Mutchus

This is a simple Audio Millivoltmeter Circuit Diagram . An audio millivoltmeter that's easy to build, accurate and extends to beyond 100kHz. This Audio Millivoltmeter circuit has a flat response from 8Hz to 50 kHz at -3 db on tbe 10-mV range. The upper limit remains the same on tbe less sensitive ranges, but the lower frequency limit covers under 1 Hz. An Audio Millivoltmeter Circuit Diagram

In most cases where you want to control an AC load, a triac or SCRs will be used. However, it is not easy to drive a triac or SCR. The drive requirement for the triac or SCR makes it sometimes difficult to control it as we want. One thing is that we can not turn the triac or SCR on or off as we desire, because once we turn it on, it latches and stays on until the next zero crossing or until current stops flowing through it. Also, driving a triac with reference to MT1 (or A1) is not as straightforward as we would want. However, a MOSFET can be controlled as we want. Set the gate high (with a sufficient voltage) and current can flow from drain to source. Set the gate low and current can no longer flow. Convenient! However, a MOSFET can only be used to control DC loads since it is a unidirectional switch - current flow can be controlled when it is flowing from drain to source, but can not be controlled from source to drain. So, certainly it can not be used to control AC loads. Right? Well...

About a year ago I came across an interesting article in Make Magazine about a guy who took his Fossil Wrist PDA and installed an Apple II emulator on it.   He was able to load many of the Apple II software titles and run them at regular speed.   The thought of having a fully functioning Apple computer on my wrist excited me enough to give it a try.      People that are attempting to do this should be familiar with the Palm OS as well as using jot or Graffiti 2 as an input method.   The Fossil Wrist PDA (now discontinued) features a tiny gray 160×160 pixel screen, the same number of pixels as most palm devices up to Palm III, with 16 shades of gray. The watch runs Palm OS 4.1 with its 66MHz processor and has a tiny stylus hidden in the watch clasp. It is able to carry out most PDA functions, and run any normal Palm OS-compatible application (up to 4.1). It features 8 Mb of RAM (about 7.7 Mb available to user) and 4 Mb of flash memory. Like other Palm OS de...

Welcome to the never ending saga of Andy and his reflow controllers. About a year ago I published a project writeup showing how I built a PID-based reflow controller. It featured a 640×360 graphical LCD from the Sony U5 Vivaz mobile phone and was all-surface mount. It worked well and continues to serve me well to this day but I always thought that there were improvements that I could make in several areas. Firstly, there’s no reason why it should have been all surface-mount. The LCD in particular has a 0.4mm connector that many people will find very hard to solder by hand. After all, presumably you’re building a reflow controller to help solve that very problem. Chicken and egg. [ ]