Ketika merakit suatu rangkaian misalnya amplifier audio senang rasanya bila rangkaian yang dibuat bekerja dengan baik dan mengeluarkan suara yang jernih. Tapi tidak apa-apa inti dari artikel ini menunjukkan bagaimana cara memasang TC saja. Diasarankan menggunakan speaker dengan ukuran 6 hingga 12 Inch, Trafo CT 18V 3Ampere dan pendingin. Aug 09, 2018 Trafo ct (yang di video menggunakan trafo 5 amp ct,tetapi bisa juga menngunakan trafo ct ukuran amp yang lain) 2.Dioda brigde (yang di video menggunakan dioda brigde 25 amp ).
Cara membuat cas aki baik cas aki motor,cas aki mobil dari yang sederhana sampai cas aki otomatis,untuk aki kering maupun aki basah,dari yang memakai trafo ataupun yang AC matic bahkan ada yang membuat cas aki dari cas laptop atau bekas psu komputer,kali ini kita akan belajar bersama membuat cas aki dengan trafo ct tetapi menggunakan dioda model brigde,komponen untuk cas aki tersebut adalah:1. Trafo ct (yang di video menggunakan trafo 5 amp ct,tetapi bisa juga menngunakan trafo ct ukuran amp yang lain)2.Dioda brigde (yang di video menggunakan dioda brigde 25 amp )untuk bagian kipas dan indikator:1.Dioda 2 amp2. Elco 1000 uf / 25 volt3.kipas dc 12 volt.4. Resistor 1k 1k5 ohm5.
Thecircuit operation is pretty straight-forward, and very modifiable.The output voltage is compared with a stable reference voltage, andbased on the error the TL494 adjusts the duty cycle to compensate. Theoutput from the TL494 drives a BJT full-bridge, which drives the gatedrive transformer (GDT). The GDT controls the IRFP450 power mosfets.The IRFP450s are in a half-bridge configuration and run the main powertransformer at the duty cycle decided by the TL494 chip. The outputfrom the main power transformer is rectified and filtered, and finallythe output voltage is measured again by the TL494. This is calledclosed-loop operation.
Each section of the circuit is dicussed furtherdown. I've made anto aid modification or design, and all of the math I required is in it I believe. Just ask if something is missing. PWM Generation and Overcurrent detection SectionIn my experience the logic section with GDT and fan(s) consumes about15W +/- 5W.
Keep this in mind when looking for a small 16V powersource. Iron-cored wall warts work well for this purpose. Pin 14 on theTL494 generates a regulated 5V output, which is used for providing astable reference voltage. I do not use it for the 5V source in thecomparator section, as I don't want to load it down.
One of the erroramps on the TL494 is used to determine the duty cycle. The reference isdivided by 2 with two 15k resistors and fed to pin 2 giving a 2.5Vreference. The output voltage from the supply is sent through a divideras well, and depending on the potentiometer setting will provide anoutput voltage of 2.5V at different voltages (15-48V). With lowresistance the ratio is low and it only takes 15V before the divideroutput is 2.5V, high potentiometer resistance results in a large ratioand high voltage required before 2.5v is reached. From pin 3 to pin 2is a gain compensation network, consisting of a capacitor and resistor.The purpose of this is to stabilize the control loop, and it's designis far too complex for amatures to understand. (I haven't even tried.)All you need to know is that the capacitor's impedance will vary withfrequency, in effect giving a frequency dependent resistor. Thiscoupled with the 180k resistor gives the error amp frequency dependentgain, allowing for stabilization depending on the load, duty cycle andfrequency.
Like I said, you don't want to know. The overcurrent detection works by sensing current with a shuntresistor, which is a resistor from your load to real/circuit ground.Thanks to Ohm's Law (U=R.I.
POWER SectionRectified mains is filtered (this is optional) mainly to keep noisefrom the supply from traveling back up mains and disturbing otherappliances. I built an unregulated and sloppy SMPS for an amplifierbefore this project, without a filter of course, and whenever I turnedit on my brother's amplifier in another room would start humming. Soyes, it is somewhat important. Mains is rectified with a beefy bridgeand filtered with a large storage capacitor.
Between the bridge andcapacitor is a NTC. NTCs have a negative thermal coefficient, hence thename. What they do is have low resistance at high temperature, and highresistance at low temp. In this circuit one is used to limit the inrushcurrent to the man filter capacitor.
Since a large capacitor willprovide a substantial load when empty, it can draw enough current whenstarting up the PSU to blow fuses or a breaker. The NTC prevents thisby limiting the initial current, and slowly letting more through as itheats up. The problem is that when drawing 500W or more large NTCsare needed which aren't easy to find or very practical, so the NTC canbe omitted. If the filter capacitor causes your breaker to trip use alight-bulb/switch like in my MKII multipurpose inverter.
The two 120kresistors simply bleed away charge on the filter capacitor when thesupply is turned off.From the GDT outputs come alternating square-wave pulses 180 degreesout of phase, which control the IRFP450s. Together with the two3µF capacitors they form a half-bridge, which sends alternatingcurrent through the main power transformer.
The two 3µFcapacitors will carry all of the load current, and should bepolypropylene foil type capacitors. Some designs use electrolytics forthe half-bridge and filter capacitors in one, but I've found that theelectrolytic heat up and eventually fail when used this way. The amountof averagecurrent sent through the transformer is controlled by the duty cycle,which is controlled by the TL494. The secondary is center-tapped sodual diode rectification can be use. For filtration of the rectifiedoutput a 33µH inductor and 1000µF capacitor are used. Thedouble 400V 16A rectifiers seem to beoverkill, but I found them necessary. They were reasonably cheapanyway.Experiments with 60V Schottky diodes resulted in plenty offailures for some unknown reason, so I would go no lower than 100V, andrate the diodesgenerously for the current.
This is your workhorse remember!The power transformer itself was put together from an old ATX core,which is ideal since they are used in this exact same fashion andfrequency. They might not be large enough for continuous operation atmore than 300W, but enough to last shorter runs at twice that. A goodquestion is how to design a transformer for 750W operation. Whatlimits power in transformers is how much power they can dissipate.A core can lose power through losses tied to drive frequency and/ormagnetic flux being too high, but that's about it unless I'm mistaken.The other losses are copper losses from the windings, and ideally youwant to fill the entire window area with copper to reduce theresistance as much as possible. So if you can the required number ofturns in at the required thickness in the winding area, the core islarge enough. The resistance of the wires, even if only 0.5 ohms candrop a decent amount of voltage. Now the DC resistance might seem low,but remember that the skin effect kicks in too, increasing theeffective AC resistance. At 45kHz, for 16A capable wire I would usefour strands of 22AWG twisted together as litz wire.
The primary onlyhas to handle about 4-5A at full load, so bifilar 22AWG should beenough.