Archive for the ‘Optoelectronics’ Category:

2021-09-28 Qualcomm CEO’s Chip Shortage Opinion

Almost 3 minute video.

2020-06-11 Optocouplers Don’t Always Protect

From FB comment Monty Ross It’s true that optocouplers are used for isolation. But I have seen whole sections of PC boards with a hole burned where the optocouplers used to be. It is incredible how much damage the power lines do to the PC boards due to high voltage spikes in the power. Transformers

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2017-07-13 Don’t Use Your Original Remote Control 

From FB reply My remotes seem to go bad all the time.  Batteries low or dead, battery juice leaking on the circuit board, broken wires from falling off the table, getting sticky or worn, etc.  I try to minimize the wear and tear on the original remote.  I never use the original remote, I use a cheap

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2016-02-23 Joule Thief With Daylight Shutoff

I designed my Blue Blinky with a daylight shutoff, using a LED as the light sensor and an additional transistor to amplify the minuscule current that the LED puts out.  This worked just great because there is the point across the timing capacitor where the current is very low, and it takes very little current

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2015-05-03 Light Emitting Paper

Quantsuff emailed us a link about a new material summarized at  I have a few thoughts that I’d like to add. The stuff should be great for illumination.  But I have doubts about its use for display purposes.  Displays have millions of very small pixels.  If one or a few get contaminated with dust

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2014-03-19 7 Year Long Running Joule Thief

A few months ago I came across a 7 Year Joule Thief  video from Xee2vids on YouTube (link below).  It’s a conventional Joule Thief except that the resistor has been increased to 2 megohms, and a 100 pF capacitor has been added from the resistor to ground.  He calculates that the LED  should run for

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2013-11-20 LEDs Power TE Flasher, Not JT Flasher

My recent two blogs on powering a flasher with four red LEDs used a flasher made by modifying a Joule Thief.  It works fine, but it requires a toroid core and wire; the flasher I blogged earlier does not require any inductor.  It is a switched capacitor or charge pump,. and it works okay with

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2013-10-27 Low Power Joule Thief With Photocell

One Joule Thief I have not built (at least not in the same JT) is the low power JT with the CdS photocell.  Almost all of my JTs with daylight shutoff used a LED as a light sensing diode, and then most were flashers.  I have a bunch of CdS photocells but I haven’t really

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2013-08-12 Using CdS Photocells in a Low Current Circuit

A common circuit such as a night light may use a CdS photocell to turn it off during daylight hours and on during night time.  The photocell is connected to a circuit that senses the voltage and turns the rest of the circuit on and off at a threshold point.  The photocell is in series

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2013-01-30 IR Remote Emulator Learns and Sends

I’ve thought about this a number of times in the recent past.  There used to be a .ZIP file on the ‘netcalled Xanadu Zapper which consisted of plans and code to implement an IR xmit/recv interface for the PC along with code for learning and sending the IR codes.  Many years ago I built the

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