"SAKit" the Simple Amplifier Kit PART NO. 2210061
Build your 1st op amp with the SAKit!
The Simple Amplifier Kit (hereafter SAKit) is ideal for engineers, hobbyists & technicians who want to know analog circuits @ the transistor level before delving into analog ICs.
Description:
SAKit is a VFB (Voltage Feedback) operational amplifier designed to make use of five transistors with class AB output stage hookup as an AC coupled non-inverting amplifier. It is the embodiment of a simple classical op amp (a class A output stage will reduce transistor count to four at the expense of lower current sinking capability & efficiency). Although this circuit is quite simple (some might say trivial!!) because there are no emitter constant current source, collector current mirror, output current limiting, etc. it serves to illustrate the starting point in op amp design. Once the kit is built on a breadboard you have a fully functional, one-channel audio amplifier, complete with 2 inch 8 ohm speaker & 3.5 mm phone plug to verify audio performance (subjectively) using an ordinary mobile phone with mp3 player. A 3.5 mm phone jack is provided to listen via headphones. The 3.5 mm jack & plug, speaker & 5 ohms resistor must be soldered to AWG 22 solid wire before inserting into the breadboard.
2 BC546 transistors (Q1 & Q2) with resistors R2 & R3 forms the differential input stage, a 2N3906 transistor with capacitor C3 & resistor R6 as voltage gain stage (aka VAS). Output stage consists of TIP31 Q4 & TIP32 Q5 transistors, diodes D1 to D3 & resistors
R7 & R8. Input signal is applied to capacitor C1. Feedback network is composed of C2, R4 & R5; short C1 & C2 to amplify DC signal.
Capacitors C8 & C9 prevent DC voltage reaching the speaker. R9 is optional to protect the output stage from short circuit.
Recommended power supply is +-15V.
The kit comes with an adjustable dual-tracking reference as DC input voltage to the amplifier and a uA741 (maybe the most popular) op amp for operation comparison.
Details of op amp circuit analysis & operation can be found at
1. http://www.ecircuitcenter.com/Circuits_Audio_Amp/Basic_Amplifier/Basic_Audio_Amplifier.htm
2. The Art of Electronics 2nd Edition pages 236 to 238, Paul Horowitz & Winfield Hill, Cambridge University Press 1980, 1989, ISBN
0-521-37095-7

Time Required: 2 hours depending on experience
Experience Level: Beginner
Required tools and parts:
1. Breadboard (Jameco Part no. 2157693)
2. Multimeter example Fluke 115 True RMS Multimeter (Jameco Part no. 1537328)
3. Benchtop Power Supply example MASTECH HY3002-2-R 2X 30VDC@2A (Jameco Part no. 211722)
4. Pliers Long Nose (Jameco Part no. 177608)
5. Wire Cutter (Jameco Part no. 179902)
6. Screwdriver (Jameco Part no. 34041)
7. Wire Hook-up Solid 22 AWG (Jameco Part no. 2152876, 2152905, 2153553)
8. Solder (Jameco Part no. 73576)
9. Audio source such as CD Walkman, mobile phone, mp3 player, notebook, tablet etc.
Optional
1. Scope example EZ DIGITAL OS-5020 (Jameco Part no. 2145220)
2. Potentiometer Adjustment Tool (Jameco Part no. 153315)
3. Wire Cutter Stripper (Jameco Part no. 215889)
4. Headphones
Qty Jameco SKU Component Name
1 179354 NPN Transistor
Transistor Q4 is a component of the op amp circuit.
1 181841 PNP Transistor
Transistor Q5 is a component of the op amp circuit.
2 806645 TO-92 General Purpose NPN Transistor
Transistors Q1 & Q2 are components of the op amp circuit.
1 178618 2N3906 PNP Transistor
Transistor Q3 is a component of the op amp circuit.
3 179215 1N4148 DO-35 Diode
Diodes D1, D2 & D3 are components of the op amp circuit.
2.2uF 50V Radial Capacitor 1 93729
Capacitor C1.
2 691340 100K Ohm Resistor
Resistors R1 & R4.
1 690814 620 Ohm Resistor
Resistor R2 is a component of the op amp circuit.
1 691067 6.8K Ohm Resistor
Resistor R3 is a component of the op amp circuit.
1 31114 47uF 50V Radial Capacitor
1 15413 220pF 50V Ceramic Capacitor
Capacitor C3 is a component of the op amp circuit.
1 661546 1.5K Ohm Resistor
Resistor R6 is a component of the op amp circuit.
2 660295 5 Ohm Wirewound Resistor
Resistors R7 & R8 are components of the op amp circuit.
1 661239 75 Ohm Resistor
Resistor R9 is optional for output stage short circuit protection.
1 690988 3.3K Ohm Resistor
Resistor R5.

1
1
2
6 2146302
Capacitors C4, C5, C10, C11, C12 & C13
0.1uF 50V Capacitor
2 93761
Capacitors C6 & C7
100uF 25V Radial Capacitor
1368771
826793
2163882
8 Pin Voltage Reference
LM358P Dual Op-Amp
10KOhm Metal Film Resistor
Resistors R11 & R12
1 240427 10k Potentiometer
Trimmer R10 for adjusting dual-tracking reference.
1 231176 Male Stereo Plug
For connecting to CD Walkman, mobile phone, notebook, tablet etc. headphones output.
1 2095437 Audio Jack
To listen via headphones.
2 2178689
Heat sink for transistors Q4 & Q5
TO-220 Black Heat sink
1 691104
For checking +-output swing@10k load.
1
2
320362
609705
10K Ohm Resistor
2" 8 Ohm Round Speaker
2200uF 35V Radial Capacitor
Capacitors C8 & C9
1 830522 8 Pin General Purpose Op-Amp
Op Amp IC for operation comparison with SAKit.
Step 1 - SAKit circuit schematic
Assemble the components on the breadboard according to the circuit schematic.

Step 2 - Transistor placement
Layout transistors onto the solder less breadboard according to the schematic diagram.
Step 3 - Passive component placement & connection
Connect components via AWG 22 solid wire by following the schematic diagram. Assorted color wire is recommended to ease troubleshooting. Solder AWG 22 solid wire to speaker, 5 ohms resistor, 3.5 mm jack & plug prior insertion into the breadboard.

Step 4 - Adjustable Dual-Tracking Reference circuit schematic
Assemble the components on the breadboard according to the circuit schematic.
Step 5 - IC placement
Place ICs onto the solder less breadboard by following the schematic diagram.

Step 6 - Passive component placement & connection
Connect components via AWG 22 solid wire by following the schematic diagram. Assorted color wire is recommended to ease signal tracing and troubleshooting.