Three Reasons the Summer is Warmer Than the Winter

Created with ChatGPT.

A common misconception is that the Earth is closer to the Sun in summer, but it's actually further away. Diagrams would be better for explaining this. I'll get around to it, but I'll try to do it with words for now. 

Less atmosphere to pass through

Because of the greater elevation of the Sun in summer, the distance light has to travel through the atmosphere is shorter than it would be if the Sun were low in the sky. The Sun feels hotter in summer because of this and also the filtering effect is the reason the Sun looks dimmer and redder when it's low in the sky near sunset as light gets scattered and absorbed. Because of the higher intensity of illumination of the Earth's surface in summer, this makes air temperatures higher as the ground warms up and transfers its heat to the ambient air. This atmospheric filtering effect wouldn't happen on the Moon, irrespective of the Sun's elevation, because there's no atmosphere.

Lower angle of incidence

Because the Sun is higher in the sky, when solar radiation hits the Earth's surface, it's spread out less than in winter (compare the difference between a torch shone perpendicular to a wall and at an acute angle). Greater solar irradiance, measured in watts per square metre (W/m²), warms the ground more, which in turn heats the air above it. This is why solar panels are angled so that the Sun's rays strike them as close as possible to right angles, maximising the irradiance they receive.

Longer days 

Because of the tilt of the Earth, days are longer and nights are shorter. This gives more time for the Sun to warm up the ground, raising the average air temperature higher than in winter. Night-time temperatures remain mild because the ground acts as a thermal reservoir and stores heat. If the Sun mysteriously disappeared, ground and air temperatures would continue to fall over days and months to a level hundreds of degrees below 0 °C.

What Are Voltage Regulators Used For?

78XX series of voltage regulators. E.g. 7805 and 7812 having regulated outputs of plus 5 volts and plus 12 volts respectively. Silverxxx, CC BY SA 3.0 Unported via Wikimedia Commons.

We're surrounded by electronic gadgets and appliances, and even devices that don't appear to be electronic may use electronic circuitry internally. For electronics to work properly, it's imperative that voltage be stable and constant. That's the job of a voltage regulator. In this article, we'll explore voltage regulators in a little more detail.

An L7805 linear voltage regulator on a printed circuit board (PCB). This regulator outputs 5 volts at currents up to 1 amp. © Raimond Spekking / CC BY-SA 4.0 (via Wikimedia Commons)

What Is a Voltage Regulator?

A voltage regulator is an electronic device used to keep the voltage output of a power supply at a constant level, independent of the current drawn by a load and changes in the input voltage supplied to it. In general, these devices are implemented as a single integrated circuit (IC) in a variety of package formats or as separate modules, consisting of several discrete components and possibly integrated circuits. A regulator that reduces voltage is called a buck regulator, and one that increases voltage is called a boost regulator.

What Affects the Output of an Unregulated Voltage Source?

The output voltage of an unregulated voltage source depends on:

• Load current: The output of an unregulated voltage source will drop as the current increases. This is because of internal resistance, which causes a voltage drop as current flows. This voltage drop subtracts from the ideal internal voltage source and causes the output of the supply to be lower than the open circuit voltage without a load. We'll examine this in more detail later and work out the equations for output voltage versus load resistance.
• Battery charge state: If a voltage source is a battery, the output voltage can vary depending on its state of charge or discharge.
• Input voltage to the unregulated voltage source: The output voltage of an unregulated power supply powered by the mains can also change as the mains voltage changes.

For more information on basic electricity and volts, amps and watts, see my guide: How to Understand Electricity: Volts, Amps and Watts Explained on Appliances

Block diagram of a voltage regulator. Vout may be greater or less than Vin. © Eugene Brennan

Why Does Voltage Vary if a Regulator Isn't Used? A Detailed Analysis

All linear electrical networks containing only voltage sources, current sources and resistances (which include power supplies and batteries) can be modeled as a Thévenin equivalent circuit with an ideal voltage and a source resistance in series, as shown in the diagram below. The ideal voltage source produces a voltage that doesn't change no matter what current is drawn from it. So, for instance, if the voltage source is 12 V and one million amps are drawn, it still outputs that voltage. Such devices don't exist in real life, and all voltage supplies have internal resistance that causes a voltage drop as the voltage source is loaded.

