Senin, 14 April 2014

High Quality Intercom

Salam Electrical Engineer yang setia membaca artikel pada blog ini. Semoga tetap bersemangat untuk belajar dan terus belajar tentang elektronika. Pada kesempatan kali ini saya akan berbagi tentang Rangkaian High Quality Intercom Gunakan fitur Translate di sebelah kanan untuk menterjemahkan teks berbahasa inggris, selamat membaca, semoga bermanfaat.


This circuit consists of two identical intercom units. Each unit contains a power supply, microphone preamplifier, audio amplifier and a Push To Talk (PTT) relay circuit. Only 2 wires are required to connect the units together. Due to the low output impedance of the mic preamp, screened cable is not necessary and ordinary 2 core speaker cable, or bell wire may be used.

The schematic can be broken into 34 parts, power supply, mic preamp, audio amplifierand PTT circuit. The power supply is designed to be left on all the time, which is why no on / off switch is provided. A standard 12 V RMS secondary transformer of 12VA will power the unit. Fuses are provided at the primary input and also secondary, before the rectifier. The 1 A fuse needs to be a slow blow type as it has to handle the peak rectifier current as the power supply electrolytics charge from zero volts.

The microphone amplifier is a 2 transistor direct coupled amplifier. BC108B transistors will work equally well in place of the BC109C transistors. The microphone used is a 3 terminal electret condenser microphone insert. These are popular and require a small current to operate. The preamp is shown in my audio circuit section as well, but has a very high gain and low distortion. The last transistor is biased to around half the supply voltage; this provides the maximum overload margin for loud signals or loud voices. The gain may be adjusted with the 10k preset. Sensitivity is very high, and a ticking clock can easily be heard from the distantloudspeaker.

The amplifier is based on the popular National Semiconductor LM380. A 50 mV input is all that's required to deliver 2W RMS into an 8 ohm loudspeaker. The choice of loudspeaker determines overall sound quality. A small loudspeaker may not produce a lot of bass, I used an old 8 inch radio loudspeaker. The 4.7u capacitor at pin 1 of the LM380 helps filter out any mains hum on the power supply. This can be increased to a 10u capacitor for better power supply rejection ratio.

The push to talk (PTT) circuit is very simple. A SPDT relay is used to switch between mic preamplifier output or loudspeaker input. The normally closed contact is set so that each intercom unit is "listening". The non latching push button switch must be held to talk. The 100u capacitor across the relay has two functions. It prevents the relays back emf from destroying the semiconductors, and also delays the release of the relay. This delay is deliberate, and prevents any last word from being "chopped" off.

Setting Up and Testing
This circuit does not include a "call" button. With this intercom pressing the Push to Talk button sends your voice to the opposite station, and vice versa. Setup is simple, set to volume to a comfortable level, and adjust the mic preset while speaking with "normal volume" from one meter away. You do not need to be in close contact with the microphone, it will pick up a conversation from anywhere in a room. If the units are a long way away, there is a tendency for the cable to pick up hum, or radio interference. There are various defenses against this. One way is to use a twisted pair cable, each successive turn cancels the interference from the turn before. Another method is to use a small capacitor of say 100n between the common terminal of each relay and ground. This shunts high frequency signals to earth. Another method is to use a low value resistor of about 1k. This will shunt interference and hum, but will shunt the speech signal as well. However as the output impedance of each mic preamp is low, and the speech signals are also low,this will have little effect on speech but reduce interference to an acceptable level.

Minggu, 13 April 2014

Line Follower ROBOT Controlled by 2051

Salam Electrical Engineer yang setia membaca artikel pada blog ini. Semoga tetap bersemangat untuk belajar dan terus belajar tentang elektronika. Pada kesempatan kali ini saya akan berbagi tentang Line Follower ROBOT Controlled by 2051. Gunakan fitur Translate di sebelah kanan untuk menterjemahkan teks berbahasa inggris, selamat membaca, semoga bermanfaat.

Kuskel Robot- This Robot use two motors control  rear wheels and the single front wheel is free. It has 4-infrared sensors on the bottom for detect black tracking tape, when the sensors detected black color, output of  comparator, LM324 is low logic and the other the output is high.
Microcontrollor AT89C2051 and H-Bridge driver L293D were used  to control direction and speed of motor.
Fig 1. Circuit diagram of my Robot.

Fig 2. Circuit diagram of Infrared sensors and comparators.

Fig 4. Position of sensors,  left hand side is side view and right hand side is top view.
Software
Software for write to AT89C2051 is robot1.hex ,which was written by C-language ,the  source code is robot1.ccompiled by using MC51 in TINY model with my start up code robot.asm .
MPEG files
Sample of competition between 2051 and 68HC11.

  • movie1.mpg (1,303kB)

  • movie2.mpg (373kB)
  • Sabtu, 12 April 2014

    Rangkaian Lampu LED Sepeda Motor 2x20



    Salam Electrical Engineer yang setia membaca artikel pada blog ini. Semoga tetap bersemangat untuk belajar dan terus belajar tentang elektronika. Pada kesempatan kali ini saya akan berbagi tentang 
    Rangkaian Lampu LED Sepeda Motor 2x20. Gunakan fitur Translate di sebelah kanan untuk menterjemahkan teks berbahasa inggris, selamat membaca, semoga bermanfaat.

