Crescendo revisited

Crescendo revisited elektor november 1983 Crescendo revisited Figure 1. Here we repro- duce part of the circuit diagram of the Crescendo showing the resistors mentioned in tip no. 1 (R27 ... 30) and the interchanged test points of tip no. 5. 1 200 mA 1000¶ 100V 220n =1 maw CiT 12 V 400 mW 11-62 It is almost a year since we published the Cresendo MOSFET power amp and in that time we have discovered a few tips we think are worth passing on to our readers: 1. Wirewound resistors were specified for R27 . . . R30. However, the self-induct- ance of R27and R28 in particular can give rise to short oscillations during positive half- cycles, in other words when T11 and T12 are conducting. There are two methods of getting around this problem. Leave the wire wound resistors as they are and connect a capacitor of 1 nF between the source sides of R27 and R28 (see figure 1). Alternatively replace each of R27 . . . R30 by five 1 SZ 1 W carbon resistors connected in parallel. 2. The low-pass filt...