TDA2822 Integrated Amplifier Circuits General

General integrated amplifier circuit external components and need more larger heatsink. This paper presents a simple amplifier circuit, made easy. TDA2822 amplifier integrated circuits used in music players, portable DVD and other audio playback; power is not great but you can satisfy the requirements of the hearing, and the circuit is simple, good sound quality, wide voltage range of characteristics such as the amateur production Small amp better choice.

Circuit as shown in Figure 5-107.TDA2822M amp with an integrated circuit to a BTL, (the use of mono and stereo when two) external components only one resistance and two capacitors, with no heatsink, the playback results were satisfactory.
Selection and installation of components:
IC TDA2822M to 8 feet dual inline package, if available can not buy TDA2822 instead, TDA2822 and TDA2822M the same package, which difference is: TDA2822M from 3 V to 15 V can work, and the maximum operating voltage TDA2822 only 8V. TDA2822 must use the voltage dropped to 8 V below. Numerical informal request R1, 10 k generally choose the carbon film resistors. C1 choice of polyester 0.1 uF capacitor, C2 for 100 uF/16V the electrolytic capacitor.

Figure 5-108 its printed circuit board map.

As a simple circuit, the PCB can be engraved shovel role of the rule of law James Shuimo sandpaper or a small amount of water polishes kraft paper, water wash dry, apply a layer of rosin alcohol solution, stem directly after the solder components to the copper foil surface. Welding good after the inspection correct, then no access to speakers, connected to power, between the positive and negative output voltage should be less than 0.1 V. Connected to speakers, hand-touch input, the speaker should be given greater "Ong" sound. Then try to enter the sound signal. Circuit boards do not have to drilling,


Should be used Note: Because this amp for direct coupling, it can not be with DC input signal components. If a DC input signal components must be input in a series connection of around 4.7-10 uF capacitor separated, otherwise, they will have great DC current flow through speakers, so as fever burned. In practice, if 5-107 plans to conduct appropriate reforms are desirable effect.

To improve the circuit as shown in Figure 5-109.

In use found that the volume opened the largest TDA2822M fever when hot, can give TDA2822M produced a heatsink, generally shown in Figure 5-110. Heatsink can be thick lmm, long 38 mm, width of 25 mm made of aluminum plate. And in the heatsink on the reopening of 5-to 6-10 mm, width l mm the slot, then do along the dotted line into a hot film, "I" shape. When first installed heatsink on the release point in TDA2822M. Click 5-111 (a) use the thin Bangzha to bear. It should be noted that the TDA2822M the pin number written on the side of the heatsink, so as to avoid mistakes when welding. And heatsink, volume open only to the most warm, good cooling effect. This method can also be used for other small integrated circuit heat dissipation. Amp circuit caused by two Walkman stereo power continue, to promote two small speakers, good effect.

You can build on the stereo two-channel input circuit, the use of power when a small point, but has it.

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88 108 MHz Voltage Controlled Oscilator for PLL Controller This Circuit will explain the PLL unit and the VCO Voltage Controlled Oscillator which w

88-108 MHz Voltage Controlled Oscilator for PLL Controller

This Circuit will explain the PLL unit and the VCO (Voltage Controlled Oscillator) which will create the FM modulated RF signal up to 400mW. the schematic to follow my function description. The main oscillator is based around the transistor Q1. This oscillator is called Colpitts oscillator and it is voltage controlled to achieve FM frequency modulation) and PLL control.

Q1 should be a HF transistor to work well, but in this case I have used a cheap and common BC817 transistor which works great. The oscillator needs a LC tank to oscillate properly. In this case the LC tank consist of L1 with the varicap D1 and the two capacitor (C4, C5) at the base-emitter of the transistor. The value of C1 will set the VCO range.

The large value of C1 the wider will the VCO range be. Since the capacitance of the varicap (D1) is dependent of the voltage over it, the capacitance will change with changed voltage. When the voltage change, so will the oscillating frequency. In this way you achieve a VCO function. You can use many different varicap diod to get it working. In my case I use a varicap (SMV1251) which has a wide range 3-55pF to secure the VCO range (88 to 108MHz).

Inside the dashed blue box you will find the audio modulation unit. This unit also include a second varicap (D2). This varicap is biased with a DC voltage about 3-4 volt DC. This varcap is also included in the LC tank by a capacitor (C2) of 3.3pF. The input audio will passes the capacitor (C15) and be added to the DC voltage. Since the input audio voltage change in amplitude, the total voltage over the varicap (D2) will also change. As an effect of this the capacitance will change and so will the LC tank frequency.

You have a Frequency Modulation of the carrier signal. The modulation depth is set by the input amplitude. The signal should be around 1Vpp. Just connect the audio to negative side of C15. Now you wonder why I dont use the first varicap (D1) to modulate the signal? I could do that if the frequency would be fixed, but in this project the frequency range is 88 to 108MHz.

If you look at the varicap curve to the left of the schematic. You can easily see that the relative capacitance change more at lower voltage than it does at higher voltage. Imagine I use an audio signal with constant amplitude. If I would modulated the (D1) varicap with this amplitude the modulation depth would differ depending on the voltage over the varicap (D1). Remember that the voltage over varicap (D1) is about 0V at 88MHz and +5V at 108MHz. By use two varicap (D1) and (D2) I get the same modulation depth from 88 to 108MHz.

Now, look at the right of the LMX2322 circuit and you find the reference frequency oscillator VCTCXO. This oscillator is based on a very accurate VCTCXO (Voltage Controlled Temperature controlled Crystal Oscillator) at 16.8MHz. Pin 1 is the calibration input. The voltage here should be 2.5 Volt. The performance of the VCTCXO crystal in this construction is so good that you do not need to make any reference tuning.

A small portion of the VCO energy is feed back to the PLL circuit through resistor (R4) and (C16). The PLL will then use the VCO frequency to regulate the tuning voltage. At pin 5 of LMX2322 you will find a PLL filter to form the (Vtune) which is the regulating voltage of the VCO. The PLL try to regulate the (Vtune) so the VCO oscillator frequency is locked to desired frequency. You will also find the TP (test Point) here.

The last part we havent discussed is the RF power amplifier (Q2). Some energy from the VCO is taped by (C6) to the base of the (Q2). Q2 should be a RF transistor to obtain best RF amplification. To use a BC817 here will work, but not good.

The emitter resistor (R12 and R16) set the current through this transistor and with R12, R16 = 100 ohm and +9V power supply you will easy have 150mW of output power into 50 ohm load. You can lower the resistors (R12, R16) to get high power, but please dont overload this poor transistor, it will be hot and burn up… Current consumption of VCO unit = 60 mA @ 9V.

Printed Circuit Board (PCB.pdf)
This is how the real board should look when you are going to solder the components.
It is a board made for surface mounted components, so the cuppar is on the top layer.

Parts List
100 = R7, R12, R16
330 = R4
1k = R1, R2, R3, R10
3.3k = R11
10k = R5, R6, R14, R17
20k = R13
43k = R9
100k = R8, R15
3.3pF = C2, C16
15pF = C4, C6
22pF = C5
1nF = C1, C3, C8, C17, C22, C23
100nF = C7, C9, C11, C12, C13, C14, C19, C20
2.2uF = C15, C18
220uF = C10, C21
L1 = 3 turns diam 6.5mm (Everything from 6 to 7 mm will work good!)
L2, L3, L4 = 10uH
D1, D2 = SMV1251
Q1 = BC817-25
Q2 = BFG193
X1 = 16.800 MHz VCTCXO Reference oscillator
V1 = 78L05
IC1 = LMX2322 

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