Category Archives: Electronics

555 Timer Math


Introduction I have never used a 555 timer for a home project and now I have several applications for this handy device up at my cabin in Northern Minnesota. I thought I would cover some of the basics in this … Continue reading

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Inductive Car Sensor Math


Introduction Spring has come to Minnesota and I want to build an outdoor electronics project — this is one of my favorite activities. I have decided to build a car sensor for my cabin in northern Minnesota. This car sensor … Continue reading

Posted in Cabin, Electronics | 2 Comments

Using a D-Size Battery String for a UPS Energy Source


Introduction I am looking at supporting an Uninterruptible Power Source (UPS) that uses twelve D-size alkaline batteries for its energy source. Telecom service providers like D-size alkaline batteries because their subscribers can purchase them at many local grocery stores. They … Continue reading

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A Simple Frequency-to-Voltage Converter


Introduction I often build small electronics projects for use around my home. I recently put together a small sensor interface that converts the inductance of a sensor to a digital signal with a frequency that is related to the inductance … Continue reading

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Schmitt Trigger Design Math


Introduction I have a home project that requires me to design a Schmitt trigger circuit. There are numerous places on the web where you can find design equations for the Schmitt trigger constructed using an open-drain comparator. Unfortunately, these design … Continue reading

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Mathcad Solution to an LVPECL to LVDS Matching Problem


Introduction A circuit question walked into my cube the other day. An engineer in another group was working his way through an application note and he found the presentation unclear — I agreed with him. The application note provided an … Continue reading

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Rigging Cables is Really Important


I have been rather frustrated lately with the number of field failures I have encountered that are related to the humble cable tie (Figure 1 – Source). There are several problems related to cable ties. They are easy to over-tighten … Continue reading

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Example of Error Calibration


Introduction I was reviewing a test report today for an optical receiver with an integrated power measurement sensor. This sensor is not particularly accurate — its accuracy was specified as within ± 3 dB of true. This is not good … Continue reading

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A PCB Thermal Computation Example


Introduction I am doing some self-training on electronic thermal analysis. As part of my self-training ritual, I often work through vendor application notes. This post will show how I work through an application note using Mathcad. You might think that … Continue reading

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Australian Phone Line Impedance Math


Introduction I am doing some work with international phone circuits and I noticed that the Australian government has test procedures that model the characteristic impedance of the phone line using a resistor/capacitor circuit (see Figure 1). In the US, we … Continue reading

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