Para pengganti

Habitat Asli

Di habitat aslinya gurame hidup di perairan tawar yang tergenang seperti rawa, danau, dan situ. Namun, beberapa jenis gurame dapat hidup di perairan payau. Selain itu, gurame dapat hidup di habitat air tergenang yang keruh dan tidak dapat ditinggali oleh ikan tawes atau ikan mas. Gurame dapat bertelur dan berkembang biak di air yang keruh sekali pun. Namun, sebenarnya gurame lebih menyukai perairan yang lebih jernih dan tenang.

Ikan ini akan hidup sengsara di perairan yang digenangi tanaman air mengapung seperti eceng gondok. Hal ini karena gurame harus mengambil udara langsung dari udara bebas dengan labirinnya. Alat ini tidak berguna jika gurame tidak dapat menyembul ke permukaan air. Di kolam yang ditutupi tanaman air yang mengapung, gurame akan lebih sering bergerak horisontal.

Perkembangbiakan dan Pertumbuhannya

Gurame berkembang biak sepanjang tahun dan tidak tergantung pada musim. Kematangan kelamin biasanya dicapai saat gurame berumur 2-3 tahun. Sebelum induk betina bertelur, induk jantan akan membuat sarang untuk meletakkan telur. Sarang telur dibuat dari ijuk, serpihan bambu, atau tanaman kering yang ada di dalam kolam. Sarang berdiameter 30 – 40 cm ini diletakkan di tempat yang tersembunyi.

Setelah induk betina meletakkan telur ke sarang, induk jantan akan membuahi telur tersebut. Induk jantan juga akan menjaga telur hingga menetas. Biasanya telur akan menetas setelah berumur lima hari. Usai perkawinan, menjaga keturunan menjadi kewajiban induk betina. Telur yang menetas menghasilkan larva yang akan terus tumbuh membesar. Berikut tahap pertumbuhan gurame berdasarkan umurnya.

Kebiasaan Makan

Di alam bebas, gurame mempunyai kebiasaan makan makanan yang spesifik pada setiap stadium pertumbuhannya. Gurame stadium larva dan benih umumnya memakan jasad renik seperti fitoplankton, zooplankton, chlorella, kutu air, larva serangga, dan serangga air.

Sementara itu, gurame dewasa cenderung lebih menyukai tumbuhan. Gurame dewasa biasanya memakan tumbuhan air yang lunak seperti azolla, hydrilla, kangkung air, genjer, dan apu-apu. Di kolam budi daya, gurame dewasa juga menyukai daun singkong, daun pepaya, dan daun talas atau sente, yang diberikan oleh petani. Namun dalam budi daya secara intensif, pemberian pakan alami belum cukup. Petani biasanya juga memberikan pelet atau pakan buatan pabrik agar pertumbuhannya optimal.

Sumber :
http://agraris.adakata.com/habitat-ikan-gurame/

Nilai perolehan devisa dari perdagangan ekspor aneka kerajinan berbahan baku bambu buatan masyarakat Bali bernilai 4,4 juta dolar AS selama Januari - Mei 2011.

Kreativitas perajin bambu Bali masih mendapat tempat di hati konsumern luar negeri, kata Kepala Seksi Ekspor Dinas Perindustrian dan Perdagangan Provinsi Bali, Putu Bagiada SE di Denpasar Rabu.

Hal itu terbukti, krisis ekonomi global yang masih dirasakan masyarakat dunia, tidak berpengaruh besar terhadap perdagangan ekspor barang kerajinan berbahan baku bambu, bahkan masih ada saja yang diekspor.

Ia menjelaskan, perolehan devisa tersebut atas pengapalan sebanyak 2,9 pcs, selama januari-Mei 2011 turun tipis yakni 7,4 persen, jika dibandingkan dengan periode sama 2010 yang mencapai 4,7 juta dolar.

Stabil jumlah kerajinan itu ke luar negeri tentu berkat masyarakat kreatif dalam menciptakan rancang bangun (desain) yang diinginkan pasar seperti kursi dan meja tamu yang dipadukan dengan rotan.

Pengusaha luar negeri ada yang meminta aneka kerajinan bambu yang bentuknya sesuai gambar atau rancangan yang dibawa dari negaranya, tentu dengan harga yang disepakati sebelumnya, kata Bagiada.

