Diagram Diagosis

BURGLAR ALARM USING IC TIMER 555/556 ELECTRONIC DIAGRAM

10W Stereo Audio Amplifier Circuit Diagram :

100W POWER AMPLIFIER USING TDA7293 CIRCUIT DIAGRAM

The TDA7293 amplifier specifications might lead you to believe that it can use supply voltages of up to ±50V. With zero input signal (and therefore no output) it might, but I dont recommend anything greater than ±35V if 4 ohm loads are expected, although ±42V will be fine if you can provide good heatsinking. In general, the lower supply voltage is more than acceptable for 99% of all applications, and higher voltages should not be used unless there is no choice. Naturally, if you can afford to lose a few ICs to experiments, then go for the 42V supplies (obtained from a 30+30V transformer).

The presented article explains a simple buck converter or an SMPS circuit using the IC VIPer12A from STMicroelectronics. The circuit uses negligible number of external components yet is able to operate directly from mains AC input.


Looking at the given circuit diagram we see that the input stage incorporates a surge limiting resistor which quite acts like a fuse, a diode for rectifying the AC, and an LC filter network for further filtration of the DC riples.

The LC filter employed here ensures better DC stabilization and enhanced EMI response.

The capacitor Cin1 may be introduced for further reinforcing the EMI functionality.

The IC VIPer12A becomes the main PWM processor device which single handedly performs the entire buck conversion in the circuit.

The main specifications of the configuration may be understood as follows:

• AC input voltage Vinac 80 - 285Vac
• Output current Iout 30mA
• Output current Iout2 50mA
• Output voltage Vout1 +24±10%V
• Output voltage Vout2 +5V±5%
• Switching frequency 60 kHz
• Output Power ~ 1W

The circuit facilitates two outputs, rhe 24V output is achieved through a buck converter configuration while the 5V output via fly back mode.

The feedback voltage to the IC is acquired from Vout1 for the required regulation of the output, this supply is also applied to the IC Vdd pin.

The above wiring becomes possible by using a single high voltage diode and just one capacitor, to be precise D1 and C3, making the connections and costing much simpler.

The employed inductor L consists of two windings which are coupled across with each other over a common ferrite core.

The winding are done through appropriate turn ratios, where N1 = 200 turns and N2 = 60 turns. Both these are wound over a PANASONIC ELC10D152E ferrite core material.

Zener diodes z1 and z2 are installed in order to safeguard the outputs against over voltages.

A dummy load resistor is fixed across Vout1 so that appropriate regulation can be executed over both the outputs during open load situations.


Though the addition of the above resistor affects the efficiency a bit, it superbly improves voltage regulation response of the circuit.

The rectifier diodes fixed at the output are fast response fast recovery types. D1 is a high voltage diode as it might be subjected to high reverse voltages delivered by the DC bus voltage...... D2 is a normal diode.



Parts List for the proposed simple SMPS buck converter circuit:

Rr 10W 1/2W
Rf 10KW 1/4W
Rburden 4.7kW 1/4W
Cin 4.7 μF, 450V Electrolytic Capacitor
C1 33 μF, 50V Electrolytic Capacitor
C2 100 μF, 16V Electrolytic Capacitor
C3 1 μF, 25V Electrolytic Capacitor
C4 22 nF Ceramic capacitor
Dr Diode 1N4007
D1 Diode BA159 (fast)
D2 Diode 1N4148 (fast)
D3 Diode 1N4004
Dz 22V Zener
Dz1 27V Zener
Dz2 5.6V Zener
L 1.5 mH
Lf 470 μH Inductor
IC1 STMicroelectronics VIPer12ADIP


PCB Design and Component Layout of the above explained SMPS buck converter circuit using IC VIPer12A

This is the simple design and sensitivity and selectivity of the receiver are good. This circuit is use a compact three transistor, regenerative receiver with fixed feedback. The circuit is based on transistor as core of the operation. The transistor that is used is BC549. This is the figure of the circuit.


The tuned circuit is designed for medium wave, but the circuit will work up to much higher frequencies if a different tuning coil and capacitor are used. Q1 and Q2 form a compound transistor pair featuring high gain and very high input impedance. This is necessary so as not to unduly load the tank circuit. Q1 operates in emitter follower, Q2 common emitter, self stabilizing bias is via the 120k resistor and the tuning coil. As Q2 operates in common emitter its base voltage will be a V be drop higher than ground or about 0.71V in my test sample. The 120k resistor provides regenerative feedback, between Q2 output and the tank circuit input and its value affects the overall performance of the whole circuit.

The tuning coil can be salvaged from an old AM receiver. However to make your own wind about 50 to 60 turns of 26 swg enamel coated copper wire over a 3/8 inch ferrite rod about 3 inches long. This circuit is powered by 9 VDC.