UptownMaker

A friend was asking after a circuit for making pulses from a pushbutton on push and release. Two ways immediately suggest themselves- using a PIC and using a differentiator. The PIC is easy for me, at least- I have a small stock of 12F683s which are 8-pin devices. Add a bypass cap and you're in business- you could even reprogram it to change the delay, debounce the input, etc. Of course, not everyone has a PIC programmer, and I feel like it's a pretty trivial app for a PIC, so I'll not talk much more about it. The differentiator circuit is a little more involved. Apologies for the crappiness of the image- LTSpice doesn't generate great output images, for one, and this was part of a larger image (it started NPN based, and generated negative going pulses; that's where Q3, Q4, etc etc went). V3 is the switch- in the application, it should be a 100-ohm pull-up to 5V and a switch that yanks C2 to ground when it's closed. R4 pulls up the base of Q3 and Q4, keeping the...

For those in the electronics world, SPICE simulation can be a great way to answer the "will my circuit work as advertised" question without breadboarding. It's a great sanity check- if it don't work in SPICE, it won't* work on a breadboard. LTSpice is Linear Technologies' own incarnation of SPICE. It's a nice little product, and comes with models for many of Linear's products (power supplies, op-amps, etc) along with many supporting components from other manufacturers (diodes, transistors, capacitors, inductors, etc) and generic parts (555s, LEDs, etc). Obviously, they provide it expecting people to download it, sim up a solution involving Linear parts and then sell eleventy-billion a year, thus providing a nice income stream for Linear (and it works- LTSpice makes it much more likely that I'll reach for a Linear part for power supply design than another manufacturer's parts). But for the tinkerer, it means that there's a free, very po...

A few weeks ago, I purchased 10 Atmega328P's from Mouser , naively thinking it would be easy enough to get them working on a breadboard as an Arduino sans the fancy (expensive) board. I was planning to use an FTDI USB to TTL serial data cable to bootload (I bought a 5V one, then realized that the two 3.3V ones I already had would work fine- lesson one of this saga). I also bought a some 16MHz crystals and the appropriate capacitors. At this point, I want to extend my thanks to whomever it was that decided a 6-pin AVRISP compatible ICSP header would be a value-add to the Arduino. I know that 95% of the Arduino users out there will NEVER use it, but I am very grateful. So, first hurdle- I figure I'll take one of the 328s and upgrade my Arduino (it was one of the, what, six? Duemilanove's that shipped with a 168 from the factory). Supposedly, the Arduino IDE has the capability of loading the bootloader onto a blank chip through an AVRISP, but I'll be buggered if I co...