Soldering as a method of procrastination sort of got out of hand, and I ended up building a functional tremolo unit by piecing together circuit topographies from the datasheets of op-amps and using my existing knowledge of electronics. I’ve been meaning to really dig my teeth into electronics, but I’ve been constrained by funds, my glasses being broken, and also a lack of drive to work. This time round, I’ve got glasses, drive, and finally bought some higher quality more audio-suited op-amps. I breadboarded a very simple circuit of my own designing, and am currently in the process of soldering it onto stripboard. It comprises firstly an active attenuator, in the form of one half of a TL072 configured as an inverting amplifier with variable gain below 1, and secondly there is a ‘square’ wave (it’s rather wonky, and I borrowed the oscilloscope from uni to view my waveforms in hopes of figuring out how to sculpt the wave in a better manner – this is one of the problems im working on) oscillator that controls the gain of the amp via a homemade vactrol.

It barely functions, is intermittently noisy, but has lit the spark in me for further development. It also filters audio slightly as the gain rolls off. This is due (I think) to very small inbuilt capacitors within the TL072 interacting with feedback resistors to make a filter when resistance is low (or high….?). Regardless, it has many quirks and I happen to like those a lot, it has inspired me to create interesting, unpredictable circuits and instruments.

I have lofty dreams of building many things. A combo amp with numerous cones of wildly varying sizes, each with its own gain control. This will be implimented for reamping and filtering by using the relative gain of the cones to create a different frequency response. I would also like to build some very crappy distortion pedals, a super simple polyphonic synthesiser also appeals greatly to me.

With regards to my tremolo, I have ideas about how to fix its various problems. I think the noise may be coming from power supply and PCB layout; I plan on using a TLE2426 chip to engineer a buffered virtual ground as opposed to my existing solution (which is prone to voltage drift… I think?) that consists of a voltage divider with corresponding capacitors to support any excessive current draw. With regards to PCB layout, I still need to do some research on how to mitigate inductance-based interferance, but I know that it is a problem that can easily occur. Shielding the circuit from RF interferance is also a priority – I will be using old tins, which I can ground (if made of conductive metal).