Tips for Choosing a quality Power Amplifier

Here are some tips you need to note:

1. Pick of the power that suits your needs. For personal use such as exercise, etc., is sufficient to choose an amplifier with a power of 15-20 watts. In most small power amplifiers are already available facilities such as Head Phone jack (eg Guitar Amplifier Laser 20) which is very useful especially for young people who have a habit of playing music until midnight. By leveraging these channels to Head Phone, then secured another household or neighbors will not be disturbed our music sound. Sound good hasilnya.Apabila amplifier system we will use to train together in a full band with drums, etc., then you should choose a larger power amplifier that is 70 watts or above. Thus the sound produced from the amplifier and sound system will not be drowned by the sound of pounding and pounding beat Drum.Untuk use on stage, you will need a higher power that is at least 125 watts or more, because this amplifier will be able to once we use as a monitor of musical instruments were playing.

2. Choose the facilities we need. Do not buy amplifiers which have facilities that we do not really need when it is increasing the price we pay. Unless the same price we can get better facilities, there is no harm in our selection.

3. Choose a good quality amplifier. If we need an amplifier to your keyboard, then it is advisable to select an amplifier that does not change the color of the original sound generated by the keyboard musical instrument they will be (flat). There are many amplifiers that produce different sounds from the original sound, if this happens there will be other voices that would reduce the original character of the actual sound produced by the keyboard because of the addition or subtraction of a particular frequency. Usually this happens at a very low frequency (low bass) or very high frequency (high treble). (Try the sound system rental, sound rental service) For amplifiers Electric Guitar and Electric Bass this (flat characteristic) does not apply because it specifically for these two types of instruments are required specificity of character frequency. Basically for Electric Guitar amplifier output is not needed for low frequency and high. For Electric Bass needed a low frequency, but not required a high frequency. We can learn from the rental place and the sound system rental-quality musical instrument.

4. Model and performance amplifier can be considered final. The desired model will depend on individual taste. A good model according to a person, not necessarily a good thing according to those who lainnya.Pada most professional musicians model will be the last option or not too overlooked. They will be more concerned with the quality and facilities of the amplifier. Maybe we can find also in the rental services professional sound and musical instrument rental place bagus.Demikian brief tips on choosing an amplifier, hopefully this can help to determine the right choice before you buy an amplifier and produce sound quality music is also of course .

Tips for Choosing Quality Amplifier

1. Pick of the power to suit your sound system. For personal use such as exercise is sufficient to choose an amplifier with 1-20watt power. In most electronic devices / small power amplifiers are already available facilities such as head phone jack (eg laser20 guitar amplifier) ​​is very useful especially for young people who have a habit of playing music until midnight. By leveraging the channel for these headphones, then secured another household or neighbors will not be disturbed "attraction" we. If the amplifier sound system we will use to train together in a group full band * with drum and band instrument, then you should choose a power amplifier 70watt or above. Thus the sound produced from the amplifier will not be drowned by the sound of pounding and pounding drum beats. For use on stage, you will require more resources than most, namely at least 125watt or more, because this amplifier will be at the same we use as a monitor of musical instruments were playing.

2. Select the facilities we need. Do not buy a multimedia system / amplifier that has the facilities that we do not really need, if it is increasing the price we pay. Unless the same price we can get better facilities, there is no harm in our selection.

3. Choose a good quality amplifier. If we need an amplifier to your keyboard, then it is advisable to select an amplifier that does not change the original color generated by the keyboard (flat). There are many Indonesian musical instrument amplifier that produces a different sound from the original sound, if this happens there will be other voices that would reduce the original character of the actual sound produced by the keyboard because of the addition or subtraction of a certain frequency speaker system. Usually this happens at a very low frequency. (Low bass) or very high frequency (high treble). To Lighting System, Electric Amplifier Electric Bass Guitar and this (flat characteristic) does not apply because it specifically for these two types of instruments required specificity of character frequency. Basically for Electric Guitar not dipelukan amplifier output for low frequencies and high. For Electric Bass needed a low frequency, but not required a high frequency.

4. Models and appearance can be thought being given to the last amplifier. The desired model will depend on individual taste. A good model according to a person not necessarily a good thing by other people.

In most professional musicians, models will be the last option or not too overlooked. They will be more concerned with the quality and features of the amplifiers for musical instruments. But if you are confused, you could just rent equipment or hire sound system rental equipment.

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Rangkaian Power Supply for tube amplifier

Power supply for EL-34 tube is specially designed for the purposes of power supply at the push-pull amplifier with EL-34 tube as in article 35 Watt Tube Power Amplifier Push Pull before.
Power supply for EL-34 tube amplifier is made with transformers CT and 2 pieces diode as rectifier. Mechanical filters are applied in the power supply uses 3 levels. Power supply for tube power amplifier can deliver output voltages +220 VDC. Circuit details can be seen in the following figure.

