EE novice here. I have an analog synth oscillator core which produces a sync pulse each time the waveform resets. I'd like to generate a short series of pulses triggered from each sync pulse, ideally with configurable count (from, say, 2 to 5) and manually tunable rate (generally much higher than the sync pulse rate, say 500-5000Hz). The pulse sequence must start synchronized to the input pulse -- it can't be a free-running oscillator that is just gated from the input.

Needn't be a pure analog solution but I don't want to involve an MCU. I'm looking for a low part count solution for easy breadboard experimentation more than for a particular result.

The goal is to get something like VOSIM, but I don't care much about the pulse shape; square digital pulses are fine. Bonus points if the pulses in the train decay in amplitude from the first to the last, but also not a requirement. The design shown in Fig. 11 of that paper is much more complex than I'm looking for.

Can anyone offer ideas for a starting point?

  • \$\begingroup\$ Fig 11 shows the design of the Osc. Which parts would you like to cut out in the sound? \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jun 9 at 18:10
  • \$\begingroup\$ @SunnyskyguyEE75 That's using an 8x128 RAM to hold a sampled representation of a carefully shaped pulse, and involves a number of buffers, counters, DACs, and a VCA; I'm looking for something cruder and simpler. Starting from Fig. 11 and cutting out the elements unnecessary to my requirements might be a fruitful approach, but seems like it might not be optimal. \$\endgroup\$ – Russell Borogove Jun 9 at 19:09
  • \$\begingroup\$ You need to be much more explicit about what "optimal" means to you. How much "cruder" can you allow? How much "simpler" does the solution need to be? It's hard to give you advice when you aren't clear about your requirements. You want configurable count, variable pulse rate, and decaying amplitude. This problem screams for an MCU, so why won't you use one? \$\endgroup\$ – Elliot Alderson Jun 9 at 19:21
  • \$\begingroup\$ I'm a professional software developer interested in learning different ways of solving problems. Using an MCU here won't teach me anything, and in fact the entire rest of the oscillator would go away. I'm being vague about requirements because I don't want to rule out oddball approaches. \$\endgroup\$ – Russell Borogove Jun 9 at 19:43
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    \$\begingroup\$ Being vague about the requirements wastes the time of the people who would normally try to help you. I'm not going to offer a suggestion if you might just say, "sorry, that's not what I'm looking for". If you are doing this just for the learning experience, why do you care about how "optimal" it is? \$\endgroup\$ – Elliot Alderson Jun 9 at 23:19

I made my best effort to make a simple design.

It uses the leading edge to create a variable one-shot to enable clocking of a variable speed Schmitt Trigger Astable to a Johnson (ring) Counter. The R weighting values convert the rotating "1" in the parallel output 10000000 to create a 5Vpp sine wave burst from 500 to 5 kHz. Rather than a variable digital-controlled pulse counter, I chose a variable Pulse width..

enter image description here

I don't think it will sound as nice as it looks, with a rather bland robotic sound. Have fun.


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