Building synths these days means ordering parts from various suppliers.
Olders synths often use parts developed decades ago.
IC packaging has evolved from the simple through hole in the 1970's to mini SMD & STM today
It's essential to know pin numbers.
Each pin has a special function.
Pin 1 is always located below the notch, dot or band in a DIP package.
Pins are numbered counter clockwise, starting from pin 1.
Thus, the last pin, is always located above pin 1.
ICs are also classified into families:
The 3most common are:
1. TTL (Transistor - Transistor - Logic)
2. CMOS
3. Linear - mainly amps, oscillators, regulators, etc
Packages
So many ......
The most common are:
1. Dual In-line Package (DIP)
2. Small Outline Package (SOP)
3. Quad Flat Package (QFP)
4. Ball Grid Array (BGA)
1. DIP = Dual inline package.
It's through hole.
It consists of two rows of pins . It connects to a circuit board with either a through-hole or a socket.
The pins are spaced by 0.1" (2.54mm). This is a standard spacing designed for fitting into breadboards and other prototyping boards.
The IC is designed to fit perfectly into the big gap in the centre of the breadboard.
There is a 0.3″ (7.62 mm) spacing between the two rows of pins.
This type of package is great for your synth DIY experiments.
2. SOP = Small Outline Packages
When it comes to Surface mount, you will often use SOP (Small-outline package) types for the ICs.
These usually have a rectangular shape with pins along two edges.
With SOIC packages, each pin is spaced by about 0.05" (1.27mm)
Another common IC SMD package is the TSOP (Thin small-outline package).
They are very low-profile (about 1mm) and have tight lead spacing (as low as 0.5mm).
SSOP (shrink small-outline package) is an even smaller version of SOIC packages.
This bevel also lies on the side with the dot marking pin 1.
You can also see the notch .
Sometimes, the ICs are so small, that the dot isn't visible or present.
Thus, look for the bevel when trying to orientate the chip
TSSOP (thin-shrink small-outline package) is yet another variation.
It has a rectangular surface mount plastic package with gull-wing leads.
It is also smaller and thinner than a TSOP with the same lead count.
The TSSOP comes in body sizes of 3.0mm, 4.4mm and 6.1mm.
Lead counts range from 8 to 80.
You may com across these adapters:
They are useful for converting various Small Outline packages
(SOP/SSOP/TSOP/TSSOP/MSOP/QSOP) to dual in line package (DIP) format.
3. QFP = Quad Flat Packages.
Mostly, these are flat and square.
You will see the component with leads along each of the four edges.
QFPs can have pin numbers ranging from 32 pins to 304 pins.
It all depends on the pitch range.
The shape can vary too ... include low-profile and thin.
Micro-controllers are getting pretty common in Synth DIY, esp in Eurorack
4. Ball Grid Array (BGA)
You hopefully wont encounter any of these in synth DIY.
One side is covered with balls of solder. These are the connectors.
You will need special instruments ...either a reflow oven or hot air gun to work with these.
Specialised rework stations, vacuum devices to lift the IC, and thermocouples to monitor the temperature are needed when repairing these.
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Transistors and diodes often use this type
The old metal cans. These are named : TO-3/5/8/18/39/46/52/72
These can have many more than just 3 pins.
In the 1960's early chips were housed mainly in either TO-5 or TO-18 packages
These were commonly used to package bipolar transistors.
The metal can was ok, but as more and more leads were added something more
durable was needed.... thus the DIP package was invented.