The above power supply circuit has a high output voltage so that need to be considered in the manufacture and perakitanya because electricity can tesengat (stun). Power Supply For Tube Power Amplifier With Diode EL-34 was created specifically for the power amplifier tube push pull EL-34.

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Rear Fog Lamp For Vintage Cars Diagram Circuit

According to current legislation in many countries, vintage cars must also be fitted with a fog lamp at the rear. In modern cars, there is a bit of circuitry associated with the fog lamp switch to prevent the fog lamp from going on when the lights are switched on if the driver forgot to switch it off after the last patch of fog cleared up. The circuit described here extends that technology back in time. The circuit is built around a dual JK flip-flop (type 4027). T3 acts as an emitter follower, and it only supplies power to the circuit when the lights are switched on.

For safety reasons, the supply voltage is tapped off from the number plate lamp (L2), because it is on even if you accidentally drive with only the parking lights on. The wire that leads to the number plate lamp usually originates at the fuse box. As the states of the outputs of IC1a and IC1b are arbitrary when power is switched on, the reset inputs are briefly set high by the combination of C1, R1 and T1 when the lights are switched on (ignition switch on). That causes both Q outputs (pins 1 and 15) to go low. IC1a and IC1b are wired in toggle mode (J and K high).

The Set inputs are tied to ground (inactive). The driver uses pushbutton switch S1 to generate a clock pulse that causes the outputs of the flip-flops to toggle. The debouncing circuit formed by C2, R4 and T2 is essential for obtaining a clean clock pulse, and thus for reliable operation of the circuit. C1 and C2 should preferably be tantalum capacitors. The Q output of IC1b directly drives LED D1 (a low-current type, and yellow according to the regulations). The Q output of IC1a energises relay Re1 via T4 and thus applies power to the rear fog lamp L1.Circuit diagram:

Rear Fog Lamp Circuit Diagram For Vintage Cars

Free-wheeling diode D2 protects T4 against inductive voltage spikes that occur when the relay is de-energised. In older-model cars, the charging voltage of the generator or alternator is governed by a mechanical voltage regulator. These regulators are less reliable than the electronic versions used in modern cars. For that reason, a Zener diode voltage-limiter circuit (D3 and R9) is included to keep the voltage at the emitter of T3 below 15 V and thus prevent the 4027 from being destroyed by an excessively high voltage.

The supply voltage for the circuit is tapped off from the fuse box. An accessory terminal is usually present there. Check to make sure it is fed from the ignition switch. The pushbutton switch must be a momentary-contact type (not a latching type). Ensure that the pushbutton and LED have a good ground connection. Fit the LED close to the button.The following ‘Bosch codes’ are used in the schematic:

• 15 = +12 V from ignition switch
• 58K = number plate lamp
• 86 = relay coil power (+) IN
• 85 = relay coil power OUT
• 30 = relay contact (+) IN
• 87 = relay contact OUT

Author: Eric Vanderseypen - Copyright: Elektor Electronics Magazine

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Rear Light After Glow For Bicycles

This article is of interest only to readers whose bicycle lights are powered by a dynamo. The laws on bicycle lights in the United Kingdom are stricter than in other countries and a dynamo is, therefore, a rarity in this country. From the point of view of traffic safety it is advisable (in UK obligatory) for cyclists to have the rear lamp of their bicycle to light even when they are at standstill.

In principle, it is not very difficult to modify the existing rear light with afterglow: all this needs is a large enough energy reservoir. Since the after-glow is required for short periods of time only, a battery is not required: a large value capacitor, say, 1 F, is quite sufficient.As the diagram shows, in the present circuit, the normal rear light bulb is replaced by two series-connected bright LEDs, D2 and D3. These are clearly visible with a current of only 6 mA (compared with 50 mA of the bulb).

The current is set with series resistor R1. The LEDs are shunted by the 1 F capacitor, C1. Since the working voltage of this component is only 5.5 V, it is, in spite of its high value, physically small. An effective regulator is needed to limit the dynamo voltage adequately. Normal regulators cannot be used here, since they do not work at low voltages. Moreover, such a device would discharge the capacitor when the cycle is at standstill.

Rear Light After Glow Circuit Diagram:

Fortunately, there is a low-drop type that meets the present requirements nicely: the Type LP2950CZ5.0. Of course, the dynamo output voltage needs to be rectified before it can be applied to the regulator. In the present circuit, this is effected by half-wave rectifier D1 and buffer capacitor C2. Diode D1 is a Schottky type to keep any losses low – important for this application, because the ground connection via the bicycle frame usually causes some losses as well. The value of buffer capacitor has been chosen well above requirements to ensure that C1 is charged during the negative half cycles of the dynamo voltage.

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Multipurpose Circuit For Telephones

This add-on device for telephones can be connected in parallel to the telephone instrument. The circuit provides audio-visual indication of on-hook, off-hook, and ringing modes. It can also be used to connect the telephone to a  CID (caller identification device) through a re-lay and also to indicate tapping or misuse of telephone lines by sounding a buzzer.