As current increases through the internal resistance of the source, R_int in the diagram below, it causes a potential drop across the resistor. The potential drop equals the current through the source resistance, multiplied by the resistance R_int. This potential drop subtracts from the ideal voltage V, so the voltage at the output terminals of the Thévenin equivalent circuit at the load R_L, which we'll call V_L is:

V_L = V - IR_int

Any linear electrical network can be modeled as a Thévenin equivalent circuit (enclosed within the red dotted line) with an ideal voltage source V and a source resistance Rint in series. RL is a connected load. © Eugene Brennan

On open circuit, with no load connected (R_L is infinite) and I is zero, so:

V_L = V - IR_int = V - 0R_int = V

The output voltage on open circuit is the same as the ideal voltage source.

What is the output voltage with a load connected?

To work out the voltage with a load connected, we need to find the current I.

The total resistance of the circuit is the sum of the Thévenin equivalent source resistance R_int and load resistance R_L in series.

The current through both resistors is given by Ohm's law as:

I = V/(R_int + R_L)

The voltage at the load equals the current I flowing through the load, multiplied by the resistance of the load. If the load voltage is V_L, then substituting for I from the equation above gives us:

V_L = IR_L = VR_L/(R_int + R_L)

Dividing the numerator and denominator of the right hand side of the equation by R_L gives:

V_L = V/(R_int/R_L + 1)

We can see that if R_L is infinite, i.e., on open circuit:

V_L = V/(R_int/∞ + 1) = V/(0 + 1) = V

So, the output voltage is the same as that of the ideal voltage source.

When RL = 0, i.e. a short circuit:

V_L = V/(R_int/0 + 1) = V(∞ + 1) = 0

The output voltage is zero when the load resistance is zero.

(Strictly speaking, division by 0 is undefined in math, but we can practically think of division by 0 giving an infinite result and dividing by infinity as giving 0 in the equations above.)

In between these values, as the load resistance falls, the R_int/R_L + 1 term in the denominator of the equation increases, and V_L decreases. This is the crux of the problem. As a supply is loaded and load resistance falls and more current is drawn, the output voltage of a non-regulated supply falls. A regulator solves this problem.

It's important to remember that the Thévenin equivalent circuit is just a model, and there aren't actually an ideal voltage source and series resistor component in, for example, an AA cell, bench power supply, lithium battery or power supply in an appliance or gadget. The model just describes how a supply behaves.

What Are the Two Types of Voltage Regulators?

There are two types of semiconductor regulators: the linear regulator and switching regulator.

Linear Regulator

There are two types:

• Series regulator. This uses a pass transistor such as a bi-junction transistor (BJT) or metal–oxide–semiconductor field-effect transistor (MOSFET) and associated circuitry to control voltage. The pass transistor effectively works as a controlled dropper resistor in series between the input supply and the regulator output. A typical regulator has a 5-volt output. So, if the input voltage is 14 volts, it drops that voltage from 14 to 5 volts.

  The control circuitry in the regulator monitors the regulator output voltage, and if the load tries to take more current and output voltage tries to fall, the control circuit reduces the resistance of the pass element so that it drops less voltage in order to maintain the output at a constant 5 volts. Similarly, if the load takes less current, the resistance is increased. A linear regulator is a classic negative feedback control system (like the governor on an engine, keeping speed constant as the load increases/decreases).

• Shunt regulator. This uses a device such as a Zener diode in parallel with the load. A Zener diode has a characteristic such that the voltage drop across its terminals is relatively constant, independent of the current through it. By placing the diode in parallel with a load, this has the effect of stabilising voltage and keeping it the same as the Zener diode voltage.

Disadvantages of Linear Regulators

Since the pass component in the regulator is in series with the load, the current supply from the source is the same as that supplied to the load. However, since the voltage is dropped by the pass component, power is wasted as heat in the device. The higher the input voltage, the greater the wastage since P = VI, where V is the drop across the regulator, I is the current through the load and P is the power, dissipated as heat. The lower the input voltage, the better, and a small or large heat sink may be needed, depending on the ambient temperature and voltage drop. Basic regulators need about a 2-volt difference between input and output voltages to work, but low-dropout regulators are available, which can work with a smaller difference between IP and OP.

