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Recently added diagrams and projects
January 18, 2011
The bi-directional sequencer uses a 4 bit binary up/down counter (CD4516) and two "1 of 8 line decoders" (74HC138 or 74HCT138) to generate the popular "Night Rider" display. A Schmitt Trigger oscillator provides the clock... [more]
January 18, 2011
When power is applied, the 15K resistor and 10uF cap at pin 15 will reset the counters to the zero count where pin 3 is at +12 and all other outputs are at zero. The... [more]
January 18, 2011
The LED flasher circuits below operate on a single 1.5 volt battery. The circuit on the upper right uses the popular LM3909 LED flasher IC and requires only a timing capacitor and LED. [more]
January 16, 2011
Here's a circuit that takes advantage of the photo-voltaic voltage of an ordinary LED. The LED voltage is buffered by a junction FET transistor and then applied to the inverting input of an op-amp with... [more]
January 16, 2011
This circuit is used to slowly illuminate and fade a pair of red LEDs (light emitting diodes). The fading LEDs could be installed as 'eyes' in a small pumpkin or skull as a Halloween attraction,... [more]
January 16, 2011
This circuit is similar to the "Fading Red Eyes" circuit (in the LED section) used to fade a pair of red LEDs. In this version, the lamps are faded by varying the duty cycle so... [more]
January 16, 2011
In the circuit, a quad voltage comparator (LM339) is used as a simple bar graph meter to indicate the charge condition of a 12 volt, lead acid battery. A 5 volt reference voltage is connected... [more]
January 16, 2011
The circuit below illustrates powering a LED (or two) from the 120 volt AC line using a capacitor to drop the voltage and a small resistor to limit the inrush current. Since the capacitor must... [more]
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