Electronic Components 101

Ray Wilson authored this content while he was actively running MFOS as the founder and resident genius.
We retain the content because it reflects a valuable point of view representing that time and place.

Article by Ray Wilson
Here is a good place to see what electronic components look like. It is important to be able to recognize them in the wild. These are general examples and I'll add more as I think of them. You will find components in all shapes, sizes and ratings so as I say this is a small sampling of the type most likely to be found in an analog synthesizer.
Banana Jack
They come in a variety of colors. You plug a banana plug into a banana jack. They are used in circuits that share a common ground since they only connect one wire.

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Banana Plug
They come in a variety of colors. You plug a banana plug into a banana jack. They are used in circuits that share a common ground since they only connect one wire.

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Phone Jack 1/4" Stereo
This is a stereo phone jack (TRS tip-ring-sleeve) which is typically used for headphones. In guitar foot pedals it can be used to switch the ground to the circuit so that it is only powered when the guitar cord jack is inserted.

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Phone Jack 1/4" Mono
This is a mono phone jack used to permit connection with a phone plug.

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Diode (High Speed) Glass Package
This is a typical high speed diode like the 1N914 or 1N4148. Zener diodes also come in this form factor. Notice the band at one end. It marks the diode's cathode. The other end is called the anode.

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Power Diode
Higher power diodes have greater junction capacitance and are not suited for logic switching circuits like high speed diodes are. Power Zener diodes also come in this form factor. You can make a bridge rectifer out of diodes like this. These are typically used in power supplies or spike suppression across coils.

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LED General Purpose
LEDs (Light Emitting Diode) come in a variety of colors (and spectrums) now and in multi-color as well. The longer lead is the anode and the LED typically has a flattened side to mark the cathode.

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Bridge Rectifier
This package contains four high power diodes arranged in a diode bridge. It is used for full wave rectification in power supplies.

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Transistor TO92 Pkg.
This is a transistor. There are many many different kinds of transistors and you need to make sure that you get the right one for any application. The leads have different functions depending on the type of transistor. You also need to make sure that you orient the transistor correctly when inserting it into a PC board.

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DIP IC Packages
DIP (dual inline package) ICs. These ICs are in plastic DIPs but they also come in ceramic but they look pretty much the same. DIPs come in from 6 to 80 or more pins. Notice the divet on one end. That is the end that the chip's pin one is on. In addition to the divet there is usually a dimple next to pin one of the IC. Always make sure you install your chip in the correct orientation or you will destroy it if power is applied to it backwards. The example symbol shows a CD4013 chip.

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DIP IC Sockets
These are IC sockets with machined pins. They provide a good connection to the pins of the IC. They permit you to easily replace a bad or suspect IC. These sockets have gold contact fingers. Make sure you buy the correct ones for your chips as far as number of pins go. Notice the divet on one end. That is the end that the chip's pin one goes on. Always make sure you install your sockets in the correct orientation or you may end up inserting a chip the wrong way and destroying it.

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Electrolytic Capacitor (Aluminum)
This is a typical aluminum polarized electrolytic capacitor. This is the radial lead configuration. They also come in axial configuration (leads coming out of the sides like an axle). Notice that the negative side is marked. This is because you must install polarized electrolytic capacitors properly. The negative side must always be at or below the potential of the other lead. Sometimes the positive terminal is marked. Usually the positive lead is longer than the negative lead (when new). There are also non-polarized aluminum capacitors. They look pretty much like this too but do not have a polarity indicator. They come in many colors. They range in value from micro-farads to farads. They have a wide range of voltage ratings. For synth work 25V or more is typical.

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Tantalum Capacitor
This is a tantalum capacitor. They are known for low leakage and high capacitance in a small package.

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Ceramic Cap
This is a typical ceramic capacitor. Ceramic capacitors are non-polarized so there is no need to put them into the board in a particular orientation. They come in many many values (from pico-farads to micro-farads) and many voltage ratings (from 10s of volts to 1000s of volts). They come in many sizes. Typically lead spacing of 0.2" (5mm) works well but you can always bend the leads of smaller or larger caps to fit the PCB. For synth work 50V or higher is more than enough.