In on-hook mode, 48V DC supply is maintained across the telephone lines. In this case, the bi-colour LED glows in green, indicating the idle state of the telephone. The value of resistor  R1 can be changed some-what to adjust the  LED glow, with-out loading the telephone lines (by trial and error).  In on-hook mode of the hand-set, potentiometer VR1 is so adjusted that base of  T1 (BC547) is forward biased, which, in turn, cuts off transistor T2 (BC108). While adjusting  potmeter  VR1, en-sure that the  LED glows only in green and not in red.

Multipurpose Circuit For Telephones Circuit Diagram

When the handset is lifted, the volt-age drops to around 12V  DC. When this happens, the voltage across transistor T1’s base-emitter junction falls below its conduction level to cut it off. As a result transistor pair T2-T3 starts oscillating and the piezo-buzzer starts beeping (with switch S1 in on position). At the same time, the bi-colour LED glows in red. In ringing mode, the bi-colour LED flashes in green in synchronization with the telephone ring. A  CID can be connected using a relay.

The relay  driver  transistor can be connected via point  A as shown in the circuit. To use the circuit for warning against misuse,  switch  S1 can be left in on position to activate the piezo buzzer when anyone tries to tap the telephone line. (When the telephone  line is tapped, it’s  like the off-hook mode of the telephone hand-set.)  Two 1.5V pencil cells can provide Vcc1 power supply, while a separate power supply for Vcc2 is recommended to avoid draining the battery. However, a single 6-volt supply source can be used in con-junction with a 3.3V zener diode to cater to both Vcc2 and Vcc1 supplies.

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SOFT START MECHANISM FOR L200 VOLTAGE REGULATOR ELECTRONIC DIAGRAM

SOFT START MECHANISM FOR L200 VOLTAGE REGULATOR ELECTRONIC DIAGRAM

Ic (constant current) is charge capacitor C, where Ic = Vsc/R.

The output reaches its nominal value after the time ton. Vo-Vsc=(Ic.ton)/C.

ton=C.[(Vo-0.45)/0.45].R = CVoR/0.45.

Vo follows the voltage in pin 2 at less than 0.45 volt. It is because voltage of more than 0.45 V can’t be produced between pin 2 and pin 5. Read More

Tips for Choosing a quality Power Amplifier

Here are some tips you need to note:

1. Pick of the power that suits your needs. For personal use such as exercise, etc., is sufficient to choose an amplifier with a power of 15-20 watts. In most small power amplifiers are already available facilities such as Head Phone jack (eg Guitar Amplifier Laser 20) which is very useful especially for young people who have a habit of playing music until midnight. By leveraging these channels to Head Phone, then secured another household or neighbors will not be disturbed our music sound. Sound good hasilnya.Apabila amplifier system we will use to train together in a full band with drums, etc., then you should choose a larger power amplifier that is 70 watts or above. Thus the sound produced from the amplifier and sound system will not be drowned by the sound of pounding and pounding beat Drum.Untuk use on stage, you will need a higher power that is at least 125 watts or more, because this amplifier will be able to once we use as a monitor of musical instruments were playing.

2. Choose the facilities we need. Do not buy amplifiers which have facilities that we do not really need when it is increasing the price we pay. Unless the same price we can get better facilities, there is no harm in our selection.

3. Choose a good quality amplifier. If we need an amplifier to your keyboard, then it is advisable to select an amplifier that does not change the color of the original sound generated by the keyboard musical instrument they will be (flat). There are many amplifiers that produce different sounds from the original sound, if this happens there will be other voices that would reduce the original character of the actual sound produced by the keyboard because of the addition or subtraction of a particular frequency. Usually this happens at a very low frequency (low bass) or very high frequency (high treble). (Try the sound system rental, sound rental service) For amplifiers Electric Guitar and Electric Bass this (flat characteristic) does not apply because it specifically for these two types of instruments are required specificity of character frequency. Basically for Electric Guitar amplifier output is not needed for low frequency and high. For Electric Bass needed a low frequency, but not required a high frequency. We can learn from the rental place and the sound system rental-quality musical instrument.

4. Model and performance amplifier can be considered final. The desired model will depend on individual taste. A good model according to a person, not necessarily a good thing according to those who lainnya.Pada most professional musicians model will be the last option or not too overlooked. They will be more concerned with the quality and facilities of the amplifier. Maybe we can find also in the rental services professional sound and musical instrument rental place bagus.Demikian brief tips on choosing an amplifier, hopefully this can help to determine the right choice before you buy an amplifier and produce sound quality music is also of course .

Tips for Choosing Quality Amplifier

1. Pick of the power to suit your sound system. For personal use such as exercise is sufficient to choose an amplifier with 1-20watt power. In most electronic devices / small power amplifiers are already available facilities such as head phone jack (eg laser20 guitar amplifier) ​​is very useful especially for young people who have a habit of playing music until midnight. By leveraging the channel for these headphones, then secured another household or neighbors will not be disturbed "attraction" we. If the amplifier sound system we will use to train together in a group full band * with drum and band instrument, then you should choose a power amplifier 70watt or above. Thus the sound produced from the amplifier will not be drowned by the sound of pounding and pounding drum beats. For use on stage, you will require more resources than most, namely at least 125watt or more, because this amplifier will be at the same we use as a monitor of musical instruments were playing.

