Plinky Synth 4U DIY Expander - build notes

 These are my build notes for the Plinky Synth expander.

The Plinky synth is an 8 voice, polyphonic touch synth.

I'm building the expander for a friend.

Links

+ https://plinkysynth.com/docs/expander-manual

This is the 4HP expander (not the 2HP version).

The LEDs are pre soldered.

as are most of the components.

I soldered in the Jacks 1st.

There are 2 green ones for the MIDI ... they go above the USB connector (at the top of the PCB).

This 8 pin header connects the two boards.

solder it next

there is a 10pin header... euro power?

Not sure if this is needed if you are powering from the Plinky.

i soldered it in anyway.

The 16 pin header connects to the plinky

Some final pics.

A  really easy build!

a side on view.

Upcoming Elk Elektroniks synth meeting

There is a synth meeting coming up soon in Wollongong, NSW, Australia.

Ed from Elk Elektroniks is organising the event.

Contact him if you are interested in performing

https://www.elkelektronik.com.au/synth-sessions

Save the date: Saturday 18th October 2025 from 7pm  

Location: Society City, 274-278 Crown St, Wollongong NSW 2500

https://societycitywollongong.com/

https://www.unicornkills.com/scevents

Behmore coffee roaster - Ethiopian

 Some Ethiopian Guji Wamena Gr1.

The Guji Zone lies approximately 300 to 400 km south of Addis Ababa in the Oromia Region.

In 2002, Guji itself detached from Yirgacheffe, which had previously been folded in with the Sidamo name. The Guji region takes its name from the Oromo people, a tribe that has farmed coffee on the land for generations.

“Guji Wamena” refers to coffees from the Hambela/Wamena districts inside Guji, now famous for floral, fruity, and tea-like Ethiopian profiles.

common notes: blueberry, jasmine, citrus, peach

elevation:  1,800–2,200 meters

The region uses washed vs natural processing 

I used this recipe from Roast Rebels as a guide.

https://roastrebels.com/roestprofile-behmor-2020sr-plus/

These were my settings

Quantity : 270g green beans

Preheat : none

Start : P5 (for 8 mins)

8       : P4 (for 6 mins)

14     : P3 (for 2 mins).... FC

16     : Cool (run the full 13 min cooling cycle)

first crack occurred at 14 mins .

For a lighter roast cut the P3 time to 1 min 

or

press Cool at the end of the P4 cycle.

I started with 270g  and finished with 225.6 g

16.44% water loss

Thus a dark roast.

La Pavoni Europiccola V1.4 - c1966

Some pics of my Rev 1 Europiccola

This is from 1966.

The portafilter size is 49mm

Side view

Very simple machine that produces great espresso.

The internal wiring

Rompler Synths

 A ROMpler is a digital synthesizer that plays back pre-recorded sounds stored in its Read-Only Memory (ROM) instead of generating them from scratch. The term is a blend of "ROM" and "sampler". Unlike a traditional sampler, a rompler cannot record new audio; its sounds are pre-loaded by the manufacturer and are often realistic emulations of instruments like pianos, guitars, and strings, or synthetic tones. 

Note that earlier digital synthesizers, which used short-cycle sampled waveforms, are usually not considered romplers but are either called "PCM synthesizers" or "wavetable synthesizers" because the sampled waveform in this case is usually only made of a single full cycle (or a handful of full cycles) of the wave and would therefore be a fraction of a second in length. 

Why use romplers?

Romplers are known for their unique, imperfect, and "vintage" character, often heard in genres like IDM and ambient music. The way samples are stretched and looped can create subtle imperfections that add a distinctive "character" to the sound.

Using pre-made samples speeds workflow & provides "instant results" with ready-to-use Instrument Racks. The sounds are typically presented as "presets," offering instant access to a variety of high-quality tones without the need for complex programming.

While the core sound source is fixed, most romplers allow for sound shaping through filters, envelopes (like ADSR), and effects.

The advantage about using  rompler is their ease for the new user.

Its basicall a load of sample libraries, in a box.

Is the lack of sound source editing something to be ashamed of.??

They come with samples already loaded so you can focus on creating melodies.

The Orbit, for instance, contains samples of a Moog Modular, ARP 2500 and 2600, TR-808 and Fairlight CMI Ilx.

Popular early romplers include the Roland D-50 and the Korg M1. 

Classic hardware romplers include the Roland JV-1080 and JD-990, Korg M1 and Triton, and E-mu Proteus series. 

