RadioLocman.com Electronics ru
Advanced Search +
  

08-17-2009

Tan Timer

Six timing positions suited to different skin types
Timing affected by sunlight intensity

Circuit diagram:

Tan Timer

Parts:

 

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 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

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

 

Notes:

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. Please pay attention to use only one switch at a time when the device is off, or the ICs could be damaged.

Slices ↓
Radiolocman facebook Radiolocman twitter Radiolocman google plus