    Rangkaian Lampu LED Sepeda Motor ini sangat sederhana yang hanya menggunakan beberapa komponen saja tapi hasilnya sangat memuaskan. Konsumsi dayanya sangat kecil cukup 6 Volt saja sangat cocok untuk sepeda motor anda.
    The 555 circuit below is a flashing bicycle light powered with four C,D or AA cells (6 volts). Two sets of 20 LEDs will alternately flash at approximately 4.7 cycles per second using RC values shown (4.7K for R1, 150K for R2 and a 1uF capacitor). Time intervals for the two lamps are about 107 milliseconds (T1, upper LEDs) and 104 milliseconds (T2 lower LEDs). Two transistors are used to provide additional current beyond the 200 mA limit of the 555 timer. A single LED is placed in series with the base of the PNP transistor so that the lower 20 LEDs turn off when the 555 output goes high during the T1 time interval. The high output level of the 555 timer is 1.7 volts less than the supply voltage.

    Circuit  Project: 40 LED Bicycle Light

    Adding the LED increases the forward voltage required for the PNP transistor to about 2.7 volts so that the 1.7 volt difference from supply to the output is insufficient to turn on the transistor. Each LED is supplied with about 20mA of current for a total of 220mA. The circuit should work with additional LEDs up to about 40 for each group, or 81 total. The circuit will also work with fewer LEDs so it could be assembled and tested with just 5 LEDs (two groups of two plus one) before adding the others.

    Jumat, 11 April 2014

    Kontrol Mute Volume Sentuh

    Salam Electrical Engineer yang setia membaca artikel pada blog ini. Semoga tetap bersemangat untuk belajar dan terus belajar tentang elektronika. Pada kesempatan kali ini saya akan berbagi tentang Rangkaian Kontrol Mute Volume Sentuh. Gunakan fitur Translate di sebelah kanan untuk menterjemahkan teks berbahasa inggris, selamat membaca, semoga bermanfaat.

    Here is another simple circuit to mute the volume of Audio devices through simple touch. It exploits the action of the flip-flops in the timer IC 555 to reduce the volume of the Audio amplifier. IC NE555 is designed in the toggle mode. Its lower and upper comparator inputs are connected to the touch plates which can be membrane switches or two pieces of conducting plates. The inputs of comparators are stabilized through R1 and R2 to avoid floating.

    Circuit Project: Touch controlled Mute Switch

    When the touch plate connected to pin 2 is touched momentarily, output of IC1 goes high and T1 conducts. The centre tap of the volume control is connected to the collector of T1. So when T1 conducts current going to the amplifier drains through T1. This reduces the volume.IC1 remains latched in this position with LED on. When the touch plate connected to pin 6 is touched momentarily, output of IC1 goes low and T1 turns off. This restores the volume.

    Senin, 17 Maret 2014

    Power Amplifier for Laptop

    Salam Electrical Engineer yang setia membaca artikel pada blog ini. Semoga tetap bersemangat untuk belajar dan terus belajar tentang elektronika. Pada kesempatan kali ini saya akan berbagi tentang Rangkaian Power Amplifier for Laptop. Gunakan fitur Translate di sebelah kanan untuk menterjemahkan teks berbahasa inggris, selamat membaca, semoga bermanfaat.


    Usually, the audio output from a laptop’s built-in speakers is low. A power amplifier is required to get a high volume. Here is a simple circuit to amplify the laptop’s audio output. The circuit is built around power amplifier IC LA 4440 (IC1) and a few other components. LA4440 is a dual channel audio power amplifier. It has low distortion over a wide range of low to high frequencies with good channel separation. Inbuilt dual channels enable it for stereo and bridge amplifier applications.


    In dual mode LA4440 gives 6 watts per channel and in bridge mode 19- watt output. It has ripple rejection of 46 dB. The audio effect can be realized by using two 6-watt speakers. Connect pins 2, 6 and ground of IC1 to the stereo jack which is to be used with the laptop. Assemble the circuit on a general-purpose PCB and enclose in a suitable cabinet. The circuit works off regulated 12V power supply. It is recommended to use audio input socket in the circuit board. Use a proper heat-sink for LA4440.

    Minggu, 16 Maret 2014

    12 VDC-220 VAC 50W Power Inverter Circuit

    Salam Electrical Engineer yang setia membaca artikel pada blog ini. Semoga tetap bersemangat untuk belajar dan terus belajar tentang elektronika. Pada kesempatan kali ini saya akan berbagi tentang Rangkaian 12 VDC-220 VAC 50W Power Inverter Circuit. Gunakan fitur Translate di sebelah kanan untuk menterjemahkan teks berbahasa inggris, selamat membaca, semoga bermanfaat.

