Automatic contrast meter


Posted on Aug 17, 2012

The circuit arrangement consists of a photo-amplifier which feeds a voltage derived from varying light levels in an enlarger to a pair of peak detectors. One follows the peak positive voltage and the other the peak negative voltage. The capacitors used for storing the voltage peaks in the followers also form part of sample and hold circuits which are then switched to hold after the measurement. Their outputs represent the maximum and minimum values of light intensity


Automatic contrast meter
Click here to download the full size of the above Circuit.

A differential amplifier then computes the ratio of these values, and the result is displayed on an LED bargraph meter.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

VHF remote control
Dc-voltmeter
Electronic Slot Machine Circuit
Stepper Motor Generator
Symmetric Output for USB Audio DAC
Balanced Low Noise Microphone Preamp
Touch light switch delay circuit
Alternating current voltage amplifier transistor



Top