Phono RIAA Preamplifier 1

Phono RIAA Preamplifier 1

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�� CD �� . �� , �� PHONO, �� . �� C1-10 �� [1].�� RIAA [Fig.2]. �� 50�� 500�� IC1-3, �� R4-5, C2 [R17-18, C11] �� 2122�� R7-8, C3 [R20,21, C12]. �� C2,3,11,12 �� 1% � �� 5% [2]. �� , �� , �� , �� , �� . �� , �� RCA, �� , �� Led D1, �� . �� . �� , �� , �� . �� , �� R9-22, �� .

RIAA

Fig.2- RIAA recommended equalization characteristic

The CD henceforth has prevailed for the reproduction of music. Exist however many that they dispose a old classic turntable, with moving magnet head, they have however amplifier that does not dispose a PHONO input, but dispose LINE inputs. The capacitors C1-10 should be selected so, as to they suit with the head characteristics, that we use [1]. The circuit it undertakes it simultaneously elevate the head low voltage in LINE level and it makes the essential response correction according to the RIAA standard [Fig2]. This correction him they make for the frequencies of 50HZ and 500HZ the filter in the feedback of IC1-3, constituted from the R4-5, C2 [ R17-18, C11 ] and frequency 2122HZ with pathetic filter R7-8, C3 [ R20,21, C12 ]. Capacitors C2,3,11,12 should have tolerance 1% or if they are also measured matching with a capacitance meter, it can they are tolerance 5% [2]. The circuit use one simple, but good power supply, is enough it�s armor-clad by the remainder circuit, if it needs, with a aluminium, so that we avoid the noises. All the circuit can be placed in a small box, from which will only come out the RCA jack, the main power cable, in the back box part and the Diode Led D1, in front part. Good it�s are placed a Fuse and a good small switch. The signal from the circuit outputs, with a good cable, is led to a free LINE input of amplifier or preamplifier. If the output signal level, is not that we want, we can change the resistors R9-22, with other value so that we adapt the level.

Part List

R1-14=47Kohm	C1-10=100pF [1]*See text	C29-30=4.7uF 25V
R2-3-15-16=10Kohm	C2-11=150nF 100V MKT [2]*See text	IC1-2-3-4=OP27-NE5534
R4-5-17-18=1Kohm	C3-12=15nF 100V MKT [2]*See text	IC5=7815
R6-19=220ohm	C4-13=1uF 100V MKT	IC6=7915
R7-8-20-21=10Kohm	C5-14=100nF 100V MKT	D1=LED RED 3mm
R9-22-27=1.2Kohm	C6-7-15-16=47nF 100V MKT	BR1=Bridge Rectifier 100V 1.5A
R10-23=100ohm	C8-9-17-18=47uF 25V	T1= 2X15V 1.5VA PCB transformer
R11-24=47ohm	C19-20=2200uF 25V Low profile	J1-2-3-4=RCA Pcb connectors
R12-13-25-26=47ohm	C21-22-23-24=47nF 100V MKT	J5=connector 5mm pin to pin
R28-29=100Kohm	C25-26-27-28=100nF 100V MKT	All the resistors is 1/4W 1%

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Sam Electronic Circuits 8/01

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