Undoubtedly, Power Supply is THE most overlooked and ignored area in Tone Building. In most cases, people don’t even think about power supply criticality while developing their RIG.
In a normal household level power supply, you can mainly face 3 problems related to safety:
- Ground Fault
- Reverse Polarity
- Neutral Fault
Beside these safety related problems, another issue that has more to do with tone is harmonics & EMI/RF Interference, we will see in detail about these issues as well along with ways to handle them.
The top Thick pin of any power connector is the Ground/Earth Pin which is actually made longest & thickest… ever wondered why???… Well this is because this is connected through the wire to the body of the equipment, in case of any internal short circuit the mains gets connected to body and since ground offers least resistance, a huge current flows. to withstand this current the material of the pin should be thick and heavy duty.
I believe this explanation about the pin very well describes the importance of why this is important. It is important for your safety and the equipments safety.
In any case you should never ever attempt to run any equipment on 2 pin. 3 Pin sturdy connector with proper ground check must be ensured before plugging in.
In many cases, there is an issue of polarity! As per standard, the Right pin should be live and Left should be Neutral. In case of reverse polarity the equipment will work but adverse impacts and noise problems, along with danger of shock is quite high.
Neutral is a circuit conductor that carries current in normal operation, which is connected to ground (or earth). An open (Broken) neutral connection poses serious threat to safety.
In order to ensure the absence of these faults, one should always use a tester to check for these. This tester is normally an inexpensive device that looks something like this…
There are also power strips that come with a tester and EMI/RF interference filter installed.
Power Supply Harmonics
Any electrical engineers one of the biggest challenge is to reduce the harmonic as much as possible. While for a normal person its advisable to use a power conditioner, but the problem is the heavy price tag attached to it.
Lets see how by understanding the problem we can handle it effectively.
Harmonic voltages and currents in an electric power system are a result of non-linear electric loads (Fans, TVs, Fluorescent Lamps, etc.) (Refer Image, the blue graph is the harmonic produced by a normal CFL).
Essentially Harmonic refers to the frequency of a signal (Voltage/Current) which is integral multiple of the fundamental frequency.
A pure sinusoidal voltage is a conceptual quantity produced by an ideal AC generator.
When a sinusoidal voltage is applied to a certain type of load, the current drawn by the load is determined by the voltage and impedance and follows the voltage waveform. These loads are referred to as linear loads; examples of linear loads are resistive heaters, incandescent lamps, etc. In contrast, some loads cause the current to vary disproportionately with the voltage during each cyclic period. These are classified as nonlinear loads, and the current taken by them has a nonsinusoidal waveform.
When there is significant impedance in the path from the power source to a nonlinear load, these current distortions will also produce distortions in the voltage waveform at the load.
These higher harmonics which are essentially the multiples of fundamental supply frequency (50Hz) lead to oscillations and cause hum.
An obvious and effective way to kill this harmonic is to use a FILTER that can bypass the harmonic to ground before going to the main equipment. The same philosophy is applied to counter EMI (Electro Magnetic Interference) caused by heavy transformers or other large equipments operating nearby and also RF (Radio Frequency).
Rather than going too much into Electrical Engineering, I’ll explain the basics of Filters.
There are 4 Basic types of Filters:
Low Pass Filter, which allows Low Frequency to pass and bypasses High Frequency, a High Pass Filter which does the opposite, a Band Pass Filter which allows a band of frequencies and a Band Stop Filter, which blocks a band of frequencies.
So how does an EMI/Harmonic/RF filter looks like???
To sum up, you should ensure following layout to ensure proper power Supply for Safety and minimum noise.