Category: led display
Using AC for LED Christmas Lights
| May 21, 2011 | Posted by admin under led display |
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This circuit uses low-voltage AC to drive a string of 50 or so bi-color LEDs (two LEDs connected in inverse parallel). Power to the LEDs is controlled by the Triac and the two optocouplers which have their photo-transistors effectively connected in inverse-parallel. Depending on which optocoupler is turned on, the Triac applies positive, negative or…
LED Light Pen using BC547
| May 17, 2011 | Posted by admin under led display, led lamp, led light |
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Physicians and repair engineers often use small light pens for visual examination Spurposes. Rugged and expensive as these pens may be, their weak point is the bulb, which is a ‘serviceable’ part. In practice, that nearly always equates to ‘expensive’ and / or ‘impossible to find’ when you need one. LEDs have a much longer…
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