2. Select the facilities we need. Do not buy a multimedia system / amplifier that has the facilities that we do not really need, if it is increasing the price we pay. Unless the same price we can get better facilities, there is no harm in our selection.

3. Choose a good quality amplifier. If we need an amplifier to your keyboard, then it is advisable to select an amplifier that does not change the original color generated by the keyboard (flat). There are many Indonesian musical instrument amplifier that produces a different sound from the original sound, if this happens there will be other voices that would reduce the original character of the actual sound produced by the keyboard because of the addition or subtraction of a certain frequency speaker system. Usually this happens at a very low frequency. (Low bass) or very high frequency (high treble). To Lighting System, Electric Amplifier Electric Bass Guitar and this (flat characteristic) does not apply because it specifically for these two types of instruments required specificity of character frequency. Basically for Electric Guitar not dipelukan amplifier output for low frequencies and high. For Electric Bass needed a low frequency, but not required a high frequency.

4. Models and appearance can be thought being given to the last amplifier. The desired model will depend on individual taste. A good model according to a person not necessarily a good thing by other people.

In most professional musicians, models will be the last option or not too overlooked. They will be more concerned with the quality and features of the amplifiers for musical instruments. But if you are confused, you could just rent equipment or hire sound system rental equipment.

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Mains Emergency Voltage Cut Out Circuit for Computers

 lf the voltage of the mains supply of a computer rises too high, components on the printed circuit boards can easily be damaged or even destroyed.

This emergency cutout placed between the mains supply and the load interrupts the supply when the voltage level exceeds a predetermined value. . For many reasons it is possible for the output voltage of a power supply to rise to a dangerous level. The emergency cutout described here has been set to the maximum supply voltage of 5.25 V that is stated by the manufacturers of TTL ICs. Zener diode D1 starts conducting just before the stated zener voltage is reached. A small current flows in the and gate circuit of thryristor Th1; the level of this current can be set with preset potentiometer P1 connected in parallel with the gate cathode circuit of Th1. When the mains supply rises, the current ’through the zener diode becomes large enough to cause the thyristor to fire. The firing level lies between 5.2 . . . 6 V. As soon as the thyristor fires, the mains supply voltage drops substantially because the thyristor virtually short-circuits the mains supply. ln the case of a supply without current limiting, fuse F1 prevents the current attaining too high a value.

The rating of the fuse depends, of course, on the load requirement. During testing and adjusting of the circuit, it is important that the thyristor continues to conduct after it has been fired until its current has dropped to zero. The firing voltage level can be set by means of a mains supply with a current limiter before it is put into use, lf it proves impossible, for instance because of tolerances of the zener diode, to set the firing voltage to the required value, try using a 5.1 V zener diode.

If the voltage of the mains supply of a computer rises too high, components on the printed circuit boards can easily be damaged or even destroyed. This emergency cut-out placed between the mains supply and the load interrupts the supply when the voltage level exceeds a predetermined value.

For many reasons it is possible for the output voltage of a power supply to rise to a dangerous level. The emergency cut-out described here has been set to the maximum supply voltage of 5.25 V that is stated by the manufacturers of TTL ICs. Zener diode D1 starts conducting just before the stated zener voltage is reached. A small current flows in the anode-gate circuit of thryristor Th1.

The level of this current can be set with preset potentiometer P1 connected in parallel with the gate-cathode circuit of Th1. When the mains supply rises, the current through the zener diode becomes large enough to cause the thyristor to fire. The firing level lies between 5.2 . . 6 V.

As soon as the thyristor fires, the mains supply voltage drops substantially because the thyristor virtually short-circuits the mains supply. In the case of a supply without current limiting, fuse F1 prevents the current attaining too high a value.

The rating of the fuse depends, of course, on the load requirement. During testing and adjusting of the circuit, it is important that the thyristor continues to conduct after it has been fired until its current has dropped to zero. The firing voltage level can be set by means of a mains supply with a current limiter before it is put into use. If it proves impossible, for instance because of the tolerances of the zener diode to set the firing voltage to the required value, try using a 5.1 V zener diode.
Circuit Description

Referring to the given circuit diagram of a simple DC short circuit protector for computers, the functioning may be grasped with the following points:

The zener diode along with R1 and P1 forms a voltage reference or threshold level for the thyristor gate which is connected at the the center of the above network.

P1 is adjusted to the desired threshold level at which the thyristor is required to be fired.

As long as the input voltage stays below this set level the thyristor remains inactive and the supply output to the computer undergoes a normal execution.

