Tan Timer

Six timing positions suited to different skin types

Timing affected by sunlight intensity

Circuit diagram

Tan Timer-Circuit diagram


  • R1 47K 1/4W Resistor
  • R2 1M 1/4W Resistor
  • R3,R5 120K 1/4W Resistors
  • R4 Photo resistor (any type)
  • C1,C3 10µF 25V Electrolytic Capacitors
  • C2 220nF 63V Polyester Capacitor
  • D1,D2 1N4148 75V 150mA Diodes
  • IC1 4060 14 stage ripple counter and oscillator IC
  • IC2 4017 Decade counter with 10 decoded outputs IC
  • Q1 BC337 45V 800mA NPN Transistor
  • SW1 2 poles 6 ways Rotary Switch (see notes)
  • SW2 SPST Slider Switch
  • BZ1 Piezo sounder (incorporating 3KHz oscillator)
  • B1 3V Battery (two 1.5V AA or AAA cells in series etc.)

Device purpose:

This timer was deliberately designed for people wanting to get tanned but at the same time wishing to avoid an excessive exposure to sunlight. A Rotary Switch sets the timer according to six classified Photo-types (see table). A Photo resistor extends the preset time value according to sunlight brightness (see table). When preset time ends, the beeper emits an intermittent signal and, to stop it, a complete switch-off of the circuit via SW2 is necessary.

Photo-type, Features and Exposure time

  • I & children Light-eyed, red-haired, light complexion, freckly 20 to 33 minutes
  • II Light-eyed, fair-haired, light complexion 28 to 47 minutes
  • III Light or brown-eyed, fair or brown-haired, light or slightly dark complexion 40 to 67 minutes
  • IV Dark-eyed, brown-haired, dark complexion 52 to 87 minutes
  • V Dark-eyed, dark-haired, olive complexion 88 to 147 minutes
  • VI The darkest of all 136 to 227 minutes
  • Note that pregnant women belong to Photo-type I


  • Needing only one time set suitable for your own skin type, the rotary switch can be replaced by hard-wired links.
  • A DIP-Switch can be used in place of the rotary type. Pay attention to use only a switch at a time when the device is off, or the ICs could be damaged.
author: RED Free Circuit Designs
circuit from http://www.redcircuits.com/