Voltages and Packages

Linear voltage regulators are commonly available in the TO220 package with voltages of ± 5 V, 6 V, 9 V, 12 V, and 15 V. The 780XX series can output a current of up to 1.5A. Regulators with higher current outputs are also available in different packages. Adjustable voltage regulators, such as the LM317, are also available.

Block diagram of a series linear regulator. © Eugene Brennan

A basic regulator made from discrete components can be made using a pass transistor, Zener diode and resistor to bias the diode. The Zener diode acts as a reference voltage, the potential drop across it staying relatively stable as the voltage of the unregulated input to the power supply varies.

Taking KVL about the base circuit:

V_D = V_L + V_be

So V_L = V_D - V_be

If the load increases and V_L tries to fall, V_D remains constant. However, V_be increases, causing an increase in base current. This increases the collector current and decreases the collector-emitter voltage, increasing V_L to compensate.

Schematic of a basic voltage regulator. The Zener diode sets a reference voltage and the transistor keeps the output voltage reasonably stable as current changes. © Eugene Brennan

Switching Regulators

A switching regulator, on the other hand, works differently. Unlike a linear regulator, which can be very inefficient and waste power as heat, switching regulators can be up to 95% efficient. In buck mode (reducing voltage), they work by chopping the input voltage to the regulator into a pulsed waveform and applying this to a capacitor/inductor, which effectively works as a tank, smoothing the chopped waveform (analogous to the way an engine flywheel smooths the pulsed intermittent power from the cylinders). The duty cycle (how long the pulse is on) of the switching waveform is varied depending on the demand of the load in order to keep the op voltage constant.

Disadvantages of Switching Regulators

Since a switching regulator runs at high frequency, switching voltages on and off can generate a lot of electromagnetic interference (EMI). Most countries have regulations for the amount of EMI emitted by products sold, governing the level of both interference radiated through the air and through power cords. Most appliances have EMI filters to reduce this interference, but some still get transmitted. If you turn on a radio and switch it to the AM band and tune away from a channel and hold the radio close to a device such as a computer or a phone, you can hear the interference as noise on the radio.

Another issue with switching regulators is that switching noise can make its way to sensitive electronics in the device. So extra filtering is necessary to reduce this.

References

Boylestad, Robert L. (1968). Introductory Circuit Analysis. (6th ed. 1990) .Merrill Publishing Company, London, England.

Donald G. Fink, H. Wayne Beatty (1978). Standard Handbook for Electrical Engineers Eleventh Edition, Mc Graw Hill.

Millman, J., & Grabel, A. (1987). Microelectronics. McGraw-Hill.

Linear and switching voltage regulator fundamental part 1. Texas Instruments. https://www.ti.com/lit/an/snva558/snva558.pdf

Disclaimer

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualised advice from a qualified professional.

© 2022 Eugene Brennan

How to Measure Length, Distance and Area on Google Maps

Public domain image from Canva

The Google Maps measuring tool can be used to measure the distance between two points, and the result is displayed in feet and metres. Alternatively, values are displayed in miles and kilometres if a user zooms out to view a greater-sized region of the map.

Recently, I discovered that it's also possible to draw lines around a region on a map and calculate the area enclosed by those line segments. In this guide, we'll first explore how to measure distance using Google Maps on a desktop (or laptop), and then how to measure area.

How to Measure Length

First let's measure the diagonal length of the field in the photo below.

Imagery © 2022 Google. Imagery © Maxar Technologies. Map data © 2022

Step 1. Right-Click to Bring Up the Context Menu

Right-click on the map and select "Measure Distance " from the pop-up menu. A small circular marker appears.

Imagery © 2022 Google. Imagery © Maxar Technologies. Map data © 2022

Step 2. Select the Start Point

Left-click and drag the start marker to the point where you want to measure from. Alternatively, you could have right-clicked first on the point where you wanted to start from before selecting "Measure Distance" from the menu.

Imagery © 2022 Google. Imagery © Maxar Technologies. Map data © 2022

Step 3. Click on the End Point

Click the point on the map where you want to measure to. A second marker appears with a line joining it to the start marker. Distance is displayed on a panel at the bottom of the screen and also on a label adjacent to the end point on the map.

