FWIW I’ve just built the selfsame circuit, but noticed that it doesn’t seem to work if D1 is not connected.
Maybe try this if it still fails to work after you’ve replaced the BJTs with FETs.
@Billy: 2 questions if I may
- 5459s are fairly easy to obtain here (South Africa), unlike 5457s and 5458s, which are scarcer than hen’s teeth. However they don’t always seem to be a comfortable straight swap. Some (unwanted) distortion creeps in, or so it appears to my ears. Do they behave similarly to 5457s, or should one adjust bias resistors or what have you? BTW I’m not assuming there’s a straightforward answer to this one.
2. For some unknown reason, on my build the rate pot works the other way round (i.e CW gets slower). I’ve double checked the installation and it looks ok. Just wanted to check that this is intended? If so, well and good and I haven’t entirely lost the plot.
Thanks again and hope this doesn’t entirely Muddy the Waters (pun intended). Best, Marc