Tempat tidur malas yang biasa dibuat menggunakan bahan kayu jati dan sejenisnya, kini bisa dibuat dengan bahan baku bambu, ternyata hasil karya perajin di Bali disenangi serta dibeli oleh konsumen luar negeri.

Semakin laris aneka kerajinan berbahan baku bambu menyebabkan perajin Bali kesulitan bahan baku sehingga mendatangkan dari Jawa maupun Lombok, sebab bambu yang ada di daerah ini semakin terbatas.

Bambu tidak saja dijadikan barang furniture, juga bisa dianyam dibuat gedeg lembaran, supaya tahan terhadap rayap, pengrajin memolesi lembaran gedek dengan disinfektan, setelah dijemur, gedek siap diekspor.

Masyarakat Bali yang dinilai kreatif dalam menciptakan barang kerajinan mampu memikat konsumennya dan laku terjual ke pasaran ekspor maka tidak mengherankan kalau devisa dari kerajinan bambu masih stabil.

Power supply circuit with transformer (transformator, trafo) are still much in demand although today we have  converter to convert high voltage grid (220 VAC) to a low voltage, such as 12 VDC, without transformer. One of the advantages of the power supply with transformer is the isolation of the hight voltage to low voltage,theore it is very safe. But the transformer is big, heavy and expensive. May be in the future when high-voltage converter technology is popular and available at low price, the circuit with the transformer would be obsolete. Some electronic devices such as TV, charger for: mobile phone, laptop, etc., has no longer used transformer to supply power from grid.

For circuit such as voltage step up or current step up, transformer still has no competitor.

In this article discussed a variety of power supply design, from the most simple, to the one using voltage stabilization with IC. With parameters described briefly, will help you design a power supply according to your needs.

The following schematic shows a simple power supply circuit, sometimes also called an adapter.

Transformer (T) which is widely available in the market have input voltages of 110 VAC and 220 VAC. The output voltage is 12 VAC and 24 VAC. While small transformer available with output voltage of 3, 6, 9, and 12 VAC.

For 12 volt battery charger circuit, it needs 15 volt transformer output which is rarely available in the market but can be ordered. The amount of  current needed to recharge the battery is 10% of the battery capacity. Theore 50 AH battery requires 5 amperes charging current. Do not use a transformer with just enough  current capacity, you should use the transformer with output capacity of 10 amperes to charge 50Ah battery, this way the transformer will not overheat. Read also "Charging Your Vehicle Battery".

Diodes (D) convert alternating current (AC) into direct current (DC). There are 4 pieces of diodes to form a bridge to become a full wave rectifier. It could be used only one diode on that circuit, thus forming a half-wave rectifier. But since the transformer price is very expensive, it would be better if all transformer potential is used, by installing 4 pieces of diodes. 1N4007 code number is quite popular in the market with a maximum reverse voltage specification of 1000 V and a forward current of 1 A. 1N4007 diode can handle forward current up to 30 A but only in a very short time of 8.3 milliseconds. For currents greater than 0.5 amperes, usually no longer use the 1N4007. But using diode bridge that is a large 4 pieces of diodes in a single container. Diode bridge needs heatsink for large current. Download the datasheet of 1N4007.

There will be a loss of voltage of 0.6 volts on the diode, and for large current voltage loss can reach 1.3 volts. So if it is used as a battery charger, with 15 volt transformer output, will produce diodes output voltage:


That 14.4 volts a specification recharging voltage for a wet cell battery.

But for dry cell battery which has a charging voltage of 13.8 volts, it is necessary to lower the voltage by additional 1 diode at the output:


Some electronic gadgets are using 13.8 volts power supply such as radio communication transmitter and receiver (transceiver). Some dry cell battery has charging voltage 13.5 volts. More details about the battery in the article "Why is Battery Explode?"

Condenser (C) stabilizes voltage output from diode bridge and eliminates high voltage generated by the transformer magnetic field induction. High voltage at the output of transformer is not dangerous but enough to shock if touched, because the current is weak. High voltage on the output transformer can be read by multitester if the transformer is not under load. On the battery charger, high voltage at the output can be absorbed by the battery. High voltage at the output will cause the humming and rumble (brooming) noise if the power supply is used to power amplifiers, radio transmitters, etc.. Some sensitive electronic devices can be damaged. So it is needed to add filters consisting of resistors, and capacitors, or connecting the negative (-) output to ground. Usually the size of the condenser is 47 to 1000 microfarads, depending on the load. Maximum condenser voltage ise twice above the desired output voltage. For 12 volt power supply then the maximum  voltage of condenser is 25 volts.