Popular software romplers, which can also be called sample-based synthesizers, are reFX Nexus, Spectrasonics Omnisphere, Native Instruments Kontakt, and UVI Falcon. 

Modern hardware examples include the Korg Kronos and Wavestate. 

Software

Flex - fruity loops

Nexus 3/4

KONTakt - native instruments

Roland Zenology

Steinberg HALion

Hardware

E-MU Proteus series

EMU orbit

Korg M1

Wavestate - korg

Kurzweil K2000, K250,

Roland U-110

Roland sound canvas

Roland JV 1080

Roland JV 1010, 2028, etc

Roland JD 800, JD 900

Roland MC 303

Roland MC 505

Roland MC 808

Roland MC 909

Yamaha XG, tg55, mu50

Yamaha Tg 33

Yamaha motif

Hottop roaster - auto mode - Colombia Huila - Dark & medium roast

Colombia Huila -  alte1400 - 1800

This is a Huila Specialty Coffee Powerhouse region.

The department of Huila in southern Colombia is widely regarded as one of the country's premier coffee-growing regions and is often considered the heart of Colombia's specialty coffee movement. Many of the single-origin Colombian coffees found in specialty cafés around the world come from Huila.

Why Huila is so well suited to coffee

Several factors combine to create exceptional growing conditions:

• High elevation: Most coffee is grown between about 1,400 and 2,100 meters above sea level. Higher elevations slow cherry maturation, allowing more sugars and complex flavors to develop.
• Volcanic soils: The region benefits from fertile volcanic soils that support healthy coffee plants and contribute to cup complexity.
• Andean geography: Huila sits where Andean mountain ranges converge, creating numerous microclimates. Two farms only a few kilometers apart may produce noticeably different flavor profiles.
• Consistent rainfall and temperature variation: Warm days and cool nights help cherries mature gradually and evenly. 

Common tasting notes include:

• Red fruits (raspberry, plum, cherry)
• Stone fruits (peach, apricot, nectarine)
• Caramel and brown sugar
• Citrus brightness
• Chocolate or cocoa finish
• Medium body with clean sweetness

The hallmark is often a combination of bright acidity and pronounced sweetness.

Farming structure

Unlike large plantation systems found in some coffee-producing countries, Huila is dominated by smallholder farmers. Many farms are only a few hectares in size and are family-operated. This small-farm structure has encouraged careful cultivation and a strong focus on quality rather than volume.

Popular varieties grown in Huila include:

• Caturra
• Castillo
• Typica
• Pink Bourbon
• Yellow Colombia

Many producers also experiment with exotic varieties and innovative processing methods.

Specialty coffee reputation

Huila has become synonymous with high-end Colombian coffee. The region regularly produces coffees that perform well in quality competitions and attract premium prices in international specialty markets. It is frequently cited as Colombia's most celebrated specialty coffee origin.

Notable coffee-producing municipalities include:

• Pitalito
• Acevedo
• San Agustín
• Garzón

Pitalito, in particular, is known for a strong concentration of specialty-focused producers.

Current challenges

Like much of Colombia's coffee sector, Huila faces challenges from:

• Climate change and shifting weather patterns
• Labor shortages during harvest periods
• Rising production costs
• Increased disease and pest pressure in some areas

Many growers are adapting by moving production to higher elevations, focusing on specialty-grade coffee, and adopting new farming practices.

In one sentence

If you see a coffee labeled "Huila, Colombia," you can generally expect a high-altitude washed Arabica with vibrant fruit character, caramel-like sweetness, and the kind of complexity that has made Huila one of the most respected coffee origins in the world.

---------------

the hot top roaster

Auto mode

200g in

165.5g out

% water loss 17.25% loss

 thus dark roast

When doing a auto roast on the hot-top when you turn it on, it goes into a pre-heat or cool down cycle.

(depending if you are doing a first roast when the machine is cold, or doing a 2nd /3rd roast then the machine is already hot).

The roaster needs to reach a heat of 75C .

then it starts beeping

 Load the beans.

Set the final temp.

default is 209C I think this is too hot.

I like to start with a end temp of 202C if I've never roasted these beans before, then adjust future roasts from there.

These are the final beans

TSNM buchla format - build notes - part 2

 This PCB dates from 2017 ..It's a  Mark 1

There are modern ones using Teensy 4.0 ..... Mk II

which you can still buy.

This is part two on my build notes.

