Assessment Task 1 LM386 Amplifier
The circuit shown above is an amplifier that can be used to replay sounds from various sources such as IPods and MP3 players. The circuit can also be used to mix sounds from various sources and this could provide a good extension task for those students that complete the assessment task early. The circuit will be powered via a 9 volts battery but once again could be modified to run off the mains.
Instructions
Use data sheets for the LM386 operational amplifier Design the circuit using DIYLC software, this circuit is to be manufactured on strip-board Add a switch and an LED power indicator (not shown in schematic) Check your design against the schematic and secure approval to proceed with the manufacturing phase from the lecturer Manufacture the completed design, drill the circuit board and gather the required components Populate and solder components to the circuit board using safe soldering techniques Once complete visually check the circuit board for defects, crossed tracks and dry joints Use test equipment as directed to confirm the correct function of your circuit and components Component List:
9 Volt Battery and Battery Holder LM386 Amplifier 1 x 50 nf and 1 x 100 nF ceramic Capacitors 1 x 100 uF, 1 x 10 uF and 1 x 220 uF Electrolytic Capacitors 1 x 10k Potentiometers 1 x LED (power indicator) 1 x 470 Ω (for power indicator LED) , 1 x 10 Ω resistors 1 x Switch 1 x 0.3 Watt Speaker Various Cables and Connectors
Task 1
Draw or print and attach the pin-out diagram for LM386 Operational Amplifier
LM386 Op Amp
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Include a circuit plan of either
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Task 3
Tick off each of the components used in this circuit against the items on the following list. I have completed one for you
Item Used in Item Used in circuit 1 circuit 1 Fixed Resistors Analogue/Digital IC’s
Variable Resistors Surface Mount Packages Potentiometers 10k Rectifiers
Sensing Resistors Switches (LDR etc) Fixed Capacitors Mini Transformers
Electrolytic Decoders Capacitors Diodes Regulators
Zener Diodes Encoders or Resolvers
Light Emitting Inverters or Servo Diodes (LED) Controllers Transistors Edge Connectors
Thyristors Wiring/pins/tags/wire links Fixing Spacers Small Heat Sinks
Insulators Cables
Cable Connectors Opto-Electronic Components Protection Devices
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Date …………………………………………… Task 4 Assemble the circuit and tick off the tools used to make this circuit from the following list
Item Item Heat shunts/tweezers Component forming devices Snipe nosed pliers Wire Strippers
Sleeving pliers Side or end cutters
Bolt fasteners Specialized assembly (spanners) equip Anti-static mats or straps
Briefly describe the procedure and tools you used to make this circuit using the box below
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From the following list tick off which functions you think this circuit fulfils. Once again I have given you an example, the 555 timer functions as an oscillator.
Circuit Component Circuit Component function Function Audio amplifier LM386 Filter
Signal converter Microprocessor application Signal generator Comparator
Counter/Timer Power amplifier
Oscillator Motor control
Regulated power Sensor/actuator supply circuit Logic function ADC/DAC hybrid controls circuit Display Circuit Alarm/protection circuit
Use a schematic of the circuit to highlight (circle) which components function as the circuits you have ticked off on the list above. Staple the completed schematic to this page.
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Date …………………………………………… Task 6 Test Equipment Result The resistance between power Multimeter and ground
The earth continuity Multimeter
The continuity of the power line Multimeter
The voltage levels at the power Multimeter pins for both the LM358 and the LM386
The signal at the input and output Oscilloscope of the circuit Multimeter Bench Power Supply Function Generator
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Task 7
Use the box below to briefly evaluate this exercise, stating the things you have learned whilst building the circuit, how you overcame any problems you encountered and what if anything you would do differently next time.
Evaluation
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Practical Observation Task Competent The student carried out the following tasks: Yes No Designed the circuit using DIYLC
Correctly identified the correct components to manufacture the circuit using the schematic and data sheets/charts Was able to follow the circuit plan and successfully populate the board
Correctly identified polarity dependant components
Safely soldered the components to the stripboard and carried out a visual check of the soldering Carried out a visual check on all components for signs of damage, carried out a ‘pull test’ on components to check for faulty soldering Adhered to safety regulations at all times when manufacturing the amplifier circuit, including the use of correct PPE Connect test equipment to the circuit in a safe and approved manner
Demonstrated the use of test equipment to test circuit function and trace circuit faults in a safe manner Left the workspace in a safe and tidy condition when work was completed
Assessor Feedback
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All of the work included as a part of this assessment is my own:
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All tasks complete
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