If you zoom in, you'll notice that equally-spaced graduations are added to the line joining the start and end points. In the photo below, 10 graduations are added from the 0 to 200 feet label. Distances are then labelled every 200 feet up to the end point. These regularly-spaced labels depend on the distance between the start and end points. For instance if the points were 90 miles apart, there would be labels at 20 miles, 40 miles 60 miles etc. Labels will either be metric or imperial, depend on the measurement system you've chosen for the map.

Imagery © 2022 Google. Imagery © Maxar Technologies. Map data © 2022

How to Measure Area

The steps to measuring area are similar to those for measuring length.

Step 1. Repeat the Process for Measuring Length

Using the steps above, position a start point and second point on the boundary of the region you want to measure the area of.

Imagery © 2022 Google. Imagery © Maxar Technologies. Map data © 2022

Step 2. Continue to Position Nodes Around the Perimeter of the Region

Continue to left-click and add new points or nodes around the measured region of interest. Distance from the start point is labelled at regular intervals along the complete path (in the second image below at 500, 1000 and 1500 feet). The total path length is displayed in a panel at the bottom of the screen.

Imagery © 2022 Google. Imagery © Maxar Technologies. Map data © 2022

Look at the photo below. This selection path on another map shows more clearly how intermediate distances from the start point are labelled at regular intervals along the path.

Imagery © 2022 Google. Imagery © Maxar Technologies. Map data © 2022

Step 3. Position the End Point on the Start Point

Click on the start point to complete the boundary path. The box at the bottom of the screen updates to show the enclosed area and distance (the perimeter length of the field in this example).

Imagery © 2022 Google. Imagery © Maxar Technologies. Map data © 2022

How to Convert Between Measurements

Units	How to Convert
Square feet to acres	Divide by 43560
Square metres to hectares	Divide by 10,000
Feet to miles	Divide by 5280
Metres to kilometres	Divide by 1000

Moving the Nodes to Adjust the Boundary

If the line segments don't perfectly match the boundary of interest, they can be repositioned by moving the nodes. You can do this while drawing the boundary or alternatively after fully completing it (when you've clicked on the start node again). Simply left click and drag any of the node points to adjust their position. You can also left click on a node to delete it. The panel showing distance and area at the bottom of the screen updates to show the changed measurements.

Imagery © 2022 Google. Imagery © Maxar Technologies. Map data © 2022

Suggested Reading

• 15 Advantages of GPS
  GPS (Global Positioning System) works through satellite technology and offers many advantages. I list the 15 main ones and explain why they are so beneficial.
• 7 Disadvantages of GPS
  GPS technology has revolutionized many aspects of life, especially navigation and travel. There are downsides, however, and this article lists the seven limitations of GPS.
• How to Navigate on Land Without a Compass or GPS
  Learn how to navigate on land without the use of instruments or anything but a map and some common sense skills.

Disclaimer 

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualised advice from a qualified professional.

© 2022 Eugene Brennan

Resistors in Series and Parallel: Formula Derivation and Examples

© Eugene Brennan

Formulas for Resistors in Series and Parallel

Resistors are ubiquitous components in electronic circuitry both in industrial and domestic consumer products. Often, in circuit analysis, we need to work out the values when two or more resistors are combined. In this tutorial, we'll work out the formulas for resistors connected in series and parallel.

Some Revision: A Circuit With One Resistor

In an earlier tutorial, 'How to Understand Electricity: Volts, Amps and Watts Explained on Appliances', you learned that when a single resistor with resistance R ohms was connected in a circuit with a voltage source V, the current I through the circuit was given by Ohm's Law:

Ohms Law

I = V/R

Example: A 240 V mains supply is connected to a heater with a resistance of 60 ohms. What current will flow through the heater?

Current = V/R = 240/60 = 4 amps

Schematic of a simple circuit. A voltage source V drives a current I through the resistance R. © Eugene Brennan

Derivation of Formula for Resistance When Resistors Are in Series

Now, let's add a second resistor in series. Series means that the resistors are like links in a chain, one after another. We call the resistors R₁ and R₂.
Because the resistors are linked together, the voltage source V causes the same current I to flow through both of them.

Two resistors connected in series. The same current I flows through both resistors. © Eugene Brennan

There will be a voltage drop or potential difference across both resistors.

Let the voltage drop measured across R₁ be V₁ and let the voltage measured across R₂ be V_2, as shown in the diagram below.