However if the input voltage tends to drift above the set level, the gate potential of the thyristor reaches the firing point and it fires, shorting the voltage across the output to ground.

The above action instantly drops the voltage to the safe set threshold so that now the thyristor is switched OFF.

The above triggering continues as long as the input voltage stays above the threshold mark, thus rectifying the output voltage to the safe limit, ensuring the computer a safe operating environment.

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Indicator Circuit Diagram for Model Railway System

1. A ninth reed contact is Htted at the end of the block, to enable turning off the indication for the relevant length of the track. The circuit is composed of 8 set-reset (S-R) bistables, which drive a LED each.
2. This section indication system may be a just the thing you have been looking for when you own a fairly large model railway with tunnels and tracks at several levels, and are sometimes at a loss find the where abouts of a particular train.
3. The reed contacts are actuated with the aid of a small magnet fitted to the underside of the engine. Depending on the most suitable location of the magnet, T the reed contacts are fitted in between the tracks or along- side the left or right hand rail. Several of these section indication systems may be fitted in series to enable making a con- trol panel with many lights to indicate the train positions. Observing the direction of travel of the trains, section junctions are fitted with S9 (end of previous section) and S1 (begin I of section) located next to each other.
4. This circuit uses LEDs to indicate the train’s position. Each track block is split up into 8 sections, whose starting points are marked with reed contacts (Si-S8).
5. All SET inputs are combined in a NOR gate, N1, which drives a pulse shaper and buffer to reset the bistables with a brief pulse to ensure that only the LED for the last passed track section is lit. 

Indicator circuit for model railway

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Security system for doors

This is a security schema diagram.If someone cross the LED beem.The schema will be activated.Here I have used red LED insted of the LED you can use Lazer beem too.You can connect a light or 230V alarm for this schema.but dont pass 500W.If you want more bulbs you can attach them parallely.






Parts

Q1___________BC327 45V 800mA PNP Transistor

Q2___________BC337 45V 800mA NPN Transistor

C1_____________10nF 63V Polyester Capacitor

D1_________TIC106D 400V 5A SCR

D2-D5_______1N4007 1000V 1A Diodes

R1_____________Photo resistor (any type)

R2____________100K 1W Resistor

R3____________200K 1/2W Trimmer Cermet

R4,R7_________470R 1/4W Resistors

R5_____________12K 1/4W Resistor

R6______________1K 1/4W Resistor

SK1__________Female Mains socket

PL1__________Male Mains plug & cable

Note

# PL1 can be omitted and the input mains supply wires connected in parallel to any switch controlling lamps. In this case, if the switch is left open, the schema will be able to drive the lamps; if the switch is closed, the lamps will illuminate and the schema will be by-passed.

# When ths schema operates dont touch the parts

# Due to 230 This is not suitable for kids.
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Lights Control for Model Cars Wiring diagram Schematic

The author gave his partner a radio controlled (RC) model car as a gif t. She found it a lot of fun, but thought that adding realistic lights would be a definite improvement. So the author went back to his shed, plugged in his soldering iron, and set to work equipping the car with realistic indicators, headlights, tail lights and brake lights.

Lights Control for Model Cars Circuit Diagram

The basic idea was to tap into the signal from the radio control receiver and, with a bit of help from a microcontroller, simulate indicators using flashing yellow LEDs and brake lights using red LEDs. Further red LEDs are used for the tail lights, and white LEDs for the headlights. Connectors JP4 and JP5 (channel 0) are wired in parallel, as are JP6 and JP7 (channel 1), allowing the schema to be inserted into the servo control cables for the steering and drive motor respectively. The ATtiny45 micro-controller takes power from the radio receiver via diode D1. T1 and T2 buffer the servo signals to protect IC1’s inputs from damage. 

IC1 analyses the PWM servo signals and gen-erates suitable outputs to switch the LEDs via the driver transistors. T3 drives the two left indicators (yellow), T4 the two right indica-tors, and T5 the brake LEDs (red). The red tail lights (JP2-8 and JP2-8) and the white head-lights (JP2-9 and JP2-10) are lit continuously. The brake lights are driven with a full 20 mA, so that they are noticeably brighter than the tail lights, which only receive 5 mA. If you wish to combine the functions of tail light and brake light, saving t wo red LEDs, sim-ply connect pin 10 of JP2 to pin 14 and pin 12 to pin 16. Then connect the two combined brake/tail LEDs either at JP2-5 and JP2-6 or at JP2-7 and JP2-8.

JP3 is provided to allow the use of a separate lighting supply. This can either be connected to an additional four-cell battery pack or to the main supply for the drive motor. The val-ues given for resistors R8 to R17 are suitable for use with a 4.8 V supply. JP2 can take the form of a 2x10 header.