Direct current output (VDC) of the above circuit is obtained at positive point (+) and negative point (-) of diode bridge.

For safety reason it is necessary to add a fuse (F) with value is a little smaller than maximum current output of transformer. For big and expensive transformer, there is a fuse also fitted on the input of transformer with value is slightly smaller than the maximum input current, in order to protect that expensive transformer.


Voltage Stabilization

If a more stable voltage is required and it is lower voltage of diode output voltage, then voltage stabilization circuits below may be suitable to add:

Connect Input to the output of diode bridge. Resistor Rb supplies current to transistor (T). Rb value is 220 ohm 2 watt. This resistor determines maximum current out of the transistor (T).

Zener diode (Dz) determines the output voltage of  transistor. For 14.4 volt voltage of battery charger, then use Dz with value of 15 volt 2 watt. When the output voltage of base resistor (Rb) exceeds 15 volts, this zener diode will connect to the negative, so that Rb output voltage will never exceed 15 volts. As there will be voltage loss of 0.6 volts on the transistor, so a slightly higher zener voltage is choosen.

Transistor (T) is a 2N3055, supply current is approximately 1.5 amperes with 220 ohm resistor basis (Rb). This transistor can handle voltage up to 60 volts and 115 watts of power and need cooler (heatsink). If you need a larger current then you arrange few of this transistor in parallel. Download the datasheet of 2N3055.

Higher output voltage of transformer that can be used, eg 24 volts, because the output voltage of this power supply is the same as transistor output voltage which is determined by the zener voltage.

Condenser (C2) stabilizes the output voltage of transistor. Actual value will depend on the load. But in general the value of C2 about 47 microfarads can do. Voltage rating is approximately 2 times of output voltage. For 14.4 volt battery charger, condenser with maximum voltage of 25 volts is quite safe.

Resistor (R) serves to secure transistor from spike voltage that is caused by induction load, such as electric motor, relay, solenoid, actuator, etc.. Resistor value is 10 kiloohm. This resistor can be eliminated if the power supply is never used to drive induction load.

Voltage stabilization circuit with transistor above can be simplified by using the IC (Integrated Circuit) 78xx series. Number 78 on the IC expressed as a positive voltage regulator, the last two digits express the output voltage. For example 7812, is a positive voltage regulator with an output of 12 VDC. See the following scheme:

The circuit is very simple and has only one component, the IC only. Plus some condensers for filter: C3 0.33 microfarads, and C4 0.1 microfarads. But the regulator IC is less strong when compared with the transistor. This IC can survive up to 35-40 VDC input voltage. Rating input voltage is 23 volts and maximum output current 1 ampere for L7815A, can be supplied by 24 volts transformer. In some designs, the IC supplies to 2N3055 transistor base in order to get a larger output current. Download datasheet of IC 78xx.


Voltage Adjustment

By using a diode, the output voltage of the transistor can be tuned. Diode has a stable voltage and popular to to adjust output voltage. See below schematic of voltage stabilization with transistor below:

If a diode is installed between zener and negative, the output voltage of transistor will rise. Notice different installation of diode and zener. If the diode is mounted on the base of transistor, the transistor output voltage will drop.

In the same way the diode can be used to adjust the output voltage of the IC 78xx. Installation on IC ground pin will increase IC output voltage. While diode installation on IC output pin will decrease the IC output voltage.

1N4007 diode is commonly used for voltage adjustment which has voltage of 0.6 volts. Crystal diode such as OA90 has voltage of 0.2 volts, also called germanium diode.

Circuit to monitor the battery voltage can be read in the article "Simple Battery Voltage Indicator With LED".

During recharging, battery releases hydrogen and oxygen gases. It is known that hydrogen is a flammable gas, while oxygen is a substance that helps the combustion process. So the combination of those gasses could be flammable. Mixture of hydrogen and oxygen in a certain concentration when contact with fire or high temperature though only in one small spot, it could be exploded. More details about recharging battery can be read on: Charging Your Vehicle Battery.

