A Simple Low Cost Battery Operated Function Generator Circuit 1Hz to 1MHz

To design a simple function generator circuit capable of generating sine, square and triangle output waveforms in the range of approximately 1Hz to 1MHz with a peak to peak voltage of 15 volts. The nature of the design is flexible and may make use of analogue or DDS technology. Where a microcontroller is used, it must be programmable from a blank device and the code must not use 3rd party licensed code. The firmware should be simple, lightweight and fully commented. Specialised, rare, obsolete and hard to obtain components such as ICL8038, MAX038, XR2206 or NTE864 must not be used. Particular attention should be paid to component costs. Parts should be readily available from Rapid Electronics, Farnell Electronic or RS Components. The function generator must be operated by basic controls. Menu systems using digital rotary encoders/push switches must not be used Variable frequency control: 10 turn rotary potentiometer or encoder. (seen note below) Frequency Range Select: This must be a rotary switch type selector. Selectable ranges of 10Hz, 100Hz, 1KHz, 10KHz, 100KHz, 1MHz Output voltage Control: This must be a rotary potentiometer. Waveform Seletor: This must be a rotary switch type selector. Power Switch: This must be a simple on/off switch. The switch must fully isolate power from the circuit (though the battery charging section will still operate). The function generator requires the following displays: Output frequency display: This must use 7 Segment LED displays. 7 Digits. Output voltage display: This must use 7 Segment LED displays. 3 Digits 1 Decimal Place Power indicator: When powered on the circuit must have a bi coloured LED which is illuminated green when the battery is charged, and illuminates red when the power is too low for reliable operation. This LED must also serve as a charge indicator when the circuit is turned off but charging the batteries. In this case it will show red when the battery is charging, and green when the battery is fully charged. Power supply: The circuit must be capable of operating from a battery for a period of at least 4 Hours. The circuit must be able to operate and charge from a 'Plug-top' (Wallwart) type power supply. The circuit must be capable of charging the batteries whilst in operation. The batteries must be of the Nickle Metal Hydride type. Specification: Outputs - Voltage: 0.6V to 15V peak-to-peak (0.3V to 10V into 50 Ohm) - Triangle Wave Linearity: Better than 99% - Square Wave Rise & Fall times: < 100nS - Sine Wave distortion: < 1% - Amplitude Flatness: +/- 1dB - Display Accuracy - Frequency: +/- 1%, Voltage: 5% - Display refresh rate: > 3Hz Deliverables: A schematic diagram for the complete system. A complete parts list with manufacturer and supplier order codes. Full and complete source code listing including hex files for the microcontroller if applicable. You are not required to produce a deliverable prototype, however your design must be fully verified before the assignment can be considered complete. A PCB design is NOT required but may be offered as an extension to the project. Frequency Control. The main objection to using a rotary encoder was that it can take many turns to achieve the required setting, particularly as there is a limited speed at which an encoder can be rotated before it misses pulses. This tends to make them slow and frustrating to use. A method of detecting the rate at which the encoder is being turned, which would then affect the rate of change of the frequency setting would be a way to solve this limitation. The increments could be set to suit each of the six frequency range settings. This offers the user precision control whilst allowing them to also make rapid adjustments. Note: Your bid is is for completion of the work as described above - not a starting point from which to negotiate a realistic price! Please include the word SigGen in your proposal so I can see you have actually read these project requirements.