by Phil Taylor
If you’ve ever looked inside a vintage Hi-Watt amp you’ll see a fine example of point-to-point (PTP) wiring where the components (resistors and capacitors) are mounted on tag or turret boards. A well laid out PTP circuit is a thing of beauty, however it’s labour intensive and skilled work. Each component must be soldered in position by hand and care has to be taken when bending and forming component leads to prevent stressing and damaging them.
Contrast this with printed circuit boards (PCB) where the wiring patterns are chemically etched into copper foil laminated to epoxy impregnated fibreglass board. The PCB is designed so that the components can be precisely placed in position with minimal or no bending of component leads. This not only prevents component damage but also simplifies and speeds up assembly making it possible to automate the process using machines. Automated assembly reduces manufacture costs and eliminates the possibility of other human errors such as forgetting to place or insert components in the wrong way around.
There are a couple more advantages when using a PCB. PCBs can be designed with additional copper layers for ground and power allowing the circuit layout to be optimised for low noise performance and reduce its size. Secondly, component lead lengths are kept to a minimum – sometimes there are no leads at all – reducing the number of solder connections, ensuring highest signal integrity and reliability. PCBs are utilised for many applications from guitar amps to the computers on board the Saturn V rocket that took mankind to the Moon.