    12 VDC-220 VAC 50W Power Inverter Circuit

    The ability advocate ambit is aimed to catechumen 12 VDC to 220 VAC and the action accepted as inverter. By inverting action will aftermath a 50W ability advocate that would accumulation altered baby appliances.
    The DC to AC inverters are broadly acclimated in rural electrification the crave AC ability which includes solar home systems, bloom clinics, and
    association centers. Ability Advocate can additionally be acclimated for added photovoltaic systems that catechumen ablaze activity into electricity such as weekend homes and alien cabins, boats and caravans, and baby telecom photovoltaic systems.
    Power Advocate Ambit Explanation
    The ability advocate ambit is constituted by the oscillator, annular the IC1, one affiliate IC2, one ambiguous multivibrator IC3, which accord in the achievement balanced aboveboard arresting of abundance 50HZ, chase a absorber date with Fet Q1-2, the drive date Q3-4 and the ability date Q4-5, the ability transistors Q5-6, should they are placed in heatsink.
    The diodes Zener D2-3, assure the ability transistors from voltage peaks, that are produced by the agent T1. Agent T1 are a simple ability transformer, with average reception, which is affiliated in the contacts of CO1. For the use that him we want, the T1, is placed in reverse, with accessory coil it is acclimated as primary, with the average accession she is affiliated in the absolute point of array 12V and the two added contacts are affiliated in the emitters of Q5-6, that are affiliated in the abeyant of arena alternately, depending on the rythm that actuate outputs 10 and the 11 from IC3.
    With this way while in actuality primary breeze AC current, in accessory is created 220V AC aboveboard voltage. The use of crystalic oscillator ensures actual acceptable advertence abundance 50HZ, and use a simple clear (CR1). For bigger precision, alongside with the C1, abide a capricious capacitor Cx, that ensure the adjustment of frequency, so that we booty in point P1, abundance 204.8 KHZ.
    It’s accessible that the achievement voltage in abandoned of amount is bigger than the voltage with load. Additionally the achievement voltage depend from the achievement voltage of battery. Thus for array voltage 14V, the achievement voltage is added at 10%, compared to the array voltage 12V. If the advocate assignment in amount ability 40 until 60W, again it can be acclimated agent 2X9V. Various prices of output, for array voltage 12V and agent 2X10V,
    Power Converter Parts List
    Resistor
    R1=10Mohms
    R2=100ohms
    R3=1.2Kohms
    R4=560Kohms
    R5-6=2.2Kohms
    R7-8=56 ohms 5W
    Capacitor
    CX=22pF trimmed capacitor
    C1-2=22pF ceramic
    C3=8.2nF 100V MKT C4=10uF 16V
    C5=47uF 16V
    C6=470nF 400V
    Diode
    D1=5V6 0.4W
    D2-3=47V 1W
    Transistor
    Q1-2=BS170
    Q3-4=BD139
    Q5-6=BD249
    Integrated Circuit
    IC1=4060
    IC2=4013
    IC3=4047
    Crystal
    CR1=3.2768 MHZ crystal
    Transformer-Fuse
    T1=220Vac/2X10V 2X2.2A
    F1=5A Fuse
    F2=0.25A Fuse
    Inductor
    L1=1H smoothing choke

    Sabtu, 15 Maret 2014

    Active Crossover Circuit

    Salam Electrical Engineer yang setia membaca artikel pada blog ini. Semoga tetap bersemangat untuk belajar dan terus belajar tentang elektronika. Pada kesempatan kali ini saya akan berbagi tentang Rangkaian Active Crossover Circuit. Gunakan fitur Translate di sebelah kanan untuk menterjemahkan teks berbahasa inggris, selamat membaca, semoga bermanfaat.
      

    This alive Cantankerous over is adequately beeline forward. It consists of a absorber and two 3rd order, 18 dB per octave filters. One low canyon and the added high. The cantankerous overabundance is set at 2Khz and is advised for AEK’s 400watt per access PA/Keyboard Amp systems. Obviously alone one access is apparent here.
    The band akin audio arresting enters the absorber area it is astern out of phase. This is to atone for 
    the filters which will alter the appearance afresh appropriately abiding the arresting to it’s able phase. The filters are more-or-less accepted low and aerial canyon filters appropriately however, added capacitors and resistors accept been added in adjustment to get the altruism bottomward to a minimum appliance alone E12 components.
    This ambit may not be of awfully abundant use to anyone as it was accurately advised to clothing the applications. It is not capricious or switchable for two reasons. Firstly, it didn’t charge to be back the backdrop of the apostle arrangement were already known. And secondly, the added complication was put into the accurateness of the crossover rather than it’s flexibility. The filters are akin in account to anniversary added as able-bodied as can be accepted appliance alone E12 components. If switching were to be active to accord a ambit of abundance options, aaccommodation would accept to be fabricated on clarify accuracy.
    The alone added way to accomplish a accepted crossover architecture and advance accurateness would apparently be to use Switched capacitor clarify architecture blocks. In theory, two 18or 24dB per octave filters could be complete such that they tracked anniversary added by actuality bound to the aforementioned clock. This would be a nice agreement but I haven’t had the befalling to prove this technology for this affectionate of application. My primary affair was the breach through of switching babble appliance such a design.
    Therefore this architecture represents the simplest access I could booty and still get the adapted outcome.