Voltage drop across resistors connected in series. © Eugene Brennan

From Ohm's Law, we know that for a circuit with a resistance R and voltage V:

I = V/R

Therefore, rearranging the equation by multiplying both sides by R

IR = V

or switching around

V = IR

So for resistor R₁

V₁ = IR₁

and for resistor R₂

V₂ = IR₂

Kirchoff's Voltage Law

From Kirchoff's Voltage Law, we know that the sum of voltages around a closed loop in a circuit adds up to zero. We decide on a convention, so voltage sources with arrows pointing clockwise from negative to positive are considered positive and voltage drops across resistors are negative. So, in our example:

V - V₁ - V₂ = 0

Rearranging

V = V₁ + V_{2 ................} (i.e., the voltage V equals the sum of the drops across the resistors)

Substitute for V₁ and V₂ calculated earlier

V = IR₁ + IR₂ = I(R₁ + R₂)

Divide both sides by I

V/I = R₁ + R₂

But from Ohm's Law, we know I = V/R, so rearranging:

V/I = R = total resistance of the circuit. Let's call it R_total

Therefore

V/I = R_total = R₁ + R₂

In general, if we have n resistors:

R_total = R₁ + R₂ + ...... R_n

So, to get the total resistance of resistors connected in series, we just add all the values.

Formula for resistors connected in series

Example 1

Five 10k resistors and two 100k resistors are connected in series. What is the combined resistance?

Answer

Resistor values are often specified in kiloohm (abbreviated to "k") or megaohms (abbreviated to "M")

1 kiloohm or 1k = 1000 ohms

1 megaohm or 1M = 1000,000 ohms

So total resistance = sum of the resistances

= 5 x (10k) + 2 x (100k)

= 50k + 200k

= 250k or 250,000 ohms

Example 2

Three 47 ohm, five 1.2k, four 100k and two 3.3M resistors are connected in series. What is the total resistance?

Answer

We often replace the decimal point in resistor values with the multiplier to avoid misreading if, e.g., the "dot" gets erased from the value printed on a component or in documents. So 1.2k becomes 1k2.

So total resistance = sum of the resistances

= 3 x 47 + 5 x 1k2 + 4 x 100k + 2 x 3M3

= 3 x 47 + 5 x 1200 + 4 x 100,000 + 2 x 3,300,000

= 141 + 6000 + 400,000 + 6,600,000

= 7,006,141 ohms

Derivation of Formula for Resistance of Two Resistors in Parallel

Next, we'll derive the expression for resistors in parallel. Parallel means all the ends of the resistors are connected together at one point, and all the other ends of the resistors are connected at another point.

When resistors are connected in parallel, the current from the source is split between all the resistors instead of being the same as was the case with series connected resistors. However, the same voltage is now common to all resistors.

Two resistors connected in parallel. © Eugene Brennan

Let the current through resistor R₁ be I₁ and the current through R₂ be I₂.

The voltage drop across both R₁ and R₂ is equal to the supply voltage V.

Therefore, from Ohm's Law

I₁ = V/R₁

and

I₂ = V/R₂

Kirchoff's Current Law

From Kirchoff's current we know the current entering a node (connection point) is equal to the current leaving the node.

Therefore,

I = I₁ + I₂

Substituting the values derived for I₁ and I₂ gives us

I = V/R₁ + V/R₂

= V(1/R₁ + 1/R₂)

The lowest common denominator (LCD) of 1/R₁ and 1/R₂ is R₁R₂ so we can replace the expression (1/R₁ + 1/R₂) by

R₂/R₁R₂+ R₁/R₁R₂

Switching around the two fractions

= R₁/R₁R₂+ R₂/R₁R₂

and since the denominator of both fractions is the same

= (R₁ + R₂)/R₁R₂

Therefore,

I = V(1/R₁ + 1/R₂) = V(R₁ + R₂)/R₁R₂

Rearranging by dividing by dividing both sides of the equation by V and taking the reciprocal of both sides gives us:

V/I = R₁R₂/(R₁ + R₂)

But from Ohm's Law, we know V/I = total resistance of the circuit. Let's call it R_total.

Therefore,

V/I = R_total = R₁R₂ / (R₁ + R₂)

So, for two resistors in parallel, the combined resistance is the product of the individual resistances divided by the sum of the resistances.

Formula for two resistors connected in parallel.

