Today I created Veroboard layouts for the Diode & MOSFET clipping circuits in order to create a prototype, these are shown below where a solid line represents a link between tracks and a cross represents a break.
A 1:1 scale was used so these are quite compact but still entirely discernible.
Most of the components I required to build these circuits were plentiful in the Universities existing stock which saved on budget and time. However, the high quality op amp, rare diodes and MOSFET’s were not and as such I strategically chose components similar to those stated and which would be perfect for prototyping.
– The proposed Germanium 1N34A diode was replaced by a 0A47 which, according to the datasheet which I acquired from Andrew Wylie who specialists in obsolete technologies such as this, has a forward voltage of 0.65V rather than 1V. A photocopy of this datasheet and Mr Wylie’s website and email address can be found in the related resources section of this blog.
– The 1N4148 was replaced by a 1N4004 which has a forward voltage of 1V at 1mA as opposed to the 0.6V which the former would achieve. Due to a forward voltage similar to that of the germanium diode I assumed that this would produce similar audible results but I was willing to test this fact in case of improved tonal qualities.
– The TLE2072 was replaced by a UA741 op amp, although this budget IC has a high noise floor and relatively low slew rate it stands as an acceptable alternative for prototyping.
– The IRF520 was replaced by an IRF510, the only diffrence I can find when looking at the data sheets is that the latter has a 0.5Ω Source-Drain resistance rather than 0.27Ω and a lower forward current rating which shouldn’t make too much difference to the audio.
Using the equipment in MS130, the project room, I created the symmetrical diode clipping circuit, the image below shows the (assumably) working prototype once I had finished soldering in the components and strategically breaking the tracks. Feeling confident about the success of this circuit, I left the lab with the intention of returning the next day to carry out some testing.
stompboxproject 