Circuit Wiring

Antennas are much shorter than quarter wavelength impedance obtained is very small and highly dependent on the frequency. It was a difficult game impedances over a decade of frequency coverage. Instead, the phase of the input source-follower FET Q1. A high impedance input successfully bridges Antenna characteristics at any frequency.

1/4 wavelength Active Antenna Circuit Diagram
 
transistor Q2 is used as a follower, to provide a high impedance load for Q1, but more importantly that it makes to drive low-impedance amplifier coupled to commonly Q3, which each receive a voltage amplifier. Q3 Q4 turns transistor output impedance is relatively low in impedance, which is enough to drive 50 Three dimensional receiver, Antenna input impedance.

This is a minimal circuit. right management a single IC, but the amplifier has 4 channels, 11 channels apiece watt, which is Philips IC TDA1554 run to apposite in support of listening by the side of land of your birth otherwise dressed in one vehicle. Just since the power supply 12-15 volt otherwise yearn for transpire used to open out any home acting sound organization. The at the outset 2-channel amplifier front speakers. And 2 to widen the back surround sound speakers additionally.

This circuit power supply 12 volts to 18 volts Power consumption next to 5A. The input 4 input pins 1, 2, 17 and 18 is not speaking into a horizontal input inverter Ting 2 channels (Pin 1, 17). inverse classic and input object 2 channels (pins 2, 6). with the purpose of we can function that. To output point to phase or else did not return. The output self-control be there the fourth slot on the crutch 6, 8, 12, 10, with a C7-C10 serves to boost the low frequency stability better in the past you die to the loudspeaker. The switch S1 acts on mute by urgent S1 will be stopped sound procedure circuit here Mute, and if unfasten circuit S1 supply on the point of to masterpiece. The C5 and C6 bidding filter light to smooth absent and eliminate interference.

If connect to car battery where operating voltage is about 13.2V, then each channel can give 22W(4Ω) – what is more than enough for me. This amplifier I probably will use to test audio processor TDA7313 which is stil in development phase.

I didn’t find much information about this chip on the internet so I decided to built it and try on my own. As datasheets of TDA7384 says it is low distortion, low output noise, low external component count. Also has Stand-By function and Mute function. It has several protections like from output short circuit to GND or to Vs, capable to handle very inductive loads, thermal limiter, load dump voltage. TDA7384 is an AB power amplifier cased in flexiwatt25 (eagle library is included in project archive) package wich is designed for high end car radio applications. It allows rail to rail output voltage swing with no need of boot-strap capacitors.

I have followed the schematic in datasheed when building circuit. In datasheet you may also find PCB layout but it is two layered and didn’t fit to may box I’ve chosen. So I have made single sided PCB 50X100mm.

As I put pins on PCB for ST-BY and Mute but I not using them, I connected these pins to VCC like it is shown in PCB view. According to datasheet St-By and Mute turns off amplifier if signal in input is lower than 3.5V. So it is recommended to connect these pins to Vcc if not used.

Maximum power dissipation of chip is 80W(Tcase=70ºC), so it can handle 4 channels working at power of 20W each. But of course chip in a box doesn’t have good ventilation so I’ve put a radiator to ensure that amplifier effectively dissipates heats. I didn’t try to load amplifier to maximum to se if it doesn’t heat up to much. But at normal sound level it stays warm what is normal.

Dont forget to put thermal paste between chip and radiator to ensure lower thermal resistance. And here we go – brand new power amplifier ready to go:

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