell, alarm, and so forth. the feature of the customer's sound source can be analyzed and programmed into an internal ROM by changing a mask layer durimg device fabrication

Absolute maximum rating
Supply voltage....................................... 03 to 5 Volt.
Input voltage.......................................... Vss - 0.3 to VDD+0.3 Volt.
Storage temperature.............................. -50 to 125 C.
Operating temperature........................... 0 to 70 C.
.

Police Siren circuit scheme

Rangkaian sirine police will produce sound that is almost similar to the sirens and the police can plug in the car or motorcycle. Rangkaina consists of 2 pieces IC NE 555 that serves as the frequency (multivibrator astable) that the frequency can be set to play Vr1 and Vr2.

If the sound output in the less hard (loud) you can add a brace power amplifier that has a higher brace misalanya series amplifier LM386. series has a power output greater tegangn and have the same input. To install this series you just menghubungakan output rangkain sirens and then enter in to the input. Move the speaker to the output ampilifier LM386


functions of each pin IC 555:

• Ground, is the input pin of the source of the negative DC voltage
• trigger, negative input from the lower comparators (comparator B) that maintain oscillation capacitor voltage in the lowest 1 / 3 Vcc and set RS flip-flop
• output, the output pin of the IC 555.
• reset, the pin that serves to reset the latch inside the IC to be influential to reset the IC work. This pin is connected to a PNP-type transistor gate, so the transistor will be active if given a logic low. Normally this pin is connected directly to Vcc to prevent reset
• control voltage, this pin serves to regulate the stability of the reference voltage negative input (comparator A). This pin can be left hanging, but to ensure the stability of the reference comparator A, usually associated with a capacitor of about 10nF to berorde pin groun
• threshold, this pin is connected to the positive input (comparator A) which will reset the RS flip-flop when the voltage on the capacitor from exceeding 2 / 3 Vc
• discharge, this pin is connected to an open collector transistor Q1 is connected to ground emitternya. Switching transistor serves to clamp the corresponding node to ground on the timing of certain
• vcc, pin it to receive a DC voltage supply. Usually will work optimally if given a 5-15V. the current supply can be seen in the datasheet, which is about 10-15mA.

Anti Burglar Alarm circuit basis FM Radio

This Circuit of FM radio-controlled anti- theft alarm can be used with any vehicle having 6- to 12-volt DC supply system. The mini VHF, FM transmitter is fitted in the vehicle at night when it is parked in the car porch or car park.

The receiver unit with CXA1019, a single IC-based FM radio module, which is freely available in the market at reasonable rate, is kept inside. Receiver is tuned to the transmitter's frequency. When the transmitter is on and the signals are being received by FM radio receiver, no hissing noise is available at the output of receiver. Thus transistor T2 (BC548) does not conduct. This results in the relay driver transistor T3 getting its forward base bias via 10k resistor R5 and the relay gets energised. When an intruder tries to drive the car and takes it a few metres away from the car porch, the radio link between the car (transmitter) and alarm (receiver) is broken. As a result FM radio module gene-rates hissing noise. Hissing AC signals are coupled to relay switching circ- uit via audio transformer.

These AC signals are rectified and filtered by diode D1 and capacitor C8, and the resulting positive DC voltage provides a forward bias to transistor T2. Thus transistor T2 conducts, and it pulls the base of relay driver transistor T3 to ground level. The relay thus gets de-activated and the alarm connected via N/C contacts of relay is switched on. If, by chance, the intruder finds out about the wireless alarm and disconnects the transmitter from battery, still remote alarm remains activated because in the absence of signal, the receiver continues to produce hissing noise at its output. So the burglar alarm is fool-proof and highly reliable.

Mixer circuit LM348 IC 3 Chanel

The series features three channel microphone mixer and made ​​with LM348 IC. The series of mixer channel 3 is to mix audio signals from the microphone on standard microphone amplifier. A series of mixer channel 3 is not equipped with a control tone to the use of a mixer for sound and practical covers three speakers or users at once. Sequence of images and a list of components to create a series of mixer 3 channels can be seen in the following figure.

