Archive for January 2014

Simple hFE Adapter For Cheap DMMs

Getting a rough measurement of the transistor hFE’s is useful when designing analog circuits. Unfortunately, only the lower end DMMs nowadays offer such functionality as it is becoming less and less useful to measure transistor hFEs in a world that is dominated by digital circuitry. Also hFE varies in different biasing situations and the hFE measurements on these cheap DMMs are typically done with a fixed base current (approximately 10 µA) in DC mode. But even with these limitations, hFE measurements can still be quite useful. Continue reading ‘Simple hFE Adapter For Cheap DMMs’ »

LM92 Library for Arduino

LM92 is a 12-bit + sign temperature sensor from Texas Instruments. This sensor operates on the I2C interface and can achieve an accuracy as high as ± 0.33 °C within the typical temperature measurement range. I created a comprehensive Arduino library for this sensor (the library can be downloaded towards the end) and in this post I will explain each of the functions in detail. Continue reading ‘LM92 Library for Arduino’ »

A Simple Serial Protocol

We can send and receive commands wirelessly with Arduino by using these cheap RF data link transmitters/receivers. I like these RF modules because they can be hooked up to pretty much any device that supports serial communications (e.g. devices equipped with either hardware or software UART). Continue reading ‘A Simple Serial Protocol’ »

Peltier Cooler Module Repair

I bought a couple of Peltier cooler modules on eBay a while ago for some experiments. Of course, as I expected the quality of those cheap modules were pretty poor. After a couple of hours of continuous operation, both modules failed. So I decided to take a look to see if they could be repaired. Continue reading ‘Peltier Cooler Module Repair’ »