In the dry cell battery, hydrogen and oxygen gases do not easily go out, and accumulated inside battery housing. If the battery is recharged too high and exceed the normal limits (overcharge), then production of hydrogen and oxygen are also much higher. So at some point will exceed the ability of the battery container and ultimately rupture the container aka battery to explode. Sealed battery such as dry battery (gel cell, Adsorbed Glass Mat, etc.) have higher risk of explosion then wet lead-acid battery.

Likewise, if too much battery load. When the current is going out of the battery, the battery also produces heat. If the heat is too high, then the amount of steam formed by heat is too much and the pressure will be too high and breaks battery container.

So, since the battery produces gases when recharge and discharge, then do not place it in a closed container.

Today dry cell batteries are popularly used. This type of battery has a maximum recharging voltage slightly lower than wet battery.

For example, for MK brand dry cell battery, the specification states that the charger voltage should be between 13.8-14.1 volts at a temperature of 20 degrees Celsius or 68 degrees Fahrenheit. Charger voltage must be reduced if temperature gets higher, in order to reduce gas formation. While some vehicles have a charging system with a voltage of 14.3-14.4 volts, so it can cause overcharge. At ambient temperature 30 degrees Celsius or 86 degrees Fahrenheit as in the tropics, maximum recharge voltage will drop to 13.5-13.8 volts. Theore in cooler region like the subtropics, vehicle battery exploded by overcharge has less risk.

 Few years a go, charging system voltage could be set as it was using electromagnetic switch (cut-off). Today the voltage regulation is done by Integrated Circuit (IC) and no longer adjustable. But lately there some are IC voltage regulators that can be adjusted. Apparently this adjustable IC voltage regulators are manufactured to suit a variety of different voltage to recharge batteries.

If you are using dry cell battery, the easiest way to prevent overcharge is to use a voltmeter to monitor battery voltage while driving. But now the voltmeter is not popular anymore as standard equipment on the dashboard, because IC voltage regulator is very stable. It is necessary to add a voltmeter to monitor battery voltage, if the voltage exceeds the maximum battery voltage, eg 14 volts, then immediately turn on the additional load such as lights, a/c, radio, tape, etc.. Reduce the engine revolution (RPM) by shifting to higher gear, or reduce speed.

Usually overcharge occurs when driving in the daytime with high engine revolution. High environment temperature will rise gas formation and lower gassing voltage. In some countries where it is compulsory to use headlight in the daytime, overcharge risk is lower as slightly lower alternator voltage due to current absorbed by headlight.


Now there are commercially available digital voltmeters that can be plugged into cigar lighter connector. As shown in below photo.


Circuit to monitor the battery voltage can be read in the article "Simple Battery Voltage Indicator With LED".

Shown below is a cut-off voltage regulator of an old alternator, voltage of this type regulator can be easily adjusted. The top cover is removed to show two electromagnet relays. But the regulated voltage is unstable.


Another way to prevent the battery explode by overcharge is to reduce the alternator output voltage, by placing diode in series between the alternator and battery. Diode reduces the voltage of 0.6 volts. So if your charging system voltage is 14.4 volts, then after installing diode voltage will drop to 13.8 volts. It should be ensured that the diode is capable to allow current strong enough to recharge the batteries and simultaneously turn on vehicle electrical systems such as: lights, a/c, ignition, fuel injection, engine management system, Electronic Control Unit (ECU), radio / tape, etc.. Minimum value of the current goes pass through the diode is about 50% of battery capacity, eg. for the 40AH battery, the resulting alternator current through the diode is 20 amperes. And of course the amount of current depends also to the amount of power (watts) of vehicle accessories.

Big sized diode is usually expensive and rarely sold. But it can be assembled from several small sized 2 amperes diodes. To make a big 20 A diode, it is required 10 pieces of parallel 2 A diodes. Photo below shows a parallel circuit of 2 A diodes. Alternator diode can do also.


Diagram for diode connection can be seen in the image below. Diode is connected between the alternator and battery, with the diode current flow from alternator to the battery. Supply power to the vehicle electrical system is connected to the positive pole of the battery, to ensure electric current can flow directly from the battery to the electrical system, without going through diode. The diode doesn’t allow electric current in the opposite direction.


Photo below shows the charging wire is pointed by red arrow. The cable is always the biggest of all alternator cables.


Be caul when connecting the wire from alternator to diode and to battery. Wire with large current must be well connected. Poor connection can increase resistance and generate heat, so it can end up with fire. Diode also requires cooling, place diode away from heat sources such as exhaust and radiator.