|
|
Circuits > Oscillators and timers > Tan Timer
Tan Timer
Six timing positions suited to different skin types
Timing affected by sunlight intensity
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 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 |
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. Pay attention to use
only a switch at a time when the device is off, or the ICs could be damaged.
Title: Tan Timer
Source: www.redcircuits.com
Published on: 2005-02-03
Reads: 445
Print version: 
Circuits > Oscillators and timers > Tan Timer |
|