Example

A 100 ohm resistor and a 220 ohm resistor are connected in parallel. What is the combined resistance?

Answer

For two resistors in parallel, we just divide the product of the resistances by their sum.

So total resistance = 100 x 220 / (100 + 220) = 22000/320 = 8.75 ohms

Derivation of Formula for Resistance of Multiple Resistors in Parallel

If we have more than two resistors connected in parallel, the current I equals the sum of all the currents flowing through the resistors.

Multiple resistors in parallel. © Eugene Brennan

So for n resistors

I = I₁+ I₂+ I₃. ........... + I_n

= V/R₁+ V/R₂+ V/R₃+ ............. V/R_n

= V(1/R₁+ 1/R₂ + V/R₃ ........... 1/R_n)

Rearranging

I/V = (1/R₁ + 1/R₂ + V/R₃ ........... 1/R_n)

If V/I = R_total then

I/V = 1/R_total = (1/R₁ + 1/R₂ + V/R₃ ........... 1/R_n)

So, our final formula is

1/R_total = (1/R₁ + 1/R₂ + V/R₃ ........... 1/R_n)

We could invert the right side of the formula to give an expression for R_total; however, it's easier to remember the equation for the reciprocal of resistance.
So, to calculate the total resistance, we calculate the reciprocals of all the resistances first and sum them together, giving us the reciprocal of the total resistance. Then, we take the reciprocal of this result, giving us R_total.

Formula for multiple resistors in parallel

Example

Calculate the combined resistance of three 100-ohm and four 200-ohm resistors in parallel.

Answer

Let's call the combined resistance R.

So

1/R = 1/100 + 1/100 + 1/100 + 1/200 + 1/200 + 1/200 + 1/200

We can use a calculator to work out the result for 1/R by summing all the fractions and then inverting to find R, but let's try and work it out "by hand".

So

1/R = 1/100 + 1/100 + 1/100 + 1/200 + 1/200 + 1/200 + 1/200

= 3/100 + 4/200

To simplify a sum or difference of fractions, we can use a lowest common denominator (LCD). The LCD of 100 and 200 in our example is 200

Therefore, multiply the top and bottom of the first fraction by 2 giving:

1/R = 3/100 + 4/200 = (2 x 3) / (2 x 100) + 4/200

= 6 / 200 + 4/200

= (6 + 4)/200 = 10/200

and inverting gives R = 200 / 10 = 20 ohms. No calculator needed!

Recommended Books

Introductory Circuit Analysis by Robert L Boylestad and available from Amazon covers the basics of electricity and circuit theory and also more advanced topics such as AC theory, magnetic circuits and electrostatics. It's well illustrated and suitable for high school students and also first and second-year electric or electronic engineering students. New and used versions of the hardcover 10th edition are available on Amazon. Later editions are also available.

References

Boylestad, Robert L. (1968) Introductory Circuit Analysis (6th ed. 1990) Merrill Publishing Company, London, England.

Disclaimer 

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

© 2020 Eugene Brennan

The Cork-Dublin Transmission Pipeline and Gas Distribution to Kilcullen

Gas distribution network in central Kilcullen from the interactive Dial Before You Dig website. Image courtesy Gas Networks Ireland.

On 4th March last year, a press release was issued by Uisce Éireann to media and local public representatives to the effect that:

“Civil Engineers are carrying out pre-work activities on the 225mm pipeline, which involves a localised crossing over the High Transmisison (sic) Gas main under the supervision of Gas Networks.”

That line is the Cork-Dublin gas transmission pipeline, and the work was being carried out at Kennycourt, just after the right turn for Kilgowan when heading towards Dunlavin. The 225 mm pipeline was a water main which was being installed for the Dunlavin Water Supply Rationalisation Project.

The gas transmission network in Ireland. Image courtesy Gas Networks Ireland.

The Kinsale Head Gas Field was discovered in 1971 by the US Company Marathon Oil Corporation. Gas well heads were installed in 1977 and production began in 1978. Construction of an 18-inch (450 mm) diameter pipeline to Dublin by Bórd Gáis Éireann began in 1981 and was completed in 1983. The pipeline runs cross-country through the Kennycourt, Mooretown, Carnalway, Harristown area on its way to Dublin. It passes under the river near Ardenode. It operates at 70 bar, or approximately 1015 psi (pounds per square inch). For comparison, your car tyres are pumped up to about 2.2 bar. 