Rangkian 3 channel mixer is made with 4 pieces of the operational amplifier (op-amp) in an integrated circuit LM348. A series of three channel mixer can be supplied with a voltage source DC symmetrical ± 12 volts. 3 chanel mixer circuit in the image above rangkian using microphone amplifier or microphone preamp with LM348 IC, which is defined as a voltage amplifier non-inverting. 3 canal microphone amplifier circuit above can be used to amplify and combine the signals from the microphone type moving coil (dynamic microphone). System level control and microphone volume on 3 channels mixer circuit with LM348 IC is above these tau brackish microphone preamplifier mic amp, which is intended to be a signal from the microphone 1 and the other is not affected by the other. A series of mixer 3 power amplifier channels above requires that the microphone signal can be used to drive the loudspeaker (speaker). Power amplifier to the series third channel mixer is better to use a power amplifier with symmetric voltage of ± 12 V DC supply for the system, so that the mixer and power amplifier circuit can be 1.

Audio Mixer 6 Channel

The following is a main of the mixer-6 Ch circuit. The circuit constituted by six input channels. The channels are from monophonic channels CH 1-4 and CH 5-6, are intended for stereo use. The number of input channels they want as long Itself Can Increase You Want.

The output of Each channel drives the RV1-6, that regulation potesometer level of sound. With RV7-12 We create conditions of balance Between two channels (BALANCE). All the signals from the input channels in this point are added by two adders [IC1a-b], for Each channel Here exist two Trimmer TR1-2 That adjust the gain of Each IC, adapting the level of signal of the output, in the level That We Want. They Can be suppressed if you do not need something and Standard and Poor. The next stage is a equalizer, three bands of regulation. The IC3α-b, constitute the output of the mixer, they want a one acre have gain and they want the make the essential isolation of the previous stages, with the unit That We Will drives. For whoever they want want they want use headphones, it exists a classic circuit drive of headphones, round the IC2a-b, that give the output in the JF13. It Can Also Also exist optical clue of audio levels, with a stereo VUMETER.

List component

    R1-12=4.7Kohms
    R13-24=10Kohms
    R25-26=22Kohms .
    R27-30-34-39=100ohms
    R28-29-36-37=100Kohms
    R31-42=10Kohms
    R32-41=4.7Kohms
    R33-40=10Kohms
    R35-38=47ohms
    RV1....4=47Kohms Log.
    RV5-6-13=2X47Kohms Log.
    RV7....12=10Kohms Lin. pot. Log
    C1....8=10uF 25V
    C9-11=47pF ceramic or mylar
    C10-12=47uF 25V
    C13-14=100uF 25V
    C15-16=2.2uF 16V
    C18-21=100pF ceramic or mylar
    C19-20=220uF 25V
    TR1-2=4.7Kohms trimmer
    Q1-3=BD139
    Q2-4=BD140
    IC2=NE5532 - TL072

All the Resistors is 1/4W 1% metal film C18-21=100pF ceramic or mylar

Rangkaian Regulator Variable Sederhana

A simple but less efficient method of controlling a DC voltage is to use a voltage divider and transistor emitter follower configuration. The figure below illustrates using a 1K pot to set the base voltage of a medium power NPN transistor.

power transistor which supplies most of the current to the load. The output voltage will be about 0.7 volts below the voltage of the wiper of the 1K pot so the output can be adjusted from 0 to the full supply voltage minus 0.7 volts. Using two transistors provides a current gain of around 1000 or more so that only a couple milliamps of current is drawn from the voltage divider to supply a couple amps of current at the output.

Note that this circuit is much less efficient than the 555 timer dimmer circuit using a variabe duty cycle switching approach. A fairly large heat sink is required to prevent the PNP power transistor from overheating. The advantage of the circuit is simplicity, and also that it doesn't generate any RF interference as a switching regulator does. The circuit can be used as a voltage regulator if the input voltage remains constant.

Power Supplay

Electronic devices should be powered by direct current supply DC (direct current) which is stable in order to work properly. The battery or batteries is a source of DC power supply is best. But for applications that require greater power supply, the source of the battery is not enough. Sources of power supply is a source of alternating AC (alternating current) from power plants. This requires a power supply device that can change the AC into DC current.

Rangkaian Power Supplay

Now it should not need another effort to make good pwer supplay you do not need to look for op-amps, transistors and other components, because these circuits are packaged into a single fixed voltage regulator IC. Are now widely recognized as a component of 78XX series fixed positive voltage regulator and the 79XX series is a voltage regulator to remain negative. Even these components are usually already equipped with current limiting (current limiter) and also limiting the temperature (thermal shutdown). This component is only three pins, and by adding some components alone can be a series of power supply regulation was good.

It's just to note that the IC regulator circuit that can work, the input voltage must be greater than the output voltage regulator. Usually the difference voltage Vin to the recommended VM is in the component datasheet. Usage heatshink (Aluminum cooling) is recommended if these components are used to supply large currents. In the datasheet, these components can pass the maximum current reached 1 A.

