Friday, 17 March 2023

Expresso machines 101 - boilers

 Espresso machines use different types of boilers to heat water for brewing espresso and generating steam for frothing milk. The choice of boiler type can affect the performance, consistency, and capabilities of the espresso machine. 
Here are the common types of boilers found in espresso machines:

Single Boiler: 
In single boiler espresso machines, there's only one boiler that heats water for both brewing espresso and steaming milk.

The boiler on the left is from a Gaggia Classic.
It's cast aluminium. Very cheap but reliable. 
It's only 100mls, which makes it quick to heat.
The same basic boiler can be found in machines 
from 1991 to today. A testament to its excellent design

 These machines typically have a switch or button to toggle between brewing and steaming modes. While cost-effective and suitable for home use, single boiler machines require a bit of time to switch between brewing and steaming, which can be a drawback for busy environments.




Dual Boiler: 

Dual boiler espresso machines have separate boilers for brewing and steaming, allowing users to simultaneously brew espresso and steam milk without waiting for the boiler to change temperature modes. This results in faster performance and greater consistency, making dual boiler machines popular in commercial settings and among enthusiasts who prioritize precise control over brewing parameters.

The dual on the left is from a Lelit Bianca.
They are both stainless steel.
1.5L steam boiler. 800ml coffee boiler






Heat Exchanger Boiler: 
Heat exchanger (HX) espresso machines use a single boiler with a heat exchanger mechanism. The heat exchanger allows the machine to simultaneously brew espresso and steam milk without switching between temperature modes. Water for brewing passes through a tube or coil inside the boiler, heating it to the appropriate temperature for extraction, while steam for frothing milk is generated separately. 

The pic on the left is of a profitec 400.
Part 20 is the exit water pipe for brewing coffee.
The rest of the boiler is for the steam.

Heat exchanger machines offer faster performance than single boiler machines and are often favored by home baristas and small cafes.

Thermocoil Boiler: 
Thermocoil boilers, also known as thermoblock boilers, use a heating element wrapped 
around a coil to heat water on demand. 
These boilers heat water very quickly and are commonly found in entry-level espresso
 machines due to their compact size and affordability. 

I have a Breville Bambino which can brew a decent coffee in a few minutes.
Basically, by the time Ive ground my beans its 
heated and ready to go.
It's disadvantage, is that thermocoil boilers struggle to maintain precise temperature control compared to other boiler types.



Recently, the trend is to use a thermocoil to steam and a small standard boiler to brew.
This leads to multiboiler systems.

Multi-Boiler: 
Some high-end espresso machines feature multiple boilers, with separate boilers dedicated to brewing, steaming, and hot water dispensing. 
Professional machines with multiple groupheads will have separate boilers for each group allowing you you set different temperatures & pressures simultaneously to suit different coffees.
They may even have different micro boilers for each stage of the brewing process (eg a mini boiler for the pre-infusion stage).
Multi-boiler machines offer unparalleled temperature stability and control, making them ideal for specialty coffee shops and enthusiasts who demand the highest level of performance and consistency.

The choice of boiler type depends on factors such as budget, intended use, desired features, and preferences for temperature stability and consistency. Each type of boiler has its advantages and trade-offs, so it's essential to consider these factors when selecting an espresso machine.

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Coffee index. Click here :

Thursday, 16 March 2023

Kos - Greece - part 2

 This is part two of a page on the island of Kos, Greece.
Part 1 is here:
Such a beautiful place.
And full of history too.

Also known as Cos, it is an island located in the southeastern Aegean Sea and is part of Greece. The island has a rich history that dates back to ancient times.

In Greek mythology, Kos is said to have been ruled by the demigod Asclepius, the son of Apollo, who was known for his healing abilities. Asclepius is said to have established a medical school on the island, which became famous throughout the ancient world.



In the 5th century BC, Kos became part of the Delian League, an alliance of Greek city-states led by Athens. During this time, Kos was a prosperous trading center and home to many famous philosophers, including Hippocrates, who is known as the father of modern medicine. Hippocrates established the Hippocratic School of Medicine on Kos, which became a center for medical education and research.



During the Hellenistic period, Kos was controlled by various Greek kingdoms, including the Ptolemaic dynasty of Egypt and the Seleucid Empire of Syria. In the 2nd century BC, the island came under Roman rule and remained part of the Roman Empire until the 4th century AD.



During the Byzantine era, Kos was an important center of Christianity and was home to several churches and monasteries. In the 13th century, the island was conquered by the Venetians and later by the Ottoman Empire in the 16th century.


This is part of the Ancient Agora of Kos.
It's a well-preserved archaeological site located in the heart of the modern town of Kos .
The agora was the central marketplace and civic center of the ancient city of Kos, and it played a crucial role in the social and economic life of the city.



The agora was built in the 3rd century BC and was in use until the 6th century AD. It covers an area of approximately 50,000 square meters and is surrounded by a colonnade of Doric columns. The colonnade provided shade for the vendors and shoppers who visited the agora, and it also served as a gathering place for citizens to discuss politics and other issues.