The Kinsale Head gas field ceased production in 2020.

Gas Networks Ireland doesn’t publish a fixed burial depth for transmission pipelines. High-pressure gas transmission pipelines in Europe are designed in accordance with standards such as EN 1594, which set out functional requirements for pipelines operating above 16 bar, including protection from external interference. Burial depth is determined by design and risk assessment and varies depending on location, with greater cover typically used at road crossings, railways, and other high-load areas.

You’ve probably seen the white poles along roads with what look like cowls on top, marking the line. I erroneously thought these were some type of safety vent, but when I reported a damaged one near Coghlanstown, which had probably been cut by a tractor during autumn hedge cutting, I learned they’re simply markers, and what looks like a cowl is in fact a disk which helps aerial survey teams, including helicopter patrols, identify the pipeline route. A Prior Information Notice (PIN) for Gas Networks Ireland’s aerial surveillance services was published in June 2024 on the Irish Government’s eTenders portal which stated that:

“Gas Networks Ireland requires the provision of an aerial surveillance patrol service of their gas pipeline system in the Republic of Ireland and Northern Ireland to ensure there are no works or digging being carried out on or near the pipeline and no excessive vegetation growth on or near the pipeline.”

Kilcullen’s gas supply comes from a hub connection on the Cork-Dublin pipeline located north of Ballymore Eustace. You can register and view an interactive map of the transmission and distribution network, with detail down to street level, on the Dial Before You Dig website here.

Immersion Heaters and Potential Fire Risks

Immersion heater terminal box. © Eugene Brennan

So I was doing some gardening for the sister today and she mentioned a smell that was coming from her immersion. This immediately rang alarm bells in my engineering head, knowing what was likely to have happened—So I investigated.

My Telemetry Software Didn't Control Voyager 1

Credit: NASA/JPL-Caltech

NASA's decision to switch off an instrument on Voyager 1 to keep the spacecraft operating reminded me of my much less glamorous work in a past life, when I wrote telemetry software to control pumps and other equipment in sewage and water treatment plants.. But they were only down the road from Dublin in Kildare, Laois and other places throughout the country. If the remote software didn't work, or crashed, often due to frustratingly annoying transient bugs, usually a watchdog circuit kicked in to reboot the SCADA system (Supervisory Control and Data Acquisition). If there was a big problem and frequent crashes or anomalies, technicians would reinstall software. Eventually, I added the facility to upload new versions of software. All this was much less sophisticated than the complex software that runs on computers nowadays. Voyager 1 is nearly a light day away meaning a radio signal takes nearly a day to reach the spacecraft. Not much hope of sending people out to do an upgrade. Perhaps they can upload new code.

 

Edit: Yes, they can upload new "patches" and code updates. Code is restricted to around 64k. Voyager 1 has six computers, three of which are backups. The data bus is 16 to 18 bits wide and the address bus is 12 bits wide.

How Can Insects Survive Falling From a Height?

Forces on a falling insect. © Eugene Brennan

One of the reasons insects don't hurt themselves when they fall is because they have a low terminal velocity and are travelling relatively slowly when they reach the ground. Terminal velocity is the maximum velocity attained by a falling body in a fluid such as air or water and subject to a force called drag, (resistance to motion). For humans, it's around 120 mph or 54 m/s lying flat. For an insect, it's typically around 2 m/s. Once the increasing drag force balances the weight (another force), there's no net force and an object stops accelerating (Newton's second law of motion). Also when an insect hits the ground, because it has such a small mass, the g-force on its body is small because it has to shed so little momentum, and that also helps prevents damage. So it's a combination of low terminal velocity, small mass and also having an outer protective layer or exoskeleton that gives them protection.

Learn How to Solder: A Complete Guide for Beginners

Image by permission Weller Tools

A Basic Skill When Building Electronic Circuits

Soldering is a fundamental skill essential to learn when building electronic circuits or fixing circuit boards.

