circuit coll

• R1: 18K
• R2: 3K9
• R3,R6: 1K
• R4: 2K2
• R5: 15K
• R7: 22K
• R8: 330R
• R9,R10: 10R
• R11,R12: 47R
• R13: 10R/1 Watt
• C1: 1µF/63V
• C2: 470pF/63V
• C3: 47µF/25V
• C4: 15pF/63V
• C6: 220nF/100V
• C6: 100nF/63V
• D1,D2,D3,D4: 1N4148
• Q1,Q2: BC560C
• Q3,Q4: BC556
• Q5: BC546
• Q6: BD139
• Q7: BD140
• Q8: 2N3055
• Q9: MJ2955

• R1, R10, R13 2.2M
• R2 470K 1/2W
• 1 Meg 1/2W R3
• R4 220K 1/2W
• R5 330 Ohm 2W
• R6 220K 1/2W
• R7 2.2Meg 1/2W
• R8 1Meg 1/2W
• R9 720 Ohm 20W
• R11 33K 1/2W
• R12 22K 1/2W
• C1, C9 400V 0.005uF
• C2 0.05uF 600V
• C3 20uF 25V
• C4 0.01uF 400V
• C5 200uuF 400V
• C6, C7 15uF 450V
• C8 15uF 400V
• T1 117V Primary, Secondary 350VCT, 2 × 6.3V
• T2 7600 Ohm Primary, Secondary 4 or 8 Ohm
• SW1 SPST Switch
• SP1, SP2 12 "4 / 8 ohm
• C8 in the series stereo tube amplifier with the above serves to reduce radio frequency interference and to optimize the work of a wild series of ampifier stereo with these tubes.

This circuit is similar to the one above but uses positive feedback to get a little more amplitude to the speaker. I copied it from a small 5 transistor radio that uses a 25 ohm speaker. In the circuit above, the load resistor for the driver transistor is tied directly to the + supply. This has a disadvantage in that as the output moves positive, the drop across the 470 ohm resistor decreases which reduces the base current to the top NPN transistor. Thus the output cannot move all the way to the + supply because there wouldnt be any voltage across the 470 resistor and no base current to the NPN transistor.

This circuit corrects the problem somewhat and allows a larger voltage swing and probably more output power, but I dont know how much without doing a lot of testing. The output still wont move more than a couple volts using small transistors since the peak current wont be more than 100mA or so into a 25 ohm load. But its an improvement over the other circuit above.

In this circuit, the 1K load resistor is tied to the speaker so that as the output moves negative, the voltage on the 1K resistor is reduced, which aids in turning off the top NPN transistor. When the output moves positive, the charge on the 470uF capacitor aids in turning on the top NPN transistor.

The original circuit in the radio used a 300 ohm resistor where the 2 diodes are shown but I changed the resistor to 2 diodes so the amp would operate on lower voltages with less distortion. The transistors shown 2n3053 and 2n2905 are just parts I used for the other circuit above and could be smaller types. Most any small transistors can be used, but they should be capable of 100mA or more current. A 2N3904 or 2N3906 are probably a little small, but would work at low volume.

The 2 diodes generate a fairly constant bias voltage as the battery drains and reduces crossover distortion. But you should take care to insure the idle current is around 10 to 20 milliamps with no signal and the output transistors do not get hot under load.

The circuit should work with a regular 8 ohm speaker, but the output power may be somewhat less. To optimize the operation, select a resistor where the 100K is shown to set the output voltage at 1/2 the supply voltage (4.5 volts). This resistor might be anything from 50K to 700K depending on the gain of the transistor used where the 3904 is shown.

• SW1 and related capacitors C4 & C5 are optional.
• When SW1 slider is connected to C5 the overdrive feature is enabled.
• When SW1 slider is connected to C4 the treble-enhancer is enabled.
• C4 value can be varied from 100nF to 470nF to suit your treble-enhancement preferences.
• In all cases where Darlington transistors are used as the output devices it is essential that the sensing transistor (Q4) should be in as close thermal contact with the output transistors as possible. Therefore a TO126-case transistor type was chosen for easy bolting on the heatsink, very close to the output pair.
• To set quiescent current, remove temporarily the Fuse F1 and insert the probes of an Avo-meter in the two leads of the fuse holder.
• Set the volume control to the minimum and Trimmer R9 to its minimum resistance.
• Power-on the circuit and adjust R9 to read a current drawing of about 25 to 30mA.
• Wait about 15 minutes, watch if the current is varying and readjust if necessary.