As usual the sof t ware is available as a free download from the Elektor web pages accom-panying this article[1], and ready-programmed microcontrollers are also available. The microcontroller must be taught what servo signals correspond to left and right turns, and to full throttle and full braking. First connect the fin-ished schema to the radio control electronics in the car, making sure everything is switched of f. Fit jumper JP1 to enable configuration mode, switch on the radio control transmit-ter, set all proportional controls to their cen-tre positions, and then switch on the receiver. The indicator LEDs should first flash on both sides. Then the car will indicate left for 3 s: during this time quickly turn the steering on the radio control transmitter fully to the left and the throt tle to full reverse (maximum braking).

Hold the controls in this position until the car starts to indicate right. Then set the controls to their opposite extremes and hold them there until both sides flash again. Now, if the car has an internal combustion engine (and so cannot go in reverse), keep the throttle control on full; if the car has an electric motor, set the throttle to full reverse. Hold this position while both sides are flashing. Configuration is now complete and JP1 can be removed. If you make a mistake during the configuration process, start again from the beginning.

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Preamplifier for RF Sweep Generator

Preamplifier for RF Sweep Generator Circuit diagram. The RF sweep frequency generator (‘wobbu-lator’) published in the October 2008 issue of Elektor has a receiver option that allows the instrument to be used as a direct conversion receiver. This receiver does however have a noise floor of only –80 dBm, which really should have been –-107 dBm to obtain a sensitivity of 1 µV. So, for a good receiver sommore gain is required. A wideband amplifie however, generates a lot of additional noisas well and as a consequence will not resuin much of an improvement.  As an experiment, the author developed a selective receiver with a bandwidth of about 4 MHz. Because a gain of at least 35 dB is required, the preamplifier consists of two amplifying elements. 

The input amplifier is designed around a dual gate MOSFET, type BF982. This component produces relatively little noise but pro-vides a lot of gain. The output stage uses a BFR91A for some additional gain. Preamplifiers where both the gate and the drain are tuned often struggle with feedback via their  internal capacitance. Here, the drain schema has a relatively low impedance, which prevents this from happening. In the prototype that was tested, the input and output are located at right angles with respect to each other to prevent inductive coupling (see photo). Despite the high gain, the amplifier was perfectly stable even without any shielding.  The two air-cored coils in the schema both consist of 4 turns and have an internal  diameter  of  6 mm,  made from 1-mm diameter silvered copper wire and with a tap after 1 turn.

Preamplifier for RF Sweep Generator Circuit diagram :

Preamplifier for RF Sweep Generator Circuit Diagram

 

The amplifier is mainly intended for the 144 MHz amateur band, but with other coils can also be used for the FM broadcast band, for example. FM detection is achieved by tuning near the edge of the IF filter. At an offset of 15 kHz this is only a few dB lower than at the centre of the pass-band, so that damping is not noticeable. The measured sensitivity in the 2 m band was about 1 µV (6 dB).A good antenna always contributes to the reception, of course. A wideband (scanner) outdoor antenna will give good results. Adding this wobbulator/receiver option results in a nice monitor receiver. By setting the scan frequencies of the spectrum analyser to 144 and 146 MHz (or 148 MHz where applicable), any signal within this range is directly visible. When a signal is detected it is merely a case of clicking the scan stop button and then clicking on the signal in the display window using the right mouse button. 

After this, the receiver switches directly to this frequency and you can listen to the signal. You can subsequently resume the scanning so that you can continue to look for other signals. For narrowband FM detection you need to select the FMN button in the window for the receiver and this then provides the required offset for the edge detection at 25 kHz bandwidth. This value is adjustable via the ‘setting’ menu (default is 12,500 Hz) and can be changed experimentally for best results. To power the schema you can use a 9-V battery. It is also possible to power the amplifier directly from the RF sweep generator, if output capacitor C6 is replaced with a link; in the ‘options’ menu you will then have to select the option ‘use probe’.

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Radio remote controls for toy cars

Playing cars that are controlled via radio signals is an interesting game. The much-loved toy cars children, plus a simple circuit will be the ideal toy car. This circuit families use traditional digital CMOS IC which requires very little electrical current, so it will not burden the original toy car performance.

In this system, radio signals are not transmitted continuously but only generated when the controller sends a command to the left / right or forward / backward, and even then only a radio-frequency discontinuous, so is sending pulses of radio wave frequency.

The number of pulses sent represent commands sent, GO command is represented with 8 pulses, is represented with 16 pulses LEFT, RIGHT DOWN 32 pulses and 64 pulses. Commands that can dikirimk is a combination of 2 orders once gus, which is a combination of command forward / backward and right / left, for example, could be sent forward orders and left once gus, in this case the number of pulses sent is 24, ie the sum of the forward command by 8 pulse and left the command of 16 pulses.

After a command is sent, the system stops sending commands in a certain time lag, the lag time it takes will be a series of recipients have sufficient time to fulfilling their orders well. Frequency pulses were visible on the right side of this.