The agora features several notable buildings, including the Temple of Hercules, which dates back to the 2nd century BC and was dedicated to the mythological hero. The temple was later converted into a Christian church in the 5th century AD.




Another prominent building in the agora is the Bouleuterion, which was the meeting place of the city council. The Bouleuterion was a large rectangular building with a tiered seating area and a central podium for speakers.







Visitors to the Ancient Agora of Kos can explore the ruins of the marketplace and buildings, including the columns and walls that remain standing. The site is open to the public and is a popular destination for tourists interested in ancient Greek history and architecture.



The Asklepieion of Kos is an ancient healing center located on a hillside about 3 km southwest of the town of Kos, on the island of Kos, Greece. It was one of the most important sanctuaries of Asclepius, the god of healing, in the ancient world. The Asklepieion was founded in the 4th century BC and was in use until the 7th century AD.


The Asklepieion consists of several buildings and structures, including temples, altars, and therapeutic buildings. The main temple of Asclepius was the most important building in the complex, and it was surrounded by a large courtyard where patients could receive medical treatment and participate in healing rituals.

Patients who visited the Asklepieion would go through a process of purification before being admitted to the sanctuary. Once inside, they would be treated with various methods, including herbal remedies, physical therapy, and even dream interpretation. The priests of Asclepius, known as the Asklepiades, would diagnose and treat patients, and they were known for their medical expertise.


The Asklepieion of Kos is known for its impressive architecture and beautiful location, overlooking the sea and the town of Kos. Visitors to the site can explore the ruins of the various buildings and structures, including the impressive columns and arches of the main temple. The Asklepieion is open to the public and is a popular destination for tourists interested in ancient Greek history and medicine.



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Wednesday, 15 March 2023

VC ADSR - NLC build notes - part 1

Some build notes for the Nonlinear circuits VC ADSR.
This is part 1

This uses the classic Jacky/Kirschman 555 ADSR circuit from 1980

This is a super simple circuit that uses two chip types  (a 555 timer or a CMOS 4016 & an op-amp) and some diodes. Jacky's circuit uses the 555, while Kirschman uses a 4016.
Andrew has replaced the Attack-Decay-Release pots with DIY vactrols.
This NLC module uses a 555 which controls the sequencing while the diodes switch the currents.


Its a envelope generator of course.
All in Eurorack format. The module is 10HP
 


Links:
+ BOM

The module is thus a combination of a few old circuits.... the 555 ADSR circuit
with some LDRs  & LEDs used instead of pots.
It uses black boxes made out of headers to keep the LDR/LEDs isolated from extraneous light.
Essentially these are DIY vactrols.






IC's on first
Five 072 op-amps & a 555 timer chip


BC847
LL4148



resistors, caps



trimmer








Schottky, power
rectifier?? 



I'm using a 10R
resistor for power protection.


I'm using 2.2k resistors for the Led Resistor (RL).



For the LDRs

Andrew used GL5516
I'm using GL5549

(only because I have a heap of them).
As with all these builds, experimentation is best.
Would be great to do some variations of this module using different coloured LEDs and 
LDRs












I'm using green LEDs for the vactrols 
and a blue LED for the panel just to be different.


Andrews recommendations are red or green
for the vactrol LEDs


















Make the Box next
using headers. The LEDs and LDRs will go here.

These are always a bit tricky 


Cut the male & female headers to the correct size 1st



Then solder ...



I usually start with the sides first, then the central dividers next.
The final box needs to be light proof.

To be continued...

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You can find more NLC builds here.
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Korg Volca FM 1 - Internal & external sequencer

External Sequencer

If you are using an external sequencer:
1. make sure MIDI RX ShortMessage  is On.
    The LED above pad 7 needs to be lit.
    To do this, while holding down the MEMORY button, turn the volca fm on.
     When you have finished, press the (REC) button.


2. set the MIDI channel
    While holding down the MEMORY button, turn the volca fm on.
    Keyboard buttons 1 to 16 correspond to the MIDI channels 1 to 16. 
    Press the button that corresponds to the desired channel, and the LED
    below the keyboard button will light up.
    When you have finished, press the  (REC) button.

3. make sure you clear the pattern stored in the Volca, otherwise this will play when
    you start the external sequencer.

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Internal Sequencer  

The Volca FM comes with 16 default sequences

To select a default sequence press:
[Memory] & [1-12 touch pad]


To erase (clear) whats in the memory of that sequence press
[func] + [16 - All] 
All sequence data will be erased.
or press
[func] + [Act step]  
 All values in the active step will be deleted.

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To rec something:

press [play] + [rec]
play your tune.

To save to memory press
[func] + [memory]
This is the save-ready condition. 


Now press one of the 1–16 buttons to
save the currently selected program number and sequence 
to your chosen memory slot.

If you turn the volca off / on, your settings should still be in memory