Does anyone have the schematic for pulse generator by Terence Thomas, as described in Chapter 2 of his book Sound Synthesis (ISBN 9780830692767))?

I am trying to build the sequencer, on page 58 from chapter 6 of the same book, the schematic of which I found here on this post, of the thread, simple 8 step sequecer for SL (the mis-spelling/typo in the title is intentional).

Programmable sequencer schematic - Terence Thomas

The following page (page 60), describes the oscillator used to provide a clock signal to the sequencer:

The sequencer used together with the pulse generator (described in chapter 2) form a unique control facility

I have searched for over a week now, and whilst I have a general idea of the circuit, I am missing a few details1.

From a post, on Buchla 144 dual square wave oscillator DIY, it appears that the pulse generator referred to is a UJT relaxation oscillator:

This is a “Terrence Thomas” build, from his book, from years ago, that is very similar to a Buchla, but has a 2N2646 saw-relaxation oscillator and a TL071-schmitt trigger (square-wave), with a 2N2222, for pulse modulation. The book calls for a 741, which does not work for crap, with the poor slew-rate and overall bad performance. It is a really quirky oscillator.

So I now know that it is a UJT relaxation oscillator, most probably very similar to that which Terence Thomas has posted in Unusual Components and Applications by Terence Thomas (Negisters, Unijunction transistors, Precision Resistors, and Hall Effect Devices):

UJT relaxation oscillator

However, some components (NOR gate, S2, S3, R5 and C7), which are referenced in Chapter 6, on page 60 are missing

Switch S3, on the pulse clock, provides access to the pulse output when it is in the up position, but in the down position (as in the pulse clock schematic), a single pulse mode engages. This mode of operation allows the user to advance the sequencer just one stage. A closer look at the pulse clock schematic shows that one section of the quad NOR gate, combined with switch S2, resister R5 and capacitor C7, form a bounceless switch. When switch S2 is pressed, the sequencer advances one stage only, to facilitate easy tuning.

I could order the entire book from an online retailer, even though I only need one schematic from it, but it will take over a month to arrive, as I do not reside in the US. I have checked with my local area library/libraries, and second hand retailers, and they do not have the book available. There is not an e-book/PDF version of the book either.

Does anyone have a scan of the actual schematic, from chapter 2 of the book, or a re-created schematic in Eagle? Or even a complete schematic of the sequencer including the clock circuit, with the single step circuitry?

Yes, I could use any oscillator/clock circuit, but I would like to follow Thomas's original plan.

1 I found some addition information on these two posts (1 and 2), from Analog Sequencer. However, the schematic of the oscillator, although promised, was never posted.


1 Answer 1


I purchased the book, and got hold of the schematic:

Voltage-controlled pulse generator schematic

I have also made an Eagle schematic, TT_PulseGen_V1.0.sch.


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