Here are some pictures of the lighted hat I wore on my head on the 17th of this month.I purchased some green T1 size LED's on EBAY some months ago that were designed for 12V operation, so they had a series resistor and leads attached. I thought they were still to bright for a 9V battery so a added the 680 ohm resistor from pin e of the 4051 to the +9v source.
Circuit operation of my circuit called holiday display. U1 is a quad 2 input nand Schmitt trigger. 3 of the gates are used as astable oscillators. The frequency of the oscillators is very close to the following formula: Frequency=1/2.2RC. U2 is a 1 of 8 switch. The three oscillators feed the AB&C inputs and the 1 of 8 outputs depends on the binary code to the inputs. The IN/OUT pin 3 is tied to Vdd through a resister R4 so the outputs are + with respect to Vss or ground.
I chose the 4051 and the 4093 a number of years ago because with the adjustable frequencies of the 4093 the Led’s can appear to be random with no definated sequence. Also with the outputs high thru a resistor connected between pin 3 and Vdd multiple LED’s can be put in series and still only require on current limiting resistor. I used the CMOS Cookbook by Don Lancaster as a guide. He specifies a maximum current of 25mA for the IC. There is also about 125 ohms resistance between pin 3 and the outputs, so sometimes this 120 ohms has to be figured in the maximum current for the LED’s.
I have over time used 10mA as maximum current for the older LED’s, but a lot of the newer one’s that are much brighter the current can be much less.
Moderator if this meets the requirements for a completed project, please move it to that area.
Last edited:
