UM66T-08S Melody IC projects anyone?

[gasboss775]

Tonight I bought 3 of these super simple melody generator IC's. Going to see if anything interesting can be done with them.

I'm thinking about interfacing it to some CMOS logic circuits to mess up the melody. Has anyone else tried experimenting with these chips?

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[gasboss775]

OK, well the basic tune is pretty cheesy "happy birthday," there are other varieties too. However I think it may have potential with subsequent processing. Im into CMOS just now so will likely be focussing on such technology for the required processing.

The chip is powered from 1.5 to 3 Volts so not immediately compatible with CMOS, but reasonably easy to interface.

When the chip is powered up it plays the tune once then stops. The output is just a square wave of fixed amplitude. There are no pauses between notes. When the cycle is complete the output goes low.

What I was looking for is the ability to trigger the circuit externally or for it to retrigger at the end of the cycle. In order to retrigger it is necessary to interrupt the power for a few hundred milliseconds. For some reason a shorter interruption doesn't retrigger the cycle, perhaps there's a capacitor on the chip?

I also wanted a gating input that is independent of the triggering process.

The circuit below satisfies these requirements and has been tested on a breadboard.

The output is CMOS 4000 compatible.

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[gasboss775]

Some thoughts on processing the output:

The tune is in quite a high register 2-4 KHz, not quite sure what exactly that is in musical terms, but must be a few octaves above middle C. In this respect I think there's potential to bastardize the sickly sweet tune using dividers to generate a different "melody"

I tried it with some ring modulation and I think this may have potential too, particularly if the modulating oscillator was following a pattern of its own rather than just a fixed pitch.

I also tried it with my 4093 NAND Gate Filter with reasonable results ( is more interesting that the square wave with no modulation at all! )

[gasboss775]

Tried out the UM3561 this morning:

This ones a sound effect chip rather than a melody generator. It is potentially more interesting in that in addition to the four different sound effects there's an external resistor that sets the internal clock frequency and by varying this with say a vactrol a wider range of sounds can be experienced, sadly I fried one of the control input pins by accidentally connecting it to + 12 V ( the chip works on 3V like the UM66 )

[PHOBoS]

Don't think I have used the UM3561 yet although it does sound familiar so maybe I did order it some time ago but haven't
got to using it yet. I did recently design a synth module with a similar chip though, the CK9561. I am currently working on
putting together the kits for it so once I have those finished I will upload the schematic and more info which might be useful.
Some years ago I used a melody chip intended for doorbells to make the melody mutilator. I wonder if I can find the schematic
to see what kind of chip I used for that.

But anyways, yes! there are a lot of those chips that can be fun to combine with lunettas since the output is usually a digital signal.



edit: checked a video with the UM3561 which sounds very similar if not the same as the CK9561. Using that one would have made
the PCB design a bit easier oh well, maybe I'll make a V2.0

[gasboss775]

I've got another one the SMC0608S, it outputs a series of 6 different alarm/siren type sounds then repeats. It also has an external resistor that sets the internal clock frequency and can be varied over a wide range using this. It also has a stop/reset control pin.

PHOBoS your device looked cool, what was the extension part for?

[gasboss775]

The SMC0608 turns out to be quite interesting even with some fairly simple CMOS circuitry round it. Have tried A 4024 divider, digital ring modulation using an XOR & a square wave oscillator. I've also tried feeding it into my 4093 based filter with good effect, is more effective with binary division via the 4024 prior to going into the 4093 filter.

4093 "Goschillator" Filter

[gasboss775]

Here is the interface circuit for the SMC0608S, it should work with the UM3561 too:

Notes: I used a VTL5C1 Vactrol, with others you might need to change the 3K6 resistor, for example the NSL32 vactrols require much less current and something like 47K would work for them, however I found them to be much to slow for this application. It might be worth experimenting with making one yourself as the VTL5C1 can be a bit pricey.

The top opamp, in case you're wondering provides a regulated +3 Volt supply, as the chip draws less than 1mA plus the output current the lm358 can power it directly ( the lm358 can source at least 20mA )

Power supply was + 12 V

There are identical outputs from pins 5 & 6 on the SMC0608S, so the 4K7 resistor can be connected to either of these.

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