Posted on Dec 25, 2012

A simple inventer and NAND gate can be connected to yield a highly compact and reliable digital frequency detector. This circuit can detect frequencies up to 3 MHz with 50% duty cycles. When a frequency, j,, appears at the input, points A and B detect a logical high de level. Thereupon pointE increases the latch sets and the LED lights. If the input frequency is absent and if the voltage is either at a constant high or low level, points A and B will be complementary and pointE will decrease.

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

This will reset the latch and extinguish the LED.

Leave Comment

characters left:

New Circuits



Popular Circuits

Capacitance multiplier
IR Remote-Control Checker
crystal controlled timebase
lights led circuits schematics
stereo fm circuit
15 volts power supply electronic circuit project using LT3512
Darkroom Timer v2.0A for PCB Exposure Box
Fuzzy Urn
HF BPF Builders
Linearized input bypass circuit XTR112
5W Valve RF Transmitter circuit