Kippure TV Mast Visible From Kilcullen

Kippure in the Wicklow Mountains, photographed from Kilcullen. © Eugene Brennan

I took this with my 10-year-old Nikon D5300 SLR from St. Brigid's Well on Saturday evening. The second photo below is a crop of the 6000-pixel-wide image. If you have good eyesight, you can see the 127-metre-tall television transmission mast on Kippure on a clear day. It's approximately 7 m taller than the Spire in O'Connell Street in Dublin and located 17.5 miles away from Kilcullen as the crow flies. (I can just about make it out with the naked eye). At night of course it's very noticeable, and the beacons on the mast can be seen flashing in the distance. They used to be red, but they changed them to white at some stage. I've seen the flashing from as far away as Kilmeague.

I haven't figured out why this camera always takes such dull photos. I reckon smartphones must boost the colour saturation, highlights and contrast in images to make them more vivid. I have the setting for this (can't remember what it's called) set as "neutral" in the camera so that images aren't altered. I can always change the settings later during post processing.

Edit: An FB photography group I'm a member of confirms that this is the case and images are flat if neutral photo style is selected. Saving photos as JPGs compresses images and reduces filesize, so I'm going to retake the photo and save as raw to see whether it makes much of a difference as regards detail and artefacts.

The TV mast on Kippure (a crop from the image above) © Eugene Brennan

 

Why Is Most of an Iceberg Under Water? And How Much?

Original uncaptioned image Lurens, public domain image via Pixabay.com

Ninety Percent of an Iceberg Is Below the Waterline

Icebergs can be massive, but did you know that you're only seeing literally the tip of them above the water? Yes, up to 90% of an iceberg's volume can be under water. But why does that amount sink and not just float above sea level like the rest of it? In this article we explore why.

What's the Difference Between Analogue and Digital?

© Eugene Brennan

Analogue vs. Digital

We often hear about analogue and digital in the context of communications, sound recording, cameras, TV, radio, and electronic devices. But what exactly is the difference, and is digital better than analogue? Why has digital replaced analogue in audio, digital imaging, and electronic communication?

Vodafone Internet Service Down After Thunderstorm

 

The Internet was dropping intermittently since the thunderstorm the other night. A Vodafone technician replaced the modem yesterday afternoon, but still no go. Then the service disappeared completely when the technician was still working on it.

Why Is Binary Used in Electronics and Computers?

Why is binary used in electronics? Geralt via Pixabay.com

Why Do Computers Use Binary?

The binary numbering system is the basis for the storage, transfer and manipulation of data in computer systems and digital electronic devices. This system uses base 2 rather than base 10, which is what we are familiar with for counting in everyday life.

How to Convert Decimal to Binary and Binary to Decimal

Binary number and its decimal equivalent. © Eugene Brennan

Base 2, the Basis for Binary Code

The base 2, or binary numbering system is the basis for all binary code and data storage in computing systems and electronic devices. This guide shows you how to convert from binary to decimal and decimal to binary.

How to Convert Hex to Binary and Binary to Hexadecimal

© Eugene Brennan

The Hexadecimal Numbering System

The base 16, also known as hexadecimal (abbreviated to hex) numbering system is regularly used in computer coding for conveniently representing a byte or word of data. This guide shows you how to convert from hex to binary and binary to hexadecimal.

The Andromeda Galaxy: "It's Big, And Also Faaarrr Away"

The apparent size of the Andromeda Galaxy, compared to that of the Moon. AI image created by Grok.

At a distance of 2.5 million light-years, or 24 million trillion km, the Andromeda Galaxy is the most distant object visible to the naked eye. We can see it because space is mostly empty, and light from the stellar object reaches us relatively unchanged, unlike what happens when we view distant objects on the horizon on Earth.

Loading Data for the Kilcullen 38 kV Substation.

Loading data for the Kilcullen 38 kV Substation, courtesy ESB Networks.

From the ESB Networks document 38 kV & 110 kV Station Special Load Readings. 

The table shows summer and winter loads in megawatt (MW) for transformers T41, T42 and T424.

It Came From Outer Space....

Nostoc commune (Latin name), also known as "jelly fungus". © Eugene Brennan

 Well not quite. This is probably Nostoc commune (Latin name), also known as "jelly fungus", "star jelly" or "witch's butter". It's not actually a fungus, but a colony of bacteria. There's loads of it in a patch on my yard, but it sometimes grows on lawns. It's extremely slippery on a lawn. Apparently it's eaten as a salad in the Philippines when dried out. I'm a fussy eater so I won't be trying it anytime soon.

More information on jelly fungus here on Wikipedia.