This Design Idea describes a 9V battery-voltage monitor whose total parts cost less than 34 cents (Figure 1). You configure transistor Q1 as a 10-mA current sink. LED1, a Kingbright WP7104IT, is on when the battery voltage is good. When the battery voltage nears the threshold voltage, the LED gradually dims. It goes out once […]
Configure a low-cost, 9V battery-voltage monitor Read More »
This is useful tip for anyone making or using surface mount components on PCBs. It relies on access to a laser cutter, so if you don’t have one, look away now….. I cut a plastic stencil on the laser, align it with the PCB pads and then squeegee a thin layer of solder paste through
Soldering stencils for DIY circuit boards. Read More »
All items stored in a deep freezer will thaw out if, for some reason, the temperature inside the freezer rises to the thaw point. However, a freezer monitor alarm can warn you of the rising temperature before the thaw point is reached. This simple circuit is powered by regulated 9V and built around a few
Freezer Monitor Alarm Read More »
Semtech has launched the SX1272, the first product in a new family of long-range Radio Frequency Integrated Circuits (RFICs) with a transmission range up to 15 kilometers. The SX1272 integrates Semtech’s new LoRa (long range) modulation technology to enable drastic range improvements over alternative modulation methods. Compared to a typical range of 1 to 2
Smart Meter Transceiver IC has Range of 15 km Read More »
At the heart of this circuit is a precision integrated temperature sensor, LM35 (IC1), which provides an accurate linear and directly proportional output in mV, from 0 to +155 degrees C. Designed to draw a minimal current of its own, the LM35 has very low self heating in still air. Here the output of the
Overheat Detector Alarm Read More »
To display the wave I am using XOSCILLO, a very cool and open source tool (which I wrote :P) that converts your Arduino into an oscilloscope. Circuit diagram Here is the scheme, I am using the typical instrumental amplifier(ins amp) and then another op amp to get some more gain. An ins-amp is like an
Minimal ECG using an Arduino and Xoscillo Read More »
This project details the design of a very low dropout adjustable power supply. A good power supply is essential to electronic projects, and being able to hook this up to a breadboard makes it very useful to hobbyists. It features a dropout of only 40mV – 400mV compared to 1.25V – 2.0V for a LM317
Low Dropout Adjustable Breadboard Power Supply Read More »
Description. The circuit given here is of a very useful and accurate digital voltmeter with LED display using the ICL7107 from Intersil. The ICL7107 is a high performance, low power, 3.5 digit analog to digital converter. The IC includes internal circuitry for seven segment decoders, display drivers, reference voltage source and a clock. The power
Digital voltmeter using ICL7107 Read More »
Description Create a design and simulate using EE-Sim: [MAX15050][MAX15051] The MAX15050/MAX15051 high-efficiency switching regulators deliver up to 4A load current at output voltages from 0.6V to (0.9 x VIN). The devices operate from 2.9V to 5.5V, making them ideal for on-board point-of-load and postregulation applications. Total output-voltage accuracy is within ±1% over load, line, and
MAX15050 – Design a small, efficient 4A step-down converter Read More »
I recently salvaged a vacuum fluorescent display (VFD) from a piece of old test gear. The VFD is a 13 digit 7-segment multiplexed display and I thought it would look great in a custom digital clock or something similar. While it has the model number FUTABA 13-MT-54NA, I could not find any information on the
VFD Filament Driver Using 555 Read More »
