Archive for the ‘Electronics’ Category.
This topic is nothing new and there are already quite a few good articles on the web on this. But I thought I would try to provide a more comprehensive view on this issue and give a few concrete examples on how to filter out the electrical noise from motors in your circuits. Continue reading ‘A Short Guide On Motor Electrical Noise Reduction’ »
Last week, I received two of the demo boards from Renesas. One is a YRPBRL78G13 and the other is a RPBRX62N. The RL78/G13 promotional board features a 64 pin R5F100LEA 16-bit microcontroller, which has 64K flash ROM, 4K data flash and 4K RAM. The RX62N contains a R5F562N8BDFP 32-bit microcontroller, which has 512K ROM, 32K data flash and 96K RAM Continue reading ‘My Renesas Demo Boards Arrived’ »
I have built quite a few (1,2,3) temperature measurement circuits in the past, but none of those has remote sensing capability. So I decided to make a wireless temperature sensor so that temperature measurements can be made anywhere within the range of the transmitter and the receiver. Continue reading ‘Building a Wireless Temperature Sensor’ »
I received my STM32F4-Discovery evaluation board last week. So I setup the required development environments and did a quick test. Continue reading ‘STM32F4-Discovery Board’ »
Last time I showed a simple circuit that can be used to measure unknown thermistor parameters. The circuit is basically just a power MOSFET using a voltage and duty cycle controlled PWM signal to drive the gate and thus generates a temperature reference which is measured by both the unknown thermistor and the precision temperature sensor LM335. By measuring the voltage drop across the thermistor at different temperatures, we can obtain the R-T curve of the thermistor and thus estimate the parameters that define the R-T curve using some known models. Continue reading ‘Thermistor Parameter Measurement — II’ »
Over the years, I have gathered quite a few NTC and PTC thermistors. But most of them are unmarked so it would be difficult to use them in an accurate way without knowing the parameters. So I decided to build a simple circuit that can be used to trace the temperature-resistance curve, and the parameters can then be estimated using the measured data points. Continue reading ‘Thermistor Parameter Measurement — I’ »
Typically a synchronous camera flash (e.g. slave flash) is triggered via an SCR. In this blog post, I will show you a circuit that can be used to trigger a secondary camera flash using an IGBT. Continue reading ‘Synchronous Camera Flash Trigger Using IGBT’ »
Many of the modern chips such as MEMS accelerometers and gyroscopes only come in surface mount versions and many of them come in fine pitch LGA or QFN packaging. This has created a significant challenge for people who just wanted to experiment with these components. The standard soldering technique for LGA/QFN chips is reflow soldering which requires special equipment such as reflow oven and hot air rework station. Special surface mount prototyping PCBs are also needed and these PCBs, depending on the size and complexity can be quite expensive and sometimes are pricier than the components themselves. Continue reading ‘Hand Soldering Fine Pitch LGA Chip’ »
The drive circuits for Unipolar stepper motors are usually very simple. In its simplest form, a transistor or MOSFET is used to drive each section of the windings. With this design, the control signal must be supplied programmatically to the four windings of the unipolar stepper motor via an MCU. Continue reading ‘A Unipolar Stepper Motor Driver’ »
Just because you are using a true RMS multimeter does not automatically mean you should always trust the readings of your measurements. In fact, most true RMS multimeters can only offer reliable readings under certain conditions. In this post, I will examine some of the pitfalls in RMS voltage measurements and show you some concrete examples on how RMS readings can sometimes be misleading. Continue reading ‘On RMS Voltage Measurement’ »
Most of the multimeters do not offer resistance measurement in the milliohm range. In most meters a typically Ohm range has an accuracy of 0.1 ohm and is too coarse for measuring small resistance. Of course, some of the high-end multimeters have milliohm range and there are also dedicated micro ohmmeters for even more accurate small resistance measurements, but most of them are priced way out of the range for personal use. Continue reading ‘Accurate Milliohm Measurement’ »
One of my computers has been unstable for quite some time now. It had been crashing and freezing up once a while in the past, but it has become noticeably worse in recent months and sometimes the computer would crash just minutes after boot up. Continue reading ‘Video Card Capacitor Failure’ »
One of my RSA SecureID tokens had recently expired, so I decided to do a teardown to see what is inside. While there was one such teardowns posted on EETimes a few years ago, I thought it would still be worthwhile to take it apart myself. Continue reading ‘RSA SecureID Teardown’ »
The other day, I needed to measure the AC current of my water heater without having to disconnect the wiring. Typically, you would need a clamp meter to do this. Since I don’t have a clamp meter, I thought I would just make a simple current transformer myself. Continue reading ‘Simple Current Transformer’ »
I have built some circuits that interface with computer USB ports. On several occasions, I had built the circuits but for whatever reason they did not seem to work. Since most USB firmware is rather complex in nature, it is usually useful to first identify whether the issue at hand is related to hardware or software. Continue reading ‘Troubleshooting USB Circuit’ »