In figure 4 , page 32 of issue 229 of Model Engineers Workshop the symbol for TR2 (BC 327 ) is shown as an NPN transistor rather than a PNP. This will not affect the actual circuit as the terminals are the same in both cases, but it makes the explanation of how the circuit works difficult to understand. As drawn, both transistors would turn on and of at the same time. When in reality a signal to the base will turn BC337 ON and turn BC327 OFF at the the same time.