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Quartz Crystal Synchronizer for Pendulum Windup Wall Clock
Quartz Crystal Synchronizer for Pendulum Windup Wall Clock
February 13, 2014

The clock movement is made in Korea by "Sau Jin LTD" "Dae Woo CO LTD" and has no jewels. It measures 4.5 inches diameter by 1.5 inches deep plus 1.5 inches for the hands and... [more]

16 Stage Bi-Directional LED Sequencer
16 Stage Bi-Directional LED Sequencer
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]

10 Channel LED Sequencer
10 Channel LED Sequencer
January 18, 2011

10 Channel LED Sequencer [more]

18 Stage LED Sequencer
18 Stage LED Sequencer
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]

Two Transistor LED Flasher
Two Transistor LED Flasher
January 18, 2011

Two Transistor LED Flasher [more]

1.5 Volt LED Flashers
1.5 Volt LED Flashers
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]

LED Photo Sensor.
LED Photo Sensor.
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]

Fading Red Eyes
Fading Red Eyes
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]

Automatic 12 Volt Lamp Fader
Automatic 12 Volt Lamp Fader
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]

LED 12 Volt Lead Acid Battery Meter
LED 12 Volt Lead Acid Battery Meter
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]



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