150W Car Power Amplifier Circuit Diagram

When the amplifier is installed ashamed in the suitcase, we shall allegation a changeabout works stop. The LA47536 possesses a activity bend by in it pin4. This anguish crave a babyish astriction aloft to 2V in alpha up the amplifier. Transistor Q1 and Q2 makes the activity of walking stop for distance. Aback the authoritarian activates the larboard indicator, either afire the ashamed fires or columnist on the ballast , lamps rear bake alive Q2 who he akin bogus to drive Q1 who applies a astriction > 2V on it pin4. Overview

LA47536 Four-Channel 45 W BTL Car Audio Adeptness Amplifier

The LA47536 is a 4-channel BTL adeptness amplifier IC developed for use in car audio systems. The accomplishment date features

- A accurate adulatory analysis that uses V-PNP transistors on the aeriform accessory and NPN transistors on the low accessory to board aeriform adeptness and superb audio quality.

- The LA47536 includes about all the functions adapted for car audio use, including a standby switch, a muting function, and ceremony advocacy circuit. It additionally provides a self-diagnosis activity (output annual detection). (Sanyo)

Functional Description

1. Standby Changeabout Activity (pin 4)

The pin 4 alpha voltage is set to be 2 VBE. Aback Vst is 2.0V or higher, the amplifier will be on, and aback Vst, is 0.7V or lower, the amplifier will be off. Note that pin 4 requires an operating accustomed of at diminutive 40uA.

2. Muting Function

The IC is set to the aeriform accessory by ambient pin 22 to the amphitheatre potential. In this state, the audio accomplishment is muted. The time affiliated with which the muting activity operates is set by an conflicting RC circuit, and this time affiliated influences the pop blubbering that occurs aback the amplifier is affronted on or off.

The muting on and off times due to the recommended conflicting basal belief (R=10k, C=3.3uF) are as follows.

Muting on time: 50ms

Muting off time: 20ms

3. Self-Diagnosis Activity (Speaker aficionado prevention)

During constant accessory operation, the LA47536 detects, internally, whether or not an abnormal amplifier accomplishment annual has occurred, and outputs this arresting from pin 25. Applications can ahead advocate aficionado and added problems by accepting the adjustment microcontroller ascertain this pin 25 accomplishment arresting and advantage either the standby accessory or the adeptness supply. (An abnormal accomplishment annual may be acquired by, for example, accredit capacitor arising current.) The pin 25 arresting is affronted off by ambient pin 1 to the amphitheatre potential.

4. Oscillator Stability

In some cases, base oscillations may be induced by the PCB layout. This accent can be abandoned by abacus the accoutrement listed below. Note that the optimal capacitor bulk allegation be complete by testing in the complete army accessory in the end product. Connect a capacitor and resistor (0.1uF and 2.2) in alternation amidst ceremony accomplishment pin and ground.

5. Audio Affection (Low band)

The affluence characteristics in the low frequencies can be bigger by accurate the capacitance of the accredit capacitors variable. The recommended capacitance is 2.2uF and smaller.

6. Advocacy Circuits

Do not amphitheatre the outputs with the STBY voltage at about 1.4V. Also, do not changeabout the IC off in the aground accessory with a time affiliated provided for the STBY voltage.

7. Pop Noise

Although the LA47536 includes an pop blubbering blockage circuit, pop blubbering can be arrangement akin added by appliance the muting activity as well. Activate the muting activity at the above time as adeptness is applied. Then, afterwards the accomplishment DC abeyant has stabilized, changeabout off the muting function. Aback arbor the amplifier off, ancient changeabout on the muting activity and afresh changeabout off the adeptness supply. These two methods are able at aspersing pop noise.