Flamenco Metronome

FLAMENCO METRONOME			Circuit Details

PART	Location	VALUE	FUNCTION

Rl	D8	270R	TC res. With Cl, sets freq. of 'beat' clicks.
R2	B11	470R	F/B res. Mixes 'accent' click with 'beat*
			clicks. Also sets freq. of 'accent' clicks
			to make them sound higher than the beats.
R3	J5	330R	Part of TC resistance with VRl. Limits high end
			of tempo range.
R4	F11	4K7	Bias res. for sound o/p cct.
R5	D11	1K	TC res. Sets duration of o/p clicks with C5.
R6	B12	1OOK	Bias res. for timer 1.
R7	L9	1OK	Base bias res. for Ql.
R8	MIO	4K7	Emitter bias res. for Ql. -ve pulse from
			IC3 needed to 'clear* IC2.
R9	D22	330R	Bias res. To provide a common tap off point
			for 'accent' pulses.

VR1	J3	1K Pot.	Tempo control.
VR2	B15	1K Pot.	Volume control.

C1	C7	22uF	TC capacitor. Sets freq of 'beat* clicks.
C2	G5	1OOuF	TC capacitor for clock. Acts with C3 to provide
			'normal time' tempo. Switched out of cct for
			' double time ' .
C3	G5	1OOuF	TC capacitor for clock.

C4	H6	O.1uF	Decoupling capacitor for ICI.
C5	F11	O.1uF	TC capacitor for timer 2.
C6	B14	O.1uF	Decoupling capacitor for IC4.
C7	C14	2.2uF	Sound cct coupling capacitor, chosen for optimum
			sound balance between the 2 o/p freq ' s ( subjective ) .
C8	H13	O.1uF	Decoupling capacitor for IC2.
C9	K1O	O.1uF	To prevent HF oscillation.
C1O	G15	O.1uF	Decoupling capacitor for IC3.
C11	O16	O.1uF	Decoupling capacitor for IC5.
C12	O23	O.1uF	Decoupling capacitor for IC6.
C13	P4	330uF	Decoupling capacitor for battery. Provides extra
			smoothing when plug pack is used.
C14	P5	O.1uF	To prevent HF oscillation.
C15	P7	O.1uF	To prevent HF oscillation.
C16	P8	1OOOuF	Decoupling capacitor for IC7.

Q1	L11	BC547	Non-inverting buffer.

D1-D12	E20	5mm RED LEDS	Accent indicators.
D13-D24	P20	5mm GREEN LEDS	Beat indicators.
D25 .	F5	5mm ORANGE LED	Double time indicator.
D26	B12	IN4004	Mixing diode.

IC1 A / B	I5	1/2 of 74132	Quad. Schmitt trigger NAND gate. System clock.
IC1c	C9	1/4 of 74132	Oscillator for click tone.
IC2	J12	74193	4 Bit upcounter. Upper limit of count cycle
			selected via S4.
IC3	J15	74154	4 Bit to 16 decoder. Decodes 4 Bit binary
			address from counter into max. of 12 line o/p's.
IC4	D12	556	Dual timer. Timer 1 is triggered by 'accent'
			clicks. Timer 2 is triggered by 'beat' clicks
			produced by oscillator IC1c. Timer 2 also mixes
			'accent' clicks with 'beat' clicks to produce
			the final sound heard in the speaker.
IC5 / 6	O20	7404 (2)	Provide 12 inverting buffers for beat LEDS.
IC7	O6	7805	5 Volt regulator to provide VCC for TTL chips.

S1a	O3	1/2 DPDT	Mini toggle switch. On/off switch.
S1b	B16	1/2 DPDT	Prevents C7 from discharging through speaker
			when unit is switched off.
S2	F3	DPDT	Double time switch.
S3	F20	12 Way Sw.	DIL PCB mount switch. Accent beat select.
S4	J25	12 Way Sw.	PCB mount rotary switch. Beat cycle select.

Jl	O2	2.5mm Jack.	Chassis socket for Ext. DC plugpack.
J2	B18	RCA Jack	Aux. o/p for ext. amp.
J3	C18	Headphone jack	Mini stereo head phone jach wired for mono.
SPK	Dl7	Speaker	8 Ohm-1/2 Watt, 3 inch speaker.