Enclosure not stated

5 stage envelope filter

Schematic

Check before you build · 3 values the reader of this schematic was not sure of

*k resistors: value not given, to be matched to the LDR
0.003uF and 0.002uF (stages 3 and 4): not written, inferred from the stepping .005/.004/.../.001
Op amps: type and count not given; 10 single op amps assumed (one LDR inverting stage plus one high-pass stage per stage)

Ref	Value	Normalized	Notes
Resistors 5
×5	?	?	input resistor of each LDR stage; 'tweak to match value of the LDR', no value given; read from the schematic by eye
×5	10k	10k	one per stage, between the LDR stage and the high-pass filter; read from the schematic by eye
×5	100k	100k	feedback resistor of each filter op amp; read from the schematic by eye
×1	680ohm	680	LED string resistor at the BA6124; read from the schematic by eye
×1	10k	10k	BA6124 pin 7 to ground, in parallel with the 10uf; read from the schematic by eye
Capacitors 6
×2	0.005uF	5n	stage 1 (series and feedback caps both marked *uf); read from the schematic by eye
×2	0.004uF	4n	stage 2; read from the schematic by eye
×2	0.003uF	3n	stage 3; inferred from '.005uf at stage 1, .004uf at stage 2, up to .001uf at stage 5'; read from the schematic by eye
×2	0.002uF	2n	stage 4; inferred as above; read from the schematic by eye
×2	0.001uF	1n	stage 5; read from the schematic by eye
×1	10uf	10u	electrolytic, BA6124 pin 7; read from the schematic by eye
ICs 2
×10	Op amp	OP AMP	two op amps per stage, no part number given; drawn as single sections; read from the schematic by eye
×1	BA6124	BA6124	LED VU-meter driver; the schematic mislabels it BA6214, which is a ROHM motor driver; read from the schematic by eye
Opto 1
×5	LDR	LDR	LDRs 1-5, each lit by one of the LEDs (LED/LDR pairs); no type given; read from the schematic by eye
LEDs 1
×5	LED	LED	LEDs 1-5 on BA6124 pins 1-4 and 6; read from the schematic by eye