Part 1 is here:

https://djjondent.blogspot.com/2025/06/doboz-touch-sensing-note-memory-buchla.html

Links

+ Official site

+ BOM 

+ official build notes

+ users guide:

https://drive.google.com/file/d/1aTLM4nmC7pMoK5vsYQfeug6oFMj46Xcw/view

DIY resources

https://drive.google.com/drive/folders/1SNYV-ANfFsxx2BVhXfpxuKqykUcP-Gyv

This  Mk I uses the old Teensy 3.2.

....

Teensy® 3.2

Teensy Loader Application - available for Windows, Linux and Macintosh systems

C22, C23 and IC 6 are not needed if your PSU has +5V

C16 & C21 - are these part of the +5v section of the PCB?

I've soldered c16 in anyway.

C6 --- DNP ??? do not place?

1N5819HW 2 D1, D2 DO-41 schottky rectifiers 511-1N5819

L1 = ??

L2 = ferric bead.

These are connected in parallel ... across either side of the PCB.

Thus I used one ferric beath .. the through hole one. (L1)

Caps : 47uF x 2 

-------------

C17 - 100n (SMD ceramic)?? I think this is not right.

looks like an electro maybe 33uF ??

Is it C21 in the BOM??

-----------------------------------

MPR121 board & headers

It's a Adafruit 12-Key Capacitive Touch Sensor Breakout. This connects to the touch plates of the front panel

Cut the trace on the bottom of Teensy next to VIN pin to separate VIN from VUSB. This prevents 

powering the Teensy simultaneously from USB and the eurorack power supply. 

Teensy 3.2 

The two pots - 10K B ... linear (B103)

Encoder

position  the two displays and LEDs

The lower header is tricky.

I had to do some gentle bending of the ends.

you need to keep enough room for the two matrix displays... the legs aren't long

Bend these headers so you can solder them directly to the front panel

This is a side on view

 to be continued.....

HotTop Roaster 1 - Peruvian Ceja de Selva AAA.

My first attempts using the Hottop roaster.

This is the 2K+ version.

These do produce a bit of smoke, so I'm doing the roasting on my outside balcony.

I'll roast 3 x 200g batches of a Peruvian Ceja de Selva AAA.

Peru “Ceja de Selva” coffee (the “eyebrow of the jungle”).

- Peru coffee regions

Ceja de Selva is one of Peru’s most important (and underrated) coffee regions. The name literally means “eyebrow of the jungle”—a strip of land where the Andes mountains meet the Amazon rainforest.

Grown at over 1,800 metres.

Comes from an estate at the base of the Andes.

This washed (but not overly polished) coffee produces great body with a long mid-palate profile. 

Great as a single origin espresso .

What makes this region special?

Altitude: ~1,200–2,100 m

Climate: warm days, cool nights, high rainfall

Environment: lush, biodiverse, often shade-grown

This combination slows down how coffee cherries ripen, which is key for developing sweetness and complexity

Typical cup characteristics:

Sweetness: caramel, cocoa, sometimes molasses

Fruit notes: red apple, citrus, pear, or stone fruit

Body: medium, smooth, often creamy

Acidity: balanced (not sharp, not flat)

Finish: clean, slightly chocolatey

Some roasts can show brighter notes like lemon or grape early, then settle into chocolate and nutty tones at the end.

Ceja de Selva coffee is strongly associated with:

Organic farming (often no synthetic chemicals)

Smallholder farms & cooperatives

Hand-picked cherries

Washed processing (clean, clear flavours)

These practices contribute to both ethical sourcing and a clean cup profile.

How it compares to other coffees

Compared to Ethiopian coffee → less floral, more chocolatey

Compared to Colombian coffee → similar balance, but often softer and sweeter

Compared to Brazilian coffee → lighter body, more subtle fruit

Bottom line

Peru’s Ceja de Selva coffee is all about balance + drinkability + sustainability. It won’t punch you in the face with acidity or wild flavours—instead, it gives you a smooth, layered cup that keeps you coming back.

My first roast:

Target temp was 206C

200g

I used  the Auto mode on the Hottop.

Still learning Artisan

2nd roast

200g

Target temp 199C

3rd roast

200g

Getting used to using Artisan

Still in auto-mode

Target temp 199C

Fan speed:

initial : 5

My plan was to slowly reduce heat from 100% to 80% by first crack.

So I started with 600g raw coffee and ended with 517.3 g

That's a 13.8% water loss... just into the medium roast level.

Travel links

* Peru
   -  Cusco
   -  Inca Trail
   -  Machu Picchu
   -  Lake Titicaca
   -  Nazcar Peru - Chauchilla Cemetery
   -  Arequipa - NYE celebrations 2011
   -  Acclimatizing to high altitudes