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Film Capacitor
This is a typical polyester film capacitor. Film capacitors are non-polarized so there is no need to put them into the board in a particular orientation. They come in many many values (from pico-farads to micro-farads) and many voltage ratings (from 10s of volts to 1000s of volts). They come in many sizes and colors. Typically lead spacing of 0.2" (5mm) works well but you can always bend the leads of smaller or larger caps to fit the PCB. For synth work 50V or higher is more than enough.

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Film Capacitor
Another type of film capacitor to illustrate that they come in different shapes, sizes and colors.

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Film Capacitor
Another type of film capacitor to illustrate that they come in different shapes, sizes and colors. This is an axial lead configuration.

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Film Capacitor
Another type of film capacitor to illustrate that they come in different shapes, sizes and colors.

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Polystyrene Film Capacitor
Polystyrene caps display good temperature stability and long hold times when used in sample and hold circuits. They are like film caps (described above).

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Silver Mica Capacitor
A good capacitor for temperature sensitive applications.

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Nine Volt Battery Clip
Used to connect a 9V battery to a circuit.

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Battery Holder for 9V Battery
Keeps your battery from rolling around your enclosure.

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Resistor 1/2 watt 5%
Typical 1/2 watt resistor. They come in values from ohms to meg-ohms. The resistor should not be put into a circuit where it dissipates more than 1/2 watt of power. You will notice that as the power rating of a resistor goes up so does it's size. This is because the resistor needs more surface area to dissipate the heat that comes with high power.

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Resistor 1/4 watt 5%
Typical 1/4 watt resistor. They come in values from ohms to meg-ohms. The resistor should not be put into a circuit where it dissipates more than 1/4 watt of power.

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PT094 Tempco
This is a PT094 2K Ohm .1W +/-1% T.C. +3500 PPM Wire Wound Axial Compensator. It is used in very specific situations to compensate for temperature changes in log convertors. Tempco stands for temperature compensator.

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SPST N.O Momentary Push Button
This is a small normally open pushbutton. That means that the poles (the two connection points) are not connected to one another until you press the switch. Then they are connected for as long as you continue to press the switch. A normally closed switch works in the opposite way. The poles (the two connection points) are connected to one another until you press the switch then they are open for as long as you continue to press the switch.

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SPDT Toggle Switch
A toggle switch with one "pole" and two "throws". The pole (center terminal) is connected to one of throws (outer terminals) at all times. The center "pole" is connected to either of the outer "throws" by toggling (switching) the switch.

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DPDT Switch
This is a double pole double throw switch. It has two independent SPDT switches that are controlled with the same switch bat.

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Rotary Switch
A rotary switch provides a mechanism to connect one pole to any of several others. They come with one common "pole" to many "throws" or with several common "poles" each of which can be connected to a number of "throws" simultaneously.

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Potentiometer Knob (For 1/4" Shaft)
This is a knob which fits on a 1/4" potentiometer shaft. Since the hole is round it will fit pots with round or "D" shafts. Knobs come in many forms and colors. They also come in many shaft configurations including "D", knurled, round, different sizes, etc. Be sure the knobs you buy fit the pots you buy.

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Potentiometer
This is a typical potentiometer. They come in different wattage ratings, tapers, and resistances. Usually an "A" before the value means "Audio taper". The letter "B" before the value means linear taper. The two outer terminals connect to the resistive strip of the pot. The center terminal is connected to the "wiper" which "wipes" along the resistive strip when you turn the shaft thus permitting the resistance between the terminals to be varied.

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Potentiometer (Small body)
Another typical size of potentiometer.

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Trim-pot
These are trim pots. They are normally mounted on a PC board and used to set a resistive value that you occasionally change during calibration or adjustment. They come in a variety of configurations: top adjust, side adjust, multi-turn (for precision), mount on edge, mount laying down, etc.

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