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Melody Generator for Greeting Cards: This tiny circuit comprising of a
single 3 terminal IC UM66 can be built small enough to be placed inside a greeting
card and operated off a single 3V flat button cell. There is not much to the
circuit. The UM66 is connected to its supply and its output fed to a transistor for
amplification. You can either use a 4ohm speaker or a " flat" piezoelectric tweeter
like the one found in alarm wrist watches. If you use the piezo, then it can be
connected directly between the output pin 1 and ground pin 3 without the transistor.
The UM66 looks like a transistor with 3 terminals. It is a complete miniature
tone generator with a ROM of 64 notes, oscillator and a preamplifier. When it first
came into market, it was programmed for the "Jingle bells" tune. Now they come with a
wide variety of different tunes. (added 6/06) |
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Metronome and Pitch Generator: (circuit added 9/04) |
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Metronome Circuit: This circuit uses a couple of Op-amps to produce an
interesting sound effect. The left hand CA741 is wired as a standard astable and
produces the timing pulses, controlled by C1, R2 and VR1. The output is fed via
C2 to the second op-amp and is also direct coupled via the zener ZD1 to Q1. The
right hand CA741 is configured as an integrator, its purpose being to distort the
output pulse from the first op-amp. This produces a ringing effect on the output pulse
and gives the circuit a characteristic "tick" sound. The output pulse at the
first op-amp will cause the zener and Q1 to conduct on every positive transition. The
1k resistor R8 then acts as a low impedance shunt at the input of the integrator
and produces a characteristic "tock" effect. R8,R7,R9,C3 and C4 may all be adjusted to
tailor the sound effect. (added 10/05) |
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MicroController MIDI interface: (electronic circuit added 4/05) |
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MIDI Controlled Switches: can drive up to128 individual relays, solenoids,
motors, etc. with a MIDI note-on and note-off messages (added 6/06) |
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MIDI Controller Footpedal: (electronic circuit added 4/05) |
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MIDI Drum Machine Analog Input Schematic: (electronic circuit added 4/05) |
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MIDI Drum machine project: (electronic circuit added 4/05) |
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MIDI interface/cable tester: (electronic circuit added 4/05) |
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MIDI keyboard: (electronic circuit added 4/05) |
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MIDI merger schematic: (electronic circuit added 4/05) |
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Midi Passthrough Circuit: (electronic circuit added 4/05) |
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MIDI Tester: (electronic circuit added 4/05) |
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MIDI to CV interface: (electronic circuit added 4/05) |
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Midibox 64: (diagram added 2/07) |
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Mini Metronome: Linear scale Small size. 40 to 208 beats per minute (added
3/05) |
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Mini Portable Guitar Amplifier: Can be fitted into a packet of cigarettes.
Also suitable as Fuzz-box (added 3/05) |
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Mini Portable Guitar Amplifier: Can be fitted into a packet of cigarettes.
Also suitable as Fuzz-box (added 6/06) |
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Miniature metronome: (electronic circuit added 4/05) |
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MP3 Player #3: Intersil Application Block Diagram (app note added
6/06) |
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MP3 Player (mp3playerswitzerland): (electronic circuit added 4/05) |
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MP3 Player: This is a pocket-sized MP3 player. It has attracting attention
as new kind of the portable audio. I built it let's build a thing in fashion like
that. (added 6/06) |
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Music On-Hold for Telephones: (electronic Circuit / Schematic added 10/04) |
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Musical ‘Touch’ Bell: (electronic Circuit / Schematic added 10/04) |
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Musical Instrument (Expandable) Graphic Equaliser: (electronic circuit added
1/07) |
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Musical Instrument (Expandable) Graphic Equalizer: standard equalizer plus
bonus distortion unit (added 6/06) |
