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 Home » Timer » 10 Minute UV Dental Tooth Whitener Timer
10 Minute UV Dental Tooth Whitener Timer    
Build yourself an inexpensive UV Timer light for tooth whitening. This little project could save you in the region of some £100 to £400 pounds It’s ideally for dental nurses who have to buy their own equipment.  Circuit DSN Files For Proteus
I was approached one night to sort out a problem for a friend of mines wife who accidentally put the wrong power supply into an expensive dental unit which she uses from to whiten teeth for some of the top actors in the UK. Of course she’s self employed and like most of us when your self employed and tools break down it a nightmare. The module comprised surface mount components and provides a UV Light for chemical whitening of teeth which require 10 minute exposure to cure. Of course its non repairable to its original state and being dental equipment you have to buy a complete new Unit. I came up with something far better, serviceable and costing a fraction of the of money required.

The circuit is all based round the 12f675 and uses timer interrupts a button switch for detecting when the unit has been started to start the timing sequence. The Unit must also beep at start up and count to 9 seconds keeping the Luxion led on. During the last minute the Module must beep once per second during the final minute countdown so as to notify the nurse that the exposure is complete this must be done via a buzzer emitting a high pitched beep.

The circuits is very easy to understand.

D2 ensures Reverse polarity protection. With F1 being rated at 500ma to protect the rest of the circuit. D1 is a 5v1 zenor diode rated at 500mw which is purely there to prevent over voltage protection c4 decouples the 12F675 recommended in the data sheet as close as you can to pins 1 and 8 R2 to R5 limit the current through the Luxion Led which is switched on via the FET an 1RF540 biased off via R6

R6 and R7 form the biasing network via GP1 of the CPU turning on the Fet and of course the Luxion R1 and R10 form a potential divider for the switch which activates the timer sequence so that countdown can begin when this starts the Luxion Led is turned on at the end of the final countdown I.E 10 minutes then the Luxion LED is subsequently turned off Switch sensing is done via GP0 which is de bounced when finger press of the switch is released GPO looks for a logic High to start the timer sequence and is held low when no press is detected

The buzzer sound is sent via GP2, R9 which forward biases Q2 using a PWM waveform hence our sound of the buzzer.

Circuit DSN Files For Proteus

PCB layout Files For Proteus

Circuit Diagram In PDF Format

PCB layout Files in PDF Format

C Code for the 12F675

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