## Precision Metronome and Pitch generator Circuit

Precision Frequency generator 1 to 999 Hz

Precision Metronome 1 to 999 beats per minute

**Parts:**

R1 1M 1/4W Resistor

R2 22K 1/4W Resistor

R3 6K8 1/4W Resistor

R4 4K7 1/4W Resistor

R5 47K 1/4W Resistor

R6 100K 1/4W Resistor

R7 39K 1/4W Resistor

R8 12K 1/4W Resistor

C1 47pF 63V Ceramic Capacitor

C2 2-22pF 63V Ceramic Trimmer

C3 470pF 63V Ceramic Capacitor

C4 10pF 63V Ceramic Capacitor

C5 100nF 63V Polyester Capacitor

C6 220nF 63V Polyester Capacitor

C7 22µF 25V Electrolytic Capacitor

D1-D15 1N4148 75V 150mA Diodes

IC1 4060 14 stage ripple counter and oscillator IC

IC2 4082 Dual 4 input AND gate IC

IC3 4520 Dual binary up-counter IC

IC4 4518 Dual BCD up-counter IC

IC5 4046 Micropower Phase-locked Loop IC

IC6 4040 12 stage ripple counter IC

Q1 BC337 45V 800mA NPN Transistor

XTAL 2.4576 MHz Miniature Quartz crystal

SW1 BCD Miniature Thumbswheel Switch (units)

SW2 BCD Miniature Thumbswheel Switch (tens)

SW3 BCD Miniature Thumbswheel Switch (hundreds)

SW4 SPST Slider Switch (On-off)

SW5 SPDT Slider Switch (Metronome-Pitch)

SPKR 8 Ohm, 50 mm. Loudspeaker

B1 9V PP3 Battery

Clip for 9V PP3 Battery

**Circuit operation:**

CMos IC1 and IC2B quad AND gate form a 2.4576 MHz crystal oscillator plus a 2400 times divider. IC3A provides further division by 16, obtaining a 64 Hz stable frequency square wave. This frequency is multiplied by operation of Phase Locked Loop IC5, double decade divider IC4 and IC3B 4 bit binary divider, by the number set by three miniature BCD thumbswheel switches SW1, SW2 and SW3: units, tens and hundreds respectively.

Connecting, by means of SW5, Q1 base to pin 2 of IC6, we obtain after a 64 times division, the same frequency set by thumbswheel switches with quartz precision, and no need for a scale indicator.

Volume regulation of the pitch generator is obtained trimming resistor R5. In the same manner, with SW5 set to metronome, the small speaker reproduces the frequency set by thumbswheel switches but divided by 3840, thus obtaining beats per minute ratio

author:RED Free Circuit Designs,

website: http://www.redcircuits.com/