Resistor Substitution Box



When you are designing analog circuits, you may find that you are always running to the parts bin for random resistors. It gets tiresome. And when you are biasing transistors, you would rather just wire it up and adjust for quiescent current than do all math first. It gets the job done faster. I found myself at this point alot lately. Solving equations for resistor values, then finding preferred values. Then picking out resistors from their bins and putting them into the breadboard. Take them out, replace with nearest value plus or minus. It was slowing me down, and a real inspiration killer. So I decided I should build a resistor substitution box.

Micro Professor Clone - Intro

 

About a year ago amongst the many puzzles and board games at a local thrift store I found an original Micro Professor MPF-1B for a measly $10. I vaguely remembered them from years and years ago, but I didn't recall what exactly it was. Finding a Z80 CPU on board, a hex keypad, six 7-segment LED displays and a button overlay that had writing on it vaguely reminiscent of BASIC, I was sure that this was a computer (in the original sense). I immediately bought it, fearing someone else might know what goldmine I had in my hands, and try to take it from me. Once I got it home and fired it up I instantly realized what potential this computer had. I had been looking to get into some assembly programming, and this was perfect for the job.

After running some simple programs on it (hand assembled Z80) and getting acquainted with the hardware I figured why not just make my own version of the MPF that is smaller, battery powered, portable and uses only SMD parts and can run the original monitor/BASIC program. What a hell of an idea.

eZ430-F2013 Spy Bi-Wire Breakout Connector

I have been working with the MSP430 for some time now, and just recently started working on the new Code Composer Studio v4 (I don't care too much for IAR). I received my eZ430-F2013 a while ago when Texas Instruments offered me a coupon code in my email. Surprisingly I didn't pay shipping, and when a co-worker tried the same code he had to pay $15 for shipping (needless to say he didn't get it. I told him it was a 'free' USB dev tool).

The first thing I did when I received my eZ430 was solder on some header pins to the target board. This target board has the F2013, but you can get packs of 3 F2012's for $10 from TI. To allow the pins to come out of the case I used my soldering iron (not a good idea!) to melt away the plastic. So now I can have the USB stick all closed up, but still have the F2013 connected to my circuit and the programmer/debugger at the same time. And to connect it to my circuit/breadboard I made a connecting cable from a ribbon cable laying around and some 14-pin IDC sockets.

Bluetooth NES Game Pad Headset

I have neglected my blog for a while, whilst still doing my projects and schoolwork; so I have alot to get caught up with (hopefully I can remember what I did!).

Over 3 years ago I wanted to make an NES controller into a cellular phone. My idea was more ambitious then my skills at the time, to say the least. And also, at that time I only had a Radioshack pencil soldering iron to use (that couldn't wet up, except in one tiny spot. It was horrible). So when I stumbled upon a cheap (~$18) Motorola bluetooth headset, my idea changed. Although there was some SMT soldering involved, it was much less work than wiring up the keypad of a cellphone. I couldn't find many examples on the internets of this being done except for the banana headset, and the payphone headset.

Edit: I just found this blog of an NES BT, but at the time I wasn't aware of it (just found it for completeness sake.)