Radio Control Transmitter Series

How it works Transmitter

Radio signals generated by oscillator circuit formed by transistors Q1 9016, the working frequency of the oscillator is determined by the crystal Y1 is worth 27.145 MHz. A very critical part of this oscillator circuit is T1, L1 and L2, which specifically dealt with separately at the end of this article. Working from this oscillator is controlled by NOR gate U2D 14001, while the output gate (pin 3) is worth 1, the oscillator will work and transmit radio frequency 27.145 MHz, and at the output U2D value 0 the oscillator will stop working. U2D NOR gate receives the clock signal from NOR gate U2B. NOR Gate CMOS type with the aid of resistors R4 and R5 and capacitor C8 form a low frequency oscillator circuit for controlling the clock shaper of existing digital circuits. Work of this clock generator is controlled via the input leg 6, the circuit will generate the clock if this input berlevel 0 .

NOR gate U2A and U2C form a series of Latch (RS Flip Flop), because of the influence of the resistor R2 and capacitor C11 is fed to pin 9 in U2C, when the circuit gets power supply output U2C must be 1 and the output of U2A (leg number 3) becomes 0 . This situation resulted Marja U2b clock generator works evoke reset the clock and remove the state of the enumerator 14 024 IC (U1), so that U1 started chopping and 27.145 MHz oscillator circuit sending pulses for generating a clock frequency of work.

At the start chopping, all the output of IC 14 024 enumerators in kedaan 0 , after chopping 8 Q4 output pulse (pin 6) will be a 1, after counting 16 pulses output Q5 (pin 5) to 1 , after chopping 32 Q6 output pulse (pin 4) to 1 , after counting 64 pulses output Q7 (pin 3) to 1.

Output over-output voltage used to control foot 9 U2C through diode D1 and D2, during one of the output is still worth 0 then the clock generator U2B still working, this will continue until the cathode D1 D2 dankatode be 1 so that the foot 9 U2C be a 1 as well. This situation will result in the output feet 3 U2A to 1 , which stop the clock generator U2B and resets the enumerator 14 024 danberhenti already shipping 27 145 MHz pulse frequency.

To generate the lag time for receiver circuit has enough time carrying out orders, used a series of Q2 9014, resistor R7 and capacitor C10. The amount of delay time is determined by the value of R7 and C10. Switch to send command forward / backward and to send commands left / right are two separate switches. Each switch has 3 positions, the center position means that the scalar does not send commands.

Radio Control Receiver series

How it works Receiver

Figure 2 is a picture that matched the car receiver circuit toy, serves to receive signals from the transmitter to control motor cars, so cars can move forward / backward and left / right. Transistor Q1 with the help of resistors, capacitors and T1 form as a series of radio signal receiver 27.145 MHz. T1 in this series exactly the same as T1 that is used in the transmitter circuit, means of manufacture are discussed below.

Transistor Q2 follows perlangkapannya forming circuit to convert the radio frequency pulses received from the transmitter into the box pulses that can be accepted as a digital signal by the CMOS IC. Digital signal will be received as the clock had to be chopped by chopper 14 024 IC (U2). Output 14 024 will be in accordance with the number of pulses sent by the transmitter, forward command and left (which is used as an example in the discussion of the transmitter) is the pulse number of 24, the results of counting these pulses cause the output to be 14 024 Q4 = 1 , Q5 = 1, Q6 = 0 and Q7 = 0.

Digital signal received in addition be used as a clock IC 14 024 enumerators U2 discussed above, used also to drive the 3 pieces of the time delay circuit to generate pulses which controls the circuit work.

Toll regulator will first appear after delivery frequency pulse stopped because the lag time between sending the code, this pulse serves to record the count results to the U3 14 024 14 042 (D Flip Flop), making the final conditions of 14 024 will be retained to control the motor. After the results were recorded to 14 024 14 042, 14 042 enumerator is reset by the second pulse, after the lag time for 14,042 enumerators can count start from 0 again.

The circuit formed by transistors Q3, Q4, Q7, Q8, Q9 and Q10 named as H Bridge circuit, this circuit is very reliable to drive DC motors. With this series of DC motor can be rotated to the right-to-left or stop motion. The main requirement of the use of this circuit is the base voltage of Q7 and Q10 base voltage must be opposed, for example base Q7 = 1 and the base of Q10 = 0 the motor rotates to the left, the base of Q7 = 0 and the base of Q10 = 1 the motor will spin to the right, the base Q7 = 0 and the base Q10 = 0 motor stop motion, but it should not happen, the base Q7 = 1 and the base of Q10 = 1.

Similarly, Q5, Q6, Q11, Q12, Q13 and Q14 form a H Bridge. H Bridge to the left in Figure 2 is used to control motors that adjust the cars moving left / right, while the H Bridge right part is used to control motors that regulate movement forward / backward cars. The relationship between outpur enumerator 14 042 and 14 024 Input D Flip Flop is structured so that the signal is fed to each H Bridge can not be all 1 simultaneously.

