Design Low Battery Alarm Schematic and PCB Layout

SUMMARY: We look for an engineer to design a simple low battery alarm for our new product, a 12 VDC battery powered air compressor. We require one PCB with 2 functions: a battery depletion monitor, and a driver for a piezo buzzer. Please see the detailed specifications below: FUNCTIONAL REQUIREMENTS: A. BATTERY DEPLETION MONITOR 1. It will monitor battery depletion and switch on the alarm function at 11V (+/- 1%). 2. It will be possible to alter this threshold value of 11V in the future by simply replacing a component on the PCB (e.g. resistor) with a one with different value, i.e. we do not wish the use of trimpots and other operator-adjustable components. 3. The switching of the alarm function will be sharp despite some voltage fluctuation as a result of the compressor operation. 4. No timer is required, i.e. the alarm will stay on until the battery is completely depleted or the entire device switched off by user. 5. A data sheet for the battery is attached for your review. B. PIEZO BUZZER DRIVER 1. It will be triggered by the battery depletion monitor and drive the piezoelectric component CEP-1116 from CUI Inc to produce sound. 2. The expected minimum sound level output produced by the piezo buzzer will be at least 102 DbA at 10cm. 3. The signal produced by the piezo driver will be a sweep tone (\"siren\") as per the following specifications: - Min Frequency is 1600 Hz (+/- 5%) - Max Frequency is 2300 Hz (+/- 5%) - Sweep speed is 7 Hz (+/- 10%) - Sweep law is Bi-Log. 4. The output voltage will be maximum to produce loudest possible sound within the allowable specifications of the piezo buzzer (min. 50 Vpp). 5. A data sheet for the piezo buzzer is attached for your review. NON-FUNCTIONAL REQUIREMENTS: 1. The shape and size of the PCB and the location of the input terminals (G and +) will be as per the attached SVG drawing. 2. The design will use all components either SMD or THT (if possible). SMD preferable. 3. The design will use components from the OPL library of [login to view URL] to enable the use of their PCB assembly service. 4. The design will avoid the use of autotransformers (if possible) unless they are easy to source, i.e. are usually on stock of [login to view URL] or [login to view URL] and alike. 5. The design will use minimum number of components, i.e. is simple and robust. 6. The design will strive to minimise the manufacturing costs, i.e. use standard \"cheap\" components. 7. The design will use generic components (such as IC 555), i.e. we do not wish to use very specific IC such as ZSD100 (these may be difficult to source and may be discontinued in the future, thus impact the production). OUTPUTS: 1. Documentation in Fritzing (.fzz files). If not possible, please discuss. 2. Schematic view (.fzz), PCB Layout view (.fzz), List of components (.xls). 3. One (1) prototype for us to test against the above requirements (preferably direct order from [login to view URL] with delivery to our address). SCHEDULE: We aim to complete this task within 2 weeks (ex. delivery of prototype). Please advise the steps and duration of tasks, such as: - asses requirements and define design options - draft schematic for our review - find components and draft PCB layout for our review - build and test prototype and advise results for our review - deliver prototype PREREQUISITES: Good experience with electronics design, especially driving piezo elements, oscilloscope and sound level meter. It also requires good business acumen to design PCB that is simple, robust and easy/ cheap to manufacture. COMMUNICATION: We wish to communicate with you during the process to provide inputs such as the results of our previous research, share test experience, as well as provide guidance and assist in choice of the design/layout options and component selection. Preferred means of communication is Skype and Email. The language of communication is English. REWARD: The reward is subject to our successful testing against the above requirements.