Darkroom timer


Posted on Nov 12, 2012

The darkroom timer/controller uses few external components: a display, a digit driver, keyboard, and output switching devices. A 4-digit common-cathode LED display is desirable for dark room environments. The time base is provided by shaping up the 50/60 Hz ac line. A DPDT switch (Si) is used to select a resolution of or 1 seconds and to simultaneously move the decimal point


Darkroom timer
Click here to download the full size of the above Circuit.

Timer/ controller has two switched ac outlets, one for the enlarger and one for the safe light. They are the complements of each other in that the safe light is on when the enlarger is not active and is off when the enlarger is printing. The buzzer is of the self-contained oscillator variety and operates with dc drive.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

LED Night Lamp
Simple analogue Tachometer
Automatic Turn-Off Control For Automobiles Circuit
Voltmeter Ammeter
door lock schematic
MK484 AM radio circuit design project
Sending Data Over IR Wireless Infrared Communication Link System
Wolfstone Pyrotechnics
Electronic Drum Synthesizer
12 Volt DC Power Supply Circuit
AC DIGITAL CLOCK WITH STANDBY BATTERY
Simple square wave generator



Top