For
many application there's no substitute for sheer power- low efficiency
speakers, outdoor sound systems, or maybe you like the full flavour of the dynamic range of a high power amp. Whatever your requirement-this super power module should fit the bill. How it works: The amplifier
can be divided into three separate parts. These are : the input stage,
which consists of Q1-Q9 , a high gain, low power driver; the output or
power stage- witch only has a voltage gain of four but enormous power
gain; and the power supply. The input stage is a complementary
-differential network, each ''side" with its own current source. Each
transistor in this stage is run at a collector currant of about 0.7mA.
Emitter resistors are employed
to stabilize the gain and improve linearity. The output of Q1-Q5 drives
Q7 and Q9. The latter are virtually two constant-current sources run
about 7mA collector current. With an input signal these "current"
sources are modulated out of phase - the collector current of one
decreases while the other increases. This configuration provides quite
an amount of gain. In between the bases of these two transistors is Q8,
the thermal sensing-bias transistor. The voltage across Q8 may be
adjusted by TR1, thus setting the quiescent bias current for output
stage. The output stage, Q10-Q11, Q13-Q14 and Q16-17, has a gain of
about five, set by R44 and R28 plus R29. Diodes D4 and D6 prevent
reverse biasing of Q10 and Q11 (otherwise the output would be limited).
Protectionof the output transistors is provided by Q12 and Q15 which
monitor both current and voltage in the output transistors and bypass
the base current if the limit is exceeded. Frequency stabilization
provided by capacitors C6, C11, C12 and the RC networks R31/C10 plus R46/C15. Frequency response of the amplifier
is set by C1 and C7 (lower limit), C6 sets the upper frequency limit.
If you want use the Protection DC and Balance/Bridge circuits. All the
transistors that are inside the interrupted line are placed on an
aluminium corner and he screwed on a suitable heatsink. The transistors
Q7,Q10,Q11, Q8, Q9, Q13,Q14,Q16 and Q17 placed on this aluminium
corner, with suitable isolation from this
Part List
R1-19= 1Kohm 5W R34-35= 0.1ohm 5W C14-17= 100uF 100V
R2-3= 4.7Kohm R36-43= 39ohm C15= 100nF 250V polyester
R4-5= 22ohm R37-42= 5.6Kohm 1W Q1-2-3= BC547
R6-14= 10Kohm R38-41= 220ohm 5W Q4-5-6= BC557
R7-8= 1Kohm R39-40= 0.1ohm 5W Q7-11-12= BD140 or BC640
R9-23*=10K ohm R44-45= 0.1ohm 5W Q8= BC549
R10= 10ohm *see circuit sch. R46= 4.7ohm 2W Q9-10-15= BD139 or BC639
R11-13= 2.2Kohm R47= 100ohm Q13-14= MJ15004
R12= 22Kohm C1= 2.2uF 25V Q16-17= MJ15003
R15-16= 22ohm C2-6= 330pF ceramic TR1= 2K2 Trimmer
R17-18= 4.7Kohm C3-8= 100uF 100V F1-2= 5A Fuse Fast
R20-25= 390ohm C4-9= 100nF 250V D1-3= 5.1V 0.5W Zener
R21= 6.8Kohm C5= 100nF 100V polyester D2= 62V/5W Zener or 47v and 15V in series
R22= 4.7Kohm C7= 100uF 25V D4-5= 1N4004
R24-26-33= 220ohm C10= 1.5nF 100V polyester L1=10 turns diameter 1mm in 15mm diameter tube
R27-32= 100ohm 1W C11-12= 1.5nF 100V polyester
R28...31= 100ohm C13-16= 100nF 250V polyester *Use R23=6k8 for 4 ohm loudspeakers
