12 V Mains SMPS Circuit
All this is fitted into DIP8 package (same as the 555)! Its maximum voltage is 700V, the operating frequency is 132kHz. Schematic diagram you will notice below.
It takes advantage of an integrated circuit TNY267P of a few circuits TinySwitch-II: TNY263, TNY264, TNY265, TNY266, TNY267 a TNY268.
This element combines both the control circuit as well as the transforming element (MOSFET), current and thermal fuse and self-power procedure. This is certainly everything essential for a small flyback provider. It doesn't actually need an auxiliary winding.
Due to the low power, I applied halfwave rectifier.
Voltage peaks are limited with the use of transil (zener diodes) 180V. This might be swapped with the typical parallel blend of resistance and capacitor.
Feedback is supplied with optocouplers, the minimum threshold is opted clearly making use of zener diode (ZD). ZD decides the output voltage.
It is usually more or less 1 V beyond the nominal voltage of ZD, mainly because the voltage fall of the LED optocoupler is involved. For 12 V output voltage ZD 12 V is used.
Surely i don't compel you to develop 12 V supply - output voltage can be realigned by varying 2 things: - Secondary winding is about 1.4 z / V. - ZD is about 1V less than the obligated voltage. For minimal voltage (about 5V or less) exchange fast diode on output with Schottky diode.
Optimum power of this supply in an enclosed adapter and 230V power is 13W. Transformer is a tiny ferrite EE. Fundamental column includes a cross-section of 4.5 x 4.5 mm, air gap 0.4 mm. Primary holds 140 turns of wire diameter 0.15 mm.
Secondary owes (for 12 V output) 18 turns of wire 0.4 mm. Caused by the low power the secondary is not classified to several parts. First, I ended the complete primary. The layers of wires are interlaced primarywinding.
Between primary and secondary i made use of shielding - copper tape and joined it to the cold termination of primary (not surprisingly it it not supposed to generate shorter turn!). Then I wound aq durable isolation - 12 portions of duct tape.
Next I wound the secondary turns. In the instance of complications with interference install a noise suppression circuit together with / or harness a capacitor roughly 1n / Y1 between primary and secondary side.
Complete preference are supplied by the datasheet of TNY263 - TNY268. The more significant part the number, the more significant the potency.
Observe sometimes the more recent series of TinySwitch-III: TNY274 - TNY280. In that series you can discover IC's allowing a lot more ability. They are going to also easily fit in schematic below, just the pinout is different.
