Circuit to shorten on time of leds having an optical sensor input and using a nand gate 4011 chip

Thread Starter


Joined Nov 25, 2015
Trying to copy a previous circuit and make a new one but can t get it to work. Does this drawing make sense. The unknown is the capacitance value on the left of the drawing. I ve tried 15nF but it didn t work. Timing of the led whithout the circuit is on for about 3 milliseconds and we only want it on for about a sixth to a tenth of this. I ve included a photo of the old one and the data sheets for sensor and nand gate. It might be I have a connection in the wrong place or misread a resistor. If anybody can help it would be amazing.

Thankyou very much circuit drawing.JPG


panic mode

Joined Oct 10, 2011
i don't know what is the sensor part number or what are the terminals (wire colors) used but - that cannot work, there is nothing connected from sensor to anything else other than power.


Joined Jun 22, 2012
Your drawing is totally wrong, both sensors are shorted out, so they won't work, you haven't copied it correctly.

Do you have the original circuit or an idea of what you're trying to do