Making transformer TX and RX

Transformer T1 in series transmitter and receiver, is the same stuff, and have created their own. Transformer was built using plastic transformer Koker (spare part radio) that have a step that looks 5 lanes that can be filled with rolls of wire, as shown in the photo. Using this Koker facilitate wire transformer winding. If you can not Koker similar to it, just use the usual. Koker feritnya transformer is small and is also small (3 mm) as the first is often used for assembly of 27 MHz CB radio.

Wire to the transformer can wear a wire in the unloading of these Koker, carefully open coil of wire that already exist within the Koker because the wire is smooth and quite easy to break.

Step 1: Roll away from the feet of wire fed into the number 5 ft 4 in the direction h (CW) as much as 3 rolls right in level 1 (point level above the lowest point)

Step 2: Wind the wire from leg 1 to leg 2 in a clockwise direction as much as 4 rolls right on level 2.

Step 3: Continue the roll (from step 2) clockwise a quarter roll to as much as 3 feet 3 at level three. (Can be determined exactly a quarter of the roll, because kokernya have a path cut into 4).

Making coil L1

Wind the copper wire diameter of 0.3 to 0.5 mm by 10 quarter rolls on Koker diameter about 4 mm (which will be released), also in a clockwise direction.

Making coil L2

Wind the copper wire diameter of 0.1 mm by 50 rolls of plastic Koker without ferrite diameter of about 3.5 - 4 mm (look for plastic materials from used goods) are also in a clockwise direction. The length of the section in liputi rolls along the 5 mm.

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22W Amplifier for 12V Power Supply Systems

This is a 22-W Amplifier schema that is designed for or 12-V DC power supply Systems. There are many application for  this schema,  such as in car audio  application. In car electrical  power supply system, the 12V power supply will be provided by the host vehicle’s battery. 

The capacitor C3 is used to give ripple rejection, since noisy power supply voltage is common in automotive electrical system. The power supply noise signal on car power supply is decoupled by the capacitors C2 and C1.  Smaller capacitor C2 is needed to decouple the high frequency noise, since the larger cap (C1) usually has high equivalent series inductance that prevent the high frequency noise  (such as glitch or spike) to be bypassed. 

The capacitors C5 couple the incoming audio signal to IC1 while decoupling static DC offset. For better bass response, this schema prevent rolling off of the low audio frequencies by choosing a relatively large capacitance for small signal, 10μF capacitors. Here is the schematic diagram of the  schema.

 22W Amplifier for 12V Power Supply Systems Circuit Diagram

This schema prevent power supply pop noise by muting the amplifier at the power-up. The mute input (pin 14) is fed by capacitor C6 and Resistor R1, giving delay on power-up which prevent  turn-on pop. This  R/C time constant gives about 1.4s delay to keep the output muted,  enough to make sure the amplifier reach the stable state after powered up.  

About how this muting works, the amplifier will be ON if pin 14 has at least 8.5 V. The chip will remain in muted condition if the voltage at this pin is below 3.3V.  This input pin need very low current consumption, only about 100 pA for standby (muted)  and around 40 pA when active. The R1 values must be no larger than 100,000  Ω. The R1/C6 constant should be on the second order. If time constant is too short, the turn-on pop will still be heard, but too long  time constant will give unpleasant delay.

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1000W Audio Power Amplifier for Subwoofers

Description

The IRS20124 is a high voltage, high speed power MOSFET driver with internal deadtime and shutdown functions specially designed for Class D audio amplifier applications. The internal dead time generation block provides accurate gate switch timing and enables tight deadtime settings for better THD performances. In order to maximize other audio performance characteristics, all switching times are designed for immunity from external disturbances such as VCC perturbation and incoming switching noise on the DT pin. Logic inputs are compatible with LSTTL output or standard CMOS down to 3.0 V without speed degradation. The output drivers feature high current buffers capable of sourcing 1.0 A and sinking 1.2 A. Internal delays are optimized to achieve minimal deadtime variations. Proprietary HVIC and latch immune CMOS technologies guarantee operation down to Vs= –4 V, providing outstanding capabilities of latch and surge immunities with rugged monolithic construction.

Features:

• 200 V high voltage ratings deliver up to 1000 W output power in Class D audio amplifier applications
• Integrated deadtime generation and bi-directional over-current sensing simplify design
• Programmable compensated preset deadtime for improved THD performances over temperature
• High noise immunity
• Shutdown function protects devices from overload conditions
• Operates up to 1 MHz
• 3.3 V/5 V logic compatible input

Typical Application Diagram:

Warning! This is a Typical circuit diagram:1000W Audio Power Amplifier for Subwoofers

Datasheet for IRS20124: Download

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Hacking Car Wipers for Easy Control

How do you want to have your wipers become more intelligent? In this way, they could remember how frequent you need to use them. But of course, this will need the help of an ATmega8L micro-controller.



When you need to activate the wiper, you just press the button and it will run in one course. There is a 45 seconds waiting time that if you do not press the button, it will go on standby while telling itself that only one course is needed. The system will activate the wiper again if the button is pressed before 45 seconds. The good thing is that it will remember the interval when you pressed the button.

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