Simple Low Cost Battery Operated Function Generator Circuit 1Hz to 1MHz
£20-250 GBP
Paid on delivery
To design a simple funtion 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 a platform (such as Arduino, BASIC Stamp etc) or licensed code. The firmware should be simple, lightweight and fully documented.
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, digital rotary encoders/push switches must not be used
Variable frequency control: This must be a 10 turn rotary potentiometer.
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 12 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
You are required to supply:
A schematic diagram for the complete system.
A complete parts list with manufacturer and supplier order codes.
A system description detailing the function of the design with any calibration, configuration and setup instructions.
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 asignment can be considered complete. The method of verification is to be aggreed, but may be a video demonstrating operation or a functional prototype.
You will not retain any copyright or other design rights for the project. All design rights will be transferred upon completion.
There is a potential for extension to the contract (by agreement) to design the PCB for the circuit.
Based on the feedback I have received from several bidders, some additional information:
Battery pack.
The battery pack selection will mainly be informed by enclosure space and cost. There are many standard NiMh packs available on the market offering a variety of sizes and voltages. The precise configuration has yet to be determined. You should assume the unit will operate from a 12v mains charger.
Frequency Control Potentiometer.
The main objection to using a rotary encoder for the frequency control is that it can take many turns to achieve a 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.
Of particular concern would be the 100Khz - 1MHz range which would require 900,000 steps @ 1Hz to achieve the full scale. This would require the user to make an awful lot of rotations of an encoder.
I propose therefore 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 and help to solve this limitation.
When the control is turned rapidly the frequency would be adjusted in steps of (say) 10KHz, a slower encoder turn speed the frequency would change in (say) 1Khz steps down to the slowest encoder rotation speed giving 1Hz increments. 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.
If you are confident that you can achieve a smooth and rapid operation then I would be happy to incorporate the use of a rotary encoder for frequency control instead of the 10 turn rotary potentiometer.
Project ID: #15489465
About the project
9 freelancers are bidding on average £425 for this job
hi i am an electrical engineer. i have vast experience related to circuit design and pcb design. i have done many embedded system projects. Relevant Skills and Experience i have hardware experience pcb design. let me More
~12 Hours @ standard rate of $50/Hr for design, component selection, schematic capture and time permitting board layout. Design criteria is similar to a DDS based design for an in-house project. Relevant Skills and Ex More