1.25V-15.19V Regulator/Adaptor Variabel Digital

This is a series regulator with variable output from the digital 1.25V to 15.19V The first section of the circuit comprises a digital up-down counter built around IC1, a quad 2-input NAND Schmitt trigger (IC CD4093), followed by IC2, a binary up-down counter (CD4029 IC). Two gates of IC CD4093 are used to generate the up-down logic using the push buttons S1 and S2, respectively, while the other two gates form an oscillator to provide clock pulses to IC2 (CD4029). The frequency of oscillations can be varied by changing the value of capacitor C1 or preset VR1. IC2 receives clock pulses from the oscillator and produces a binary sequential output. As long as its pin 5 is low, the counter continues to count at the rising edge of each clock pulse, but stops counting as soon as its pin 5 is brought to logic 1. Logic 1 at pin 10 makes the counter to count upwards, while logic 0 makes it count downwards. Therefore the counter counts up by closing switch S1 and counts down by closing switch S2. The output of counter IC2 is used to realize a Digitally variable resistor. This section consists of four N / O reed Relays that need just about 5mA current for their operation. (The original circuit containing quad bilateral switch IC 4066 has been replaced by reed Relays switches operated by transistorised because of unreliable operation of the former.)

The switching action is performed using BC548 transistors. External resistors are connected in parallel with the reed relay contacts. Particular if the relay contacts are opened by the control input at the base of a transistor, the correspond-ing resistor across the relay contacts gets connected to the circuit. The table shows the theoretical output for various combinations of digital inputs. The measured output is nearly equal to the theoretically calculated IC3 outputs across the regulator (LM317).

output of this regulator minimum (1.25V). As count-up switch S1 is pressed, the binary count of IC2 increases and the output starts increasing too. At the highest count output of 1111, the output voltage is 15.19V (assuming the in-circuit resistance of the preset VR2 as zero). Preset VR2 can be used for trimming the output voltage as desired. To decrease the output voltage within the range of 1.25V to 15.2V, count-down switch S2 is to be depressed.

USB Power booster circuit (USB Adaptor)

USB can be configured for connecting several peripheral devices to a single PC, Since a PC can supply only a limited power to the external devices connected through its USB port, when too many devices are connected simultaneously, there is a possibility of power shortage, Therefore an external power source has to be added to power the external devices. In USB, two different types of connectors are used: type A and type B. The circuit presented here is an addon unit, designed to add more power to a USB supply line (type-A). When power signal from the PC (+5V) is received through socket A, LED1 glows, opto-diac IC1 conducts and TRIAC1 is triggered, resulting in availability of mains supply from the primary of transformer X1.

Now transformer X1 delivers 12V at its secondary, which is rectified by a bridge rectifier comprising diodes D1 through D4 and filtered by capacitor C2. Regulator 7805 is used to stabilise the rectified DC. Capacitor C3 at the output of the regulator bypasses the ripples present in the rectified DC output. LED1 indicates the status of the USB power booster circuit. Assemble the circuit on a generalpurpose PCB and enclose in a suitable cabinet. Bring out the +5V, ground and data points in the type-A socket. Connect the data cables as assigned in the circuit and the USB power booster is r e a d y t o function.

Regulator 5 volt IC 7805

The IC 7805 provides circuit designers with an easy way to regulate DC voltages to 5v. Encapsulated in a single chip/package (IC), the 7805 is a positive voltage DC regulator that has only 3 terminals. They are: Input voltage, Ground, Output Voltage.

Although the 7805 were primarily designed for a fixed-voltage output (5V), it is indeed possible to use external components in order to obtain DC output voltages of: 5V, 6V, 8V, 9V, 10V, 12V, 15V, 18V, 20V, 24V. Note that the input voltage must, of course, be greater that the required output voltage, so that it can be regulated downwards



Features IC regulator 7805
• Output Current up to 1A
• Output Voltages of 5 Volt
• Thermal Overload Protection
• Short Circuit Protection
• Output Transistor Safe Operating Area Protection

Data max IC 7805
Input Voltage........................................ 35
Thermal Resistance Junction-Cases (TO-220)40......... 5 °C/W
Thermal Resistance Junction-Air (TO-220)............. 65 °C/W
Operating Temperature Range (KA78XX/A/R)............. 0 ~ +125 °C
Storage Temperature Range............................ -65 ~ +150 °C.